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Journal Cover Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
  [SJR: 0.717]   [H-I: 80]   [17 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1386-1425
   Published by Elsevier Homepage  [3040 journals]
  • Biomarkers of cigarette smoking and DNA methylating agents: Raman, SERS
           and DFT study of 3-methyladenine and 7-methyladenine
    • Authors: Scott G. Harroun; Yaoting Zhang; Tzu-Heng Chen; Ching-Rong Ku; Huan-Tsung Chang
      Pages: 1 - 7
      Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Scott G. Harroun, Yaoting Zhang, Tzu-Heng Chen, Ching-Rong Ku, Huan-Tsung Chang
      3-Methyladenine and 7-methyladenine are biomarkers of DNA damage from exposure to methylating agents. For example, the concentration of 3-methyladenine increases significantly in the urine of cigarette smokers. Surface-enhanced Raman spectroscopy (SERS) has shown much potential for detection of biomolecules, including DNA. Much work has been dedicated to the canonical nucleobases, with comparatively fewer investigations of modified DNA and modified DNA nucleobases. Herein, Raman spectroscopy and SERS are used to examine the adsorption orientations of 3-methyladenine and 7-methyladenine on Ag nanoparticles. Density functional theory (DFT) calculations at the B3LYP level are used to support the conclusions via simulated spectra of the nucleobases and of Ag+/nucleobase complexes. The results herein show that 7-methyladenine adsorbs upright via its N3 and N9 atoms side, similarly to adenine. 3-Methyladenine adsorbs in a very tilted or flat orientation on the Ag nanoparticles. These findings will be useful for future SERS or other nanoparticle-based bioanalytical assays for detection of these methyladenines or other modified nucleobases.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.012
      Issue No: Vol. 176 (2017)
       
  • Understanding the conformational changes and molecular structure of furoyl
           thioureas upon substitution
    • Authors: Raúl Ramos Cairo; Ana María Plutín Stevens; Tamires Donizeth de Oliveira; Alzir A. Batista; Eduardo E. Castellano; Julio Duque; Delia B. Soria; Adolfo C. Fantoni; Rodrigo S. Corrêa; Mauricio F. Erben
      Pages: 8 - 17
      Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Raúl Ramos Cairo, Ana María Plutín Stevens, Tamires Donizeth de Oliveira, Alzir A. Batista, Eduardo E. Castellano, Julio Duque, Delia B. Soria, Adolfo C. Fantoni, Rodrigo S. Corrêa, Mauricio F. Erben
      1-Acyl thioureas [R1C(O)NHC(S)NR2R3] are shown to display conformational flexibility depending on the degree of substitution at the nitrogen atom. The conformational landscape and structural features for two closely related thioureas having R1 =2-furoyl have been studied. The un-substituted 2-furoyl thiourea (I) and its dimethyl analogue, i.e. 1-(2-furoyl)-3,3-dimethyl thiourea (II), have been synthesized and fully characterized by spectroscopic (FT-IR, 1H and 13C NMR) and elemental analysis. According to single crystal X-ray diffraction analysis, compounds I and II crystallize in the monoclinic space group P21/c. In the compound I, the trans–cis geometry of the almost planar thiourea unit is stabilized by intramolecular NH⋯OC hydrogen bond between the H atom of the cis thioamide and the carbonyl O atom. In compound II, however, the acyl thiourea group is non-planar, in good agreement with the potential energy curve computed at the B3LYP/6-31+G(d,p) level of approximation. Centrosymmetric dimers generated by intermolecular NH⋯SC hydrogen bond forming R2 2(8) motif are present in the crystals. Intermolecular interactions have been rationalized in terms of topological partitions of the electron distributions and Hirshfeld surface analysis, which showed the occurrence of S⋯H, O⋯H and H⋯H contacts that display an important role to crystal packing stabilization of both thiourea derivatives.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.038
      Issue No: Vol. 176 (2017)
       
  • Spectroscopic investigation of some building blocks of organic conductors:
           A comparative study
    • Authors: V. Mukherjee; T. Yadav
      Pages: 18 - 29
      Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): V. Mukherjee, T. Yadav
      Theoretical molecular structures and IR and Raman spectra of di and tetra methyl substituted tetrathiafulvalene and tetraselenafulvalene molecules have been studied. These molecules belong to the organic conductor family and are immensely used as building blocks of several organic conducting devices. The Hartree-Fock and density functional theory with exchange functional B3LYP have been employed for computational purpose. We have also performed normal coordinate analysis to scale the theoretical frequencies and to calculate potential energy distributions for the conspicuous assignments. The exciting frequency and temperature dependent Raman spectra have also presented. Optimization results reveal that the sulphur derivatives possess boat shape while selenium derivatives possess planner structures. Natural bond orbitals analysis has also been performed to study second order interaction between donors and acceptors and to compute molecular orbital occupancy and energy.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.037
      Issue No: Vol. 176 (2017)
       
  • Qualitative and quantitative changes in phospholipids and proteins
           investigated by spectroscopic techniques in animal depression model
    • Authors: J. Depciuch; M. Sowa-Kucma; G. Nowak; M. Papp; P. Gruca; P. Misztak; M. Parlinska-Wojtan
      Pages: 30 - 37
      Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): J. Depciuch, M. Sowa-Kucma, G. Nowak, M. Papp, P. Gruca, P. Misztak, M. Parlinska-Wojtan
      Depression becomes nowadays a high mortality civilization disease with one of the major causes being chronic stress. Raman, Fourier Transform Infra Red (FTIR) and Ultraviolet-Visible (UV–vis) spectroscopies were used to determine the changes in the quantity and structure of phospholipids and proteins in the blood serum of rats subjected to chronic mild stress, which is a common animal depression model. Moreover, the efficiency of the imipramine treatment was evaluated. It was found that chronic mild stress not only damages the structure of the phospholipids and proteins, but also decreases their level in the blood serum. A 5weeks imipramine treatment did increase slightly the quantity of proteins, leaving the damaged phospholipids unchanged. Structural information from phospholipids and proteins was obtained by UV–vis spectroscopy combined with the second derivative of the FTIR spectra. Indeed, the structure of proteins in blood serum of stressed rats was normalized after imipramine therapy, while the impaired structure of phospholipids remained unaffected. These findings strongly suggest that the depression factor, which is chronic mild stress, may induce permanent (irreversible) damages into the phospholipid structure identified as shortened carbon chains. This study shows a possible new application of spectroscopic techniques in the diagnosis and therapy monitoring of depression.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.007
      Issue No: Vol. 176 (2017)
       
  • A highly selective chromogenic sensor for Mn2+, turn-off fluorometric for
           Hg2+ ion, and turn-on fluorogenic sensor for F− ion with the practical
           application
    • Authors: Neha Gupta; Divya Singhal; Ashok Kumar Singh; Neetu Singh; U.P. Singh
      Pages: 38 - 46
      Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Neha Gupta, Divya Singhal, Ashok Kumar Singh, Neetu Singh, U.P. Singh
      A colorimetric and fluorometric probe (E)-2-((8-hydroxy-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)methylene)hydrazinecarbothioamide based on thiosemicarbazide and julolidine moieties has been synthesised in pure crystalline form and characterized by 1H NMR, UV–vis, elemental analysis and single crystal XRD. The probe functioned as multitarget ion sensor, detect biologically important metal ions Hg2+ and Mn2+ in dual channel mode. Meanwhile, in mixed solvent media DMF/H2O [8:2], probe displayed selectivity for Hg2+ over other cations by the emission spectrum. Interestingly probe has been explored to recognize F− anion in DMF through ESIPT mechanism. The 1:1 binding stoichiometry of probe with Hg2+ and Mn2+ is confirmed by Job's plot through emission titration and UV–vis titration respectively. Probe is selective and sensitive to Hg2+ and Mn2+ with detection limit as low as 15μM and 0.2μM respectively. The sensing mechanism for selective ions was also scrutinized using 1H NMR experiments and computational studies.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2017.01.007
      Issue No: Vol. 176 (2017)
       
  • Ultrasensitive photoacoustic sensor based on quantum cascade laser
           spectroscopy
    • Authors: Deepak Kumar; Surya Gautam; Subodh Kumar; Saurabh Gupta; Hari B. Srivastava; Surya N. Thakur; Ramesh C. Sharma
      Pages: 47 - 51
      Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Deepak Kumar, Surya Gautam, Subodh Kumar, Saurabh Gupta, Hari B. Srivastava, Surya N. Thakur, Ramesh C. Sharma
      The paper focuses on development of ultra-sonic detection system based on laser photoacoustic spectroscopic technique and processing of signal for detection of very low quantity chemicals, explosive materials, and mixtures of these hazardous molecules. The detection system has been developed for the first time with specially designed one side open photo-acoustic cell having high quality factor. Explosive and Hazardous materials like RDX, DNT, PETN, Gun Powder, TATP (Tri acetone tri-peroxide) and their simulants like Acetone were detected in 7 to 9μm wavelength band. Lock in amplifier electronic instrument was used for the detection of hazardous chemicals and mixture of explosives in very low quantity. Detection limit of the photoacoustic ultrasonic sensor was also carried out of powder, liquid and adsorbed on surfaces.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.11.036
      Issue No: Vol. 176 (2017)
       
