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Journal Cover Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
  [SJR: 0.717]   [H-I: 80]   [7 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1386-1425
   Published by Elsevier Homepage  [3039 journals]
  • 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
    • 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.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Förster resonance energy transfer and excited state life time reduction
           of rhodamine 6G with NiO nanorods in PVP films
    • 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.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Spectroscopic investigation on porphyrins nano-assemblies onto gold
           nanorods
    • 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.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Classification and quantification of palm oil adulteration via portable
           NIR spectroscopy
    • 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.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Influence of structural and solvation factors on the spectral-fluorescent
           properties of alkyl-substituted BODIPYs in solutions
    • 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.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Photophysical behavior and photodynamic therapy activity of conjugates of
           zinc monocarboxyphenoxy phthalocyanine with human serum albumin and
           chitosan
    • 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.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Substituent effect in the photochromism of two isomeric asymmetric
           diarylethenes having pyrrole and thiophene units
    • 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.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Pyrene excimer-based fluorescent sensor for detection and removal of Fe3+
           and Pb2+ from aqueous solutions
    • 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.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Resonance Raman spectroscopy study of protonated porphyrin
    • 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.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Interaction of bombesin and its fragments with gold nanoparticles analyzed
           using surface-enhanced Raman spectroscopy
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Agnieszka Tąta, Aleksandra Szkudlarek, Younkyoo Kim, Edyta Proniewicz
      This work demonstrates the application of commercially available stable surface composed of gold nanograins with diameters ranging from 70 to 226nm deposited onto silicon wafer for surface-enhanced Raman scattering investigations of biologically active compounds, such as bombesin (BN) and its fragments. BN is an important neurotransmitter involved in a complex signaling pathways and biological responses; for instance, hypertensive action, contractive on uterus, colon or ileum, locomotor activity, stimulation of gastric and insulin secretion as well as growth promotion of various tumor cell lines, including: lung, prostate, stomach, colon, and breast. It has also been shown that 8–14 BN C-terminal fragment partially retains the biological activity of BN. The SERS results for BN and its fragment demonstrated that (1) three amino acids from these peptides sequence; i.e., l-histidine, l-methionine, and l-tryptophan, are involved in the interaction with gold coated silicon wafer and (2) the strength of these interactions depends upon the aforementioned amino acids position in the peptide sequence.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Design, synthesis and DNA-binding study of some novel morpholine linked
           thiazolidinone derivatives
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Javeed Ahmad War, Santosh Kumar Srivastava, Savitri Devi Srivastava
      The emergence of multiple drug resistance amongst bacterial strains resulted in many clinical drugs to be ineffective. Being vulnerable to bacterial infections any lack in the development of new antimicrobial drugs could pose a serious threat to public health. Here we report design and synthesis of a novel class of morpholine linked thiazolidinone hybrid molecules. The compounds were characterized by FT-IR, NMR and HRMS techniques. Susceptibility tests showed that most of the synthesized molecules were highly active against multiple bacterial strains. Compound 3f displayed MIC values which were better than the standard drug for most of the tested strains. DNA being a well defined target for many antimicrobial drugs was probed as possible target for these synthetic molecules. DNA-binding study of 3f with sm-DNA was probed through UV–vis absorption, fluorescence quenching, gel electrophoresis and molecular docking techniques. The studies revealed that compound 3f has strong affinity towards DNA and binds at the minor groove. The docking studies revealed that the compound 3f shows preferential binding towards A/T residues.
      Graphical abstract image

      PubDate: 2016-09-26T18:03:06Z
       
  • Time-resolved fluorescence observation of di-tyrosine formation in
           horseradish peroxidase upon ultrasound treatment leading to enzyme
           inactivation
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Konstantina Tsikrika, M. Adília Lemos, Boon-Seang Chu, David H. Bremner, Graham Hungerford
      The application of ultrasound to a solution can induce cavitional phenomena and generate high localised temperatures and pressures. These are dependent of the frequency used and have enabled ultrasound application in areas such as synthetic, green and food chemistry. High frequency (100kHz to 1MHz) in particular is promising in food chemistry as a means to inactivate enzymes, replacing the need to use periods of high temperature. A plant enzyme, horseradish peroxidase, was studied using time-resolved fluorescence techniques as a means to assess the effect of high frequency (378kHz and 583kHz) ultrasound treatment at equivalent acoustic powers. This uncovered the fluorescence emission from a newly formed species, attributed to the formation of di-tyrosine within the horseradish peroxidase structure caused by auto-oxidation, and linked to enzyme inactivation.
      Graphical abstract image

      PubDate: 2016-09-26T18:03:06Z
       
  • 2,3-Pyridine dicarboxylic acid functionalized gold nanoparticles: Insight
           into experimental conditions for Cr3+ sensing
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Ruqaya Shaikh, Najma Memon, Amber R. Solangi, Huma I. Shaikh, Muhammad Hassan Agheem, Syed Abid Ali, Muhammad Raza Shah, Aftab Kandhro
      Selectivity of gold nanoparticles (AuNPs) depends upon surface functionality; small changes in structure or concentration bring significant changes in the behavior of AuNPs. In this study, citrate-capped AuNPs were functionalized with ortho-dicarboxylate substituted pyridine (2,3-PDCA) and detailed studies on experimental conditions were carried out to check the stability of AuNPs and response for Cr3+. Stability of PDCA-AuNPs was found sensitive to the pH, ionic strength of buffer and its type. Capping behavior of PDCA on C-AuNPs was examined by FTIR spectroscopy. Surface morphology and size of synthesized AuNPs were confirmed by AFM, XRD, and DLS techniques where particles were found 11nm in size, monodisperse and spherical in shape. Interaction of stabilized AuNPs was tested with various metal ions; where Cr3+ induced the changes in localized surface plasmon band (LSPR) of PDCA-AuNPs which leads to a color change from wine red to violet blue. The phenomenon is explained as cooperative effect of citrate and pyridine nitrogen on surface of AuNPs in contrary to meta-dicarboxylate substituted pyridine derivatives. Further, under optimized and controlled conditions Cr3+ shows linear response with decrease in absorbance at LSPR intensity of AuNPs (518nm). Moreover, to demonstrate the applicability of method, Cr3+ was determined in the presence of Cr (VI) which shows 96% recovery.
      Graphical abstract image

