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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  [3039 journals]
  • Applications of vitamin B6 cofactor pyridoxal 5′-phosphate and pyridoxal
           5′-phosphate crowned gold nanoparticles for optical sensing of metal
           ions
    • Authors: Shilpa Bothra; Yachana Upadhyay; Rajender Kumar; Suban K Sahoo
      Pages: 1 - 6
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Shilpa Bothra, Yachana Upadhyay, Rajender Kumar, Suban K Sahoo
      Vitamin B6 cofactor pyridoxal 5′-phosphate (PLP) and PLP crowned gold nanoparticles (PLP-AuNPs) was applied for the optical chemosensing of metal ions in aqueous medium. PLP showed a visually detectable colour change from colourless to yellow and ‘turn-off’ fluorescence in the presence of Fe3+. The fluorescence intensity of PLP at 433nm was also blue-shifted and enhanced at 395nm upon addition of Al3+. When the PLP was functionalized over AuNPs surface, the wine red colour of PLP-AuNPs was turned to purplish-blue and the SPR band at ~525nm was red-shifted upon addition of Al3+, Cd2+ and Pb2+ due to the complexation-induced aggregation of nanoparticles. The developed sensing systems exhibited good selectivity and specificity for the detected analytes (Fe3+, Al3+, Cd2+ and Pb2+).
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      PubDate: 2016-11-20T22:55:35Z
      DOI: 10.1016/j.saa.2016.11.014
      Issue No: Vol. 174 (2016)
       
  • Modulation of π-spacer of carbazole-carbazole based organic dyes toward
           high efficient dye-sensitized solar cells
    • Authors: Chirawat Chitpakdee; Siriporn Jungsuttiwong; Taweesak Sudyoadsuk; Vinich Promarak; Nawee Kungwan; Supawadee Namuangruk
      Pages: 7 - 16
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Chirawat Chitpakdee, Siriporn Jungsuttiwong, Taweesak Sudyoadsuk, Vinich Promarak, Nawee Kungwan, Supawadee Namuangruk
      The effects of type and position of π-linker in carbazole-carbazole based dyes on their performance in dye-sensitized solar cells (DSSCs) were investigated by DFT and TDDFT methods. The calculated electronic energy level, electron density composition, charge injection and charge recombination properties were compared with those of the high performance CCT3A dye synthesized recently. It is found that that mixing a benzothiadizole (B) unit with two thiophene (T) units in the π-spacer can greatly shift absorption wavelength to near infrared region and enhance the light harvesting efficiency (LHE) resulting in increasing of short-circuit current density (J sc ), whereas a thienothiophene unit does not affect those properties. However, a B should be not directly connected to the anchoring group of the dye because it brings electrolyte to the TiO2 surface which may increase charge recombination rate and consequently decrease open circuit voltage (V oc ). This work shows how type and position of the π-linker affect the performance of DSSCs, and how to modulate those properties. We predicted that the designed dye derived from insertion of the B unit in between the two T units would have higher performance than CCT3A dye. The insight understanding from this study is useful for further design of higher performance dyes by molecular engineering.
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      PubDate: 2016-11-20T22:55:35Z
      DOI: 10.1016/j.saa.2016.11.010
      Issue No: Vol. 174 (2016)
       
  • UV and fluorescent spectra study the reaction between 1, 8-Naphthalimide
           derivative and hypochlorite their applications
    • Authors: Jiawei Li; Tao Liu; Fangjun Huo; Jianbin Chao; Yongbin Zhang; Caixia Yin
      Pages: 17 - 24
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Jiawei Li, Tao Liu, Fangjun Huo, Jianbin Chao, Yongbin Zhang, Caixia Yin
      Two simple, efficient turn-on fluorescent probes for hypochlorite have been rationally designed and developed by utilizing the oxidation of hypochlorite. Notably, probe 1 and 2 displayed rapid and remarkable turn-on responses to ClO− in PBS buffer solution (pH7.4). Further, the optical properties of two probes and their ClO−-addition products were confirmed by density functional theory calculations. And detection limits of two probes for ClO− based on the definition by IUPAC were calculated for 2.882nM and 0.354μM. More importantly, cell imaging experiments demonstrated that probe 1 was more suitable for detecting the ClO− in living A549 cells. And both two probes had the possibility of potentially applied in practical applications such as detecting the hypochlorite concentration of tap water and river water.
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      PubDate: 2016-11-20T22:55:35Z
      DOI: 10.1016/j.saa.2016.11.019
      Issue No: Vol. 174 (2016)
       
  • pH-dependent absorption spectra of rhodopsin mutant E113Q: On the role of
           counterions and protein
    • Authors: Peng Xie; Panwang Zhou; Ahmed Alsaedi; Yan Zhang
      Pages: 25 - 31
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Peng Xie, Panwang Zhou, Ahmed Alsaedi, Yan Zhang
      The absorption spectra of bovine rhodopsin mutant E113Q in solutions were investigated at the molecular level by using a hybrid quantum mechanics/molecular mechanics (QM/MM) method. The calculations suggest the mechanism of the absorption variations of E113Q at different pH values. The results indicate that the polarizations of the counterions in the vicinity of Schiff base under protonation and unprotonation states of the mutant E113Q would be a crucial factor to change the energy gap of the retinal to tune the absorption spectra. Glu-181 residue, which is close to the chromophore, cannot serve as the counterion of the protonated Schiff base of E113Q in dark state. Moreover, the results of the absorption maximum in mutant E113Q with the various anions (Cl−, Br−, I− and NO3 −) manifested that the mutant E113Q could have the potential for use as a template of anion biosensors at visible wavelength.
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      PubDate: 2016-11-20T22:55:35Z
      DOI: 10.1016/j.saa.2016.11.015
      Issue No: Vol. 174 (2016)
       
  • Calix[3]carbazole: A C3-symmetrical receptor for barium ion
    • Authors: Zhaozheng Yang; Zhangmin Tian; Peng Yang; Tuo Deng; Gang Li; Xue Zhou; Yan Chen; Liang Zhao; Hongyan Shen
      Pages: 32 - 36
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Zhaozheng Yang, Zhangmin Tian, Peng Yang, Tuo Deng, Gang Li, Xue Zhou, Yan Chen, Liang Zhao, Hongyan Shen
      The binding ability of calix[3]carbazole (1) to metal ions has been investigated. It is found that 1 could serve as a non crown ether based, C3-symmetrical receptor for Ba2+ via the marriage of cation–π and cation–dipole interactions. FID assay further illustrates that 1 could selectively interact with Ba2+ over Pd2+. A possible binding mechanism for [1-Ba2+] complex is proposed.
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      PubDate: 2016-11-20T22:55:35Z
      DOI: 10.1016/j.saa.2016.11.013
      Issue No: Vol. 174 (2016)
       
  • Controlling successive ionic layer absorption and reaction cycles to
           optimize silver nanoparticle-induced localized surface plasmon resonance
           effects on the paper strip
    • Authors: Jae-Chul Lee; Wansun Kim; Hun-Kuk Park; Samjin Choi
      Pages: 37 - 43
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Jae-Chul Lee, Wansun Kim, Hun-Kuk Park, Samjin Choi
      This study investigates why a silver nanoparticle (SNP)-induced surface-enhanced Raman scattering (SERS) paper chip fabricated at low successive ionic layer absorption and reaction (SILAR) cycles leads to a high SERS enhancement factor (7×108) with an inferior nanostructure and without generating a hot spot effect. The multi-layered structure of SNPs on cellulose fibers, verified by magnified scanning electron microscopy (SEM) and analyzed by a computational simulation method, was hypothesized as the reason. The pattern of simulated local electric field distribution with respect to the number of SILAR cycles showed good agreement with the experimental Raman intensity, regardless of the wavelength of the excitation laser sources. The simulated enhancement factor at the 785-nm excitation laser source (2.8×109) was 2.5 times greater than the experimental enhancement factor (1.1×109). A 532-nm excitation laser source exhibited the highest maximum local electric field intensity (1.9×1011), particularly at the interparticle gap called a hot spot. The short wavelength led to a strong electric field intensity caused by strong electromagnetic coupling arising from the SNP-induced local surface plasmon resonance (LSPR) effects through high excitation energy. These findings suggest that our paper-based SILAR-fabricated SNP-induced LSPR model is valid for understanding SNP-induced LSPR effects.
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      PubDate: 2016-11-20T22:55:35Z
      DOI: 10.1016/j.saa.2016.11.016
      Issue No: Vol. 174 (2016)
       