  • Fabrication of TiO2/ZnS nanocomposites for solar energy mediated
           photocatalytic application
    • Authors: P. Prasannalakshmi; N. Shanmugam
      Pages: 1 - 10
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): P. Prasannalakshmi, N. Shanmugam
      In the present work, we demonstrate the photocatalytic properties of nanosized TiO2, and different levels of ZnS-loaded TiO2/ZnS composites, for the degradation of the organic dyes brilliant green (BG), and methylene blue (MB) under solar light irradiation. For this process, TiO2 and the composites were synthesized by a sol-gel method. Further, the prepared products were subjected to structural, optical, and morphological characterizations. The results of the photocatalytic activity imply that for the samples studied, TiO2 loaded with an optimum level of zinc (0.25M), and sulfur (0.5M) is better able to actively degrade both BG and MB, due to its enhanced BET surface area, reduced band gap, and low charge transfer resistance.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.018
      Issue No: Vol. 175 (2017)
       
  • A facile label-free G-quadruplex based fluorescent aptasensor method for
           rapid detection of ATP
    • Authors: Haisheng Liu; Changbei Ma; Feng Ning; Hanchun Chen; Hailun He; Kemin Wang; Jun Wang
      Pages: 164 - 167
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Haisheng Liu, Changbei Ma, Feng Ning, Hanchun Chen, Hailun He, Kemin Wang, Jun Wang
      The present work demonstrates a simple, rapid and label-free ATP detection method using a fluorescent aptasensor that is based on G-quadruplex formation. In the absence of ATP, the Thioflavin T (ThT) dye binds to the G-rich ATP aptamer and forms an ATP aptamer/ThT G-quadruplex complex, which results in high fluorescence intensity. Upon addition of ATP, the ATP aptamer/ThT complex will be replaced by the formation of an ATP aptamer/ATP complex. During this process, separation of the ThT dye from the ATP aptamer/ThT complex decreases the fluorescence intensity of the reaction mixture dramatically. This fluorescence aptasensor is highly sensitive and rapid, with a detection limit of 18nM and a total reaction time of only 10min. Furthermore, this method is cost-effective and simple, removing the requirement for labeling the detection reagents with a fluorophore-quencher pair.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.033
      Issue No: Vol. 175 (2017)
       
  • Polycyclic aromatic hydrocarbons connected with Schiff base linkers:
           Experimental and theoretical photophysical characterization and
           electrochemical properties
    • Authors: Danuta Sęk; Mariola Siwy; Jan Grzegorz Małecki; Sonia Kotowicz; Sylwia Golba; Elżbieta M. Nowak; Jerzy Sanetra; Ewa Schab-Balcerzak
      Pages: 168 - 176
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Danuta Sęk, Mariola Siwy, Jan Grzegorz Małecki, Sonia Kotowicz, Sylwia Golba, Elżbieta M. Nowak, Jerzy Sanetra, Ewa Schab-Balcerzak
      A series of polyaromatic hydrocarbons with anthracene, phenanthrene and pyrene units connected with Schiff base junctions were synthesized via condensation of p-phenylenediamine and hydrazine with selected aldehydes. The effect of both hydrocarbon structures and presence of N-N- or phenyl- linked diimines on properties of the prepared azines and azomethines was analyzed. The obtained compounds were soluble in common organic solvents and melted in the range of 226–317°C. Their photophysical and electrochemical properties were investigated by UV–vis, photoluminescence spectroscopies and cyclic voltammetry (CV), respectively. Moreover, a density functional theory (DFT) was applied for calculation of their electronic and geometric structures as well as absorption and emission spectra. Additionally, their electron acceptor activity was preliminary tested in photovoltaic experiment.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.029
      Issue No: Vol. 175 (2017)
       
  • Synthesis and photophysical properties of halogenated derivatives of
           (dibenzoylmethanato)boron difluoride
    • Authors: Yuriy N. Kononevich; Nikolay M. Surin; Viacheslav A. Sazhnikov; Evgeniya A. Svidchenko; Vladimir M. Aristarkhov; Andrei A. Safonov; Alexander A. Bagaturyants; Mikhail V. Alfimov; Aziz M. Muzafarov
      Pages: 177 - 184
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Yuriy N. Kononevich, Nikolay M. Surin, Viacheslav A. Sazhnikov, Evgeniya A. Svidchenko, Vladimir M. Aristarkhov, Andrei A. Safonov, Alexander A. Bagaturyants, Mikhail V. Alfimov, Aziz M. Muzafarov
      A series of (dibenzoylmethanato)boron difluoride (BF2DBM) derivatives with a halogen atom in one of the phenyl rings at the para-position were synthesized and used to elucidate the effects of changing the attached halogen atom on the photophysical properties of BF2DBM. The room-temperature absorption and fluorescence maxima of fluoro-, chloro-, bromo- and iodo-substituted derivatives of BF2DBM in THF are red-shifted by about 2–10nm relative to the corresponding peaks of the parent BF2DBM. The fluorescence quantum yields of the halogenated BF2DBMs (except the iodinated derivative) are larger than that of the unsubstituted BF2DBM. All the synthesized compounds are able to form fluorescent exciplexes with benzene and toluene (emission maxima at λem =433 and 445nm, respectively). The conformational structure and electronic spectral properties of halogenated BF2DBMs have been modeled by DFT/TDDFT calculations at the PBE0/SVP level of theory. The structure and fluorescence spectra of exciplexes were calculated using the CIS method with empirical dispersion correction.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.025
      Issue No: Vol. 175 (2017)
       
  • Fluorescent fingerprints of edible oils and biodiesel by means total
           synchronous fluorescence and Tucker3 modeling
    • Authors: Matías Insausti; Adriano de Araújo Gomes; José Manuel Camiña; Mario Cesar Ugulino de Araújo; Beatriz Susana Fernández Band
      Pages: 185 - 190
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Matías Insausti, Adriano de Araújo Gomes, José Manuel Camiña, Mario Cesar Ugulino de Araújo, Beatriz Susana Fernández Band
      The present work proposes the use of total synchronous fluorescence spectroscopy (TSFS) as a discrimination methodology for fluorescent compounds in edible oils, which are preserved after the transesterification processes in the biodiesel production. In the same way, a similar study is presented to identify fluorophores that do not change in expired vegetal oils, to associate physicochemical parameters to fluorescent measures, as contribution to a fingerprint for increasing the chemical knowledge of these products. The fluorescent fingerprints were obtained by Tucker3 decomposition of a three-way array of the total synchronous fluorescence matrices. This chemometric method presents the ability for modeling non-bilinear data, as Total Synchronous Fluorescence Spectra data, and consists in the decomposition of the three way data arrays (samples × Δλ × λ excitation), into four new data matrices: A (scores), B (profile in Δλ mode), C (profile in spectra mode) and G (relationships between A, B and C). In this study, 50 samples of oil from soybean, corn and sunflower seeds before and after its expiration time, as well as 50 biodiesel samples obtained by transesterification of the same oils were measured by TSFS. This study represents an immediate application of chemical fingerprint for the discrimination of non-expired and expired edible oils and biodiesel. This method does not require the use of reagents or laborious procedures for the chemical characterization of samples.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.027
      Issue No: Vol. 175 (2017)
       
  • Environment sensitive fluorescent analogue of biologically active oxazoles
           differentially recognizes human serum albumin and bovine serum albumin:
           Photophysical and molecular modeling studies
    • Authors: Jyotirmay Maiti; Suman Biswas; Ankur Chaudhuri; Sandipan Chakraborty; Sibani Chakraborty; Ranjan Das
      Pages: 191 - 199
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Jyotirmay Maiti, Suman Biswas, Ankur Chaudhuri, Sandipan Chakraborty, Sibani Chakraborty, Ranjan Das
      An environment sensitive fluorophore, 4-(5-(4-(dimethylamino)phenyl)oxazol-2-yl)benzoic acid (DMOBA), that closely mimics biologically active 2,5-disubstituited oxazoles has been designed to probe two homologous serum proteins, human serum albumin (HSA) and bovine serum albumin (BSA) by means of photophysical and molecular modeling studies. This fluorescent analogue exhibits solvent polarity sensitive fluorescence due to an intramolecular charge transfer in the excited state. In comparison to water, the steady state emission spectra of DMOBA in BSA is characterized by a greater blue shift (~10nm) and smaller Stokes' shift (~5980cm−1) in BSA than HSA (Stokes'shift~6600cm−1), indicating less polar and more hydrophobic environment of the dye in the former than the latter. The dye-protein binding interactions are remarkably stronger for BSA than HSA which is evident from higher value of the association constant for the DMOBA-BSA complex (Ka ~5.2×106 M−1) than the DMOBA-HSA complex (Ka ~1.0×106 M−1). Fӧrster resonance energy transfer studies revealed remarkably less efficient energy transfer (8%) between the donor tryptophans in BSA and the acceptor DMOBA dye than that (30%) between the single tryptophan moiety in HSA and the dye, which is consistent with a much larger distance between the donor (tryptophan)-acceptor (dye) pair in BSA (34.5Å) than HSA (25.4Å). Site specific competitive binding assays have confirmed on the location of the dye in Sudlow's site II of BSA and in Sudlow's site I of HSA, respectively. Molecular modeling studies have shown that the fluorescent analogue is tightly packed in the binding site of BSA due to strong steric complementarity, where, binding of DMOBA to BSA is primarily dictated by the van der Waals and hydrogen bonding interactions. In contrast, in HSA the steric complementarity is less significant and binding is primarily guided by polar interactions and van der Waals interactions appear to be less significant in the formation of the HSA-DMOBA complex. Electrostatic interactions contribute significantly in the binding of DMOBA to HSA (−2.09kcal/mol) compared to BSA (−0.47kcal/mol). Electrostatic surface potential calculation reveals that the DMOBA binding site within HSA is highly charged compared to BSA.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.032
      Issue No: Vol. 175 (2017)
       