      PubDate: 2016-09-26T18:03:06Z
       
  • Ultrasensitive turn-on fluorescence detection of Cu2+ based on
           p-dimethylaminobenzamide derivative and the application to cell imaging
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Peng-Cheng Huang, Hao Fang, Jing-Jing Xiong, Fang-Ying Wu
      A new p-dimethylaminobenzamide derivative based compound BDIH has been synthesized. Cu2+ turned on the fluorescence of compound BDIH with a 1:2 binding stoichiometry. The fluorescent color of compound BDIH shows an evident change from colorless to bright blue upon the addition of Cu2+, which could be visibly detected by the naked eye under UV light at 365nm. More importantly, the detection limit was found to be 0.64nM which is far lower than the maximal allowed concentration of the WHO limit (31.5μM) for drinking water. This selective “turn-on” fluorescence sensor was used to identify Cu2+ in living cells using confocal fluorescence microscopy, indicating that compound BDIH has a potential application for selective detection of Cu2+ in organism.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Analytical investigation of Mudéjar polychrome on the carpentry in the
           Casa de Pilatos palace in Seville using non-destructive XRF and
           complementary techniques
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): M.A. Garrote, M.D. Robador, J.L. Perez-Rodriguez
      The pigments, execution technique and repainting used on the polychrome wood ceilings and doors in the Casa de Pilatos (Seville, Spain) were studied using portable X-ray fluorescence equipment. Cross-sections of small samples were also analysed by optical microscopy, SEM with EDX analysis, micro-Raman and micro-infrared spectroscopy and X-ray diffraction. These carpentry works are magnificent examples of the Mudéjar art made in Spain in the early 16th century. Portable X-ray fluorescence gave good information on the different components of the polychrome. The SEM-EDX study of the surfaces of small samples gave information on their components and also characterized the compounds that had been deposited or formed by environmental contamination or by the alteration of some pigments. The SEM-EDX study of cross-sections facilitated the characterization of all layers and pigments from the support to the most external layer. The following pigments were characterized: red (cinnabar/vermillion, lead oxide, iron oxides and orpiment/realgar), black (carbon black), white (white lead and titanium barium white), yellow-orange-red-brown (orpiment/realgar and iron oxides), green (chromium oxide), blue (indigo blue and ultramarine blue), and gilding (gold leaf on bole). False gold, bronze and brass were also found. The pigments were applied with the oil painting technique over a support layer that had been primed with animal glue. This support layer was gypsum in some cases and white lead in others. This study is essential to the polychrome conservation of the studied artwork, and it will help clarify uncertainties in the history and painting of Mudéjar art.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Near infrared spectroscopy combined with chemometrics for growth stage
           classification of cannabis cultivated in a greenhouse from seized seeds
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Bruna Tassi Borille, Marcelo Caetano Alexandre Marcelo, Rafael Scorsatto Ortiz, Kristiane de Cássia Mariotti, Marco Flôres Ferrão, Renata Pereira Limberger
      Cannabis sativa L. (cannabis, Cannabaceae), popularly called marijuana, is one of the oldest plants known to man and it is the illicit drug most used worldwide. It also has been the subject of increasing discussions from the scientific and political points of view due to its medicinal properties. In recent years in Brazil, the form of cannabis drug trafficking has been changing and the Brazilian Federal Police has exponentially increased the number of seizures of cannabis seeds sent by the mail. This new form of trafficking encouraged the study of cannabis seeds seized germinated in a greenhouse through NIR spectroscopy combined with chemometrics. The plants were cultivated in a homemade greenhouse under controlled conditions. In three different growth periods (5.5weeks, 7.5weeks and 10weeks), they were harvested, dried, ground and directly analyzed. The iPCA was used to select the best NIR spectral range (4000–4375cm−1) in order to develop unsupervised and supervised methods. The PCA and HCA showed a good separation between the three groups of cannabis samples at different growth stages. The PLS-DA and SVM-DA classified the samples with good results in terms of sensitivity and specificity. The sensitivity and specificity for SVM-DA classification were equal to unity. This separation may be due to the correlation of cannabinoids and volatile compounds concentration during the growth of the cannabis plant. Therefore, the growth stage of cannabis can be predicted by NIR spectroscopy and chemometric tools in the early stages of indoor cannabis cultivation.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Comparative structural and vibrational study of the four lowest energy
           conformers of serotonin
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Omkant Jha, T.K. Yadav, R.A. Yadav
      A computational investigation of all possible lowest energy conformers of serotonin was carried out at the B3LYP/6-311++G** level. Out of the 14 possible lowest energy conformers, the first 4 conformers were investigated thoroughly for the optimized geometries, fundamental frequencies, the potential energy distributions, APT and natural charges, natural bond orbital (NBO) analysis, MEP, Contour map, total density array, HOMO, LUMO energies. The second third and fourth conformers are energetically at higher temperatures of 78, 94 and 312K respectively with respect to the first one. Bond angles and bond lengths do not show significant variations while the dihedral angles vary significantly in going from one conformer to the other. Some of the vibrational modes of the indole moiety are conformation dependent to some extent whereas most of the normal modes of vibration of amino-ethyl side chain vary significantly in going from one conformer to conformer. The MEP for the four conformers suggested that the sites of the maximum positive and negative ESP change on changing the conformation. The charges at some atomic sites also change significantly from conformer to conformer.
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      PubDate: 2016-09-26T18:03:06Z
       
