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  Subjects -> CHEMISTRY (Total: 837 journals)
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CHEMISTRY (586 journals)            First | 1 2 3 4 5 6 | Last

Journal of Catalysts     Open Access  
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 11)
Journal of Chemical and Biological Interfaces     Full-text available via subscription  
Journal of Chemical Education     Full-text available via subscription   (Followers: 16)
Journal of Chemical Health Risks     Open Access   (Followers: 2)
Journal of Chemical Information and Modeling     Full-text available via subscription   (Followers: 6)
Journal of Chemical Research     Full-text available via subscription   (Followers: 5)
Journal of Chemical Science and Technology     Open Access   (Followers: 3)
Journal of Chemical Sciences     Partially Free   (Followers: 16)
Journal of Chemical Theory and Computation     Full-text available via subscription   (Followers: 12)
Journal of Cheminformatics     Open Access   (Followers: 1)
Journal of Chemistry     Open Access   (Followers: 3)
Journal of Chemometrics     Hybrid Journal   (Followers: 10)
Journal of Chromatography A     Hybrid Journal   (Followers: 53)
Journal of Chromatography Library     Full-text available via subscription   (Followers: 5)
Journal of Clinical Toxicology     Open Access   (Followers: 1)
Journal of Colloid and Interface Science     Hybrid Journal   (Followers: 13)
Journal of Computational Chemistry     Hybrid Journal   (Followers: 15)
Journal of Coordination Chemistry     Hybrid Journal   (Followers: 1)
Journal of Dispersion Science and Technology     Hybrid Journal  
Journal of Encapsulation and Adsorption Sciences     Open Access   (Followers: 5)
Journal of Environmental Chemistry and Ecotoxicology     Open Access   (Followers: 2)
Journal of Flow Chemistry     Full-text available via subscription   (Followers: 1)
Journal of Fluorescence     Hybrid Journal   (Followers: 4)
Journal of Fluorine Chemistry     Hybrid Journal   (Followers: 6)
Journal of Fuel Chemistry and Technology     Full-text available via subscription   (Followers: 5)
Journal of Great Lakes Research     Hybrid Journal   (Followers: 7)
Journal of Heterocyclic Chemistry     Hybrid Journal   (Followers: 5)
Journal of Immunoassay and Immunochemistry     Hybrid Journal   (Followers: 3)
Journal of Inclusion Phenomena and Macrocyclic Chemistry     Hybrid Journal   (Followers: 1)
Journal of Inorganic Biochemistry     Hybrid Journal   (Followers: 2)
Journal of Labelled Compounds and Radiopharmaceuticals     Hybrid Journal   (Followers: 1)
Journal of Macromolecular Science, Part A: Pure and Applied Chemistry     Hybrid Journal   (Followers: 4)
Journal of Mass Spectrometry     Hybrid Journal   (Followers: 24)
Journal of Materials Chemistry A : Materials for Energy and Sustainability     Full-text available via subscription   (Followers: 24)
Journal of Materials Chemistry B : Materials for Biology and Medicine     Full-text available via subscription   (Followers: 5)
Journal of Materials Chemistry C : Materials for Optical, Magnetic and Electronic Devices     Full-text available via subscription   (Followers: 6)
Journal of Materials Physics and Chemistry     Open Access  
Journal of Materials Research     Full-text available via subscription   (Followers: 10)
Journal of Mathematical Chemistry     Hybrid Journal   (Followers: 5)
Journal of Medicinal Chemistry     Full-text available via subscription   (Followers: 77)
Journal of Membrane and Separation Technology     Hybrid Journal  
Journal of Membrane Science     Hybrid Journal   (Followers: 11)
Journal of Modern Chemistry & Chemical Technology     Full-text available via subscription   (Followers: 2)
Journal of Molecular Catalysis A: Chemical     Hybrid Journal   (Followers: 3)
Journal of Molecular Graphics and Modelling     Hybrid Journal   (Followers: 4)
Journal of Molecular Liquids     Hybrid Journal   (Followers: 2)
Journal of Molecular Modeling     Hybrid Journal   (Followers: 4)
Journal of Molecular Recognition     Hybrid Journal   (Followers: 2)
Journal of Molecular Spectroscopy     Hybrid Journal   (Followers: 7)
Journal of Molecular Structure     Hybrid Journal   (Followers: 3)
Journal of Nanoparticles     Open Access  
Journal of Nanostructure in Chemistry     Open Access   (Followers: 4)
Journal of Natural Gas Chemistry     Full-text available via subscription   (Followers: 2)
Journal of Nepal Chemical Society     Open Access  
Journal of Nucleic Acids Investigation     Open Access   (Followers: 2)
Journal of Ocean University of China (English Edition)     Hybrid Journal   (Followers: 1)
Journal of Organometallic Chemistry     Hybrid Journal   (Followers: 13)
Journal of Photochemistry and Photobiology A: Chemistry     Hybrid Journal   (Followers: 4)
Journal of Photochemistry and Photobiology C: Photochemistry Reviews     Full-text available via subscription   (Followers: 3)
Journal of Polymer & Composites     Full-text available via subscription   (Followers: 3)
Journal of Polymer and Biopolymer Physics Chemistry     Open Access   (Followers: 2)
Journal of Polymer Science Part A: Polymer Chemistry     Hybrid Journal   (Followers: 122)
Journal of Polymers     Open Access   (Followers: 1)
Journal of Porphyrins and Phthalocyanines     Hybrid Journal   (Followers: 3)
Journal of Pure and Applied Chemistry Research     Open Access   (Followers: 1)
Journal of Raman Spectroscopy     Hybrid Journal   (Followers: 11)
Journal of Research Updates in Polymer Science     Hybrid Journal  
Journal of Saudi Chemical Society     Open Access  
Journal of Solid State Chemistry     Hybrid Journal   (Followers: 14)
Journal of Solution Chemistry     Hybrid Journal   (Followers: 4)
Journal of Structural Chemistry     Hybrid Journal  
Journal of Sulfur Chemistry     Hybrid Journal   (Followers: 2)
Journal of Superhard Materials     Hybrid Journal   (Followers: 1)
Journal of Surfactants and Detergents     Hybrid Journal   (Followers: 5)
Journal of Systems Chemistry     Open Access   (Followers: 1)
Journal of Taibah University for Science     Open Access  
Journal of the American Chemical Society     Full-text available via subscription   (Followers: 211)
Journal of the American Society for Mass Spectrometry     Hybrid Journal   (Followers: 21)
Journal of the American Society of Brewing Chemists     Full-text available via subscription   (Followers: 1)
Journal of the Bangladesh Chemical Society     Open Access  
Journal of the Chilean Chemical Society     Open Access   (Followers: 2)
Journal of the Iranian Chemical Society     Hybrid Journal   (Followers: 1)
Journal of the Korean Society for Applied Biological Chemistry     Hybrid Journal   (Followers: 1)
Journal of the Mexican Chemical Society     Open Access   (Followers: 1)
Journal of Theoretical and Computational Chemistry     Hybrid Journal   (Followers: 8)
Journal of Theoretical Chemistry     Open Access  
Journal of Wood Chemistry and Technology     Hybrid Journal   (Followers: 7)
JPC - Journal of Planar Chromatography - Modern TLC     Full-text available via subscription   (Followers: 6)
Jurnal Penelitian Sains (JPS)     Open Access  
Jurnal Teknologi Informasi     Open Access   (Followers: 3)
Karbala International Journal of Modern Science     Open Access  
Kinetics and Catalysis     Hybrid Journal   (Followers: 3)
Korea-Australia Rheology Journal     Hybrid Journal  
Langmuir     Full-text available via subscription   (Followers: 40)
Latvian Journal of Chemistry     Open Access   (Followers: 1)
Lebensmittelchemie     Hybrid Journal   (Followers: 1)
Lipid Insights     Open Access   (Followers: 1)
Luminescence     Hybrid Journal   (Followers: 1)
Macromolecular Materials & Engineering     Hybrid Journal   (Followers: 5)