  • Thermal and optical characterization of biologically synthesized ZnS
           nanoparticles synthesized from an endophytic fungus Aspergillus flavus: A
           colorimetric probe in metal detection
    • Authors: Priyanka Uddandarao; Raj Mohan Balakrishnan
      Pages: 200 - 207
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Priyanka Uddandarao, Raj Mohan Balakrishnan
      Nanostructured semiconductor materials are of great importance for several technological applications due to their optical and thermal properties. The design and fabrication of metal sulfide nanoparticles with tunable properties for advanced applications have drawn a great deal of attention in the field of nanotechnology. ZnS is a potential II–IV group material which is used in hetero-junction solar cells, light emitting diodes, optoelectronic devices, electro luminescent devices and photovoltaic cells. Due to their multiple applications, there is a need to elucidate their thermal and optical properties. In the present study, thermal and optical properties of biologically synthesized ZnS nanoparticles are determined in detail with Thermal Gravimetric Analysis (TGA), Derivative Thermogravimetric Analysis (DTG), Differential Scanning Calorimeter (DSC), Diffuse Reflectance Spectroscopy (DRS), Photoluminescence (PL) and Raman spectroscopy. The results reveal that ZnS NPs exhibit a very strong quantum confinement with a significant increase in their optical band gap energy. These biologically synthesized ZnS NPs contain protein residues that can selectively bind with metal ions in aqueous solutions and can exhibit an aggregation-induced color change. This phenomenon is utilized to quantitatively measure the metal concentrations of Cu2+ and Mn2+ in this study. Further the stability of nanoparticles for the metal sensing process is accessed by UV–Vis spectrometer, zeta potential and cyclic voltammeter. The selectivity and sensitivity of ZnS NPs indicate its potential use as a sensor for metal detection in the ecosystem.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.021
      Issue No: Vol. 175 (2017)
       
  • An excited state intramolecular proton transfer dye based fluorescence
           turn-on probe for fast detection of thiols and its applications in
           bioimaging
    • Authors: Yun Zhao; Yuanyuan Xue; Haoyang Li; Ruitao Zhu; Yuehong Ren; Qinghua Shi; Song Wang; Wei Guo
      Pages: 215 - 221
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Yun Zhao, Yuanyuan Xue, Haoyang Li, Ruitao Zhu, Yuehong Ren, Qinghua Shi, Song Wang, Wei Guo
      In this study, a new fluorescent probe 2-(2′-hydroxy-5′-N-maleimide phenyl)-benzothiazole (probe 1), was designed and synthesized by linking the excited state intramolecular proton transfer (ESIPT) fluorophore to the maleimide group for selective detection of thiols in aqueous solution. The fluorescence of probe 1 is strongly quenched by maleimide group through the photo-induced electron transfer (PET) mechanism, but after reaction with thiol, the fluorescence of ESIPT fluorophore is restored, affording a large Stokes shifts. Upon addition of cysteine (Cys), probe 1 exhibited a fast response time (complete within 30s) and a high signal-to-noise ratio (up to 23-fold). It showed a high selectivity and excellent sensitivity to thiols over other relevant biological species, with a detection limit of 3.78×10−8 M (S/N=3). Moreover, the probe was successfully applied to the imaging of thiols in living cells.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.031
      Issue No: Vol. 175 (2017)
       
  • New blue emissive conjugated small molecules with low lying HOMO energy
           levels for optoelectronic applications
    • Authors: C. Trupthi Devaiah; B. Hemavathi; T.N. Ahipa
      Pages: 222 - 228
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): C. Trupthi Devaiah, B. Hemavathi, T.N. Ahipa
      Versatile conjugated small molecules bearing cyanopyridone core (CP1–5), composed of various donor/acceptor moieties at position −4 and −6 have been designed, developed and characterized. Their solvatochromic studies were conducted and analyzed using Lippert-Mataga, Kamlet-Taft and Catalan solvent scales and interesting results were obtained. The polarizability/dipolarity of the solvent greatly influenced the spectra. The electrochemical studies were carried out using cyclic voltammetry to calculate the HOMO-LUMO energy levels. The study revealed that the synthesized conjugated small molecules possess low lying HOMO energy levels which can be exploited for application in various fields of optoelectronics.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.035
      Issue No: Vol. 175 (2017)
       
  • Highly sensitive and stable Ag@SiO2 nanocubes for label-free
           SERS-photoluminescence detection of biomolecules
    • Authors: Minh-Kha Nguyen; Wei-Nien Su; Ching-Hsiang Chen; John Rick; Bing-Joe Hwang
      Pages: 239 - 245
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Minh-Kha Nguyen, Wei-Nien Su, Ching-Hsiang Chen, John Rick, Bing-Joe Hwang
      Surface-enhanced Raman scattering (SERS) and fluorescence microscopy are a widely used biological and chemical characterization techniques. However, the peak overlapping in multiplexed experiments and rapid photobleaching of fluorescent organic dyes is still the limitations. When compared to Ag nanocubes (NCs), higher SERS sensitivities can be obtained with thin shelled silica Ag@SiO2 NCs, in contrast metal-enhanced photoluminescence (MEPL) is only found with NCs that have thicker silica shells. A ‘dual functionality’ represented by the simultaneous strengthening of SERS and MEPL signals can be achieved by mixing Ag@SiO2 NCs, with a silica shell thickness of ~1.5nm and ~4.4nm. This approach allows both the Ag@SiO2 NCs SERS and MEPL sensitivities to be maintained at ~90% after 12weeks of storage. Based on the distinguished detection of creatinine and flavin adenine dinucleotide in the mixture, the integration of SERS and MEPL together on a stable single plasmonic nanoparticle platform offers an opportunity to enhance both biomarker detection sensitivity and specificity.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.024
      Issue No: Vol. 175 (2017)
       
  • Study of the transient “free” OH radical generated in H2O-H2O2
           mixtures by stimulated Raman scattering
    • Authors: Fangfang Li; Zhiwei Ma; Shenghan Wang; Tianyu Li; Chenglin Sun; Zhanlong Li; Zhiwei Men
      Pages: 246 - 249
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Fangfang Li, Zhiwei Ma, Shenghan Wang, Tianyu Li, Chenglin Sun, Zhanlong Li, Zhiwei Men
      Forward and backward stimulated Raman scattering (SRS) were studied in the H2O2–H2O mixtures by a strong excitation laser with 532nm. Only the backward SRS (BSRS) of the H2O2-H2O system shows an unexpected SRS shoulder peak at around 3600cm−1, which is similar to the characteristic peak of “free” OH radical. The generation of the “free” OH radical is mainly attributed to the dissociation of hydrogen peroxide (HP) molecules. Simultaneously, the ionization of HP–water clusters generates a part of “free” OH radical under the Laser-induced breakdown (LIB). The interaction of water and HP is also discussed.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.026
      Issue No: Vol. 175 (2017)
       
  • Facile and controlled synthesis of aligned WO3 nanorods and nanosheets as
           an efficient photocatalyst material
    • Authors: Bilal Ahmed; Sumeet Kumar; Animesh K. Ojha; P. Donfack; A. Materny
      Pages: 250 - 261
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Bilal Ahmed, Sumeet Kumar, Animesh K. Ojha, P. Donfack, A. Materny
      In this work, we have performed a facile and controlled synthesis of WO3 nanorods and sheets in different crystal phases (triclinic, orthorhombic and monoclinic) of WO3 using the sol-gel method. The detailed structures of the synthesized materials were examined by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy measurements. The shapes and crystal phases of the WO3 nanostructures were found to be highly dependent on the calcination temperature. The variation in crystalline phases and shapes is modified the electronic structure of the samples, which causes a variation in the value of optical band gap. The value of the Raman line intensity ratio I264/I320 has been successfully used to identify the structural transition from the triclinic to the orthorhombic phase of WO3. The PL spectra of the synthesized products excited at wavelengths 380, 400, and 420nm exhibit intense emission peaks that cover the complete visible range (blue-green-red). The emission peaks at ~460 and ~486nm were caused by the near band-edge and band to band transition, respectively. The peaks in spectral range 500–600nm might be originated from the presence of oxygen vacancies lying within the energy band gap. The synthesized WO3 nanostructures showed improved photocatalytic activity for the photodegradation of MB dye. The enhanced photocatalytic activity of WO3 nanosheets compared to WO3 nanorods for photodegradation of methylene blue (MB) dye could be due to the shape of the nanostructured WO3. The sheet type of structure provides more active surface for the interaction of dye molecules compared to the rods, which results in a more efficient degradation of the dye molecules.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.11.044
      Issue No: Vol. 175 (2017)
       