  • «Оn–off» fluorescent sensors for aromatic analytes based on zinc(II)
           bis(dipyrromethenate)s
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): A.A. Ksenofontov, G.B. Guseva, E.V. Antina, E.N. Nuraneeva
      This paper presents the results of spectral-luminescence research of binuclear zinc(II) helicates with tetra-, octa-, and decamethylsubstituted 3,3′-bis(dipyrromethene)s ([Zn2 L 2]) in binary mixtures of cyclohexane with aromatic hydrocarbons (benzene, toluene, and m-xylene). Structure effects of zinc(II) helicates, and aromaticity criteria of analytes (HOMA, NICS, δ) on the fluorescence quenching efficiency of [Zn2 L 2] in the presence of aromatic compounds was considered. It was found that decamethylsubstituted 3,3′-bis(dipyrromethenate)s compared to tetra-, and octamethylsubstituted-analogs shows the highest fluorescence sensitivity to the presence of aromatic compounds. High specificity of spectral-luminescence characteristics changing in the presence of particular aromatic analytes provides the possibility of using [Zn2 L 2] helicates as new fluorescent sensors of aromatic compounds trace amount (120ppb to 56ppm) in organic media.
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      PubDate: 2016-09-26T18:03:06Z
       
  • Colorimetric detection of glucose based on gold nanoparticles coupled with
           silver nanoparticles
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Yan Gao, Yiting Wu, Junwei Di
      We have coupled gold nanoparticles (AuNPs) with silver nanoparticles (AgNPs) to assemble a plasmonic sensing platform for colorimetric detection of glucose. In this system, small AuNPs (~4nm) can act as glucose oxidase (GOD) mimic enzyme to catalytically oxidize glucose in the presence of oxygen, producing hydrogen peroxide, which dissolves AgNPs to lead the color changes. Glucose can be detected not only by naked eyes (from yellow to red) but also by spectrophotometer in the concentration range of 5–70μM, with detection limit of 3μM. More importantly, we found that l-cysteine added in the system can markedly improve the selectivity for the detection of glucose. The proposed method was used to application for the detection of glucose in human serum with satisfactory results. This system is simple and low cost without using any enzymes and organic chromogenic agents.
      Graphical abstract image

      PubDate: 2016-09-22T17:31:47Z
       
  • Pyridine–antipyrine appended indole derivative for selective recognition
           of Fe3+: Concentration dependent coloration
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Sabyasachi Ta, Sandip Nandi, Milan Ghosh, Somenath Banerjee, Debasis Das
      Combination of pyridine, antipyrine and indole in a single molecule (L2) allows selective recognition of Fe3+ colorimetrically in CH3CN. The structure of L2 is confirmed from single crystal X-ray diffraction analysis. The probe displays two different visible bands at 541nm and 715nm in the presence of Fe3+, associated with two different colors, viz. green and pink-violet allowing determination of unknown Fe3+ concentration. Interestingly, removal of 2-picolyl group from indole N-center of L2 generates L3 that behaves similarly at low Fe3+ concentration (>0 to 1.1mM) but differently at higher Fe3+ concentration (>1.1mM), indicating involvement of pyridyl-N donor towards Fe3+, and hence different coordination environment around Fe3+ at higher concentration.
      Graphical abstract image

      PubDate: 2016-09-22T17:31:47Z
       
  • Characterization of chlorophyll derivatives in micelles of polymeric
           surfactants aiming photodynamic applications
    • 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.
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      PubDate: 2016-09-22T17:31:47Z
       
  • The weak fundamental NH-stretching transition in amines
    • 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
       
  • Interaction between 8-methoxypsoralen and trypsin: Monitoring by
           spectroscopic, chemometrics and molecular docking approaches
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Yingying Liu, Guowen Zhang, Ni Zeng, Song Hu
      8-Methoxypsoralen (8-MOP) is a naturally occurring furanocoumarin with various biological activities. However, there is little information on the binding mechanism of 8-MOP with trypsin. Here, the interaction between 8-MOP and trypsin in vitro was determined by multi-spectroscopic methods combined with the multivariate curve resolution-alternating least squares (MCR–ALS) chemometrics approach. An expanded UV–vis spectral data matrix was analysed by MCR–ALS, the concentration profiles and pure spectra for the three reaction species (trypsin, 8-MOP and 8-MOP–trypsin) were obtained to monitor the interaction between 8-MOP and trypsin. The fluorescence data suggested that a static type of quenching mechanism occurred in the binding of 8-MOP to trypsin. Hydrophobic interaction dominated the formation of the 8-MOP–trypsin complex on account of the positive enthalpy and entropy changes, and trypsin had one high affinity binding site for 8-MOP with a binding constant of 3.81×104 Lmol−1 at 298K. Analysis of three dimensional fluorescence, UV–vis absorption and circular dichroism spectra indicated that the addition of 8-MOP induced the rearrangement of the polypeptides carbonyl hydrogen-bonding network and the conformational changes in trypsin. The molecular docking predicted that 8-MOP interacted with the catalytic residues His57, Asp102 and Ser195 in trypsin. The binding patterns and trypsin conformational changes may result in the inhibition of trypsin activity. This study has provided insights into the binding mechanism of 8-MOP with trypsin.
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      PubDate: 2016-09-22T17:31:47Z
       