  First | 1 2 3 4 5 6 | Last

Journal Cover   Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
  [SJR: 0.628]   [H-I: 64]   [8 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1386-1425
   Published by Elsevier Homepage  [2811 journals]
  • Investigation of role of silver nanoparticles on spectroscopic properties
           of biologically active coumarin dyes 4PTMBC and 1IPMBC
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): U.P. Raghavendra , Mahantesha Basanagouda , J. Thipperudrappa
      The role of silver nanoparticles on spectroscopic properties of biologically active coumarin dyes 4-p-tolyloxymethyl-benzo[h]coumarin (4PTMBC) and 1-(4-iodophenoxymethyl)-benzo[f]coumarin (1IPMBC) has been investigated using absorption and fluorescence spectroscopy. Silver nanoparticles are synthesized by chemical reduction method and the estimated size by Mie theory is 12nm. The absorption spectral changes of dyes in the presence of silver nanoparticles suggest their possible interaction with silver nanoparticles. The apparent association constants of the interaction are estimated using Benesi–Hildebrand model. Fluorescence quenching has been observed in both the dyes with the addition of silver nanoparticles. The Stern–Volmer plots of fluorescence quenching are found to be nonlinear showing positive deviation. The magnitudes of quenching rate parameter and fluorescence lifetime measurements indicate the presence of both collisional and static quenching mechanisms. The binding constants and the number of binding sites for the static type of quenching have been estimated from the fluorescence data. The role of diffusion, energy transfer and electron transfer processes in fluorescence quenching mechanism has been discussed.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Synthesis of a DNA-targeting nickel (II) complex with testosterone
           thiosemicarbazone which exhibits selective cytotoxicity towards human
           prostate cancer cells (LNCaP)
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Mok Piew Heng , Saravana Kumar Sinniah , Wuen Yew Teoh , Kae Shin Sim , Seik Weng Ng , Yoke Kqueen Cheah , Kong Wai Tan
      Testosterone thiosemicarbazone, L and its nickel (II) complex 1 were synthesized and characterized by using FTIR, CHN, 1H NMR, and X-ray crystallography. X-ray diffraction study confirmed the formation of L from condensation of testosterone and thiosemicarbazide. Mononuclear complex 1 is coordinated to two Schiff base ligands via two imine nitrogens and two tautomeric thiol sulfurs. The cytotoxicity of both compounds was investigated via MTT assay with cisplatin as positive reference standard. L is more potent towards androgen-dependent LNCaP (prostate) and HCT 116 (colon). On the other hand, complex 1, which is in a distorted square planar environment with L acting as a bidentate NS-donor ligand, is capable of inhibiting the growth of all the cancer cell lines tested, including PC-3 (prostate). It is noteworthy that both compounds are less toxic towards human colon cell CCD-18Co. The intrinsic DNA binding constant (Kb ) of both compounds were evaluated via UV–Vis spectrophotometry. Both compounds showed Kb values which are comparable to the reported Kb value of typical classical intercalator such as ethidium bromide. The binding constant of the complex is almost double compared with ligand L. Both compounds were unable to inhibit the action topoisomerase I, which is the common target in cancer treatment (especially colon cancer). This suggest a topoisomerase I independent-cell death mechanism.
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      PubDate: 2015-06-27T11:43:00Z
       