  • The naphthoate-modifying Cu2+-detective Bodipy sensors with the
           fluorescent ON-OFF performance unaffected by molecular configuration
    • Authors: Yuting Chen; Luyang Zhao; Jianzhuang Jiang
      Pages: 269 - 275
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Yuting Chen, Luyang Zhao, Jianzhuang Jiang
      Two new boron-dipyrromethenes decorated with 8-hydroxyquinoline-naphthoate moiety, namely 4,4-difluoro-8-(5-(8-hydroxyquinoline-naphthoate))-3,5-dimethyl-4-bora-3a,4a-diaza-s-indacene (8-HQ-N-DMe-Bodipy) (1) and 4,4-difluoro-8-(5-(8-hydroxyquinoline-naphthoate))-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene (8-HQ-N-TMe-Bodipy) (2) have been synthesized. Single crystal X-ray diffraction analysis discloses the very much similar steric arrangement of 8-hydroxyquinoline-naphthoate moiety in these two compounds as revealed by the close torsion angle of C-C-O-C bridge, 174.15 and 171.81° for 1 and 2, respectively, despite the different dihedral angle between quinoline moiety and Bodipy fluorophore for 1 (73.46°) and 2 (82.26°) due to the steric hindrance originated from the C-1/C-7 methyl substituents on Bodipy core for the latter species. Systemic optical studies unravel the red-shifted absorption and fluorescence emission together with slightly lower quantum yield for 1 relative to that of 2, indicating the configuration effect on their spectroscopic properties. However, the binding of Cu2+ with hydroxyquinoline-naphthoate receptor in both 1 and 2 leads to similar fluorescent quenching characteristic due to the photo-induced electron transfer process on the basis of density functional theory calculations, suggesting their high sensitively fluorescent ON-OFF sensing potential to Cu2+ almost unaffected by molecular configuration.
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      PubDate: 2017-01-06T22:34:32Z
      DOI: 10.1016/j.saa.2016.12.034
      Issue No: Vol. 175 (2017)
       
  • Chemically modified amino porphyrin/TiO2 for the degradation of Acid Black
           1 under day light illumination
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Balu Krishnakumar, Avula Balakrishna, Cláudia T. Arranja, Carlos M.F. Dias, Abilio J.F.N. Sobral
      In this paper, for the first time, chemically modified 5,10,15,20-meso-tetra-(para-amino)-phenyl-porphyrin/TiO2 (TPAPP/TiO2) was prepared and used for the degradation of an azo dye Acid Black 1 (AB 1) under direct sunlight. Initially, TiO2 was prepared by sol-gel method. Before making a TPAPP/TiO2 composite, the surface modification of TiO2 was carried out with glycidoxypropyltrimethoxy silane (GPTMS) which acts as a coupling agent. This is an epoxy terminated silane and could easily bond to the amino group of TPAPP through epoxy cleavage. The formation of TPAPP/TiO2 was confirmed by different characterization techniques such as FT-IR, XRD, SEM and DRS. The photocatalytic activity of TiO2 was highly influenced by TPAPP. A mechanism was proposed for AB 1 degradation by TPAPP/TiO2 under sun light.
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      PubDate: 2017-01-15T15:44:04Z
       
  • DFT study of the molecular and crystal structure and vibrational analysis
           of cisplatin
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): I. Georgieva, N. Trendafilova, N. Dodoff, D. Kovacheva
      DFT and periodic-DFT (PAW-PBE method, code VASP) calculations have been performed to study the structural and vibrational characteristics of cis-diamminedichloroplatinum(II) (cisplatin) at molecular and outside molecular level. To estimate the effect of the intermolecular interactions in crystal on the structural and vibrational properties of cisplatin, three theoretical models are considered in the present study: monomer (isolated molecule), hydrogen bonded dimer and periodic solid state structures. The work focused on the role of the theoretical models for correct modeling and prediction of geometrical and vibrational parameters of cisplatin. It has been found that the elaborate three-dimensional intermolecular hydrogen bonding network in the crystalline cisplatin significantly influences the structural and vibrational pattern of cisplatin and therefore the isolated cisplatin molecule is not the correct computational model regardless of the theoretical level used. To account for the whole intermolecular hydrogen bonding network in direction of both a and c axis and for more reliable calculations of structural and vibrational parameters periodic DFT calculations were carried out in the full crystalline periodic environment with the known lattice parameters for each cisplatin polymorph phase. The model calculations performed both at molecular level and for the periodic structures of alpha and beta cisplatin polymorph forms revealed the decisive role of the extended theoretical model for reliable prediction of the structural and vibrational characteristics of cisplatin. The powder diffraction pattern and the calculated IR and Raman spectra predicted beta polymorph form of our cisplatin sample freshly synthesized for the purposes of the present study using the Dhara's method. The various rotamers realized in the polymorph forms of cisplatin were explained by the low population of the large number of rotamers in solution as well as with the high rotamer interconversion rate due to the low energy barrier.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Syntheses, structures and fluorescence properties of three rare-earth
           containing docosatungstates
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Hailou Li, Yajie Liu, Rui Zheng, Xing Ma, Lijuan Chen, Junwei Zhao
      Three rare-earth containing docosatungstates Na3H2[RE(H2O)4][RE(H2O)5]2[W22O74H2]·36H2O [RE=DyIII (1), HoIII (2), YIII (3)] have been synthesized by reaction of Na2WO4·2H2O, dimethylamine hydrochloride (DMAHC) and RE(NO3)3·6H2O in the aqueous solution and characterized by elemental analyses, IR spectra, thermogravimetric (TG) analysis, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. 1–3 are isomorphous and each molecular unit consists of a S-shaped docosatungstate [W22O74H2]14− polyoxoanion with two supporting [RE(H2O)5]3+ cations and one disordered [RE(H2O)4]3+ cation. The [W22O74H2]14− polyoxoanion can be viewed as combination of two hendecatungstate [W11O38H]9− subunits in the staggered fashion by sharing two μ2-O atoms. The TG curves of 1–3 reveal the one-step weight loss between 25°C to 700°C. Moreover, both 1 and 2 demonstrate the characteristic luminescence emission behaviors of the corresponding RE3+ ions and their lifetime decay curves can be well fitted to the double exponential function. In addition, the CIE chromaticity coordinates of 1 and 2 have been obtained based on their corresponding emission spectra, and their dominant wavelengths and color purities have been also calculated.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Nature of phase transitions in ammonium oxofluorovanadates, a vibrational
           spectroscopy study of (NH4)3VO2F4 and (NH4)3VOF5
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Yu.V. Gerasimova, A.S. Oreshonkov, N.M. Laptash, A.N. Vtyurin, A.S. Krylov, N.P. Shestakov, A.A. Ershov, A.G. Kocharova
      Two ammonium oxofluorovanadates, (NH4)3VO2F4 and (NH4)3VOF5, have been investigated by temperature-dependent infrared and Raman spectroscopy methods to determine the nature of phase transitions (PT) in these compounds. Dynamics of quasioctahedral groups was simulated within the framework of semi-empirical approach, which justified the cis-conformation of VO2F4 3− (C 2v ) and the C 4v geometry of VOF5 3−. The observed infrared and Raman spectra of both compounds at room temperature (RT) revealed the presence at least of two crystallographically independent octahedral groups. The first order PT at elevated temperatures is connected with a complete dynamic disordering of these groups with only single octahedral state. At lower temperatures, the octahedra are ordered and several octahedral states appear. This PT is the most pronounced in the case of (NH4)3VOF5, when at least seven independent VOF5 3− octahedra are present in the structure below 50K, in accordance with the Raman spectra. Ammonium groups do not take part in PTs at higher and room temperatures but their reorientational motion freezes at lower temperatures.
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      PubDate: 2017-01-15T15:44:04Z
       
  • A cockspur for the DSS cells: Erythrina crista-galli sensitizers
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Paula Enciso, Jean-David Decoppet, Michael Grätzel, Michael Wörner, Franco M. Cabrerizo, María Fernanda Cerdá
      Dye sensitized solar cells were assembled employing a mixture of anthocyanins extracted from red ceibo's flowers. At the literature different extraction procedures are reported to extract anthocyanins from natural products and sensitize the cells. In order to compare them, different methods were followed to set the cells under the same conditions. Assembled cells showed very interesting conversion efficiency values, reaching a 0.73% value for extracts purified using C18 column, in open cells under illumination using a solar light simulator, 1 sun, 1.5 AM. Data reported herein prove that anthocyanins obtained from ceibo's flower, after simple further purification, might represent an excellent, cheap and clean alternative for the development of DSS cells.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Microscopic solvation environments in a prototype room-temperature ionic
           liquid as elucidated by resonance Raman spectroscopy of iodine and bromine
           