  • Electronic states of Myricetin. UV–Vis polarization spectroscopy and
           quantum chemical calculations
    • 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
       
  • Fluorescence enhancement of glutathione capped CdTe/ZnS quantum dots by
           embedding into cationic starch for sensitive detection of rifampicin
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Zari Hooshyar, Ghasem Rezanejade Bardajee
      In this study, we describe the synthesis of a new quantum dots (QDs) by embedding glutathione capped CdTe/ZnS QDs into cationic starch biopolymer (CS-GSH-CdTe/ZnS QDs). The fluorescence intensity of prepared QDs was significantly enhanced. When QDs interacted with rifampicin, the fluorescence intensity of the CS-GSH-CdTe/ZnS QDs was highly quenched compared with GSH-CdTe/ZnS QDs. Based on the above, a new fluorescent nanosensor for simple, sensitive and selective detection of rifampicin was developed. The fluorescence quenching was well described by the typical Stern–Volmer equation. After optimization, the linear range of the as-prepared QDs fluorescence intensity versus the concentration of rifampicin was F0/F=0.0422Q+1.109 (R2 =0.99). The detection limit was 0.06×10−6 mol/L. The proposed method with satisfactory results was used to detect rifampicin in commercial capsules and tablets.
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      PubDate: 2016-09-17T15:34:56Z
       
  • New insights about the hydrogen bonds formed between acetylene and
           hydrogen fluoride: π⋯H, C⋯H and F⋯H
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Denize S. Silva, Boaz G. Oliveira
      A theoretical study of hydrogen bond strength and bond properties in the C2H2 ⋯(HF)-T, C2H2 ⋯2(HF)-T, C2H2 ⋯2(HF), C2H2 ⋯3(HF) and C2H2 ⋯4(HF) complexes was carried out at the B3LYP/6-311++G(d,p) theory level. In these systems, a strength competition between the π⋯H and C⋯H interactions was examined. Specifically the F⋯H hydrogen bond, its properties were studied through a comparison between the hydrogen fluoride and the higher-order complexes (trimer, tetramer and pentamer). Regarding the electronic properties, the hydrogen bond strength could not be determined by the supermolecule approach. Thus, the hydrogen bond energies were computed via NBO calculations. Additionally to NBO, the ChelpG charge calculations were used to interpret the intermolecular charge transfer. The QTAIM integrations were useful to predict the covalent character of the π⋯H, C⋯H and F⋯H hydrogen bonds. Moreover, values of hybrid orbitals (s and p) and atomic radii were also determined in order to justify the red shifts in the stretch frequencies of the HF bonds.
      Graphical abstract image

      PubDate: 2016-09-17T15:34:56Z
       
  • Identification and classification of textile fibres using ATR-FT-IR
           spectroscopy with chemometric methods
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Pilleriin Peets, Ivo Leito, Jaan Pelt, Signe Vahur
      The possibility of classification of single- and two-component textile materials using ATR-FT-IR spectra and chemometric methods, principal component analysis (PCA) and discriminant analysis, was assessed. Altogether 89 textile samples belonging to 26 different types (11 one- and 15 two-component textiles) were investigated. It was found that PCA classification using only two or three principal components (PCs) enables identifying different one- and two-component textiles, although with two important limitations: it was not always possible to distinguish between the cellulose-based fibres (cotton, linen and in some cases viscose) and it was only partly possible to distinguish between silk and wool. The statistical discriminant analysis can use as many PCs as there are sample classes and due to that can discriminate between single-component fibres, including viscose from linen and cotton as well as silk from wool. Besides that, in both of these cases, involving optical microscopy as an additional technique enabled unequivocal identification of the fibres. The possibilities of semi-quantitative analysis of mixed fibres (cotton-polyester, wool-polyester and wool-polyamide) with PCA were investigated and it was found that approximate quantitative composition is obtainable if for the mixed fibre sample a number of spectra are averaged in order to minimize the effect of structural inhomogeneity. For approximate content determination 25 spectra of selected two-component samples were registered for calibration and the averaged spectrum for each sample was computed. Due to the structural inhomogeneity of mixed textiles, obtaining accurate quantitative composition from real samples is not possible with ATR-FT-IR. The main problems with ATR-FT-IR-PCA classification are (1) difficulties in getting high quality spectra from some textiles (e.g. polyacrylic), (2) inhomogeneity of the textile fibres in the case of two-component fibres and (3) intrinsic similarity between the spectra of some fibres (e.g. cotton and linen). In order to test the homogeneity of mixed fibres, microscopic and IR-microspectroscopic analysis was carried out.
      Graphical abstract image