  • Identification of protein secondary structures by laser induced
           autofluorescence: A study of urea and GnHCl induced protein denaturation
    • Authors: Manjunath Siddaramaiah; Satyamoorthy Kapaettu; Bola Sadashiva Satish Rao; Suparna Roy; Subhash Chandra; K.K. Mahato
      Pages: 44 - 53
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Manjunath Siddaramaiah, Satyamoorthy Kapaettu, Bola Sadashiva Satish Rao, Suparna Roy, Subhash Chandra, K.K. Mahato
      In the present study an attempt has been made to interrogate the bulk secondary structures of some selected proteins (BSA, HSA, lysozyme, trypsin and ribonuclease A) under urea and GnHCl denaturation using laser induced autofluorescence. The proteins were treated with different concentrations of urea (3M, 6M, 9M) and GnHCl (2M, 4M, 6M) and the corresponding steady state autofluorescence spectra were recorded at 281nm pulsed laser excitations. The recorded fluorescence spectra of proteins were then interpreted based on the existing PDB structures of the proteins and the Trp solvent accessibility (calculated using “Scratch protein predictor” at 30% threshold). Further, the influence of rigidity and conformation of the indole ring (caused by protein secondary structures) on the intrinsic fluorescence properties of proteins were also evaluated using fluorescence of ANS-HSA complexes, CD spectroscopy as well as with trypsin digestion experiments. The outcomes obtained clearly demonstrated GnHCl preferably disrupt helix as compared to the beta β-sheets whereas, urea found was more effective in disrupting β-sheets as compared to the helices. The other way round the proteins which have shown detectable change in the intrinsic fluorescence at lower concentrations of GnHCl were rich in helices whereas, the proteins which showed detectable change in the intrinsic fluorescence at lower concentrations of urea were rich in β-sheets. Since high salt concentrations like GnHCl and urea interfere in the secondary structure analysis by circular dichroism Spectrometry, the present method of analyzing secondary structures using laser induced autofluorescence will be highly advantageous over existing tools for the same.
      Graphical abstract image

      PubDate: 2016-11-20T22:55:35Z
      DOI: 10.1016/j.saa.2016.11.017
      Issue No: Vol. 174 (2016)
       
  • Water as probe molecule for midgap states in nanocrystalline strontium
           titanate by conventional and synchronous luminescence spectroscopy under
           ambient conditions
    • Authors: Sean Taylor; Alexander Samokhvalov
      Pages: 54 - 61
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Sean Taylor, Alexander Samokhvalov
      Alkaline earth metal titanates are broad bandgap semiconductors with applications in electronic devices, as catalysts, photocatalysts, sorbents, and sensors. Strontium titanate SrTiO3 is of interest in electronic devices, sensors, in the photocatalytic hydrogen generation, as catalyst and sorbent. Both photocatalysis and operation of electronic devices rely upon the pathways of relaxation of excited charge in the semiconductor, including relaxation through the midgap states. We report characterization of nanocrystalline SrTiO3 at room temperature by “conventional” vs. synchronous luminescence spectroscopy and complementary methods. We determined energies of radiative transitions in the visible range through the two midgap states in the nanocrystalline SrTiO3. Further, adsorption and desorption of vapor of water as “probe molecule” for midgap states in the nanocrystalline SrTiO3 was studied, for the first time, by luminescence spectroscopy under ambient conditions. Emission of visible light from the nanocrystalline SrTiO3 is significantly increased upon desorption of water and decreased (quenched) upon adsorption of water vapor, due to interactions with the surface midgap states.
      Graphical abstract image

      PubDate: 2016-11-20T22:55:35Z
      DOI: 10.1016/j.saa.2016.11.011
      Issue No: Vol. 174 (2016)
       
  • A dual analyte fluorescent chemosensor based on a furan-pyrene conjugate
           for Al3+ & HSO3−
    • Authors: Derin Don; K. Velmurugan; J. Prabhu; N. Bhuvanesh; A. Thamilselvan; R. Nandhakumar
      Pages: 62 - 69
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Derin Don, K. Velmurugan, J. Prabhu, N. Bhuvanesh, A. Thamilselvan, R. Nandhakumar
      A simple chalcone based dual analyte fluorescent probe FPC for Al3+ and HSO3 − ions was developed. FPC detects both the analytes through a “turn off-on” approach and by the PET and ICT mechanism. FPC showed high selectivity and sensitivity for Al3+ and HSO3 − ions detection over other interfering and competing metal ions. In addition, the LOD of FPC for sensing Al3+ and HSO3 − ions was found to be 1.60×10−7 M and 0.17×10−6 M respectively. An electrochemical desalination technique was employed for the complete removal of Al3+ ions from the environmental water samples by using the probe FPC.
      Graphical abstract image

      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.021
      Issue No: Vol. 174 (2016)
       
  • A new 2-(2′-hydroxyphenyl)quinazolin-4(3H)-one derived acylhydrazone for
           fluorescence recognition of Al3+
    • Authors: Lijun Tang; Shuangli Ding; Keli Zhong; Shuhua Hou; Yanjiang Bian; Xiaomei Yan
      Pages: 70 - 74
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Lijun Tang, Shuangli Ding, Keli Zhong, Shuhua Hou, Yanjiang Bian, Xiaomei Yan
      A new 2-(2′-hydroxyphenyl)quinazolin-4(3H)-one derived acylhydrazone (QP) was designed and synthesized as a fluorescent sensor. In Tris∙HCl buffer (10mM, pH7.4)/ethanol (1/9, v/v) solution, QP exhibits a highly selective fluorescence response to Al3+ over other metal ions with a significant blue-shifted and enhanced emission at 473nm. QP interacts with Al3+ reversibly through a 1:2 binding ratio with a detection limit of 4.79×10−8 M. Potential applicability of QP for Al3+ detection in tap and lake water samples were also examined by ‘proof-of-concept’ experiments.
      Graphical abstract image

      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.026
      Issue No: Vol. 174 (2016)
       
  • Graphene oxide-based fluorescent sensor for sensitive turn-on detection of
           sinapine
    • Authors: Xia Xiang; Ling Han; Zhen Zhang; Fenghong Huang
      Pages: 75 - 79
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Xia Xiang, Ling Han, Zhen Zhang, Fenghong Huang
      Sinapine (SP) has attracted extensive attention in food and medical field because it is a crucial component in many plants with unique physiological activities. Here, we reported a fluorescent sensor based on the unique properties of graphene oxide (GO) for rapid, sensitive detection of SP concentration. In this strategy, GO has stronger affinity toward SP and can be also served as a quencher for DNA fluorescence probe. The fluorescence can make a recovery by the addition of SP, which can competitively desorb probe from the surface of GO, and the SP can thus be monitored by recording the fluorescence change. Because of the low background assays and high quenching ability offered by GO, the developed method provides a great potential for plant-derived molecules research.
      Graphical abstract image

      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.025
      Issue No: Vol. 174 (2016)
       
  • High pressure Raman scattering study on Sm2Mo4O15 system
    • Authors: S.D. Silva Santos; W. Paraguassu; M. Maczka; P.T.C. Freire
      Pages: 80 - 85
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): S.D. Silva Santos, W. Paraguassu, M. Maczka, P.T.C. Freire
      High-pressure Raman experiments were performed on Sm2Mo4O15 system up to 7.9GPa. We show that this system exhibits an irreversible structural amorphization at 5.0GPa. In contrast to any other molybdates and tungstates experiencing pressure-induced amorphization, this structural change in Sm2Mo4O15 has strongly first-order character. This amorphous phase can be originated from the hindrance of a crystalline structural phase transition from the P 1 ¯ to P2/m structure. Additionally, the assignment of Raman modes of the ambient-pressure phase of Sm2Mo4O15 was proposed based on lattice dynamics calculations.
      Graphical abstract image

      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.024
      Issue No: Vol. 174 (2016)
       
  • Selective and sensitive fluorimetric determination of carbendazim in apple
           and orange after preconcentration with magnetite-molecularly imprinted
           polymer
    • Authors: Raif İlktaç; Nur Aksuner; Emur Henden
      Pages: 86 - 93
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Raif İlktaç, Nur Aksuner, Emur Henden
      In this study, magnetite-molecularly imprinted polymer has been used for the first time as selective adsorbent before the fluorimetric determination of carbendazim. Adsorption capacity of the magnetite-molecularly imprinted polymer was found to be 2.31±0.63mgg−1 (n=3). Limit of detection (LOD) and limit of quantification (LOQ) of the method were found to be 2.3 and 7.8μgL−1, respectively. Calibration graph was linear in the range of 10–1000μgL−1. Rapidity is an important advantage of the method where re-binding and recovery processes of carbendazim can be completed within an hour. The same imprinted polymer can be used for the determination of carbendazim without any capacity loss repeatedly for at least ten times. Proposed method has been successfully applied to determine carbendazim residues in apple and orange, where the recoveries of the spiked samples were found to be in the range of 95.7–103%. Characterization of the adsorbent and the effects of some potential interferences were also evaluated. With the reasonably high capacity and reusability of the adsorbent, dynamic calibration range, rapidity, simplicity, cost-effectiveness and with suitable LOD and LOQ, the proposed method is an ideal method for the determination of carbendazim.
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      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.029
      Issue No: Vol. 174 (2016)
       
  • Spectroscopic investigation, vibrational assignments, HOMO-LUMO, NBO, MEP
           analysis and molecular docking studies of oxoaporphine alkaloid
           liriodenine
    • Authors: Renyer A. Costa; Priscilla Olliveira Pitt; Maria Lucia B. Pinheiro; Kelson M.T. Oliveira; Kahlil Schwanka Salomé; Andersson Barison; Emmanoel Vilaça Costa
      Pages: 94 - 104
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Renyer A. Costa, Priscilla Olliveira Pitt, Maria Lucia B. Pinheiro, Kelson M.T. Oliveira, Kahlil Schwanka Salomé, Andersson Barison, Emmanoel Vilaça Costa
      A combined experimental and theoretical DFT study of the structural, vibrational and electronic properties of liriodenine is presented using B3LYP function with 6-311G (2d, p) basis set. The theoretical geometry optimization data were compared with the X-ray data for a similar structure in the associated literature, showing similar values. In addition, natural bond orbitals (NBOs), HOMO-LUMO energy gap, mapped molecular Electrostatic Potential (MEP) surface calculation, first and second order hyperpolarizabilities were also performed with the same calculation level. Theoretical UV spectrum agreed well with the measured experimental data, with transitions assigned. The molecular electrostatic potential map shows opposite potentials regions that forms hydrogen bonds that stabilize the dimeric form, which were confirmed by the close values related to the C O bond stretching between the dimeric form and the experimental IR spectra (1654cm−1 for the experimental, 1700cm−1 for the dimer form). Calculated HOMO/LUMO gaps shows the excitation energy for Liriodenine, justifying its stability and kinetics reaction. Molecular docking studies with Candida albicans dihydrofolate reductase (DHFR) and Candida albicans secreted aspartic protease (SAP) showed binding free energies values of −8.5 and −8.3kcal/mol, suggesting good affinity between the liriodenine and the target macromolecules.
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      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.018
      Issue No: Vol. 174 (2016)
       