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Satyen Saha, Hajime Okajima, Osamu Homma, Hiro-o Hamaguchi
      Microscopic solvation environments in a prototype ionic liquid, bmimTf2N; 1-butyl-3-methyl-imidazolium-bis(trifluoromethanesulfonyl)imide, have been studied with the use of halides, X2 and Xn − (X=I, Br; n =3,5), as molecular probes. Resonance Raman spectroscopy has been used to detect these halogen species existing in bmimTf2N as well as in reference solvents including heptane, cyclohexane, KX/H2O and benzene. In heptane and cyclohexane, only free X2 species are detected. In KX/H2O, only Xn − and, in benzene, only benzene-X2 complexes are detected. On the contrary, free X2 and Xn − are concomitantly detected in bmimTf2N, indicating that there are two distinct solvation environments in bmimTf2N, non-polar environments that solvate free X2 and polar environments that stabilize Xn −. These two distinct solvation environments are most likely to arise from microscopic structural heterogeneity of ionic liquids.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Unique optical properties of Eu3+ doped l-histidine hydrochloride mono
           hydrate single crystals from low temperature growth technique
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): K. Ramachandra Rao, S. Rajyalakshmi, Ch.Satya Kamal, B. Brahmaji, Jacek B. Jasinski, T.K. Visweswara Rao
      A low-temperature solution method was utilized to grow single crystals of Eu3+ doped l-histidine hydrochloride monohydrate. The quality of the crystals was confirmed by high-resolution X-ray diffraction measurements with full width at half maximum (FWHM) of rocking curve at 8arc per sec. The incorporation of Eu3+ ions into the lattice was confirmed by functional group analysis using Fourier Transform Infrared (FTIR) spectroscopy. The amount of Eu3+ ions was found to be 0.08 weight (%) using energy dispersive X-ray analysis. The crystal's thermal and mechanical properties were tested as well. The unique spectral properties such as UV–Vis transmittance, nonlinear optical efficiency (NLO), photoluminescence (PL) and its lifetime were measured. The PL study revealed that the intensity of 5D0 → 7F2 emission of Eu3+ is stronger than that of 5D0 → 7F1 emission and the decay measurement showed a life time of 7.2410μs. The photoluminescence results prove that l-histidine hydrochloride monohydrate is a new, highly efficient host material for europium ion red emissions.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Optical and vibrational properties of phosphorylcholine-based contact
           lenses—Experimental and theoretical investigations
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Katarzyna Filipecka, Rafał Miedziński, Maciej Sitarz, Jacek Filipecki, Małgorzata Makowska-Janusik
      The Raman, MIR and UV–vis spectroscopy have been used to characterize Omafilcon A material constructing the one of the Proclear family contact lenses. The Omafilcon A is hydrogel material composed of 2-hydroxyethyl methacrylate (HEMA) and 2-methacryloyloxyethyl phosphorylcholine (PC) polymers crosslinked with ethyleneglycol dimethacrylate (EGDMA). Vibrational and electronic properties of the Omafilcon A material were also investigated by quantum chemical calculations. Experimentally obtained Raman, MIR and optical spectra were compared to the theoretical ones calculated applying RHF and DFT methodology. The quantum chemical calculations were performed for isolated monomers of lenses compounds as well as for their dimers and trimers to elucidate the effect of Omafilcon A polymerization and the role of an individual components.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Hassle free synthesis of nanodimensional Ni, Cu and Zn sulfides for
           spectral sensing of Hg, Cd and Pb: A comparative study
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Zarina Ansari, Shib Shankar Singha, Abhijit Saha, Kamalika Sen
      A simple room temperature synthesis method of Ni, Cu and Zn sulfide nanoparticles (NPs) in aqueous medium is reported here. The NPs stabilized in aqueous medium by the citrate ions were characterized by UV–vis, ζ potentials, TEM and Raman spectroscopic techniques. The solid NPs could be isolated from the aqueous medium when allowed to stand for a prolonged time (~20h). The solids were also characterized by IR and powder X-ray analysis. The nanoparticles were further used for the development of facile optical sensing and detection of heavy metal ions at trace scale. Alterations in the absorption spectra of the generated NPs were indicative of their interactions with heavy metal ions. Raman spectral measurements further validate the detection technique. It is found that out of the three synthesized nanoparticles, nickel sulfide NP is a specific sensor for mercury ions whereas zinc sulfide and copper sulfide NPs act as sensors for Hg2+, Cd2+ and Pb2+.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Electrochemical studies of DNA interaction and antimicrobial activities of
           MnII, FeIII, CoII and NiII Schiff base tetraazamacrocyclic complexes
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Anuj Kumar, Vinod Kumar Vashistha, Prashant Tevatia, Randhir Singh
      Tetraazamacrocyclic complexes of MnII, FeIII, CoII and NiII have been synthesized by template method. These tetraazamacrocycles have been analyzed with various techniques like molar conductance, IR, UV–vis, mass spectral and cyclic voltammetric studies. On the basis of all these studies, octahedral geometry has been assigned to these tetraazamacrocyclic complexes. The DNA binding properties of these macrocyclic complexes have been investigated by electronic absorption spectra, fluorescence spectra, cyclic voltammetric and differential pulse voltammetric studies. The cyclic voltammetric data showed that i pc and i pa were effectively decreased in the presence of calf thymus DNA, which is a strong evidence for the interaction of these macrocyclic complexes with the calf thymus DNA (ct-DNA). The heterogeneous electron transfer rate constant found in the order: KCo II >KNi II >KMn II which indicates that CoII macrocyclic complex has formed a strong intercalated intermediate. The Stern-Volmer quenching constant (KSV) and voltammetric binding constant were found in the order KSV(CoII)>KSV(NiII)>KSV(MnII) and K+(CoII)>K+(NiII)>K+(MnII) which shows that CoII macrocyclic complex exhibits the high interaction affinity towards ct-DNA by the intercalation binding. Biological studies of the macrocyclic complexes compared with the standard drug like Gentamycin, have shown antibacterial activities against E. coli, P. aeruginosa, B. cereus, S. aureus and antifungal activity against C. albicans.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Synthesis, pH dependent photometric and electrochemical investigation,
           redox mechanism and biological applications of novel Schiff base and its
           metallic derivatives
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Abdur Rauf, Afzal Shah, Abdul Aziz Khan, Aamir Hassan Shah, Rashda Abbasi, Irfan Zia Qureshi, Saqib Ali
      A novel Schiff base, 1-((2, 4-dimethylphenylimino)methyl)naphthalen-2-ol abbreviated as (HL) and its four metallic complexes were synthesized and confirmed by 1H and 13C NMR, FTIR, TGA and UV–Visible spectroscopy. Schiff base was also characterized by X-ray analysis. The photometric and electrochemical responses of all the synthesized compounds were investigated in a wide pH range. Structures of the compounds were optimized computationally for the evaluation of different physico-chemical parameters. On the basis of electrochemical results the redox mechanistic pathways of the compounds were proposed. The cytotoxicity analysis on Hela cells revealed that HL and its complexes inhibit cell growth as revealed from their IC50 values (HL):106.7μM, (L2VO): 40.66μM, (L2Sn): 5.92μM, (L2Zn): 42.82 and (L2Co): 107.68μM. The compounds were tested for anti-diabetic, triglyceride, cholesterol, anti-microbial, anti-fungal and enzyme inhibition activities. The results revealed that HL and its complexes are promising new therapeutic options as these compounds exhibit strong activity against cancer cells, diabetics, fungal and microbial inhibition.
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      PubDate: 2017-01-15T15:44:04Z
       
  • On the spectroscopic analyses of 3-Hydroxy-1-Phenyl-Pyridazin-6(2H)one
           (HPHP): A comparative experimental and computational study
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): M.A.M. El-Mansy, M.S. El-Bana, S.S. Fouad
      We have systematically calculated various physical characteristics such as optimized molecular structural parameters, vibrational frequencies, HOMO-LUMO energy gap, total dipole moment and thermochemical parameters: nuclear repulsion energy, ionization energy, electron affinity, global hardness, electronic chemical potential, global electrophilicity index and finally softness (ζ) using DFT/B3LYP utilizing 6-311G(d,p) basis set for 3-Hydroxy-1-Phenyl-Pyridazin-6(2H)one (HPHP). Also, HPHP nonlinear optical (NLO) properties have been checked by DFT/B3LYP utilizing 6-311G(d,p) basis set. In addition, we have investigated the influence of exposure to UV radiation on HPHP physical properties at the same level of theory. Our results show that HPHP possesses a dipole moment (2.68Debye) and HOMO-LUMO energy gap of 3.99eV that emphasize its high applicability for manufacturing photovoltaic devices such as solar cells. After exposure to UV radiation, the HPHP dipole moment has been lowered from 2.68 to 2.3Debye due to UV radiation. Moreover, a double spin in HPHP has been observed, as electrons are aligned according to their spin state. Electrons (spin ↑) and (spin ↓) are aligned in alpha and beta levels with energy gaps 3.82 and 3.17eV, respectively. This anomalous behavior may be justified by considering that HPHP undergoes anomalous Zeeman-like effect. The presence of this phenomenon in HPHP introduces it as a modern organic semiconductor which has high applicability to be used in modern spintronics.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Non-invasive techniques for revealing the palette of the Romantic painter
           Francesco Hayez
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Laura Rampazzi, Valentina Brunello, Cristina Corti, Elena Lissoni
      This paper describes the first systematic analysis of the palette of Francesco Hayez, one of the most outstanding artists of European Romanticism, whose painting technique has never been extensively investigated despite the plethora of artistic studies. He lived in a particular moment in the history of painting, as in the first half of the 19th century many synthetic pigments were available, also in tin tubes, but traditional materials were still used. Sixteen paintings on canvas and on panels, created between 1823 and 1868, were analyzed in situ through non-invasive techniques (infrared reflectography and infrared reflection spectroscopy). Imaging investigation provided clues on painting technique, revealing some cases of pentimenti and underdrawings. A preliminary survey was carried out on a hundred pure pigments used up to the 19th century and on new synthetic colours, in order to attain reference spectra for the interpretation of painting spectra. The portable infrared instrument provided insight into Hayez's painting materials, identifying barite, ivory black, lead-tin yellow, Naples yellow, ochres, Prussian blue, and white lead. The pigments were often blended, to obtain a unique fabric appearance or to attain cold shades. The results pointed to a siccative oil as a binder, mixed with white lead so that it could act as a catalyzer in polymerization reactions, and in some cases with a proteinaceous binder and resins. The preparation was made with gypsum and white lead mixed with a siccative oil. The results showed that the artist used a typical traditional palette, throughout his career, in order to lead to brilliant colours and with long-term stability. Anyway, the possible presence of cobalt blue in a few paintings suggests that Hayez had probably started testing the new colours, since the second decade of 19th century.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Conjugated polymer with carboxylate groups-Hg2+ system as a turn-on
           fluorescence probe for label-free detection of cysteine-containing
           compounds
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Hongyu Mi, Mingming Guan, Jilin Liu, Hongyan Shan, Qiang Fei, Yanfu Huan, Guodong Feng
      In this work, a turn on fluorescent sensor, based on Hg2+ coordination conjugated polymer, was developed to detect cysteine-containing compounds. The fluorescence of conjugated polymer (poly(2,5-bis (sodium 4-oxybutyrate) -1,4 - phenylethynylene-alt-1,4-phenyleneethynylene; PPE-OBS) would be quenched by Hg2+ because of the coordination-induced aggregation and electron transfers of PPE-OBS toward Hg2+. When there were some cysteine-containing compounds in PPE-OBS-Hg2+ system, the fluorescence of PPE-OBS would be recovered. It indicated that the PPE-OBS-Hg2+ system could be used to detect cysteine-containing compounds. Under the optimized conditions, the experiment results showed that there were particularly linear range, high sensitivity and selectivity over other amino acids. The limit of detection (LOD) of cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) were 0.725μmolL−1, 0.982μmolL−1 and 1.21μmolL−1 by using this sensor. In addition, Cys standard recovery in several green tea drink and honey samples was also demonstrated. The recovery of Cys was range from 96.3 to 105.0% and RSD was less than 3.25%. The satisfactory results demonstrated that the proposed method could be as a potential fluorescent method for determining cysteine-containing compounds in real samples.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Enzyme-catalyzed Michael addition for the synthesis of warfarin and its
           determination via fluorescence quenching of l-tryptophan
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): Yusheng Yuan, Liu Yang, Shaopu Liu, Jidong Yang, Hui Zhang, Jingjing Yan, Xiaoli Hu
      A sensitive fluorescence sensor for warfarin was proposed via quenching the fluorescence of l-tryptophan due to the interaction between warfarin and l-tryptophan. Warfarin, as one of the most effective anticoagulants, was designed and synthesized via lipase from porcine pancreas (PPL) as a biocatalyst to catalyze the Michael addition of 4-hydroxycoumarin to α, β-unsaturated enones in organic medium in the presence of water. Furthermore, the spectrofluorometry was used to detect the concentration of warfarin with a linear range and detection limit (3σ/k) of 0.04–12.0μmolL−1 (R2 =0.994) and 0.01μmolL−1, respectively. Herein, this was the first application of bio-catalytic synthesis and fluorescence for the determination of warfarin. The proposed method was applied to determine warfarin of the drug in tablets with satisfactory results.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Handheld new technology Raman and portable FT-IR spectrometers as
           complementary tools for the in situ identification of organic materials in
           modern art
    • Abstract: Publication date: 5 April 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 176
      Author(s): M. Vagnini, F. Gabrieli, A. Daveri, D. Sali
      A non-invasive approach has been carried out to characterize painting materials used in modern artworks conserved in the art collection of Carandente's museum at Palazzo Collicola in Spoleto (Italy). This work is focused on the cross-validation of the handheld BRAVO Raman spectrometer, that uses a sequentially Shifted Excitation (SSE) to mitigate fluorescence, for the characterization specifically of organic materials. The analytical procedure, combining XRF, Raman and reflection infrared spectroscopy, allowed a complete characterization of the artists' palettes; particularly eight different synthetic dyes belonging to the class of pigment red (PR) and pigment yellow (PY.), synthetic and traditional binders, such as alkyd resin and lipids have been easily identified.
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      PubDate: 2017-01-15T15:44:04Z
       