      PubDate: 2016-09-17T15:34:56Z
       
  • A highly selective fluorescent probe based on coumarin for the imaging of
           N2H4 in living cells
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Song Chen, Peng Hou, Jing Wang, Lei Liu, Qi Zhang
      A turn-on fluorescence probe for highly sensitive and selective detection of N2H4 was developed based on hydrazine-triggered a substitution- cyclization-elimination cascade. Upon the treatment with N2H4, probe 1, 4-methyl-coumarin-7-yl bromobutanoate, displayed a remarkable fluorescence enhancement (25-fold) with a maximum at 450nm. This probe can quantitatively detect N2H4 with a extremely low detection limit as 7×10−8 M. Moreover, cell imaging experiments have indicated that probe 1 has potential ability to detect and image N2H4 in biological systems.
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      PubDate: 2016-09-17T15:34:56Z
       
  • A comparative study on the effect of Curcumin and Chlorin-p6 on the
           transport of the LDS cation across a negatively charged POPG bilayer:
           Effect of pH
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): G.K. Varshney, S.R. Kintali, P.K. Gupta, K. Das
      We report the use of interface selective Second Harmonic generation technique to investigate the transport of the LDS cation across POPG liposomes in the pH range of 4.0 to 8.0 in the presence and absence of two amphiphilic drugs, Curcumin and Chlorin-p 6 (Cp 6 ). Our results show that bilayer permeability of liposomes is significantly affected by the presence of the drugs and pH of the medium as evidenced by significant changes in the transport kinetics of the LDS. Studies carried out in the pH range 4.0–8.0 show that while Cp 6 significantly enhanced the transport of LDS at pH4.0, the transport of the cation was seen to increase with increasing pH, with maximum effect at pH7.4 for Curcumin. The pH dependent bilayer localization of both the drugs was investigated by conducting steady state FRET studies using DPH labeled lipids as donors. The FRET results and the relative population of the various ionic/nonionic species of the drugs at different pH suggest that distance dependent interaction between the various ionic species of the drugs and polar head groups of the lipid is responsible for the observed pH dependence enhancement of the drug induced membrane permeability. Another interesting observation was that the stability of Curcumin in presence of POPG liposomes was observed to degrade significantly near physiological pH (7.4 and 8.0). Although this degradation did not affect the liposome integrity, interestingly this was observed to enhance the transport of the LDS cation across the bilayer. That the degradation products of Curcumin are equally effective as the drug itself in enhancing the membrane permeability lends additional support to the current opinion that the bioactive degradation products of the drug may have a significant contribution to its observed pharmacological effects.
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      PubDate: 2016-09-17T15:34:56Z
       
  • Spectroscopic, structural characterizations and antioxidant capacity of
           
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Moamen S. Refat, Samy M. El-Megharbel, M.A. Hussien, Reham Z. Hamza, Mohamed A. Al-Omar, Ahmed M. Naglah, Walid M. Afifi, Mohamed I. Kobeasy
      New binuclear chromium (III) niacinamide compound with chemical formula [Cr2(Nic)(Cl)6(H2O)4]·H2O was obtained upon the reaction of chromium (III) chloride with niacinamide (Nic) in methanol solvent at 60°C. The proposed structure was discussed with the help of microanalytical analyses, conductivity, spectroscopic (FT-IR and UV–vis.), magnetic calculations, thermogravimetric analyses (TG/TGA), and morphological studies (X-ray of solid powder and scan electron microscopy. The infrared spectrum of free niacinamide in comparison with its chromium (III) compound indicated that the chelation mode occurs via both nitrogen atoms of pyridine ring and primary –NH2 group. The efficiency of chromium (III) niacinamide compound in decreasing of glucose level of blood and HbA1c in case of diabetic rats was checked. The ameliorating gluconeogenic enzymes, lipid profile and antioxidant defense capacities are considered as an indicator of the efficiency of new chromium (III) compound as antidiabetic drug model.
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      PubDate: 2016-09-17T15:34:56Z
       
  • Study on binding and fluorescence energy transfer efficiency of Rhodamine
           B with Pluronic F127-gold nanohybrid using optical spectroscopy methods
    • 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.
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      PubDate: 2016-09-17T15:34:56Z
       
  • Spectroscopic study for a chromium-adsorbed montmorillonite
    • 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.
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      PubDate: 2016-09-17T15:34:56Z
       
  • Raman monitoring of a catalytic system at work: Influence of the reactant
           on the sensitivity to laser-induced heating
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Josefine Schnee, Eric M. Gaigneaux
      Characterizing catalysts under working conditions is crucial to understand and to optimize their behavior and performance. However, when Raman spectroscopy is used, attention has to be paid to laser-induced artefacts. While laser irradiation is often claimed to lead to a temperature gradient between the integral catalyst bed and the sampling point, neither the circumstances when such effect appears, nor if it systematically occurs or not, are really explored in details. The present paper shows that the sensitivity of a catalyst to laser-induced heating largely depends on the gas composition under which the analysis is done, in particular that it depends whether the catalyst has adsorbed reactant molecules or not. These aspects are here addressed via the Raman in situ exploration of H3PW12O40. This heteropolyacid is a widely used acid catalyst due to its very high Brönsted acidity, approaching the superacid region. In particular, we have investigated the impact of laser irradiation in the Raman monitoring of solid H3PW12O40 at work under a flow of methanol in nitrogen at 50°C. When 1 single spectrum of H3PW12O40 was measured after 3h of exposure to methanol, the characteristic CH vibration bands of adsorbed methanol appeared. However, when spectra were measured continuously throughout the experiment, the same CH vibration bands were observed only during the first hour, then they disappeared and the characteristic bands of polyaromatic molecules appeared. Under continuous laser irradiation, adsorbed methanol was thus converted into polyaromatic coke as resulting from a laser-induced heating. However, the spectra collected under pure nitrogen show that the laser does not heat the catalyst in the absence of methanol. UV–Vis revealed the reason of the laser-induced heating in the presence of methanol, and the subsequent formation of coke. Actually the catalyst gets reduced by the adsorbed methanol, what darkens the catalyst bed. Such a darkening renders the catalyst sensitive to laser-induced heating, which in turn leads to the formation of coke. Under continuous laser irradiation, methanol thus auto-initiated its own catalytic conversion, finally leading to the deposition of coke. Such artefact must be avoided if one wants to study the true behavior of the catalyst at work. This paper shows that, for reducible samples analyzed in the presence of reductive molecules, this is only possible by shining the laser intermittently and not continuously. More generally, it actually shows that the adequate way to irradiate a catalyst (continuous vs intermittent) in an in situ/operando Raman analysis depends on the gas flow composition.
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      PubDate: 2016-09-17T15:34:56Z
       