  • Investigations of the Rg-BrCl (Rg=He, Ne, Ar, Kr, Xe) binary van der Waals
           complexes: ab initio intermolecular potential energy surfaces, vibrational
           states and predicted pure rotational transition frequencies
    • Authors: Song Li; Rui Zheng; Shan-Jun Chen; Yan Chen; Peng Chen
      Pages: 105 - 117
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Song Li, Rui Zheng, Shan-Jun Chen, Yan Chen, Peng Chen
      The intermolecular potential energy surfaces (PESs) of the ground electronic state for the Rg-BrCl (Rg=He, Ne, Ar, Kr, Xe) van der Waals complexes have been constructed by using the coupled-cluster method in combination with the augmented quadruple-zeta correlation-consistent basis sets supplemented with an additional set of bond functions. The features of the anisotropic PESs for these complexes are remarkably similar, which are characterized by three minima and two saddle points between them. The global minimum corresponds to a collinear Rg-Br-Cl configuration. Two local minima, correlate with an anti-linear Rg-Cl-Br geometry and a nearly T-shaped structure, can also be located on each PES. The quantum bound state calculations enable us to investigate intermolecular vibrational states and rotational energy levels of the complexes. The transition frequencies are predicted and are fitted to obtain their corresponding spectroscopic constants. In general, the periodic trends are observed for this complex family. Comparisons with available experimental data for the collinear isomer of Ar-BrCl demonstrate reliability of our theoretical predictions, and our results for the other two isomers of Ar-BrCl as well as for other members of the complex family are also anticipated to be trustable. Except for the collinear isomer of Ar-BrCl, the data presented in this paper would be beneficial to improve our knowledge for these experimentally unknown species.
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      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.020
      Issue No: Vol. 174 (2016)
       
  • Stabilization of cytochrome b5 by a conserved tyrosine in the secondary
           sphere of heme active site: A spectroscopic and computational study
    • Authors: Shan Hu; Bo He; Xiao-Juan Wang; Shu-Qin Gao; Ge-Bo Wen; Ying-Wu Lin
      Pages: 118 - 123
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Shan Hu, Bo He, Xiao-Juan Wang, Shu-Qin Gao, Ge-Bo Wen, Ying-Wu Lin
      Heme proteins perform a large array of biological functions, with the heme group bound non-covalently or covalently. To probe the stabilization role of conserved tyrosine residue in the secondary sphere of heme site in heme proteins, we herein used cytochrome b 5 (Cyt b 5) as a model protein, and mutated Tyr30 to Phe or His by removal of Tyr30 associated H-bond network and hydrophobic interaction. We performed thermal-induced unfolding studies for the two mutants, Y30F Cyt b 5 and Y30H Cyt b 5, as monitored by both UV–Vis and CD spectroscopy, as well as heme transfer studies from these proteins to apo-myoglobin, with wild-type Cyt b 5 under the same conditions for comparison. The reduced stability of both mutants indicates that both the H-bonding and hydrophobic interactions associated with Tyr30 contribute to the protein stability. Moreover, we performed molecular modeling studies, which revealed that the hydrophobic interaction in the local region of Y30F Cyt b 5 was well-remained, whereas Y30H Cyt b 5 formed an H-bond network. These observations suggest that the conserved Tyr30 in Cyt b 5 is not replaceable due to the presence of both the H-bond network and hydrophobic interaction in the secondary sphere of the heme active site. As demonstrated here for Cyt b 5, it may be of practical importance for design of artificial heme proteins by engineering a Tyr in the secondary sphere with improved properties and functions.
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      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.032
      Issue No: Vol. 174 (2016)
       
  • Effect of smoking cessation in saliva compounds by FTIR spectroscopy
    • Authors: Laís Morandini Rodrigues; Taciana Deprá Magrini; Celina Faig Lima; Jaqueline Scholz; Herculano da Silva Martinho; Janete Dias Almeida
      Pages: 124 - 129
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Laís Morandini Rodrigues, Taciana Deprá Magrini, Celina Faig Lima, Jaqueline Scholz, Herculano da Silva Martinho, Janete Dias Almeida
      Introduction Smoking is currently considered one of the biggest risk factors for the development of various diseases and early death. Fourier transform infrared (FTIR) spectroscopy is a valuable tool for analysis of biofluids such as saliva and is considered useful for diagnostic purposes. The aim of this study was to evaluate the effect of smoking cessation on saliva composition by FTIR spectroscopy. Methods We analyzed the saliva of participants in two groups: a smoker group made up of 10 chronic smokers and a former smoker group made up of 10 individuals who had stopped smoking. Members of both groups had similar smoking history. Results The results showed few differences in spectral intensity between the groups; however, spectral peaks were slightly increased in the group of smokers in the bands for DNA, indicating modification of its content or cell necrosis. They were also increased for the mannose-6-phosphatase molecule, which is expressed in prostate and breast carcinomas. In the former smoker group, the peak of thyociante was decreased and the band referring to collagen increased in intensity, which indicates a better tissue regeneration capacity. Conclusion Considering these results and the fact that tobacco intake was similar between the groups, it can be concluded that there was recovery of tissue regeneration capacity with smoking cessation during the study period, although the effects found in smokers persisted in the bodies of those who had given up smoking.
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      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.009
      Issue No: Vol. 174 (2016)
       
  • Spectroscopic investigation and direct comparison of the reactivities of
           iron pyridyl oxidation catalysts
    • Authors: Yang Song; Howard G. Mayes; Matthew J. Queensen; Eike B. Bauer; Cynthia M. Dupureur
      Pages: 130 - 137
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Yang Song, Howard G. Mayes, Matthew J. Queensen, Eike B. Bauer, Cynthia M. Dupureur
      The growing interest in green chemistry has fueled attention to the development and characterization of effective iron complex oxidation catalysts. A number of iron complexes are known to catalyze the oxidation of organic substrates utilizing peroxides as the oxidant. Their development is complicated by a lack of direct comparison of the reactivities of the iron complexes. To begin to correlate reactivity with structural elements, we compare the reactivities of a series of iron pyridyl complexes toward a single dye substrate, malachite green (MG), for which colorless oxidation products are established. Complexes with tetradentate, nitrogen-based ligands with cis open coordination sites were found to be the most reactive. While some complexes reflect sensitivity to different peroxides, others are similarly reactive with either H2O2 or tBuOOH, which suggests some mechanistic distinctions. [Fe(S,S-PDP)(CH3CN)2](SbF6)2 and [Fe(OTf)2(tpa)] transition under the oxidative reaction conditions to a single intermediate at a rate that exceeds dye degradation (PDP=bis(pyridin-2-ylmethyl) bipyrrolidine; tpa=tris(2-pyridylmethyl)amine). For the less reactive [Fe(OTf)2(dpa)] (dpa=dipicolylamine), this reaction occurs on a timescale similar to that of MG oxidation. Thus, the spectroscopic method presented herein provides information about the efficiency and mechanism of iron catalyzed oxidation reactions as well as about potential oxidative catalyst decomposition and chemical changes of the catalyst before or during the oxidation reaction.
      Graphical abstract image

      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.030
      Issue No: Vol. 174 (2016)
       
  • Conformational equilibrium of phenylacetic acid and its halogenated
           analogues through theoretical studies, NMR and IR spectroscopy
    • Authors: Mariana N. Levandowski; Thiago C. Rozada; Ulisses Z. Melo; Ernani A. Basso; Barbara C. Fiorin
      Pages: 138 - 146
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Mariana N. Levandowski, Thiago C. Rozada, Ulisses Z. Melo, Ernani A. Basso, Barbara C. Fiorin
      This paper presents a study on the conformational preferences of phenylacetic acid (PA) and its halogenated analogues (FPA, CPA, BPA). To clarify the effects that rule these molecules' behaviour, theoretical calculations were used, for both the isolated phase and solution, combined with nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. Most conformations of phenylacetic acid and its halogenated derivatives are stabilized through the hyperconjugative effect, which rules the conformational preference. NMR analyses showed that even with the variation in medium polarity, there was no significant change in the conformation population. Infrared spectroscopy showed similar results for all compounds under study. In most spectra, two bands were found through the carbonyl deconvolution, which is in accordance with the theoretical data. It was possible to prove that variation in the nature of the substituent in the ortho position had no significant influence on the conformational equilibrium.
      Graphical abstract image

      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.10.050
      Issue No: Vol. 174 (2016)
       