  • Co-metal-organic-frameworks with pure uniform crystal morphology prepared
           via Co2+ exchange-mediated transformation from Zn-metallogels for luminol
           catalysed chemiluminescence
    • Authors: Xue Qian Tang; Bo Wen Xiao; Chun Mei Li; Dong Mei Wang; Cheng Zhi Huang; Yuan Fang Li
      Pages: 11 - 16
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Xue Qian Tang, Bo Wen Xiao, Chun Mei Li, Dong Mei Wang, Cheng Zhi Huang, Yuan Fang Li
      Cation exchange-mediated transformation from Zn-metallogels (MOGs), which was a mild facile strategy relative to the demanding hydrothermal method, was employed to develop Co2+ metal-organic frameworks (Co-MOFs) at room temperature. The obtained Co-MOFs was of uniform octahedral morphology and possessed high activity to catalyze luminol chemiluminescence without extra oxidants. By adding cysteine, the CL emission of luminol-Co-MOFs system was further enhanced. Based on this phenomenon, Co-MOFs was utilized to build a practical sensing platform for cysteine determination. Under the optimized conditions, the relative CL intensity (ΔI) was proportional to the concentration of cysteine in the range of 2–10μM, and the detection limit was 0.49μM (3S/N). Moreover, the established method was applied to the determination of cysteine in commercially available pharmaceutical injections.
      Graphical abstract image

      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.12.014
      Issue No: Vol. 175 (2016)
       
  • Near infrared spectroscopy combined with multivariate analysis for
           monitoring the ethanol precipitation process of fraction I+II+III
           supernatant in human albumin separation
    • Authors: Can Li; Fei Wang; Lixuan Zang; Hengchang Zang; Manel Alcalà; Lei Nie; Mingyu Wang; Lian Li
      Pages: 17 - 23
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Can Li, Fei Wang, Lixuan Zang, Hengchang Zang, Manel Alcalà, Lei Nie, Mingyu Wang, Lian Li
      Nowadays, as a powerful process analytical tool, near infrared spectroscopy (NIRS) has been widely applied in process monitoring. In present work, NIRS combined with multivariate analysis was used to monitor the ethanol precipitation process of fraction I+II+III (FI+II+III) supernatant in human albumin (HA) separation to achieve qualitative and quantitative monitoring at the same time and assure the product's quality. First, a qualitative model was established by using principal component analysis (PCA) with 6 of 8 normal batches samples, and evaluated by the remaining 2 normal batches and 3 abnormal batches. The results showed that the first principal component (PC1) score chart could be successfully used for fault detection and diagnosis. Then, two quantitative models were built with 6 of 8 normal batches to determine the content of the total protein (TP) and HA separately by using partial least squares regression (PLS-R) strategy, and the models were validated by 2 remaining normal batches. The determination coefficient of validation (R p 2), root mean square error of cross validation (RMSECV), root mean square error of prediction (RMSEP) and ratio of performance deviation (RPD) were 0.975, 0.501g/L, 0.465g/L and 5.57 for TP, and 0.969, 0.530g/L, 0.341g/L and 5.47 for HA, respectively. The results showed that the established models could give a rapid and accurate measurement of the content of TP and HA. The results of this study indicated that NIRS is an effective tool and could be successfully used for qualitative and quantitative monitoring the ethanol precipitation process of FI+II+III supernatant simultaneously. This research has significant reference value for assuring the quality and improving the recovery ratio of HA in industrialization scale by using NIRS.
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.12.016
      Issue No: Vol. 175 (2016)
       
  • New anthracene-based Schiff bases: Theoretical and experimental
           investigations of photophysical and electrochemical properties
    • Authors: Danuta Sek; Mariola Siwy; Marzena Grucela; Grzegorz Małecki; Elżbieta M. Nowak; Gabriela Lewinska; Jerzy Santera; Katarzyna Laba; Mieczyslaw Lapkowski; Sonia Kotowicz; Ewa Schab-Balcerzak
      Pages: 24 - 35
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Danuta Sek, Mariola Siwy, Marzena Grucela, Grzegorz Małecki, Elżbieta M. Nowak, Gabriela Lewinska, Jerzy Santera, Katarzyna Laba, Mieczyslaw Lapkowski, Sonia Kotowicz, Ewa Schab-Balcerzak
      The new Schiff bases bearing anthracene unit were synthesized from 2-aminoanthracene and various aldehydes such as: benzaldehyde, 4-(diphenylamino)benzaldehyde, 9-phenanthrenecarboxaldehyde, 9-anthracenecarboxaldehyde, and biphenyl-4-carboxaldehyde, 2-naphthaldehyde. Resulted azomethines were characterized by IR, NMR (1H and 13C), elemental analysis and UV–vis spectroscopy. The imine consists of anthracene and biphenyl moieties exhibited liquid crystal properties and their nematic phase showed Schlieren texture. The photoluminescence measurements carried out in solution and in solid state as blend with PMMA revealed the ability of the imines to emission of the blue light with quantum yield efficiency in the range of 2.18–6.03% in blend. Based on the electrochemical experiment they showed value of energy gap (Eg) in the range of 2.5–2.7eV. Additionally, density functional theory (DFT) was applied for calculations of both electronic structure and spectroscopic properties of synthesized Schiff bases. Moreover, the results obtained from preliminary tests of application of the azomethines in organic photovoltaic (OPV) devices confirmed their electron acceptor character.
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.12.013
      Issue No: Vol. 175 (2016)
       