  • Probing interaction of a fluorescent ligand with HIV TAR RNA
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Liang Qi, Jing Zhang, Tian He, Yuan Huo, Zhi-Qi Zhang
      Trans-activator of Transcription (Tat) antagonists could block the interaction between Tat protein and its target, trans-activation responsive region (TAR) RNA, to inhibit Tat function and prevent human immunodeficiency virus type 1 (HIV-1) replication. For the first time, a small fluorescence ligand, ICR 191, was found to interact with TAR RNA at the Tat binding site and compete with Tat. It was also observed that the fluorescence of ICR 191 could be quenched when binding to TAR RNA and recovered when discharged via competition with Tat peptide or a well-known Tat inhibitor, neomycin B. The binding parameters of ICR 191 to TAR RNA were determined through theoretical calculations. Mass spectrometry, circular dichroism and molecular docking were used to further confirm the interaction of ICR 191 with TAR RNA. Inspired by these discoveries, a primary fluorescence model for the discovery of Tat antagonists was built using ICR 191 as a fluorescence indicator and the feasibility of this model was evaluated. This ligand-RNA interaction could provide a new strategy for research aimed at discovering Tat antagonists.
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      PubDate: 2016-09-09T05:54:01Z
       
  • Visual and light scattering spectrometric method for the detection of
           melamine using uracil 5′-triphosphate sodium modified gold nanoparticles
           
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Lijiao Liang, Shujun Zhen, Chengzhi Huang
      A highly selective method was presented for colorimetric determination of melamine using uracil 5′-triphosphate sodium modified gold nanoparticles (UTP-Au NPs) in this paper. Specific hydrogen-bonding interaction between uracil base (U) and melamine resulted in the aggregation of AuNPs, displaying variations of localized surface plasmon resonance (LSPR) features such as color change from red to blue and enhanced localized surface plasmon resonance light scattering (LSPR-LS) signals. Accordingly, the concentration of melamine could be quantified based on naked eye or a spectrometric method. This method was simple, inexpensive, environmental friendly and highly selective, which has been successfully used for the detection of melamine in pretreated liquid milk products with high recoveries.
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      PubDate: 2016-09-09T05:54:01Z
       
  • Fluorometric immunoassay for human serum albumin based on its inhibitory
           
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Seda S. Marukhyan, Vardan K. Gasparyan
      Quantitative determination of HSA was conducted by competitive immunoassay. Inhibition of aggregation of antibody conjugated quantum dots (QD) with albumin conjugated silver nanoparticles (AgNPs) in the presence of HSA was conducted. If antibody-loaded CdSe QDs aggregate with HSA-coated silver nanoparticles the distance between the two kinds of nanoparticles will be reduced enough to cause fluorescence resonance energy transfer (FRET). In this case the yellow fluorescence of the Ab-QDs is quenched. However if HSA (antigen) is added to the Ab-QDs their surface will be blocked and they cannot aggregate any longer with the HSA-AgNPs. Hence, fluorescence will not be quenched. The drop of the intensity of fluorescence (peaking at 570nm) is inversely correlated with the concentration of HSA in the sample. The method allows to determine HSA in the 30–600ng·mL− 1 concentration range.
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      PubDate: 2016-09-04T05:25:50Z
       
  • A multi-analytical approach for the characterization of wall painting
           materials on contemporary buildings
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Donata Magrini, Susanna Bracci, Emma Cantisani, Claudia Conti, Antonio Rava, Antonio Sansonetti, Will Shank, MariaPerla Colombini
      Samples from Keith Haring's wall painting of the Necker Children Hospital in Paris were studied by a multi-analytical protocol. X-ray fluorescence (XRF), powder X-ray diffraction (XRDP), Electron microscope (SEM-EDS), Infrared and Raman spectroscopy (μ-FT-IR and μ-Raman) measurements were performed in order to characterize the materials and to identify the art technique used to produce this contemporary work. Materials from the mural suffered from severe detachments of materials and several fragments were found on the ground beneath. Some of these fragments, which were representative of the whole palette and stratigraphic sequence, were collected and studied. The fragments were sufficiently large to enable non-invasive measurements to be performed in order to characterize the materials. A comparison of the data of the techniques applied revealed that Haring's palette was composed of organic pigments such as Naphtol red, phthalocyanine blue and green and Hansa yellow, in accordance with those used previously by the artist in other painted murals.
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      PubDate: 2016-09-04T05:25:50Z
       
  • “Long-distance” H/D isotopic self-organization phenomena in scope of
           the infrared spectra of hydrogen-bonded terephthalic and phthalic acid
           crystals
    • 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.
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      PubDate: 2016-09-04T05:25:50Z
       