  • Raman, infrared and NMR spectral analysis, normal coordinate analysis and
           theoretical calculations of 5-(methylthio)-1,3,4-thiadiazole-2(3H)-thione
           and its thiol tautomer
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Tarek A. Mohamed , Usama A. Soliman , Ibrahim A. Shaaban , Wajdi M. Zoghaib , Lee D. Wilson
      Raman (3400–100cm−1) and infrared (4000–200cm−1) spectra of 5-(methylthio)-1,3,4-thiadiazole-2(3H)-thione (C3H4N2S3; MTT) were measured in the solid state, and the 1H/13C NMR spectra were obtained in DMSO-d6 . Initially, twelve structures were proposed as a result of thiol–thione tautomerism and the internal rotation about the C–S bonds. The energies and vibrational frequencies of the optimized structures were calculated using the 6-31G(d) basis set with the methods of MP2 and DFT/B3LYP with Gaussian 98 quantum calculations. Additionally, 1H/13C NMR chemical shifts were predicted for the thiol (structure 5) and thione (structure 9) tautomers by means of B3LYP/6-311+G(d,p) calculations utilizing the GIAO approximation and the PCM solvation model. After complete relaxation of twelve candidate isomers, the thione tautomer (structure 9) was favored owing to its low energy and its predicted real spectral frequencies. These results agree with the recorded infrared and Raman results, in addition to the observed/calculated 1H and 13C NMR spectra. Aided by normal coordinate analysis and potential energy distributions (PEDs), complete vibrational assignments have been proposed for all observed fundamentals for the thione tautomer. With the aid of MP2/6-31G(d) potential surface scans, CH3, CH3S, and SH barriers to internal rotations were estimated with the optimized structural parameters from the MP2 method with the 6-31G(d) basis set. The results are discussed herein and compared with similar model compounds whenever appropriate.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Inhibiting plasmon catalyzed conversion of para-nitrothiophenol on
           monolayer film of Au nanoparticles probed by surface enhanced Raman
           spectroscopy
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Hua-Yi Weng , Qing-Hua Guo , Xing-Rong Wang , Min-Min Xu , Ya-Xian Yuan , Ren-Ao Gu , Jian-Lin Yao
      The plasmon catalyzed surface reaction has been attracted considerable attention due to its promising application in heterogeneous catalysis. This kind of plasmon catalysis played bilateral roles in driving the unconventional reactions or destructing the surface molecule layer. The acceleration or inhibition on this catalysis is still remained significant challenge. In this paper, monolayer film of Au nanoparticles was fabricated at air/water interface as substrates both for surface enhanced Raman spectroscopy (SERS) and plasmon catalyzed surface reaction. The influence from several issues, involving surfactants, coadsorption species, the solvent and water, were systemically investigated to probe the acceleration and inhibition on the plasmon catalysis reaction. The concentration and molecular weight of surfactant polyvinylpyrrolidone (PVP) exhibited significant influence in the reactive activity for the plasmon catalyzed dimerization of para-nitrothiophenol (PNTP) to p,p′-dimercaptoazobenzene (DMAB). A suitable molecular weight of 10,000 and concentration of 10mg/mL were beneficial for improving the conversion efficiency of PNTP to DMAB. The higher molar ratio of coadsorbed 1-octanethiol and the aprotic solvents resulted in the inhibition of dimerization because 1-octanethiol occupied the surface sites to isolate the adsorbed PNTP molecules with a larger distance and lack of proton source. The plasmon catalysis occurred in ionic liquids suggested that water was essential for the dimerization of PNTP, in which it was used to accelerate the reaction rate and severed as the hydrogen source.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Albumin-induced circular dichroism in Congo red: Applications for studies
           of amyloid-like fibril aggregates and binding sites
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Débora Naliati de Vasconcelos , Valdecir Farias Ximenes
      Congo red (CR), one of the most commonly used dyes for the identification of amyloid fibril aggregates, is also a ligand of native bovine serum albumin (BSA). Induced circular dichroism (ICD) is a phenomenon observed when a chiral compound induces chirality in an achiral one. Here, we study the spectral properties and analytical applications of ICD in Congo red provoked by its interaction with BSA. The complex BSA:CR displays a strong ICD spectrum with a positive band at 412nm and two negative bands at 356 and 490nm. The use of site I and site II albumin ligands as warfarin and ibuprofen, respectively, provoked different alterations in the Congo red ICD spectrum. The BSA binding sites were modified by oxidation and the ICD signal was sensitive to this alteration. The thermal treatment of the BSA:CR complex (30–90°C) was monitored by ICD at 490nm and showed a sigmoidal pattern typical of phase transition in proteins. The altered ICD spectrum is consistent with the formation of amyloid-like fibril aggregates in BSA, which was confirmed by thioflavin T and Rayleigh scattering assays. In conclusion, the ICD provoked by the binding of Congo red to albumin may represent a new spectroscopic technique for studying alterations in the structure of albumin regarding its binding sites and the formation of amyloid aggregates.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Detection of adulteration in acetonitrile using near infrared spectroscopy
           coupled with pattern recognition techniques
    • Abstract: Publication date: 5 December 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 151
      Author(s): Le-Qian Hu , Chun-Ling Yin , Zhi-Peng Zeng
      In this paper, near infrared spectroscopy (NIR) in cooperation with the pattern recognition techniques were used to determine the type of neat acetonitrile and the adulteration in acetonitrile. NIR spectra were collected between 400nm and 2498nm. The experimental data were first subjected to analysis of principal component analysis (PCA) to reveal significant differences and potential patterns between samples. Then support vector machine (SVM) were applied to develop classification models and the best parameter combination was selected by grid search. Under the best parameter combination, the classification accuracy rates of three types of neat acetonitrile reached 87.5%, and 100% for the adulteration with different concentration levels. The results showed that NIR spectroscopy combined with SVM could be utilized for determining the potential adulterants including water, ethanol, isopropyl alcohol, acrylonitrile, methanol, and by-products associated with the production of acetonitrile.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Synthesis, crystal structures and photoluminescence of anthracen- and
           pyrene-based coumarin derivatives
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Hui Zhang , Hao Tong , Yuling Zhao , Tianzhi Yu , Peng Zhang , Jianfeng Li , Duowang Fan
      Two new anthracen- and pyrene-based coumarin derivatives, 3-(4-(anthracen-10-yl)phenyl)coumarin (4) and 3-(4-(pyrene-1-yl)phenyl)coumarin (5), were synthesized and characterized by FT-IR, 1H NMR, element analysis and single crystal X-ray crystallography. The UV–vis absorption and photoluminescence spectra of these coumarin derivatives were investigated. The results show that compound 4 and 5 exhibit blue and blue-green emissions, respectively, under ultraviolet light excitation. Compared with the compound 4, the emission peak of compound 5 was bathochromically shifted by about 80nm due to the more planar structure and larger π-conjugation.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Label-free fluorescence strategy for sensitive detection of exonuclease
           activity using SYBR Green I as probe
    • Abstract: Publication date: 5 December 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 151
      Author(s): Min Xu , Baoxin Li
      A label-free and sensitive fluorescence assay for exonuclease activity is developed using commercially available SYBR Green I (SG) dye as signal probe. A proof-of-concept of this assay has been demonstrated by using exonuclease III (Exo III) as a model enzyme. In this assay, double-stranded DNA (dsDNA) can bind SG, resulting in a strong fluorescence signal of SG. Upon the addition of Exo III, dsDNA would be digested, and SG emits very weak fluorescence. Thus, Exo III activity can be facilely measured with a simple fluorescence reader. This method has a linear detection range from 1U/mL to 200U/mL with a detection limit of 0.7U/mL. This label-free approach is selective, simple, convenient and cost-efficient without any complex DNA sequence design or fluorescence dye label. The method not only provides a platform for monitoring activity and inhibition of exonuclease but also shows great potential in biological process researches, drug discovery, and clinic diagnostics.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Far infrared spectra of solid state l-serine, l-threonine, l-cysteine, and
           l-methionine in different protonation states
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Thomas Gaillard , Aurélien Trivella , Roland H. Stote , Petra Hellwig
      In this study, experimental far infrared measurements of l-serine, l-threonine, l-cysteine, and l-methionine are presented showing the spectra for the 1.0–13.0 pH range. In parallel, solid state DFT calculations were performed on the amino acid zwitterions in the crystalline form. We focused on the lowest frequency far infrared normal modes, which required the most precision and convergence of the calculations. Analysis of the computational results, which included the potential energy distribution of the vibrational modes, permitted a detailed and almost complete assignment of the experimental spectrum. In addition to characteristic signals of the two main acid-base couples, CO2H/CO2 − and NH3 +/NH2, specific side chain contributions for these amino acids, including CCO and CCS vibrational modes were analyzed. This study is in line with the growing application of FIR measurements to biomolecules.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Synthesis, crystal structure, photoluminescence property of a series of
           3d–4f coordination supramolecular complexes
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Jian Song , Cheng-Ren Li , Qi Xu , Xue-Ting Xu , Li-Xian Sun , Yong-Heng Xing
      A series of 3d–4f heterobinuclear complexes were constructed by employing the 2,2′-bipy (2,2′-bipy=2,2′-bipyridine) ligand and corresponding metal ions (MII/LnIII, M=CoII, CuII and ZnII; LnIII =NdIII, SmIII, EuIII and TbIII). Elemental analyses, IR, UV–vis–NIR spectra, PXRD and single crystal X-ray diffraction analysis reveal that complexes 1–4, 5–8, and 9–12 are isomorphous, respectively. The zero-dimensional structures are further connected to 2D or 3D supramolecular network structures via extensive intermolecular hydrogen bonds. Luminescence studies for the heterobinuclear complexes containing SmIII, EuIII and TbIII reveal that the chromophoric composed of ZnII/L may efficiently sensitize the luminescence of the rare earth cations which acts as an antenna, whereas the existence of CuII leads to the quenching of the luminescence of LnIII ions.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Synthesis, structure, protein binding of Cu(II) complexes with a
           tridentate NNO Schiff-base ligand
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Mei Li , ShuJuan Huang , Cheng Ye , YongRong Xie
      Four new Cu(II) complexes (1, 2, 3 and 4) in the presence of different anions (Cl−, Br−, I− and ClO4 −) have been prepared by tridentate NNN Schiff-base ligand (N,N-dimethyl-N′-[phenyl(2-pyridyl)methylene]ethane-1,2-diamine) and well characterized by single-crystal X-ray diffraction, elemental analysis, IR and UV–Vis spectroscopy. The interactions of complexes 1–4 with human serum albumin (HSA) have been investigated in Tris–HCl buffer solution at pH 7.4 by spectroscopic methods and a molecular docking technique. Experimental results proved that the four complexes quench the fluorescence of HSA through a static quenching mechanism. Thermodynamic parameters were calculated from Van’t Hoff equation. The distance r between the donor (HSA) and acceptor (complexes 1–4) has been obtained by means of Förester resonance energy transfer (FRET). Molecular docking results indicated that the main active binding sites for complexes 1, 2 and 4 are site III in subdomain IB and for complex 3 is site II in subdomain III A. The combination of molecular docking results and fluorescence experimental results indicate that the interaction between 1–4 and HSA are dominated by hydrophobic forces as well as hydrogen bonds.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Spectral, morphological, linear and nonlinear optical properties of
           nanostructured benzimidazole metal complex thin films
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): P.A. Praveen , R. Ramesh Babu , K. Jothivenkatachalam , K. Ramamurthi
      Metal organic materials are widely investigated to find their suitability for nonlinear optical applications due to the advantage of combined organic and inorganic properties. In this work benzimidazole based metal organic thin films of dichlorobis (1H-Benzimidazole) Co(II) and dichlorobis (1H-Benzimidazole) Cu(II) were deposited by chemical bath deposition method. The deposited films were annealed at 100, 150 and 200°C to investigate the effect of annealing on the properties of thin films. Surface homogeneity of the films was increased with the annealing temperature due to the surface diffusion of the films and the same was evidently shown by Raman spectroscopy and Atomic Force Microscopy studies. But annealing the films at 200°C yielded bulk patches on the surface due to the distortion of molecules. Linear and nonlinear optical properties of the films annealed at 150°C showed relatively higher transmittance and improved nonlinear optical properties than the other as prepared and annealed samples.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Structural characterization of new Schiff bases of sulfamethoxazole and
           sulfathiazole, their antibacterial activity and docking computation with
           DHPS protein structure
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Sudipa Mondal , Santi M. Mandal , Tapan Kumar Mondal , Chittaranjan Sinha
      New Schiff bases (1, 2) of substituted salicylaldehydes and sulfamethoxazole (SMX)/sulfathiazole (STZ) are synthesized and characterized by elemental analysis and spectroscopic data. Single crystal X-ray structure of one of the compounds (E)-4-((3,5-dichloro-2-hydroxybenzylidene)amino)-N-(5-methylisoxazol-3-yl)benzenesulfonamide (1c) has been determined. Antimicrobial activities of the Schiff bases and parent sulfonamides (SMX, STZ) have been examined against several Gram-positive and Gram-negative bacteria and sulfonamide resistant pathogens; the lowest MIC is observed for (E)-4-((3,5-dichloro-2-hydroxybenzylidene)amino)-N-(thiazol-2-yl)benzene sulfonamide (2c) (8.0μgmL−1) and (E)-4-((3,5-dichloro-2-hydroxybenzylidene)amino)-N-(5-methylisoxazol-3-yl)benzene sulfonamide (1c) (16.0μgmL−1) against sulfonamide resistant pathogens. DFT optimized structures of the Schiff bases have been used to carry out molecular docking studies with DHPS (dihydropteroate synthase) protein structure (downloaded from Protein Data Bank) using Discovery Studio 3.5 to find the most preferred binding mode of the ligand inside the protein cavity. The theoretical data have been well correlated with the experimental results. Cell viability assay and ADMET studies predict that 1c and 2c have good drug like characters.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Structural and spectroscopic characterization of
           4-(3-methyl-3-phenylcyclobutyl)-2-(2-propylidenehydrazinyl)thiazole: A
           combined experimental and DFT analysis
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Fatih Şen , Muharrem Dinçer , Alaaddin Cukurovali
      We investigated the structural and spectroscopic properties of the title compound by means of experimental and DFT quantum chemical methods. The crystal structure of compound was brought to light by single crystal X-ray diffraction method, and were characterized spectroscopically using FT-IR and NMR spectra. FT-IR spectrum in solid state was observed in the region 4000–400cm−1. The 1H and 13C NMR spectra were recorded in CDCl3 solution. The molecular geometry were those obtained from the X-ray structure determination was optimized using density functional theory (DFT/B3LYP) method with the 6-31G(d, p) and 6-31+G(d, p) basis sets in ground state. From the optimized geometry of the molecule, geometric parameters (bond lengths, bond angles, torsion angles), vibrational assignments and chemical shifts of the title compound have been calculated theoretically and compared with the experimental data. Although theoretical calculations were carried out in gas phase, no significant differences in these values.
      Graphical abstract image Highlights