  • Energy transfer and colour tunability in UV light induced Tm3+/Tb3+/Eu3+:
           ZnB glasses generating white light emission
    • Authors: V. Naresh; Kiran Gupta; C. Parthasaradhi Reddy; Byoung S. Ham
      Pages: 43 - 50
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): V. Naresh, Kiran Gupta, C. Parthasaradhi Reddy, Byoung S. Ham
      A promising energy transfer (Tm3+ →Tb3+ →Eu3+) approach is brought forward to generate white light emission under ultraviolet (UV) light excitation for solid state lightening. Tm3+/Tb3+/Eu3+ ions are combinedly doped in zinc borate glass system in view of understanding energy transfer process resulting in white light emission. Zinc borate (host) glass displayed optical and luminescence properties due to formation of Zn(II)x–[O(−II)]y centres in the ZnB glass matrix. At 360nm (UV) excitation, triply doped Tm3+/Tb3+/Eu3+: ZnB glasses simultaneously shown their characteristic emission bands in blue (454nm: 1D2 → 3F4), green (547nm: 5D4 → 7F5) and red (616nm: 5D0 → 7F2) regions. In triple ions doped glasses, energy transfer dynamics is discussed in terms of Forster-Dexter theory, excitation & emission profiles, lifetime curves and from partial energy level diagram of three ions. The role of Tb3+ in ET from Tm3+ →Eu3+ was discussed using branch model. From emission decay analysis, energy transfer probability (P) and efficiency (η) were evaluated. Colour tunability from blue to white on varying (Tb3+, Eu3+) content is demonstrated from Commission Internationale de L'Eclairage (CIE) chromaticity coordinates. Based on chromaticity coordinates, other colour related parameters like correlated colour temperature (CCT) and colour purity are also computed for the studied glass samples. An appropriate blending of such combination of rare earth ions could show better suitability as potential candidates in achieving multi-colour and warm/cold white light emission for white LEDs application in the field of solid state lightening.
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.12.023
      Issue No: Vol. 175 (2016)
       
  • Structural, spectroscopic and molecular docking studies on
           2-amino-3-chloro-5-trifluoromethyl pyridine: A potential bioactive agent
    • Authors: R. Mohamed Asath; R. Premkumar; T. Mathavan; A. Milton Franklin Benial
      Pages: 51 - 60
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): R. Mohamed Asath, R. Premkumar, T. Mathavan, A. Milton Franklin Benial
      The most stable, optimized structure of the 2-amino-3-chloro-5-trifluoromethyl pyridine (ACTP) molecule was predicted by the density functional theory calculations using the B3LYP method with cc-pVQZ basis set. Antitumor activity of the ACTP molecule was evaluated by molecular docking analysis. The structural parameters and vibrational wavenumbers were calculated for the optimized molecular structure. The experimental and theoretical vibrational wavenumbers were assigned and compared. Ultraviolet-visible spectrum was simulated and validated experimentally. The molecular electrostatic potential surface was simulated. Frontier molecular orbitals and related molecular properties were computed and further density of states spectrum was simulated. The natural bond orbital analysis was also performed to confirm the bioactivity of the ACTP molecule. The molecular docking analysis reveals the better inhibitory nature of the ACTP molecule against the colony-stimulating factor 1 (CSF1) gene which causes tenosynovial giant-cell tumor. Hence, the ACTP molecule can act as a potential inhibitor against tenosynovial giant-cell tumor.
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.11.037
      Issue No: Vol. 175 (2016)
       
  • Temperature assisted radiative and non-radiative recombination mechanisms
           in sillimanite (Al2SiO5) mineral
    • Authors: J.M. Kalita; G. Wary
      Pages: 61 - 66
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): J.M. Kalita, G. Wary
      Temperature assisted luminescence in sillimanite (Al2SiO5) mineral was studied using thermoluminescence (TL). TL characteristics were studied in un-annealed and different annealed samples. Analysis showed that in the un-annealed sample, there was four electron trapping sites at depths ~0.56, 0.87, 1.08, 1.32eV and a hole trapping site at depth ~3.63eV from the conduction band acting as a recombination center. Further analysis on the annealed samples showed that the 0.56eV trapping site was a pressure induced surface trap and it disappeared after annealing. However, the other trapping and recombination sites were found to be stable under thermal treatment. Due to this trap distribution, three partially overlapping glow peaks were observed. The glow peaks were found to be affected by thermal quenching. The thermal quenching parameters were evaluated from the composite glow curves by using Computerized Resolved Peak (CRP) technique. The activation energies for thermal quenching (W) estimated from the three peaks were found to be ~0.69±0.05, 0.92±0.06 and 1.15±0.03eV respectively and the pre-exponential factors (C) were ~1.12×108, 2.65×1010 and 9.23×1011 respectively. Based on the analysis, a band model was proposed and the whole radiative and non-radiative recombination mechanisms were discussed.
      Graphical abstract image

      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.12.019
      Issue No: Vol. 175 (2016)
       
  • A novel combined approach of diffuse reflectance UV–Vis-NIR spectroscopy
           and multivariate analysis for non-destructive examination of blue
           ballpoint pen inks in forensic application
    • Authors: Raj Kumar; Vishal Sharma
      Pages: 67 - 75
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Raj Kumar, Vishal Sharma
      The present research is focused on the analysis of writing inks using destructive UV–Vis spectroscopy (dissolution of ink by the solvent) and non-destructive diffuse reflectance UV–Vis-NIR spectroscopy along with Chemometrics. Fifty seven samples of blue ballpoint pen inks were analyzed under optimum conditions to determine the differences in spectral features of inks among same and different manufacturers. Normalization was performed on the spectroscopic data before chemometric analysis. Principal Component Analysis (PCA) and K-mean cluster analysis were used on the data to ascertain whether the blue ballpoint pen inks could be differentiated by their UV–Vis/UV–Vis NIR spectra. The discriminating power is calculated by qualitative analysis by the visual comparison of the spectra (absorbance peaks), produced by the destructive and non-destructive methods. In the latter two methods, the pairwise comparison is made by incorporating the clustering method. It is found that chemometric method provides better discriminating power (98.72% and 99.46%, in destructive and non-destructive, respectively) in comparison to the qualitative analysis (69.67%).
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.12.008
      Issue No: Vol. 175 (2016)
       
  • Synthesis, structure, spectral properties and DFT quantum chemical
           calculations of 4-aminoazobenzene dyes. Effect of intramolecular hydrogen
           bonding on photoisomerization
    • Authors: Anton Georgiev; Emil Bubev; Deyan Dimov; Denitsa Yancheva; Ivaylo Zhivkov; Jozef Krajčovič; Martin Vala; Martin Weiter; Maria Machkova
      Pages: 76 - 91
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Anton Georgiev, Emil Bubev, Deyan Dimov, Denitsa Yancheva, Ivaylo Zhivkov, Jozef Krajčovič, Martin Vala, Martin Weiter, Maria Machkova
      In this paper three different “push-pull” 4-aminoazobenzene dyes have been synthesized in order to characterize their photochromic behavior in different solvents. The molecular geometry was optimized by DFT/B3LYP functional combined with the standard 6–31+G(d,p) basis set for trans (E) and cis (Z) isomers and the energy levels of HOMO and LUMO frontier orbitals were computed using IEFPCM solvation in CHCl3 and DMF. The calculated results were compared to the experimental optical band gap and HOMO values of cyclic voltammetry. The intramolecular six-membered hydrogen bond was formed in both isomers of the synthesized dyes. The thermodynamic parameters such as total electronic energy E (RB3LYP), enthalpy H 298 (sum of electronic and thermal enthalpies), free Gibbs energy G 298 (sum of electronic and thermal free Gibbs energies) and dipole moment μ were computed for trans (E) and cis (Z) isomers in order to estimate the ΔE trans→cis , Δμ trans→cis, ΔH trans→cis , ΔG trans→cis and ΔS trans→cis values. The NBO analysis was performed in order to understand the intramolecular charge transfer and energy of resonance stabilization. The solvatochromic shift was evaluated by UV-VIS spectroscopy in CHCl3 (nonpolar), EtOH (polar protic) and DMF (polar aprotic) solvents to determine the electron withdrawing and donating properties of the substituents on electron transitions energy. Through the increasing solvent polarity a strong bathochromic shift is observed. The photoisomerization experiments have been performed in two solvents CHCl3 (nonpolar) and DMF (polar aprotic) by UV light irradiation with λ=365nm at equal concentrations and time of illuminations. The electronic spectra were computed by TD-DFT after geometry optimization using IEFPCM solvation in CHCl3 and DMF. The degree of photoisomerization was calculated for the three azo chromophores in both solvents. By using first derivative of the UV-VIS spectra it was possible to resolve the overlapped electron transitions absorption bands. The existing intramolecular hydrogen bond in the azo chromophores was discussed in relation to the isomerization mechanisms and relative stability of the cis (Z) isomers.
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.12.005
      Issue No: Vol. 175 (2016)
       
  • A series of stilbazolium salts with A-π-A model and their third-order
           nonlinear optical response in the near-IR region
    • Authors: Yiwen Tang; Hui Liu; Hui Zhang; Dandan Li; Jian Su; Shengyi Zhang; Hongping Zhou; Shengli Li; Jieying Wu; Yupeng Tian
      Pages: 92 - 99
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Yiwen Tang, Hui Liu, Hui Zhang, Dandan Li, Jian Su, Shengyi Zhang, Hongping Zhou, Shengli Li, Jieying Wu, Yupeng Tian
      A series of water-soluble stilbazolium salts with A-π-A (A: Acceptor) model have been synthesized and fully characterized. The results obtained from absorption spectra and TD-DFT computational studies show that there is a relative strong intramolecular charge transfer (ICT) transition from pyridine unit to pyridine cation of the stilbazolium salts. Furthermore, it is found that the three stilbazolium salts (T1, T2, T3) show the strong two-photon absorption (2PA) response in the near-infrared (IR) region by Z-scan technique using femtosecond laser. And the stilbazolium salt T3 shows the largest two-photon absorption cross-section and third-order nonlinear optical (NLO) coefficient χ(3) at 730nm, indicating the different terminal substituent group of the pyridinium plays a vital role in third-order NLO behavior.
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.12.017
      Issue No: Vol. 175 (2016)
       