  • Color-tunable emission and energy transfer investigation in
           Sr3Y(PO4)3:Ce3+,Tb3+ phosphors for white LEDs
    • 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.
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      PubDate: 2016-09-04T05:25:50Z
       
  • A novel application of carbon dots for colorimetric determination of
           fenitrothion insecticide based on the microextraction method
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): A. Larki
      In this work, the intrinsic colorimetric property of carbon dots (CDs) was utilized for the determination of fenitrothion by applying dispersive liquid-liquid microextraction (DLLME) method. Label free CDs are extracted into carbon tetrachloride via assistance of trioctylmethylammonium chloride (Aliquat 336), which also acts as a disperser agent in this technique. The enriched CDs show an absorption signal at 365nm, which increases in the presence of fenitrothion. The absorbance increase of CDs in organic phase was used as an analytical signal for the determination of fenitrothion. The synthesized CDs were characterized by UV–visible, fluorescence, Fourier transform infrared (FT-IR) and transmission electron microscopic (TEM). Under the optimized conditions, beer's law was obeyed in the range of 1.0–250.0ngmL−1 of fenitrothion with the limit of detection for fenitrothion was 0.2ngmL−1. The relative standard deviation for eight replicate measurements of fenitrothion at concentrations of 25 and 100ngmL−1 were calculated to be 1.5 and 3.7%, respectively. The proposed method was successfully applied in the determination of fenitrothion in water samples with satisfactory results.
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      PubDate: 2016-09-04T05:25:50Z
       
  • The efficacy assessments of alkylating drugs induced by nano-Fe3O4/CA for
           curing breast and hepatic cancer
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Kui He, Ying Ma, Bin Yang, Caishuang Liang, Xiaoming Chen, Changqun Cai
      A new method to evaluate the anticancer activity at the molecular level has been developed. In our assay, the interaction between alkylating anticancer drugs-Fe3O4/CA with DNA has been investigated for the Resonance Light Scattering (RLS) signal enhancement. Water-based nano-Fe3O4, as a probe, has the ability of good solubility, biodegradability and low bulk resistivity etc. The experimental results show that, the activity order of three kinds of drugs is Nimustine (ACNU)>Semustine (Me-CCNU)>Chlormethine (HN2), which is satisfied with the results of the cell apoptosis experiment and the IC50 by MTT method. This assay is simple, sensitive and high efficient. And the theoretical basics for the development of new anticancer drugs as well as the assessments of their efficacy to cure breast and hepatic cancer have been provided.
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      PubDate: 2016-09-04T05:25:50Z
       
  • Effect of aligning pulse train on the orientation and alignment of a
           molecule in presence of orienting pulse
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Ashish Tyagi, Anjali Maan, Dharamvir Singh Ahlawat, Vinod Prasad
      Field-free molecular alignment is studied theoretically in presence of orienting laser pulse and a delayed Infrared laser (IRL) pulse train. The pulse shapes taken are sine square (sin 2) and square. The degree of alignment can be significantly enhanced by the combination of orienting pulse and IRL pulse train compared with only IRL pulse train. Special emphasis is laid on time delay between orienting and aligning pulse, the width and shape of the pulse train. By adjusting the time delay, width and intensity of coupling laser one can suppress a population of particular state while simultaneously enhancing the population of desired states.
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      PubDate: 2016-09-04T05:25:50Z
       
  • Sensitive arginine sensing based on inner filter effect of Au
           nanoparticles on the fluorescence of CdTe quantum dots
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Haijian Liu, Ming Li, Linye Jiang, Feng Shen, Yufeng Hu, Xueqin Ren
      Arginine plays an important role in many biological functions, whose detection is very significant. Herein, a sensitive, simple and cost-effective fluorescent method for the detection of arginine has been developed based on the inner filter effect (IFE) of citrate-stabilized gold nanoparticles (AuNPs) on the fluorescence of thioglycolic acid-capped CdTe quantum dots (QDs). When citrate-stabilized AuNPs were mixed with thioglycolic acid-capped CdTe QDs, the fluorescence of CdTe QDs was significantly quenched by AuNPs via the IFE. With the presence of arginine, arginine could induce the aggregation and corresponding absorption spectra change of AuNPs, which then IFE-decreased fluorescence could gradually recover with increasing amounts of arginine, achieving fluorescence “turn on” sensing for arginine. The detection mechanism is clearly illustrated and various experimental conditions were also optimized. Under the optimum conditions, a decent linear relationship was obtained in the range from 16 to 121μgL−1 and the limit of detection was 5.6μgL−1. And satisfactory results were achieved in arginine analysis using arginine injection, compound amino acid injection, even blood plasma as samples. Therefore, the present assay showed various merits, such as simplicity, low cost, high sensitivity and selectivity, making it promising for sensing arginine in biological samples.
      Graphical abstract image