  • Design, synthesis, characterization and cation sensing behavior of
           amino-naphthoquinone receptor: Selective colorimetric sensing of Cu(II)
           ion in nearly aqueous solution with mimicking logic gate operation
    • Authors: C. Parthiban; Kuppanagounder P. Elango
      Pages: 147 - 153
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): C. Parthiban, Kuppanagounder P. Elango
      An amino-naphthoquione receptor (R1) has been rationally designed, synthesized and characterized using 1H and 13C NMR, LCMS and single crystal X-ray diffraction studies. The receptor exhibits an instantaneous colour change from yellow to blue selectively with Cu(II) ions in water-DMF (98:2% v/v) medium. The results of UV–Vis and fluorescence spectral studies indicates that the mechanism of sensing involves formation of a 1:1 complex between R1 and Cu(II) ion. The proposed mechanism has been confirmed through product analysis using FT-IR, UV–Vis, EPR and HRMS studies in addition to magnetic moment and elemental analysis measurements. The formed [Cu(R1)Cl2] possess a square planar geometry. The binding constant for the interaction of Cu(II) ion with the present unsubstituted quinone is found to be relatively higher than that with quinones containing electron withdrawing chlorine atom and electron releasing methyl group reported in literature. The detection limit of Cu(II) ion in aqueous solution by R1 is observed to be 8.7nM. The detection of Cu(II) ion by R1 in aqueous solution produces remarkable changes in the electronic and fluorescence spectra, which is applied to construct logic gate at molecular level.
      Graphical abstract image

      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.022
      Issue No: Vol. 174 (2016)
       
  • Solvatochromic fluorescence properties of phenothiazine-based dyes
           involving thiazolo[4,5-b]quinoxaline and benzo[e]indole as strong
           acceptors
    • Authors: Saurabh S. Deshpande; Haribhau S. Kumbhar; Ganapati S. Shankarling
      Pages: 154 - 163
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Saurabh S. Deshpande, Haribhau S. Kumbhar, Ganapati S. Shankarling
      The present work describes the photophysical properties of two newly synthesized compounds, namely (E)-10-butyl-3-(2-(thiazolo[4,5-b]quinoxalin-2-yl)vinyl)-10H-phenothiazine (PTQ) and (E)-10-butyl-3-(2-(1,1-dimethyl-1H-benzo[e]indol-2-yl)vinyl)-10H-phenothiazine (PBI). A strong intramolecular charge transfer (ICT) is observed in both dyes as indicated from absorption and emission studies on varying the solvent polarity. This can be concluded from the large Stokes shifts among these dyes as PTQ exhibits large Stokes shift with >270nm and PBI around 200nm. The effect of increasing polarity caused drastic increase in the charge transfer process leading to twisted intramolecular charge transfer (TICT) process in both the dyes PTQ and PBI. Time-resolved emission studies and non-radiative decay rate constant indicates that the excited states of both dyes behave differently with respect to solvent polarity. The non-radiative decay constant increases dramatically with the solvent polarity specifying change of ICT emissive states in non-polar solvent while TICT emitting states in highly polar solvent. On the other hand, PBI follows a general trend initially exhibiting higher non-radiative decay constant in non-polar solvent like cyclohexane, lowest in moderate polarity owing to the ICT emissive state but with increase in the polarity, the non-radiative decay constant again increases indicating TICT states.
      Graphical abstract image

      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.10.045
      Issue No: Vol. 174 (2016)
       
  • Synthesis and fluorescence studies of nine 1,5-benzodiazepine-2,4-dione
           derivatives: Dual emission and excimer fluorescence
    • Authors: Hamid Reza Qomi; Azizollah Habibi; Seyyed Mohammad Shahcheragh
      Pages: 164 - 170
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Hamid Reza Qomi, Azizollah Habibi, Seyyed Mohammad Shahcheragh
      The photophysical properties of nine 1,5-benzodiazepine-2,4-dione (BZD) derivatives were investigated using absorption and fluorescence spectral techniques in dimethyl sulfoxide. The trend of red shifts caused by the substitutions had full compliance with the trend of decreasing the calculated band gap (ΔELUMO-HOMO) by semi-empirical AM1 and DFT/B3LYP/6-311+G* computational methods. The positive solvatochromism of BZD a demonstrated the π–π* nature of the singlet excited state. Dual fluorescence was observed in the emission spectra of BZD f and g, while their spectrum in different concentration showed only one peak short wavelength (SW) in dilute solutions. The main peak in SW around 370nm was attributed to the monomer of BZD (f* or g*) and the broader emission shifted to the visible region around 400nm in middle wavelength (MW) to the intermolecular excimer emission of BZD ([f/f]*or [g/g]*). The observed phenomena, such as solvatochromism, dual fluorescence, some red shifts caused by substitution, and larger Stokes shift indicated the existence of intramolecular charge transfer (ICT) in the BZDs series. The phosphorescence emission of the BZDs demonstrated their intersystem crossing (ISC) process.
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      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.028
      Issue No: Vol. 174 (2016)
       
  • Fructosylation induced structural changes in mammalian DNA examined by
           biophysical techniques
    • Authors: Asif Zaman; Zarina Arif; Khursheed Alam
      Pages: 171 - 176
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Asif Zaman, Zarina Arif, Khursheed Alam
      Glycosylation of DNA, proteins, lipids, etc. by reducing sugars, can lead to the formation of advanced glycation end products (AGEs). These products may accumulate and involve in the pathogenesis of a number of diseases, contributing to tissue injury via several mechanisms. In this study, fructosylation of calf thymus dsDNA was carried out with varying concentrations of fructose. The neo-structure of fructosylated-DNA was studied by various biophysical techniques and morphological characterization. Fructosylated-DNA showed hyperchromicity, increase in fluorescence intensity and decrease in melting temperature. The CD signal of modified-DNA shifted in the direction of higher wavelength indicative of structural changes in DNA. FTIR results indicated shift in specific band positions in fructosylated-DNA. Morphological characterization of fructosylated-DNA exhibited strand breakage and aggregation. The results suggest that the structure and conformation of DNA may be altered under high concentrations of fructose.
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      PubDate: 2016-11-27T08:07:01Z
      DOI: 10.1016/j.saa.2016.11.027
      Issue No: Vol. 174 (2016)
       
  • Chemical profiling and adulteration screening of Aquilariae Lignum
           Resinatum by Fourier transform infrared (FT-IR) spectroscopy and
           two-dimensional correlation infrared (2D-IR) spectroscopy
    • Authors: Lei Qu; Jian-bo Chen; Gui-Jun Zhang; Su-qin Sun; Jing Zheng
      Pages: 177 - 182
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Lei Qu, Jian-bo Chen, Gui-Jun Zhang, Su-qin Sun, Jing Zheng
      As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p =0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR.
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      PubDate: 2016-12-05T10:09:05Z
      DOI: 10.1016/j.saa.2016.11.008
      Issue No: Vol. 174 (2016)
       
  • Raman spectroscopy and quantum-mechanical analysis of tautomeric forms in
           cytosine and 5-methylcytosine on gold surfaces
    • Authors: Dinh Bao Nguyen; Thanh Danh Nguyen; Sangsoo Kim; Sang-Woo Joo
      Pages: 183 - 188
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Dinh Bao Nguyen, Thanh Danh Nguyen, Sangsoo Kim, Sang-Woo Joo
      Spectral differences between cytosine (Cyt) and 5-methylcytosine (5MC) were investigated by means of Raman spectroscopy with a combination of density functional theory (DFT) calculations. Surface-enhanced Raman scattering (SERS) revealed discriminating peaks of 5MC from those of Cyt upon adsorption on gold nanoparticles (AuNPs). Among the notable features, the multiple bands between 850 and 700cm−1 for the ring-breathing modes of 5MC and Cyt could be correlated well with the simulated spectra based on the DFT calculations of the adsorbates on the gold cluster atoms. The relative energetic stabilities of the enol/keto and the amino/imino tautomeric forms of Cyt and 5MC have been estimated using DFT calculations, before and after binding six atom gold clusters. Among the six tautomeric forms, the 7H keto amino and the 4H imino trans forms are expected to be predominant in binding gold atoms, whereas the enol trans/cis conformers would coexist in the free gas phase. Our approach may provide useful theoretical guidelines for identifying 5MC from Cyt by analyzing Raman spectra on gold surfaces on the basis of quantum-mechanical calculations.
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      PubDate: 2016-12-05T10:09:05Z
      DOI: 10.1016/j.saa.2016.11.004
      Issue No: Vol. 174 (2016)
       
  • Spectrometric assay for horseradish peroxidase activity based on the
           linkage of conjugated system formed by oxidative decarboxylation
    • Authors: Masaki Yamaguchi; Shingo Sato
      Pages: 189 - 194
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Masaki Yamaguchi, Shingo Sato
      Horseradish peroxidase (HRP)-catalyzed oxidation of 2,2-bis[3-acethylfilicinic acid-5-yl]acetic acid (BAFA, 4) produces Dehydro-3,3’-diacetyl-5,5’-methylenedifilicinic acid (DDMF, 3). A new photometric hydrogen donor (4) for peroxidase (POD)-catalyzed oxidation was demonstrated to be potentially useful for spectrocolorimetric and spectrofluorometric determination of HRP. Our developed colorimetric (absorption at 483nm) and fluorometric (emission at 529nm) systems both gave a linear calibration curve for HRP (y=0.0025×+0.0237; R2 =0.9997, and y=0.241×+3.194; R2 =0.9914, respectively) in the same concentration range of 9.1×10−8–1.1×10−6 nmol/L. The calculated K m and V max values of 5.10×10−4 M and 5.13×10−6 M/min, respectively. The results indicate that the quantification of HRP using BAFA 4 as hydrogen donor is possible.
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      PubDate: 2016-12-05T10:09:05Z
      DOI: 10.1016/j.saa.2016.11.012
      Issue No: Vol. 174 (2016)
       