      PubDate: 2015-06-27T11:43:00Z
       
  • Comparative high pressure Raman studies on perfluorohexane and
           perfluoroheptane
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): C. Kavitha , Chandrabhas Narayana
      High pressure Raman spectroscopic studies on perfluorohexane and perfluoroheptane have performed up to 12GPa. Perfluorohexane under goes two pressure induced transitions: (1) liquid–solid transition at 1.6GPa and (2) solid–solid transition at 8.2GPa. On the contrary, perfluoroheptane under goes three phase transitions, they are as follows: (1) liquid–solid transition at 1.3GPa, (2) intermediate solid I transition at 3GPa, (3) solid II transition at 7GPa. The change in slope (dω/dP) shows that the solid I transition at 3.0GPa could be the conversion of mid-gauche defect into trans conformers for perfluoroheptane. The pressure induced Raman spectra and the behavior of individual band with pressure shows that the solid phase comprises more than one conformer beyond crystallization. The intensity ratio for both the compounds shows that the high pressure phase beyond 8.2 and 7.0GPa tends to have close packing with distorted all-trans conformers.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Raman microspectroscopic analysis of decorative pigments from the Roman
           villa of El Ruedo (Almedinilla, Spain)
    • Abstract: Publication date: 5 December 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 151
      Author(s): Laura Dara Mateos , Daniel Cosano , Manuel Mora , Ignacio Muñiz , Rafael Carmona , César Jiménez-Sanchidrián , José Rafael Ruiz
      In this work, we analysed the preparatory layer and paintings in the hypocaustum of the Roman villa of El Ruedo (Almedinilla, southern Spain). The specimens studied were from the III and IV centuries. Raman microscopy was for the first time used here to examine Roman pictures in the south of the Iberian peninsula. The results obtained allowed us to establish the chemical nature of the different pigments used by the Roman artists. All were applied over a preparatory layer consisting of limewash. The different colours used (black, white, red, yellow, green and blue) were obtained by using carbon, calcite, gypsum, hematite, goethite, green earth and Egyptian blue. Some exhibited various hues that were obtained by mixing the previous compounds. Worth special note is the incipient presence of blue pigments, which were rarely used in Roman Hispania owing to their scarcity and high price.
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      PubDate: 2015-06-27T11:43:00Z
       