      PubDate: 2016-09-04T05:25:50Z
       
  • A multi-state fluorescent switch based on a diarylethene with an acridine
           unit
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Zhaoyan Tian, Shiqiang Cui, Chunhong Zheng, Shouzhi Pu
      A new asymmetrical fluorescent diarylethene derivative with an acridine unit was synthesized by Schiff base condensation. The derivative was sensitive to lights and special metal ions. Stimulated by UV/vis lights and Zn2+, distinct changes were observed in UV–vis and fluorescent spectra. Upon addition of Zn2+, the derivative emission peak was blue-shifted by 34nm and the emission intensity was enhanced by 16 fold, accompanied by the fluorescent color changed from red to light yellow, due to the formation of a 1:1 metal/ligand complex. The complex exhibited excellent fluorescence switching upon irradiation with UV light. Taking advantage of the lights and Zn2+ stimuli (inputs), and fluorescence intensity at 580nm (output), a molecular logic gate was constructed. Moreover, a new absorption band centered at 420–450nm emerged upon exposure to Zn2+. The dramatic color change of the solution made the ‘naked-eyes’ detection of Zn2+ possible.
      Graphical abstract image

      PubDate: 2016-09-04T05:25:50Z
       
  • PLS-LS-SVM based modeling of ATR-IR as a robust method in detection and
           qualification of alprazolam
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): Elahehnaz Parhizkar, Mohammad Ghazali, Fatemeh Ahmadi, Amirhossein Sakhteman
      According to the United States pharmacopeia (USP), Gold standard technique for Alprazolam determination in dosage forms is HPLC, an expensive and time-consuming method that is not easy to approach. In this study chemometrics assisted ATR-IR was introduced as an alternative method that produce similar results in fewer time and energy consumed manner. Fifty-eight samples containing different concentrations of commercial alprazolam were evaluated by HPLC and ATR-IR method. A preprocessing approach was applied to convert raw data obtained from ATR-IR spectra to normal matrix. Finally, a relationship between alprazolam concentrations achieved by HPLC and ATR-IR data was established using PLS-LS-SVM (partial least squares least squares support vector machines). Consequently, validity of the method was verified to yield a model with low error values (root mean square error of cross validation equal to 0.98). The model was able to predict about 99% of the samples according to R2 of prediction set. Response permutation test was also applied to affirm that the model was not assessed by chance correlations. At conclusion, ATR-IR can be a reliable method in manufacturing process in detection and qualification of alprazolam content.
      Graphical abstract image

      PubDate: 2016-09-04T05:25:50Z
       
  • Experimental and theoretical study of photo- and electroluminescence of
           divinyldiphenyl and divinylphenanthrene derivatives
    • Abstract: Publication date: 15 February 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 173
      Author(s): L.G. Samsonova, R.R. Valiev, K.M. Degtyarenko, D.A. Sunchugashev, I.N. Kukhta, A.V. Kukhta, T.N. Kopylova
      Electronic absorption and luminescence spectra of four new compounds of divinyldiphenyl and divinylphenanthrene derivatives are investigated experimentally in tetrahydrofuran solutions and thin films obtained by thermal vacuum deposition and by spin coating of these substances embedded into polyvinylcarbazole matrix. Molecular geometry optimizations and electronic spectra have been calculated in the framework of XMC-QDPT2/6-31G (d, p) and TDDFT/B3LYP/6-31G (d, p) levels of theory. We have fabricated and studied OLED devices with the structure ITO/PEDOT:PSS/NPD/L/Ca/Al and ITO/PEDOT:PSS/PVK+L/Ca, where L is the luminophore. It is demonstrated that the photo-and electroluminescence spectra of divinyldiphenyl are not identical and undergo strong changes depending on the method of sample preparation.
      Graphical abstract image

      PubDate: 2016-09-04T05:25:50Z
       
  • Raman investigation on the behavior of parasibirskite CaHBO3 at high
           pressure
    • 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.
      Graphical abstract image

      PubDate: 2016-09-04T05:25:50Z
       
  • Vibrational monitor of early demineralization in tooth enamel after in
           vitro exposure to phosphoridic liquid
    • 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.
      Graphical abstract image

      PubDate: 2016-09-04T05:25:50Z
       
  • Determination of dopamine hydrochloride by host-guest interaction based on
           water-soluble pillar[5]arene
    • 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.
      Graphical abstract image

      PubDate: 2016-09-04T05:25:50Z
       
  • Molecular characteristics of a fluorescent chemosensor for the recognition
           of ferric ion based on photoresponsive azobenzene derivative
    • Abstract: Publication date: 15 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 171
      Author(s): Zhen Chi, Xia Ran, Lili Shi, Jie Lou, Yanmin Kuang, Lijun Guo
      Metal ion recognition is of great significance in biological and environmental detection. So far, there is very few research related to the ferric ion sensing based on photoresponsive azobenzene derivatives. In this work, we report a highly selective fluorescent “turn-off” sensor for Fe3+ ions and the molecular sensing characteristics based on an azobenzene derivative, N-(3,4,5-octanoxyphenyl)-N′-4-[(4-hydroxyphenyl)azophenyl]1,3,4-oxadiazole (AOB-t8). The binding association constant was determined to be 6.07×103 M−1 in ethanol and the stoichiometry ratio of 2:2 was obtained from Job's plot and MS spectra. The AOB-t8 might be likely to form the dimer structure through the chelation of ferric ion with the azobenzene moiety. Meanwhile, it was found that the photoisomerization property of AOB-t8 was regulated by the binding with Fe3+. With the chelation of Fe3+, the regulated molecular rigidity and the perturbed of electronic state and molecular geometry was suggested to be responsible for the accelerated isomerization of AOB-t8 to UV irradiation and the increased fluorescence lifetime of both trans- and cis-AOB-t8-Fe(III). Moreover, the reversible sensing of AOB-t8 was successfully observed by releasing the iron ion from AOB-t8-Fe(III) with the addition of citric acid.
      Graphical abstract image

      PubDate: 2016-07-27T09:19:09Z
       
 
 
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