  • Cysteine optical sensing with an up-conversion host and two chemosensors
           derived from rhodamine: Construction, characterization and performance
    • Authors: Chen Lin; Fang Zhigang
      Pages: 195 - 202
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Chen Lin, Fang Zhigang
      This paper focused on two rhodamine chemosensors for cysteine optical sensing. To minimize their photobleaching caused by excitation light, up-conversion NaYF4:Yb3+/Er3+ nanocrystals were prepared and used as excitation host. Photophysical measurement on this host and the two chemosensors suggested that chemosensor absorption matched well with host emission. An efficient energy transfer between them was discussed and confirmed by their spectral analysis and emission lifetime comparison. Job's plot suggested that our chemosensors followed a simple recognition mechanism towards cysteine with binding stoichiometry of 1:1. Both chemosensors showed emission “off-on” effect triggered by cysteine and good photostability. Linear working curves with maximum sensitivity of 2.61 were obtained. S substituent was positive to improve selectivity.
      Graphical abstract image

      PubDate: 2016-12-05T10:09:05Z
      DOI: 10.1016/j.saa.2016.11.035
      Issue No: Vol. 174 (2016)
       
  • Double injection/single detection asymmetric flow injection manifold for
           spectrophotometric determination of ascorbic acid and uric acid: Selection
           the optimal conditions by MCDM approach based on different criteria
           weighting methods
    • Authors: Samira Boroumand; Mansour Arab Chamjangali; Ghadamali Bagherian
      Pages: 203 - 213
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Samira Boroumand, Mansour Arab Chamjangali, Ghadamali Bagherian
      A simple and sensitive double injection/single detector flow injection analysis (FIA) method is proposed for the simultaneous kinetic determination of ascorbic acid (AA) and uric acid (UA). This method is based upon the difference between the rates of the AA and UA reactions with Fe3+ in the presence of 1, 10-phenanthroline (phen). The absorbance of Fe2+/1, 10-phenanthroline (Fe-phen) complex obtained as the product was measured spectrophotometrically at 510nm. To reach a good accuracy in the differential kinetic determination via the mathematical manipulations of the transient signals, different criteria were considered in the selection of the optimum conditions. The multi criteria decision making (MCDM) approach was applied for the selection of the optimum conditions. The importance weights of the evaluation criteria were determined using the analytic hierarchy process, entropy method, and compromised weighting (CW). The experimental conditions (alternatives) were ranked by the technique for order preference by similarity to an ideal solution. Under the selected optimum conditions, the obtained analytical signals were linear in the ranges of 0.50–5.00 and 0.50–4.00mgL−1 for AA and UA, respectively. The 3σ detection limits were 0.07mgL−1 for AA and 0.12mgL−1 for UA. The relative standard deviations for four replicate determinations of AA and UA were 2.03% and 3.30% respectively. The method was also applied for the analysis of analytes in the blood serum, Vitamine C tablets, and tap water with satisfactory results.
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      PubDate: 2016-12-05T10:09:05Z
      DOI: 10.1016/j.saa.2016.11.031
      Issue No: Vol. 174 (2016)
       
  • Development of a coumarin-furan conjugate as Zn2+ ratiometric fluorescent
           probe in ethanol-water system
    • Authors: Chao-rui Li; Si-liang Li; Zheng-yin Yang
      Pages: 214 - 222
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Chao-rui Li, Si-liang Li, Zheng-yin Yang
      In this study, a novel coumarin-derived compound bearing the furan moiety called 7-diethylamino-3-formylcoumarin (2′-furan formyl) hydrazone (1) has been designed, synthesized and evaluated as a Zn2+ ratiometric fluorescent probe in ethanol-water system. This probe 1 showed good selectivity and high sensitivity towards Zn2+ over other metal ions investigated, and a decrease in fluorescence emission intensity at 511nm accompanied by an enhancement in fluorescence emission intensity at 520nm of this probe 1 was observed in the presence of Zn2+ in ethanol-water (V : V=9 : 1) solution, which provided ratiometric fluorescence detection of Zn2+. Additionally, the ratiometric fluorescence response of 1 to Zn2+ was nearly completed within 0.5min, which suggested that this probe 1 could be utilized for sensing and monitoring Zn2+ in environmental and biological systems for real-time detection.
      Graphical abstract image

      PubDate: 2016-12-05T10:09:05Z
      DOI: 10.1016/j.saa.2016.11.034
      Issue No: Vol. 174 (2016)
       
  • Tyrosine fluorescence probing of conformational changes in
           tryptophan-lacking domain of albumins
    • Authors: N.G. Zhdanova; E.G. Maksimov; A.M. Arutyunyan; V.V. Fadeev; E.A. Shirshin
      Pages: 223 - 229
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): N.G. Zhdanova, E.G. Maksimov, A.M. Arutyunyan, V.V. Fadeev, E.A. Shirshin
      We addressed the possibility of using tyrosine (Tyr) fluorescence for monitoring conformational changes of proteins which are undetectable via tryptophan (Trp) fluorescence. The model objects, human (HSA) and bovine (BSA) serum albumins, contain one and two Trp residues, respectively, while Tyr is more uniformly distributed over their structure. The results of the investigation of albumins interaction with ethanol using intrinsic Trp and Tyr steady-state and time-resolved picosecond fluorescence indicated the presence of an intermediate at 10% (v/v) of ethanol in solution, that was supported by the results of extrinsic fluorescence measurements with the Nile Red dye. Based on the comparison of HSA and BSA Trp and Tyr fluorescence, it was suggested that conformational changes at low ethanol concentration are located in the domain III of albumins, which lacks tryptophan residues. The sensitivity of Tyr fluorescence to domain III alterations was further verified by studying albumins interaction with GdnHCl.
      Graphical abstract image

      PubDate: 2016-12-05T10:09:05Z
      DOI: 10.1016/j.saa.2016.11.038
      Issue No: Vol. 174 (2016)
       
  • A novel ratiometric fluorescent probe based on 1, 8-naphthalimide for the
           detection of Ho3+ and its bioimaging
    • Authors: Huifang Zhang; Tao Liu; Caixia Yin; Yin Wen; Jianbin Chao; Yongbin Zhang; Fangjun Huo
      Pages: 230 - 235
      Abstract: Publication date: 5 March 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 174
      Author(s): Huifang Zhang, Tao Liu, Caixia Yin, Yin Wen, Jianbin Chao, Yongbin Zhang, Fangjun Huo
      A ratiometric fluorescent probe for the detection of Ho3+ in DMSO-aqueous medium was designed and synthesized based on 1, 8-naphthalimide. The probe displayed response to Ho3+ with a fluorescence decrease at 512nm and enhancement at 480nm, accompanying with a distinct fluorescence change from bright yellow-green to cyan. Besides, the probe exhibited a lower detection limit (6×10−8 M) and could be used in intracellular fluorescence imaging. To the best of the knowledge, it was the first ratiometric fluorescent probe for Ho3+ detection. This probe was expected to be a useful tool for further elucidating the roles of Ho3+ in materials, biology and environment.
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      PubDate: 2016-12-05T10:09:05Z
      DOI: 10.1016/j.saa.2016.11.039
      Issue No: Vol. 174 (2016)
       
  • Determination of dopamine hydrochloride by host-guest interaction based on
           water-soluble pillar[5]arene
    • Authors: Xue-Dong Xiao; Lin Shi; Li-Hui Guo; Jun-Wen Wang; Xiang Zhang
      Pages: 6 - 12
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Xue-Dong Xiao, Lin Shi, Li-Hui Guo, Jun-Wen Wang, Xiang Zhang
      The supramolecular interaction between the water-soluble pillar[5]arene (WP[5]) as host and dopamine hydrochloride (DH) as guest was studied by spectrofluorometry. The fluorescence intensity of DH gradually decreased with increasing WP[5] concentration, and the possible interaction mechanism between WP[5] and DH was confirmed by 1H NMR, 2D NOESY, and molecular modelling. Based on significant DH fluorescence, a highly sensitive and selective method for DH determination was developed for the first time. The fluorescence intensity was measured at 312nm, with excitation at 285nm. The effects of pH, temperature, and reaction time on the fluorescence spectra of the WP[5]-DH complex were investigated. A linear relationship between fluorescence intensity and DH concentration in the range of 0.07–6.2μgmL−1 was obtained. The corresponding linear regression equation is ΔF =25.76 C +13.56 (where C denotes the concentration in μgmL−1), with the limit of detection equal to 0.03μgmL−1 and the correlation coefficient equal to 0.9996. This method can be used for the determination of dopamine in injection and urine samples. In addition, the WP[5]-DH complex has potential applications in fluorescent sensing and pharmacokinetics studies of DH.
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      PubDate: 2016-09-04T05:25:50Z
      DOI: 10.1016/j.saa.2016.08.050
      Issue No: Vol. 173 (2016)
       