  • Fourier transform infrared spectroscopy provides an evidence of papain
           denaturation and aggregation during cold storage
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Brankica Rašković , Milica Popović , Sanja Ostojić , Boban Anđelković , Vele Tešević , Natalija Polović
      Papain is a cysteine protease with wide substrate specificity and many applications. Despite its widespread applications, cold stability of papain has never been studied. Here, we used differential spectroscopy to monitor thermal denaturation process. Papain was the most stabile from 45°C to 60°C with ΔG°321 of 13.9±0.3kJ/mol and T m value of 84±1°C. After cold storage, papain lost parts of its native secondary structures elements which gave an increase of 40% of intermolecular β-sheet content (band maximum detected at frequency of 1621cm−1 in Fourier transform infrared (FT-IR) spectrum) indicating the presence of secondary structures necessary for aggregation. The presence of protein aggregates after cold storage was also proven by analytical size exclusion chromatography. After six freeze–thaw cycles around 75% of starting enzyme activity of papain was lost due to cold denaturation and aggregation of unfolded protein. Autoproteolysis of papain did not cause significant loss of the protein activity. Upon the cold storage, papain underwent structural rearrangements and aggregation that correspond to other cold denatured proteins, rather than autoproteolysis which could have the commercial importance for the growing polypeptide based industry.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Synthesis of Ag–ZnO with multiple rods (multipods) morphology and
           its application in the simultaneous photo-catalytic degradation of methyl
           orange and methylene blue
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): M. Arab Chamjangali , G. Bagherian , A. Javid , S. Boroumand , N. Farzaneh
      In this study, the photo-decolorization of a mixture of methylene blue (MB) and methyl orange (MO) was investigated using Ag–ZnO multipods. The photo-catalyst used, ZnO multipods, was successfully synthesized. The surface of ZnO microstructure was modified by deposition of different amounts of Ag nanoparticles (Ag NPs) using the photo-reduction method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis and atomic absorption spectroscopy. The photo-catalytic efficiency of Ag–ZnO is mainly controlled by the amount of Ag NPs deposited on the ZnO surface. The results obtained suggest that Ag–ZnO containing 6.5% Ag NPs, has the highest photo-catalytic performance in the simultaneous photo-degradation of dyes at a shorter time.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Experimental and theoretical spectroscopic study and structural
           determination of nickel(II) tridentate Schiff base complexes
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Ali Hossein Kianfar , Hossein Farrokhpour , Parin Dehghani , Hamid Reza Khavasi
      Some new complexes of [NiL(PR3)] (where L=(E)-1-[(2-amino-5-nitrophenyl)iminio-methyl]naphthalene-2-olate (L1), (E)-1-[(2-hydroxiphenyl)iminio-methyl]naphthalene-2-olate (L2), R=Bu and Ph) containing tridentate ONN and ONO Schiff bases were synthesized and characterized by IR, UV–Vis, 1H-NMR spectroscopy and elemental analysis. The geometry of [NiL1(PBu3)] and [NiL2(PBu3)] complexes were determined by X-ray crystallography. It was indicated that the complexes have a square planar structure and four coordinates in the solid state. Theoretical calculations were also performed to optimize the structures of the ligands and complexes in the gas phase and ethanol solvent, separately to confirm the structures proposed by X-ray crystallography. In addition, UV–Visible and IR spectra of the complexes were calculated and compared with the corresponding experimental spectra to complete the experimental structural identification.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • CdTe quantum dots as a novel biosensor for Serratia marcescens and
           Lipopolysaccharide
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Sh. Ebrahim , M. Reda , A. Hussien , D. Zayed
      The main objective of this work is to synthesize CdTe quantum dots (QDs) conjugated with Concanavalin A (Con A) as a novel biosensor to be selective and specific for the detection of Lipopolysaccharide (LPS). In addition, the conjugated CdTe QDs–Con A was used as fluorescence labels to capture Serratia marcescens bacteria through the recognition between CdTe QDs–Con A and LPS of S. marcescens. The appearance of the lattice plans in the high resolution transmission electron photograph indicated a high crystalline with an average size of 4–5nm for the CdTe QDs. The results showed that the relative fluorescence intensity of CdTe QDs–Con A decreased linearly with LPS concentration in the range from 10 to 90fg/mL and with correlation coefficient (R 2) equal to 0.9713. LPS surrounding the S. marcescens bacteria was bound to the CdTe QDs–Con A and leads to quenching of PL intensity. It was found that a good linear relationship between the relative PL intensity and the logarithmic of cell population of S. marcescens in range from 1×10 to 1×106 CFU/mL at pH 7 with R 2 of 0.952 was established.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Low-frequency vibrational properties of crystalline and glassy
           indomethacin probed by terahertz time-domain spectroscopy and
           low-frequency Raman scattering
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Tomohiko Shibata , Tatsuya Mori , Seiji Kojima
      In order to clarify the intermolecular vibrations, the low-frequency modes of the glassy and crystalline states of model pharmaceutical indomethacin have been studied using broadband terahertz time-domain spectroscopy and low-frequency Raman scattering. In the crystalline γ-form, the center of symmetry was suggested by the observation of the exclusion principle of the infrared (IR) and Raman selection rules in the frequency range between 0.2 and 6.5THz. In addition, a boson peak of the glassy state was observed in both IR and Raman spectra and their frequency showed apparent discrepancy. The intermediate correlation length of the glassy structure was estimated to be about 2.5nm. The existence of hydrogen bonded cyclic dimers in a glassy state was suggested by the observation of the infrared active intermolecular vibrational mode of the hydrogen bonded cyclic dimers as a broad peak at 3.0THz in the IR spectrum.
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      PubDate: 2015-06-27T11:43:00Z
       
  • Using IR and Raman spectra to explain the catalytic activity of the
           Fe(II)/Fe(III) pair toward the cleavage of peptide bonds
    • Abstract: Publication date: 5 December 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 151
      Author(s): Felipe G. Camacho , Wagner A. Alves
      IR and Raman experiments of formamide (FA) solutions containing variable amounts of Fe(II) and Fe(III) salts were carried out. The ν CO vibration is downshifted whereas the ν CN mode is upshifted in the presence of the divalent ion. As the trivalent ion is added to the solvent, upshifts of both ν CO and ν CN vibrations are observed. These spectral patterns are related to the distinct FA forms that are stabilized by each ion. Fe(II) is surrounded by 6 ionic FA species while neutral ones coordinate to the trivalent ion with formation of [Fe(FA)3Cl]2+ and [Fe(FA)2(Cl)2]+. In higher salt compositions [FeCl4]− is also identified in the spectra. Our vibrational results are very well corroborated by biological studies on the catalytic activity of the Fe(II)/Fe(III) pair in oxidative cleavage processes of polypeptides and proteins.
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      PubDate: 2015-06-27T11:43:00Z
       