  • Extinction, emission, and scattering spectroscopy of 5–50 nm
           citrate-coated gold nanoparticles: An argument for curvature effects on
           aggregation
    • Authors: Milad Rabbani Esfahani; Vasanta L. Pallem; Holly A. Stretz; Martha J.M. Wells
      Pages: 100 - 109
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Milad Rabbani Esfahani, Vasanta L. Pallem, Holly A. Stretz, Martha J.M. Wells
      The interaction of macromolecules with gold nanoparticles (GNPs) is of interest in the emerging field of biomedical and environmental detection devices. However, the physicochemical properties, including spectra, of GNPs in aqueous solution in the absence of metal–macromolecular interactions must first be considered before their activity in biological and environmental systems can be understood. The specific objective of this research was to experimentally illuminate the role of nanoparticle core size on the spectral (simultaneous consideration of extinction, emission, and scattering) versus aggregation behaviors of citrate-coated GNPs (CT-GNPs). It is difficult to find in the literature systematic simultaneous presentation of scattering, emission, and extinction spectra, including the UV range, and thus the present work will aid those who would use such particles for spectroscopic related separations or sensors. The spectroscopic behavior of CT-GNPs with different core sizes (5, 10, 30, and 50nm) was studied in ultra-pure water at pH6.0–6.5 employing UV–visible extinction, excitation-emission matrix (EEM), resonance Rayleigh scattering, and dynamic light scattering (DLS) spectroscopies. The CT-GNP-5 and CT-GNP-10 samples aggregated, absorbed light, and emitted light. In contrast, the CT-GNP-30 and CT-GNP-50 samples did not aggregate and did not emit light, but scattered light intensely. Multimodal peaks were observed in the intensity-based DLS spectra of CT-GNP-5 and CT-GNP-10 samples. Monomodal peaks in the volume-based DLS spectra overestimated particle diameters by 60% and 30% for the CT-GNP-5 and CT-GNP-10 samples, respectively, but underestimated diameters by 10% and 4% for the CT-GNP-30 and CT-GNP-50 samples. The volume-based DLS spectra indicated that dimer and trimer aggregates contributed most to the overall volume of particles in the 5- and 10-nm CT-GNPs, whereas the CT-GNP-30 and CT-GNP-50 samples did not aggregate. Here, we discuss the potential influence that differences in preparation, ionic strength, zeta potential, and conformation of adsorbed citrate anions (due to surface curvature of corona) may exert on the aggregation and spectral observations in these data. In particular, the severe surface curvature of the 5- and 10-nm GNP corona may affect the efficiency of the di-/tribasic citrate compatiblizer molecule to shield the core from interactions with light and from GNP–GNP homoaggregation.
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.11.052
      Issue No: Vol. 175 (2016)
       
  • Effect of Zinc oxide nanoparticle on Fluorescence Resonance Energy
           transfer between Fluorescein and Rhodamine 6G
    • Authors: Jaba Saha; Arpan Datta Roy; Dibyendu Dey; D. Bhattacharjee; Pabitra Kumar Paul; R. Das; Syed Arshad Hussain
      Pages: 110 - 116
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Jaba Saha, Arpan Datta Roy, Dibyendu Dey, D. Bhattacharjee, Pabitra Kumar Paul, R. Das, Syed Arshad Hussain
      Fluorescence Resonance Energy Transfer between two dyes Fluorescein and Rhodamine 6G were investigated in solution in the presence and absence of Zinc oxide nanoparticle. Zinc oxide nanostructure is used as the fluorescence enhancing agent for the present study since donor (Fluorescein) fluorescence increase significantly in presence of nanoparticle. Accordingly, the energy transfer efficiency in the presence of nanoparticle increases. The maximum efficiency was 69% for acceptor (Rhodamine 6G) concentration of 0.75×10−5 M. The energy transfer efficiency was found to be pH sensitive and it varies from 4.15% to 90.00% in mixed dye solution for a change in pH from 1.5 to 10.0. With proper calibration it is possible to use the present system under investigation to sense pH which is better with respect to our previous reported results [Spectrochim. Acta Part A. 149 (2015) 143–149] as it can sense a wide range of pH and with better sensitivity.
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.12.002
      Issue No: Vol. 175 (2016)
       
  • Phenazine-based colorimetric and fluorescent sensor for the selective
           detection of cyanides based on supramolecular self-assembly in aqueous
           solution
    • Authors: Hai-Li Zhang; Tai-Bao Wei; Wen-Ting Li; Wen-Juan Qu; Yan-Li Leng; Jian-Hui Zhang; Qi Lin; You-Ming Zhang; Hong Yao
      Pages: 117 - 124
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Hai-Li Zhang, Tai-Bao Wei, Wen-Ting Li, Wen-Juan Qu, Yan-Li Leng, Jian-Hui Zhang, Qi Lin, You-Ming Zhang, Hong Yao
      Taking advantages of both the well-known phenazine structure and the mechanism of the supramolecular self-assembly and deprotonation process, the fluorescent and colorimetric sensor (ZL) was designed and synthesized, behaving as a circulation utilization (above 10 times) receptor for selective detection of cyanide anion (CN−) in aqueous media. Upon the addition of CN−, the sensor displayed obvious color changes from yellow to jacinth by naked eyes and the fluorescence immediately quenched (<10s). With respect to other common anions, the sensor possessed high selectivity and sensitivity (0.05μM) for cyanide anions. In addition, the test strips of ZL were fabricated, which could serve as practical colorimetric and fluorescent sensor for “in-the-field” measurements.
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.12.022
      Issue No: Vol. 175 (2016)
       
  • A new unsymmetrical azine derivative based on coumarin group as dual-modal
           sensor for CN− and fluorescent “OFF–ON” for Zn2+
    • Authors: Jing-Han Hu; You Sun; Jing Qi; Qiao Li; Tai-Bao Wei
      Pages: 125 - 133
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Jing-Han Hu, You Sun, Jing Qi, Qiao Li, Tai-Bao Wei
      A simple chemosensor YS based on coumarin group was designed and synthesized. Its structure was determined by single crystal X–ray diffraction analysis. In the presence of cyanide the sensor showed an immediate visible change in color from colorless to pale yellow by naked–eyes and produced a strong blue fluorescence rapidly in DMSO/H2O (3:7, v/v). The detection limit on fluorescence response of the sensor to CN− is down to 1.69×10−7 M. In addition YS could show fluorescence turn–on response rapidly for Zn2+ over other metals ions such as Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Cr3+ and Mg2+ in aqueous solutions. Notably, this sensor served as a molecular switch, which was controlled by Zn2+ and EDTA cyclically. Test strips based on YS were fabricated, which could act as a convenient and efficient CN− and Zn2+ test kit. This chemosensor could achieve the detection of two ions, which need not depend on two different sensors.
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.12.009
      Issue No: Vol. 175 (2016)
       
  • Energy transfer at heterogeneous protein-protein interfaces to investigate
           the molecular behaviour in the crowding environment
    • Authors: Chikashi Ota
      Pages: 145 - 154
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): Chikashi Ota
      Investigation of the behaviour of proteins in crowded environments is crucial for understanding the role of proteins in biological environments. In this study, the behaviour of bovine serum albumin (BSA) in crowded (highly concentrated) environments was investigated using time-resolved fluorescence spectroscopy as a model system. By using energy transfer as a molecular ruler, the crowding effect was clearly observed in the time resolved spectra. In addition, by using both time resolved anisotropy measurement and Raman spectroscopy, more detail insights from conformational and dynamic points of view were described. Consequently, it was revealed that in the highly concentrated solution, most of the BSA molecules are in the fast-reversible oligomeric state and the association at the “hard” and “soft” interfaces between protein surfaces occurred in a highly crowded environment with the aid of a charge-charge and short-range attractive interface. From both the conformational and dynamic aspects, the detail spectroscopic understanding of the behaviour of BSA in the crowding environment was obtained.
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.12.010
      Issue No: Vol. 175 (2016)
       
  • A comprehensive approach to ascertain the binding mode of curcumin with
           DNA
    • Authors: P. Haris; Varughese Mary; P. Aparna; K.V. Dileep; C. Sudarsanakumar
      Pages: 155 - 163
      Abstract: Publication date: 15 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 175
      Author(s): P. Haris, Varughese Mary, P. Aparna, K.V. Dileep, C. Sudarsanakumar
      Curcumin is a natural phytochemical from the rhizoma of Curcuma longa, the popular Indian spice that exhibits a wide range of pharmacological properties like antioxidant, anticancer, anti-inflammatory, antitumor, and antiviral activities. In the published literatures we can see different studies and arguments on the interaction of curcumin with DNA. The intercalative binding, groove binding and no binding of curcumin with DNA were reported. In this context, we conducted a detailed study to understand the mechanism of recognition of dimethylsulfoxide-solubilized curcumin by DNA. The interaction of curcumin with calf thymus DNA (ctDNA) was confirmed by agarose gel electrophoresis. The nature of binding and energetics of interaction were studied by Isothermal Titration Calorimetry (ITC), Differential Scanning Calorimetry (DSC), UV–visible, fluorescence and melting temperature (Tm) analysis. The experimental data were compared with molecular modeling studies. Our investigation confirmed that dimethylsulfoxide-solubilized curcumin binds in the minor groove of the ctDNA without causing significant structural alteration to the DNA.
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      PubDate: 2016-12-27T12:06:17Z
      DOI: 10.1016/j.saa.2016.11.049
      Issue No: Vol. 175 (2016)
       
 
 
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