  • Vibrational monitor of early demineralization in tooth enamel after in
           vitro exposure to phosphoridic liquid
    • Authors: Giuseppe Pezzotti; Tetsuya Adachi; Isabella Gasparutti; Giulio Vincini; Wenliang Zhu; Marco Boffelli; Alfredo Rondinella; Elia Marin; Hiroaki Ichioka; Toshiro Yamamoto; Yoshinori Marunaka; Narisato Kanamura
      Pages: 19 - 33
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Giuseppe Pezzotti, Tetsuya Adachi, Isabella Gasparutti, Giulio Vincini, Wenliang Zhu, Marco Boffelli, Alfredo Rondinella, Elia Marin, Hiroaki Ichioka, Toshiro Yamamoto, Yoshinori Marunaka, Narisato Kanamura
      The Raman spectroscopic method has been applied to quantitatively assess the in vitro degree of demineralization in healthy human teeth. Based on previous evaluations of Raman selection rules (empowered by an orientation distribution function (ODF) statistical algorithm) and on a newly proposed analysis of phonon density of states (PDOS) for selected vibrational modes of the hexagonal structure of hydroxyapatite, a molecular-scale evaluation of the demineralization process upon in vitro exposure to a highly acidic beverage (i.e., CocaCola™ Classic, pH=2.5) could be obtained. The Raman method proved quite sensitive and spectroscopic features could be directly related to an increase in off-stoichiometry of the enamel surface structure since the very early stage of the demineralization process (i.e., when yet invisible to other conventional analytical techniques). The proposed Raman spectroscopic algorithm might possess some generality for caries risk assessment, allowing a prompt non-contact diagnostic practice in dentistry.
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      PubDate: 2016-09-04T05:25:50Z
      DOI: 10.1016/j.saa.2016.08.036
      Issue No: Vol. 173 (2016)
       
  • Raman investigation on the behavior of parasibirskite CaHBO3 at high
           pressure
    • Authors: S.V. Goryainov; Y. Pan; M.B. Smirnov; W. Sun; J.-X. Mi
      Pages: 46 - 52
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): S.V. Goryainov, Y. Pan, M.B. Smirnov, W. Sun, J.-X. Mi
      Knowledge about the stability of hydrous borates and borosilicates at high pressures are of critical importance to our understanding on the boron geochemical cycle. Raman spectroscopic measurements of parasibirskite CaHBO3, containing the [BO2(OH)] groups, have been made to pressures up to 5.4GPa. The Raman data show that a progressive structural evolution from ambient pressure to 5.4GPa can be accounted for by the same monoclinic phase P21/m, where the splitting of several Raman bands observed at some pressures is interpreted as the effect of the complex disordering in the H-bond network that has bifurcated H-bonds and ½–occupied H sites. There is no unambiguous evidence for phase transition to the ordered P21 monoclinic phase predicted by first-principles calculations at T =0K (W. Sun et al., Can. Miner., 2011). On the contrary, the disordering of parasibirskite, evidenced by the widening and attenuating Raman spectra, increases markedly at high pressures above 4.5GPa that results in incipient amorphization. Comparison of theoretical (lattice-dynamical) and experimental Raman spectra allows the reliable interpretation of almost all observed bands. The strongest symmetric B-O stretching band v 1 at the wavenumber 908cm−1, which is split into a doublet at high pressures, exhibits a shift rate of 4.22cm−1/GPa for the main component.
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      PubDate: 2016-09-04T05:25:50Z
      DOI: 10.1016/j.saa.2016.08.040
      Issue No: Vol. 173 (2016)
       
  • “Long-distance” H/D isotopic self-organization phenomena in scope of
           the infrared spectra of hydrogen-bonded terephthalic and phthalic acid
           crystals
    • Authors: Henryk T. Flakus; Barbara Hachuła; Jakub T. Hołaj-Krzak; Faisal A. Al-Agel; Najeh Rekik
      Pages: 65 - 74
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Henryk T. Flakus, Barbara. Hachuła, Jakub T. Hołaj-Krzak, Faisal A. Al-Agel, Najeh Rekik
      This paper deals with the experimental and theoretical studies of abnormal properties of terephthalic acid (TAC) and phthalic acid (PAC) crystals manifested in the H/D isotopic exchange. The widely utilized deuteration routine appeared to be insufficiently effective in the case of the h6-TAC isotopomer. In the case of the d4-TAC derivative the isotopic exchange process occurred noticeably more effectively. In contrast, both isotopomers of PAC, h6 and d4, appeared much more susceptible for deuteration. A theoretical model was elaborated describing “long-distance” dynamical co-operative interactions involving hydrogen bonds in TAC and PAC crystals. The model assumes extremely strong dynamical co-operative interactions of hydrogen bonds from the adjacent (COOH)2 cycles. This leads to an additional stabilization of h6–TAC molecular chains. The interaction energies affect the chemical equilibrium of the H/D isotopic exchange. The model predicts a differentiated influence of the H and D atoms linked to the aromatic rings on to the process. In this approach the totally-symmetric CH bond stretching vibrations and the proton stretching totally symmetric vibrations couple with the π-electronic motions. It was also shown that identical hydrogen isotope atoms, H or D, in whole TAC molecules, noticeably enlarge the energy of the dynamical co-operative interactions in the crystals, in contrast to the case of different hydrogen isotopes present in the carboxyl groups and linked to the aromatic rings. The “long-distance” dynamical co-operative interactions in PAC crystals were found of a minor importance due to the electronic properties of PAC molecules.
      Graphical abstract image

      PubDate: 2016-09-04T05:25:50Z
      DOI: 10.1016/j.saa.2016.08.051
      Issue No: Vol. 173 (2016)
       
  • Spectroscopic study for a chromium-adsorbed montmorillonite
    • Authors: Maidina · Nurtay; Maierdan · Tuersun; Yuanfeng Cai; Muhammed Açıkgöz; Hongtao Wang; Yuguan Pan; Xiaoke Zhang; Xiaomei Ma
      Pages: 114 - 121
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Maidina · Nurtay, Maierdan · Tuersun, Yuanfeng Cai, Muhammed Açıkgöz, Hongtao Wang, Yuguan Pan, Xiaoke Zhang, Xiaomei Ma
      Samples of purified montmorillonite with trace amounts of quartz were subjected to different concentrations of chromium sulphate solutions for one week to allow cation exchange. The chromium-bearing montmorillonites were verified and tested using powder X-ray diffractometry (XRD), X-ray fluorescence spectrometry, electron spin resonance (ESR) spectrometry and Fourier transformation infrared (FTIR) spectroscopy to explore the occupation sites of the chromium. The ESR spectra recorded before and after the chromium exchange show clear differences: a strong and broad resonance with two shoulders at the lower magnetic field side was present to start, and its intensity as well as that of the ferric iron resonance, increased with the concentration of added chromium. The signals introduced by the chromium, for example at g=1.975 and 2.510 etc., suggested that the chromium had several occupational sites. The ESR peak with g=2.510 in the second derivative spectrum suggested that Cr3+ was weakly bounded to TOT with the form of [Cr(H2O)3]3+ in hexagonal cavities. This was verified by comparing the FTIR spectra of the pure and modified montmorillonite. The main resonance centred at g=1.975 indicated that the majority of Cr3+ occupied the interlayer region as [Cr(H2O)6]3+. The substitution of Ca2+ by Cr3+ also greatly affected the vibration of the hydrogens associate to water, ranged from 3500 to 2600cm-1 in FTIR. Furthermore, the presence of two diffraction lines in the XRD results (specifically those with d-values of 1.5171 and 1.2673nm) and the calculations of the size of the interlayer space suggested the presence of two types of montmorillonite with different hydration cations in the sample exposed to 0.2M chromium sulphate. The two diffraction lines were assigned to [Cr(H2O)6]3+ and [Cr(H2O)3O3]3+, respectively. This also suggested that the species of hydration cation was constrained by the concentration of the chromium solution.
      Graphical abstract image

      PubDate: 2016-09-17T15:34:56Z
      DOI: 10.1016/j.saa.2016.08.045
      Issue No: Vol. 173 (2016)
       
  • Study on binding and fluorescence energy transfer efficiency of Rhodamine
           B with Pluronic F127-gold nanohybrid using optical spectroscopy methods
    • Authors: Jenif Dsouza Antonisamy; Jitendriya Swain; Sasmita Dash
      Pages: 139 - 143
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Jenif Dsouza Antonisamy, Jitendriya Swain, Sasmita Dash
      This work focuses on the binding efficiency and fluorescence resonance energy transfer (FRET) of fluorescent dye Rhodamine B (Rh B) to Pluronic F127-gold nanohybrid. The formation of gold nanoparticles inside Rh B doped Pluronic F127 copolymer have been characterized using dynamic light scattering study, HR-TEM images, UV–visible spectra and fluorescence studies. Fluorescence quenching and the constant fluorescence lifetime of the Rhodamine B present in the cavity of Pluronic F127-gold nanohybrid suggested a strong binding ability (3.5×103 Lmol−1), static nature of quenching and better energy transfer efficiency of fluorescent dye towards Pluronic F127-gold (Au) nanohybrids.
      Graphical abstract image

      PubDate: 2016-09-17T15:34:56Z
      DOI: 10.1016/j.saa.2016.09.002
      Issue No: Vol. 173 (2016)
       