  • In situ study of water uptake by the seeds, endosperm and husk of barley
           using infrared spectroscopy
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): D. Cozzolino , S. Degner , J.K. Eglinton
      Variations in the amount and rates of water uptake influence the seed hydration as well as the modification of the endosperm for industrial uses (e.g., malting). The aim of this study was to investigate and interpret absorption frequencies in the mid infrared (MIR) region associated with water uptake in whole seeds, husk and endosperm of barley seeds during the initial period of soaking in water. Partial least squares (PLS) regression models for the prediction of water uptake in the set of samples yield a coefficient of determination (R 2) and a standard error in cross validation of 0.75 and 2.57 (% w/w), respectively. The biological implications of this study are that the first stages of germination can be monitored using the information derived from the MIR spectra. These results also demonstrated that whole seeds, endosperm and husk derived from the same variety or genotype have different patterns in the MIR region.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Vibrational spectroscopic studies and molecular docking study of
           2-[(E)-2-phenylethenyl]quinoline-5-carboxylic acid
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Rajeev T. Ulahannan , C. Yohannan Panicker , Hema Tresa Varghese , Robert Musiol , Joseph Jampilek , Christian Van Alsenoy , Javeed Ahmad War , T.K. Manojkumar
      FT-IR and FT-Raman spectra of 2-[(E)-2-phenylethenyl]quinoline-5-carboxylic acid were recorded and obtained and analyzed. The vibrational wavenumbers were computed using DFT quantum chemical calculations. The geometrical parameters (SDD) of the title compound are in agreement with that of similar derivatives. Stability of the molecule arising from the hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital analysis. From the natural and Mulliken charges, it can be concluded that electrophilic substitution of the quinoline scaffold is more preferred than nucleophilic substitution. From the MEP map it is evident that the negative regions are mainly localized over the carbonyl group and are possible sites for electrophilic attack. The title compound forms a stable complex with PknB as is evident from the binding affinity values and the molecular docking study suggests that the compound might exhibit inhibitory activity against PknB.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Photophysical and photosensitizing characters of
           2-phenylbenzimidazole-5-sulfonic acid. A theoretical study
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Liang Shen
      The sunscreen agent 2-phenylbenzimidazole-5-sulfonic acid (PBSA) has been reported to exhibit photosensitizing activity. In the present study, the photophysical and photosensitizing properties of PBSA were investigated by means of quantum chemical calculations with the aim to gain deeper insights into the underlying photosensitizing mechanisms. The results indicate that singlet oxygen may be generated spontaneously through direct energy transfer from triplet excited state PBSA to 3O2, and superoxide anion radical is formed through electron transfer between the anion of PBSA and 3O2. This offers some deeper insights into the photosensitizing mechanisms of PBSA.
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      PubDate: 2015-06-27T11:43:00Z
       
  • A new thio-Schiff base fluorophore with copper ion sensing, DNA binding
           and nuclease activity
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): R. Vikneswaran , Muhamad Syamir Syafiq , Naser Eltaher Eltayeb , Mohd Naqiuddin Kamaruddin , S. Ramesh , R. Yahya
      Copper ion recognition and DNA interaction of a newly synthesized fluorescent Schiff base (HPyETSC) were investigated using UV–vis and fluorescent spectroscopy. Examination using these two techniques revealed that the detection of copper by HPyETSC is highly sensitive and selective, with a detection limit of 0.39μm and the mode of interaction between HPyETSC and DNA is electrostatic, with a binding constant of 8.97×104 M−1. Furthermore, gel electrophoresis studies showed that HPyETSC exhibited nuclease activity through oxidative pathway.
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      PubDate: 2015-06-27T11:43:00Z
       
  • The triplet state of tanshinone I and its synergic effect on the
           phototherapy of cancer cells with curcumin
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Chenchen Zhang , Shan Jiang , Kun Li , Mei Wang , Rongrong Zhu , Xiaoyu Sun , Qingxiu Wang , ShiLong Wang
      The excited triplet state of tanshinone I (Tan I) extracted from the traditional Chinese medicine Salvia miltiorrhiza Bunge was characterized by laser flash photolysis. The synergic effect of Tan I on the phototherapy of cancer cells with curcumin (Cur) was also investigated by MTT assay because the excited energy transfer from the triplet state of Tan I (3Tan I∗) to Cur occurred. At the same time, the characteristic absorption spectra of 3Tan I∗ were recorded, and its molar absorption coefficient and rate constants for several excited energy transfers were obtained. The photo-therapeutic effect of Cur is enhanced by combination with Tan I.
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      PubDate: 2015-06-27T11:43:00Z
       
  • Vibrational spectroscopic study of vinyl substituted polycyclic aromatic
           hydrocarbons
    • Abstract: Publication date: 5 December 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 151
      Author(s): Anju Maurya , Shantanu Rastogi
      The mid infrared emission features observed in various astrophysical sources are attributed to polycyclic aromatic hydrocarbon (PAH) molecules. The models of emission spectra from a collection of PAHs show uncertainty in matching the 6.2μm feature. This indicates the need to consider a larger variety of PAHs and PAH derivatives. Chemical pathways towards formation of PAHs in the astrophysical environments involve vinyl substituted PAHs as intermediate products. Vibrational spectroscopic study of vinyl-PAHs is reported in the present work. The vinyl group is substituted at similar positions in eight different PAHs. The obtained optimized structures show that vinyl substitution at 2 position in acenes gives planar geometry, while all other vinyl-PAHs are non-planar. Infrared spectra is simulated for neutrals as well as for cations. The results are compared with the spectra of corresponding plain PAHs and analyzed for possible match with astrophysical observations. New features, due to vinyl group in the composite spectra, identified at 6.64, 6.92, 7.27, 8.77 and 10.35μm fall close to some sub features of the observed emission spectra. The paper provides data that may be used in the emission models particularly along proto planetary nebulae type cool objects.
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      PubDate: 2015-06-27T11:43:00Z
       
  • Determination of sucrose in date fruits (Phoenix dactylifera L.) growing
           
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Fazal Mabood , Ahmed Al-Harrasi , Ricard Boqué , Farah Jabeen , Javid Hussain , A. Hafidh , K. Hind , M.A.G. Ahmed , A. Manzoor , Hidayat Hussain , Najeeb Ur Rehman , S.H. Iman , Jahina J. Said , Sara A. Hamood
      A Near Infrared (NIR) spectroscopic method combined with multivariate calibration was developed for the determination of the amount of sucrose in date fruits growing in the Sultanate of Oman. In this study two groups of samples were used: one group of 48 sucrose standard solutions in the concentration range from 0.01% to 50% (w/v) and another group of 54 date fruit samples of 18 different varieties. The sucrose standard samples were split in two sets, i.e. one training set of 31 samples and one test set of 17 samples. All samples were measured with a NIR spectrophotometer in the wavelength range from 700 to 2500nm. The spectra collected were preprocessed using baseline correction and Savitzky–Golay 1st derivative. Partial least-squares regression (PLSR) was used to build the regression model with the training set of 31 samples. This model was then validated by using random leave-one-out cross-validation. Later, the PLS regression model was externally validated by using the test set of 17 samples of known sucrose concentration. The root mean squared error of prediction (RMSEP) was found to be of 1.5%, which shows a good prediction ability of the model. Finally, the PLS model was applied to the spectra of 54 date fruit samples to quantify their sucrose amount. It was found that the Khalas, Barnia Nizwi, Ajwa Almadina, Maan, and Khunizi varieties contain high amounts of sucrose, i.e. ranging from 36% to 60%, while Naghal, Fardh, Nashu and Qash Tabaq varieties contain the least amount of sucrose, ranging from 3.5% to 8.1%.
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      PubDate: 2015-06-27T11:43:00Z
       