  • Electronic states of Myricetin. UV–Vis polarization spectroscopy and
           quantum chemical calculations
    • Authors: Danijela Vojta; Eva Marie Karlsen; Jens Spanget-Larsen
      Pages: 182 - 187
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Danijela Vojta, Eva Marie Karlsen, Jens Spanget-Larsen
      Myricetin (3,3′,4′,5,5′,7′-hexahydroxyflavone) was investigated by linear dichroism spectroscopy on molecular samples partially aligned in stretched poly(vinyl alcohol) (PVA). At least five electronic transitions in the range 40,000–20,000cm−1 were characterized with respect to their wavenumbers, relative intensities, and transition moment directions. The observed bands were assigned to electronic transitions predicted with TD-B3LYP/6-31+G(d,p).
      Graphical abstract image

      PubDate: 2016-09-22T17:31:47Z
      DOI: 10.1016/j.saa.2016.09.012
      Issue No: Vol. 173 (2016)
       
  • The weak fundamental NH-stretching transition in amines
    • Authors: Sidsel D. Schrøder; Anne S. Hansen; Jens H. Wallberg; Anne R. Nielsen; Lin Du; Henrik G. Kjaergaard
      Pages: 201 - 206
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Sidsel D. Schrøder, Anne S. Hansen, Jens H. Wallberg, Anne R. Nielsen, Lin Du, Henrik G. Kjaergaard
      Absolute intensities of NH-stretching fundamental and overtone transitions of gas phase aniline, methylamine, ethylamine, cyclopropylamine, methylethylamine, diethylamine and pyrrolidine have been measured with long path length conventional absorption spectroscopy. To support the assignments of NH-stretching transitions, transition frequencies and intensities were calculated with the local mode model using ab initio calculated local mode parameters and dipole moment functions obtained at the CCSD(T)-F12a/VDZ-F12 level of theory. For aniline, the absolute intensities of the NH-stretching transitions show the typical decrease of approximately an order of magnitude for each successive vibrational excitation. For methylamine, ethylamine, cyclopropylamine, methylethylamine, diethylamine and pyrrolidine, the observed absolute intensities of the fundamental NH-stretching transition is weak and of similar strength or even weaker than the corresponding first overtone transition. Characteristic for the amines with a normal fundamental intensity is a conjugated double bond next to the amine group.

      PubDate: 2016-09-22T17:31:47Z
      DOI: 10.1016/j.saa.2016.09.003
      Issue No: Vol. 173 (2016)
       
  • Characterization of chlorophyll derivatives in micelles of polymeric
           surfactants aiming photodynamic applications
    • Authors: Adriana Passarella Gerola; Flavia Amanda Pedroso de Morais; Paulo Fernando A. Costa; Elza Kimura; Wilker Caetano; Noboru Hioka
      Pages: 213 - 221
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Adriana Passarella Gerola, Flavia Amanda Pedroso de Morais, Paulo Fernando A. Costa, Elza Kimura, Wilker Caetano, Noboru Hioka
      The spectrophotometric properties of chlorophylls' derivatives (Chls) formulated in the Pluronics® F-127 and P-123 were evaluated and the results have shown that the Chls were efficiently solubilized in these drug delivery systems as monomers. The relative location of the Chls in the Pluronics® was estimated from the Stokes shift and micropolarity of the micellar environment. Chls with phytyl chain were located in the micellar core, where the micropolarity is similar to ethanol, while phorbides' derivatives (without phytyl chain) were located in the outer shell of the micelle, i.e., more polar environment. In addition, the thermal stability of the micellar formulations was evaluated through electronic absorption, fluorescence emission and resonance light scattering with lowering the temperature. The Chls promote the stability of the micelles at temperatures below the Critical Micellar Temperature (CMT) of these surfactants. For F-127 formulations, the water molecules drive through inside the nano-structure at temperatures below the CMT, which increased the polarity of this microenvironment and directly affected the spectrophotometric properties of the Chls with phytyl chain. The properties of the micellar microenvironment of P-123, with more hydrophobic core due to the small PEO/PPO fraction, were less affected by lowering the temperature than for F-127. These results enable us to better understand the Chls behavior in micellar copolymers and allowed us to design new drug delivery system that maintains the photosensitizer's properties for photodynamic applications.
      Graphical abstract image

      PubDate: 2016-09-22T17:31:47Z
      DOI: 10.1016/j.saa.2016.09.019
      Issue No: Vol. 173 (2016)
       
  • Influence of structural and solvation factors on the spectral-fluorescent
           properties of alkyl-substituted BODIPYs in solutions
    • Authors: Natalia A. Bumagina; Elena V. Antina; Mikhail B. Berezin; Alexander A. Kalyagin
      Pages: 228 - 234
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Natalia A. Bumagina, Elena V. Antina, Mikhail B. Berezin, Alexander A. Kalyagin
      The spectral-fluorescent properties of alkyl-substituted BODIPYs 1–5 in organic solvents were investigated. The alkyl-substituted BODIPYs 1–5 exhibit intense chromophoric properties (lgε =4.60–5.00). Relative fluorescence quantum yield of studied compounds reaches 66–100% and weakly dependent on the structural and solvation effects. Introduction of methyl, propyl, amyl and heptyl substituents in the 2,6-positions of the pyrroles the results in a significant red shift (22–29nm) in the electronic absorption and fluorescence spectra.
      Graphical abstract image

      PubDate: 2016-09-26T18:03:06Z
      DOI: 10.1016/j.saa.2016.09.026
      Issue No: Vol. 173 (2016)
       
  • Substituent effect in the photochromism of two isomeric asymmetric
           diarylethenes having pyrrole and thiophene units
    • Authors: Renjie Wang; Xiaoxia Zhang; Shouzhi Pu; Gang Liu; Yanfeng Dai
      Pages: 257 - 263
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Renjie Wang, Xiaoxia Zhang, Shouzhi Pu, Gang Liu, Yanfeng Dai
      Two new asymmetric isomeric diarylethenes having pyrrole and thiophene units have been synthesized by one-pot reaction and characterized by single crystal X-ray diffraction analysis. The two prepared diarylethenes had disparate crystal structures, and they exhibited distinctly different photochromic behavior, both in solution and in the solid state. Their photochromism, fatigue resistance, and fluorescence were investigated systematically. The methyl group at the reactive carbon atom could significantly enhance the quantum yield of cyclization step and decrease the quantum yield of cycloreversion step, whereas a cyano group at the same position could notably suppress the photocyclization reaction and promote the photocycloreversion reaction. The results indicated that the substituent at the reactive carbon atom could readily modulate the optoelectronic and physical properties for these diarylethenes.
      Graphical abstract image

      PubDate: 2016-09-26T18:03:06Z
      DOI: 10.1016/j.saa.2016.09.029
      Issue No: Vol. 173 (2016)
       
  • Photophysical behavior and photodynamic therapy activity of conjugates of
           zinc monocarboxyphenoxy phthalocyanine with human serum albumin and
           chitosan
    • Authors: David O. Oluwole; Earl Prinsloo; Tebello Nyokong
      Pages: 292 - 300
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): David O. Oluwole, Earl Prinsloo, Tebello Nyokong
      Zinc monocarboxyphenoxy phthalocyanine (ZnMCPPc) was linked to human serum albumin (HSA) and chitosan via amide bond formation. The photophysical behavior and photodynamic therapy (PDT) activity (against human breast adenocarcinoma cell line (MCF-7 cells) of ZnMCPPc alone and its conjugates were investigated. The conjugates showed improved fluorescence, triplet and singlet oxygen quantum yields when compared to ZnMCPPc alone. The in vitro dark cytotoxicity and PDT studies were carried out at a dose of 3.6μg/mL to 57.1μg/mL. The in vitro dark cytotoxicity studies of ZnMCPPc showed cell viability <50% at 28.6μg/mL and 57.1μg/mL, while the conjugates showed > 50% in all their tested concentrations (3.6 to 57.1) μg/mL. Thus, conjugation of ZnMCPPc to HSA and chitosan improves its dark cytotoxicity, an important criteria for molecules meant for photodynamic therapy. Complex 1 showed the most efficacious PDT activity with cell viability <50% at concentration range of (14.3 to 57.1) μg/mL in comparison to the conjugates which only showed <50% cell viability at 28.6μg/mL and 57.1μg/mL for 1-HSA and 57.1μg/mL for 1-Chitosan.
      Graphical abstract image

      PubDate: 2016-09-26T18:03:06Z
      DOI: 10.1016/j.saa.2016.09.032
      Issue No: Vol. 173 (2016)
       
  • Förster resonance energy transfer and excited state life time reduction
           of rhodamine 6G with NiO nanorods in PVP films
    • Authors: B. Karthikeyan
      Pages: 301 - 306
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): B. Karthikeyan
      In the present study, we report the preparation of NiO nanorods (NNR) and its Förster resonant energy transfer (FRET) behaviour with rhodamine 6G (R6G) in a Polyvinyl pyrrolidone (PVP) polymer matrix. The prepared nanocomposite polymer (NCP) films contain PVP and R6G whose concentrations are kept constant and different concentrations of NNR. Spectral overlap between the absorption and fluorescence spectrum of R6G and NNR shows the possibility of FRET phenomena to be occurring in the prepared NCP films. Steady state and time resolved fluorescence measurements are carried out at two excitation wavelengths (330 and 510nm) to study the energy transfer process between R6G and NNR in the PVP host. The obtained results show that the energy transfer is from R6G (serves as a donor) to NNR (functions as an acceptor). Calculated radiative efficiencies, donor–acceptor distances and average lifetime also confirm the energy transfer from R6G to NNR.
      Graphical abstract image

      PubDate: 2016-09-26T18:03:06Z
      DOI: 10.1016/j.saa.2016.09.004
      Issue No: Vol. 173 (2016)
       
  • Understanding the complexation of Eu3+ with potential ligands used for
           preferential separation of lanthanides and actinides in various stages of
           nuclear fuel cycle: A luminescence investigation
    • Authors: Arijit Sengupta; R.M. Kadam
      Pages: 328 - 334
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Arijit Sengupta, R.M. Kadam
      A systematic photoluminescence based investigation was carried out to understand the complexation of Eu3+ with different ligands (TBP: tri-n-butyl phosphate, DHOA: di-n-hexyl octanamide, Cyanex 923: tri-n-alkyl phosphine oxide and Cyanex 272: Bis (2,4,4 trimethyl) pentyl phosphinic acid) used for preferential separation of lanthanides and actinides in various stages of nuclear fuel cycle. In case of TBP and DHOA complexes, 3 ligand molecules coordinated in monodentate fashion and 3 nitrate ion in bidentate fashion to Eu3+ to satisfy the 9 coordination of Eu. In case of Cyanex 923 and Cyanex 272 complexes, 3 ligand molecules, 3 nitrate ion and 3 water molecules coordinated to Eu3+ in monodentate fashion. The Eu complexes of TBP and DHOA were found to have D3h local symmetry while that for Cyanex 923 and Cyanex 272 were C3h. Judd–Ofelt analysis of these systems revealed that the covalency of EuO bond followed the trend DHOA>TBP>Cyanex 272>Cyanex 923. Different photophysical properties like radiative and non-radiative life time, branching ratio for different transitions, magnetic and electric dipole moment transition probabilities and quantum efficiency were also evaluated and compared for these systems. The magnetic dipole transition probability was found to be almost independent of ligand field perturbation while electric dipole transition probability for 5D0-7F2 transition was found to be hypersensitive with ligand field with a trend DHOA>TBP>Cyanex 272>Cyanex 923.
      Graphical abstract image

      PubDate: 2016-09-26T18:03:06Z
      DOI: 10.1016/j.saa.2016.09.021
      Issue No: Vol. 173 (2016)
       
  • Classification and quantification of palm oil adulteration via portable
           NIR spectroscopy
    • Authors: Katrul Nadia Basri; Mutia Nurulhusna Hussain; Jamilah Bakar; Zaiton Sharif; Mohd Fared Abdul Khir; Ahmad Sabirin Zoolfakar
      Pages: 335 - 342
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Katrul Nadia Basri, Mutia Nurulhusna Hussain, Jamilah Bakar, Zaiton Sharif, Mohd Fared Abdul Khir, Ahmad Sabirin Zoolfakar
      Short wave near infrared spectroscopy (NIR) method was used to detect the presence of lard adulteration in palm oil. MicroNIR was set up in two different scan modes to study the effect of path length to the performance of spectral measurement. Pure and adulterated palm oil sample were classified using soft independent modeling class analogy (SIMCA) algorithm with model accuracy more than 0.95 reported for both transflectance and transmission modes. Additionally, by employing partial least square (PLS) regression, the coefficient of determination (R 2) of transflectance and transmission were 0.9987 and 0.9994 with root mean square error of calibration (RMSEC) of 0.5931 and 0.6703 respectively. In order to remove the uninformative variables, variable selection using cumulative adaptive reweighted sampling (CARS) has been performed. The result of R 2 and RMSEC after variable selection for transflectance and transmission were improved significantly. Based on the result of classification and quantification analysis, the transmission mode has yield better prediction model compared to the transflectance mode to distinguish the pure and adulterated palm oil.
      Graphical abstract image

      PubDate: 2016-09-26T18:03:06Z
      DOI: 10.1016/j.saa.2016.09.028
      Issue No: Vol. 173 (2016)
       
  • Spectroscopic investigation on porphyrins nano-assemblies onto gold
           nanorods
    • Authors: Mariachiara Trapani; Giovanna De Luca; Andrea Romeo; Maria Angela Castriciano; Luigi Monsù Scolaro
      Pages: 343 - 349
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Mariachiara Trapani, Giovanna De Luca, Andrea Romeo, Maria Angela Castriciano, Luigi Monsù Scolaro
      The interaction between gold nanorods (Au NRs), synthesized by a conventional seeded growth protocol, and the anionic tetrakis-(4-sulfonatophenyl)porphyrin (TPPS4) has been investigated through various spectroscopic techniques. At neutral pH, the formation of H-aggregates and the inclusion of porphyrin monomers in CTAB micelles covering the nanorods have been evidenced. Under mild acidic conditions (pH=3) a nano-hybrid assembly of porphyrin J-aggregates and Au NRs has been revealed. For the sake of comparison, Cu(II) and Zn(II) metal porphyrin derivatives as well as a cationic porphyrin have been studied in the same experimental conditions, showing that: i) CuTPPS4 forms porphyrin H-dimers onto the Au NRs; ii) ZnTPPS4 undergoes to demetallation, followed by acidification of the central core and eventually aggregation onto Au NRs; iii) cationic porphyrin does not interact with Au NRs.
      Graphical abstract image

      PubDate: 2016-09-26T18:03:06Z
      DOI: 10.1016/j.saa.2016.09.025
      Issue No: Vol. 173 (2016)
       
  • Resonance Raman spectroscopy study of protonated porphyrin
    • Authors: A. Gorski; A. Starukhin; S. Stavrov; S. Gawinkowski; J. Waluk
      Pages: 350 - 355
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): A. Gorski, A. Starukhin, S. Stavrov, S. Gawinkowski, J. Waluk
      Resonance Raman microscopy was used to study the resonance Raman scattering of the diacid (diprotonated form) of free-base porphyrin (21H,23H–porphine) in a crystal powder and KBr pellets. Intensive lines in the spectral range between 100÷1000cm−1 have been detected and assigned as spectral manifestation of out-of-plane modes. The Raman spectra were simulated by means of DFT methods and compared with the experimental data. It is evident from experimental and theoretical results that the activation of out-of-plane modes arises from saddle distortion of the porphyrin macrocycle upon formation of its diprotonated form.
      Graphical abstract image

      PubDate: 2016-09-26T18:03:06Z
      DOI: 10.1016/j.saa.2016.09.038
      Issue No: Vol. 173 (2016)
       
  • Pyrene excimer-based fluorescent sensor for detection and removal of Fe3+
           and Pb2+ from aqueous solutions
    • Authors: Meili Zhao; Xiufen Zhou Jian Tang Zhifu Deng Xuan Zhi
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Meili Zhao, Xiufen Zhou, Jian Tang, Zhifu Deng, Xuan Xu, Zhi Chen, Xutian Li, Liting Yang, Li-Jun Ma
      Pyrene excimer usually serves as a chromogenic unit for developing ratiometric fluorescent sensors. But this study used excimer as a large hydrophobic group to regulate the molecular hydrophobicity, and obtained a new fluorescent sensor, N, N-bi[4(1-pyrene)-butyroyl]ornithine (1), for detection and removal of Fe3+ and Pb2+ from aqueous solutions. The coordination of 1 and Fe3+ in the aqueous solution or even pure water forms removable flocculent precipitates, accompanied by obvious fluorescent quenching of emission spectra. In aqueous solutions containing 40% (v/v) acetonitrile, the special responses exhibit a high selectivity and sensitivity to Fe3+ over other common metal ions. However, in aqueous solutions containing 40% (v/v) dimethylsulfoxide, the probe exhibits the analogous fluorescent quenching responses and the removable flocculent precipitates in the presence Fe3+ and Pb2+. These results indicate that the extremely hydrophobic 1-Fe3+/Pb2+ complexes are not only a supplement to the fluorescent sensing of Fe3+ and Pb2+, but also a requirement to the removal of Fe3+ and Pb2+ from aqueous solutions.
      Graphical abstract image

      PubDate: 2016-09-26T18:03:06Z
       
  • Color-tunable emission and energy transfer investigation in
           Sr3Y(PO4)3:Ce3+,Tb3+ phosphors for white LEDs
    • Authors: Anxiang Guan; Peican Chen Liya Zhou Guofang Wang Xiaoshan Zhang
      Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Anxiang Guan, Peican Chen, Liya Zhou, Guofang Wang, Xiaoshan Zhang, Jingqi Tang
      A novel color-tunable phosphor Sr3Y(PO4)3:Ce3+,Tb3+ was synthesized through solid-state reaction method. Several techniques, such as X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy, were used to investigate the obtained phosphors. Results of luminescence spectra and decay time measurements revealed that an efficient energy transfer occurred from Ce3+ to Tb3+ via a dipole–dipole mechanism, where Ce3+ exhibited a strong excitation band in the near-ultraviolet region. CIE chromaticity coordinates were tuned from deep blue (0.162, 0.090) to green (0.230, 0.411) by adjusting the relative concentrations between Ce3+ and Tb3+ ions. Results revealed that the as-synthesized phosphors had color-tunable characteristics and can be used as promising materials in the field of phosphor-converted white light-emitting diodes.
      Graphical abstract image

      PubDate: 2016-09-04T05:25:50Z
       
 
 
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