  • The influence of TeO2 on thermal stability and 1.53μm spectroscopic
           properties in Er3+ doped oxyfluorite glasses
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Fengchao Wang , Muzhi Cai , Rong Chen , Xufeng Jing , Bingpeng Li , Ying Tian , Junjie Zhang , Shiqing Xu
      In this work, the thermal and spectroscopic properties of Er3+-doped oxyfluorite glass based on AMCSBYT (AlF3–MgF2–CaF2–SrF2–BaF2–YF3–TeO2) system for different TeO2 concentrations from 6 to 21mol% is reported. After adding a suitable content of TeO2, the thermal ability of glass improves significantly whose ΔT and S can reach to 118°C and 4.47, respectively. The stimulated emission cross-section reaches to 7.80×10−21 cm2 and the fluorescence lifetime is 12.18ms. At the same time, the bandwidth characteristics reach to 46.41×10−21 cm2 nm and the gain performance is 63.73×10−21 cm2 ms. These results show that the optical performances of this oxyfluorite glass are very well. Hence, AMCSBYT glass with superior performances might be a useful material for applications in optical amplifier around 1.53μm.
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      PubDate: 2015-06-27T11:43:00Z
       
  • Ionization and tautomerism of methyl fluorescein and related dyes
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Nikolay O. Mchedlov-Petrossyan , Tatyana A. Cheipesh , Sergey V. Shekhovtsov , Andrey N. Redko , Vladimir I. Rybachenko , Irina V. Omelchenko , Oleg V. Shishkin
      The protolytic equilibrium of methyl ether of fluorescein is studied in water, aqueous ethanol, and in other solvents. The constants of the two-step dissociation are determined by spectrophotometry. In water, the fractions of the zwitterionic, quinonoid, and lactonic tautomes are correspondingly 11%, 6%, and 83%, as deduced from the UV–visible spectra. Corresponding study of the ionization of the methyl ether ester of fluorescein, fluorescein ethyl ester, and sulfonefluorescein allows testing the correction of the attribution of the microscopic dissociation constants of methoxy fluorescein. The results of nuclear magnetic resonance and infrared spectroscopy, as well as the X-ray analysis confirm the predomination of the lactonic structure of the molecular species in solid state and in DMSO. Contrary to it, the spectroscopic studies in both hydrogen-donor bond (HDB) and non-HBD solvents confirm that the presence of lactonic monoanion is atypical for the dye under study and, with high probability, also for the mother compound fluorescein.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Development of normalized spectra manipulating spectrophotometric methods
           for simultaneous determination of Dimenhydrinate and Cinnarizine binary
           mixture
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Nesrine T. Lamie , Ali M. Yehia
      Simultaneous determination of Dimenhydrinate (DIM) and Cinnarizine (CIN) binary mixture with simple procedures were applied. Three ratio manipulating spectrophotometric methods were proposed. Normalized spectrum was utilized as a divisor for simultaneous determination of both drugs with minimum manipulation steps. The proposed methods were simultaneous constant center (SCC), simultaneous derivative ratio spectrophotometry (S1DD) and ratio H-point standard addition method (RHPSAM). Peak amplitudes at isoabsorptive point in ratio spectra were measured for determination of total concentrations of DIM and CIN. For subsequent determination of DIM concentration, difference between peak amplitudes at 250nm and 267nm were used in SCC. While the peak amplitude at 275nm of the first derivative ratio spectra were used in S1DD; then subtraction of DIM concentration from the total one provided the CIN concentration. The last RHPSAM was a dual wavelength method in which two calibrations were plotted at 220nm and 230nm. The coordinates of intersection point between the two calibration lines were corresponding to DIM and CIN concentrations. The proposed methods were successfully applied for combined dosage form analysis, Moreover statistical comparison between the proposed and reported spectrophotometric methods was applied.
      Graphical abstract image Highlights Normalized spectrum was utilized as a divisor for simultaneous determination of Dimenhydrinate and Cinnarizine binary mixture with minimum manipulation steps. The proposed methods were simultaneous constant center, simultaneous derivative ratio spectrophotometry and ratio H-point standard addition method.

      PubDate: 2015-06-27T11:43:00Z
       
  • Investigation on the upconversion emission in 2D BiOBr:Yb3+/Ho3+
           nanosheets
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Yongjin Li , Zhiguo Song , Zhaoyi Yin , Qingliang Kuang , Ronghua Wan , Yuting Zhou , Qun Liu , Jianbei Qiu , Zhengwen Yang
      As lanthanide doped upconverting host, two dimensional (2D) nanostructure materials have remarkable advantages compare with the bulk materials, but excellent 2D upconversion nanohost is still few up to date. In this work, Yb3+/Ho3+ co-doped BiOBr nanosheets have been successfully prepared via a facile hydrothermal method, which were characterized by X-ray diffraction, transmission electron microscopy, Atomic Force Microscope, Raman spectra, Fourier transform infrared absorption and UC luminescence spectra. Under excitation at 980nm, bright green UC emission centered at 550nm accompanied with weak red (663nm) and near infrared (NIR) UC emissions (760nm) were observed. Power dependence studies revealed that NIR and red UC emissions were both dominated by a two and one-photon process due to saturation effects that is related to the special crystal structure of BiOBr nanosheets, and a different UC mechanism of NIR emission from Ho3+ was proposed accordingly.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Anticancer activity studies of a ruthenium(II) polypyridyl complex against
           human hepatocellular (BEL-7402) cells
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Wei Li , Bing-Jie Han , Jun-Hua Yao , Guang-Bin Jiang , Gan-Jian Lin , Yang-Yin Xie , Hong-Liang Huang , Yun-Jun Liu
      A Ru(II) polypyridyl complex [Ru(bpy)2(HMSPIP)](ClO4)2 (1) (bpy=2,2′-bipyridine, HMSPIP=2-(4-methylsulfonyl)phenyl-1H-imidazo[4,5-f][1,10] phenanthroline) was synthesized. The IC50 value of the complex against human hepatocellular cell BEL-7402 is 21.6±2.7μM. The complex shows no cytotoxic activity toward human lung adenocarcinoma cell A549, human osteosarcoma cell MG-63 and human breast cancer cell SK-BR-3 cells. It is easily for complex 1 to be taken up by BEL-7402 cells. The complex can enhance the reactive oxygen species (ROS) levels and induce the decrease in the mitochondrial membrane potential. The complex inhibits the cell growth in BEL-7402 cells at G2/M phase. Complex 1 can regulate the expression of Bcl-2 family proteins. The results show that the complex induces apoptosis of BEL-7402 cells through a ROS-mediated mitochondrial dysfunction pathway.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Supramolecular effect of curcurbit[7]uril on the binding mode of
           2-(4-(dimethylamino) styryl)-1-methylpyridinium iodide with Calf Thymus
           DNA: From minor groove to intercalative
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Anamika Manna , Sankar Chakravorti
      The effect of curcurbit[7]uril (CB[7]) in the binding mode of 2-(4-(dimethylamino) styryl)-1-methylpyridinium (DASPMI) with Calf Thymus DNA has been discussed in this paper. Red shift, intensity change in absorption and emission spectra and presence of isosbestic point with increasing concentration of CB[7] in groove bound DASPMI–DNA complex indicates a change in binding pattern. Appearance of a third slower component in lifetime decay in presence of CB[7] which gets more slow in high CB[7] concentration is indicative of a new type of binding. Major changes in ct-DNA bands in circular dichroism spectra with addition of CB[7] make a strong case for intercalative binding. Increased computed values of binding constant associated with diminishing quenching constant in presence of potassium iodide make a positive candidate for intercalative binding. Formation of big spherical condensate in DASPMI–DNA complex in presence of CB[7] which grows bigger in higher CB[7] concentration shows a morphological change. Molecular docking nicely portrays the intercalative nature of binding corroborating the experimental evidences.
      Graphical abstract image Highlights The binding mode of 2-(4-(dimethylamino) styryl)-1-methylpyridinium (DASPMI) with Calf Thymus DNA in aqueous solution changes from groove to intercalative when complexed with cucurbit[7]uril.

      PubDate: 2015-06-27T11:43:00Z
       
  • Using different chemical methods for deposition of copper selenide thin
           films and comparison of their characterization
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Betül Güzeldir , Mustafa Sağlam
      Different chemical methods such as Successive Ionic Layer Adsorption and Reaction (SILAR), spin coating and spray pyrolysis methods were used to deposite of copper selenide thin films on the glass substrates. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDX) spectroscopy and UV–vis spectrophotometry. The XRD and SEM studies showed that all the films exhibit polycrystalline nature and crystallinity of copper selenide thin films prepared with spray pyrolysis greater than spin coating and SILAR methods. From SEM and AFM images, it was observed copper selenide films were uniform on the glass substrates without any visible cracks or pores. The EDX spectra showed that the expected elements exist in the thin films. Optical absorption studies showed that the band gaps of copper selenide thin films were in the range 2.84–2.93eV depending on different chemical methods. The refractive index (n), optical static and high frequency dielectric constants (ε 0, ε ∞) values were calculated by using the energy bandgap values for each deposition method. The obtained results from different chemical methods revealed that the spray pyrolysis technique is the best chemical deposition method to fabricate copper selenide thin films. This absolute advantage was lead to play key roles on performance and efficiency electrochromic and photovoltaic devices.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Thiophene aldehyde-diamino uracil Schiff base: A novel fluorescent probe
           for detection and quantification of cupric, silver and ferric ions
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Hassan H. Hammud , Shawky El Shazly , Ghassan Sonji , Nada Sonji , Kamal H. Bouhadir
      A new Schiff base from the condensation of 5,6-diamino-1,3-dimethyluracil with 5-methylthiophene-2-carboxaldehyde was synthesized. The compound was characterized by spectral data (UV–Vis, IR, 1H NMR, fluorescence, MS). Ethanolic solutions of the Schiff base exhibit a strong fluorescence emission at 385nm (λ ex =341nm), and have been employed as a “turn-off” fluorescent probe for selective detection of Ag+, Cu2+ and Fe3+ ions in presence of other cations such as Na+, K+, Ca2+ and Mg2+ ions abundant in natural water. The interaction between the tested compound and copper, silver or iron ions is associated with a significant fluorescence decrease, showing detection limits of 2.1–14.2ppb. Under optimal conditions, the developed sensor was successfully employed to determine Ag+, Cu2+ and Fe3+ ions in real samples and proved to be selective and sensitive.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Energetic stabilities of thiolated pyrimidines on gold nanoparticles
           investigated by Raman spectroscopy and density functional theory
           calculations
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Erdene-Ochir Ganbold , Jinha Yoon , Kwang-Hwi Cho , Sang-Woo Joo
      The adsorption structures of 2-thiocytosine (2TC) on gold surfaces were examined by means of vibrational Raman spectroscopy and quantum mechanical density functional theory calculations. The 1H-thione-amino form was calculated to be most stable among the six examined tautomers. The three plausible binding geometries of sulfur, pyrimidine nitrogen, and amino group binding modes were calculated to estimate the binding energies of the 1H-thione-amino form with six gold cluster atoms. Thiouracils including 2-thiouracil (2TU), 4-thiouracil (4TU), and 6-methyl-2-thiouracil (6M2TU) were also studied to compare their relative binding energies on gold atoms. The intracellular localization of a DNA base analog of 2TC on gold nanoparticles (AuNPs) in HeLa cells was identified by means of surface-enhanced Raman scattering. AuNPs were modified with 2TC by self-assembly. Our dark-field microscopy and z-depth-dependent confocal Raman spectroscopy indicated that 2TC-assembled AuNPs could be found inside cancer cells. On the other hand, we did not observe noticeably strong Raman peaks in the cases of thiouracils including 2TU, 4TU, and 6M2TU. This may be due to the additional amino group of 2TC, which can lead to a stronger binding of adsorbates on AuNPs.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Molecular structure, spectroscopic characterization, HOMO and LUMO
           analysis of 3,3′-diaminobenzidine with DFT quantum chemical
           calculations
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Mehmet Karabacak , Sibel Bilgili , Ahmet Atac
      In this work, infrared, Raman and UV spectra of 3,3′-diaminobenzidine (3,3-DAB) were carried out by using density functional theory (DFT)/B3LYP method with 6-311G(d,p) basis set. FT-IR and FT-Raman spectra were recorded in the region 4000–400 and 4000–50cm−1, respectively. The geometrical parameters, energies and wavenumbers were obtained and fundamental vibrations were assigned on the basis of the potential energy distribution (PED) of the vibrational modes. The UV spectrum of the investigated compound was recorded in the range of 200–400nm in ethanol and water solutions. The electronic properties, such as excitation energies, absorption wavelengths, HOMO and LUMO energies were performed by DFT/B3LYP approach and the results were compared with experimental observations. Thermodynamic properties, Mulliken atomic charges and molecular electrostatic potential (MEP) were calculated for the title molecule. Also the nonlinear optical properties of 3,3-DAB molecule were explored theoretically. As a result, the calculated results were compared with the observed values and generally found to be in good agreement.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Structural, optical and magnetic properties of γ-irradiated SiO2
           xerogel doped Fe2O3
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): H.H. Mahmoud , I.K. Battisha , F.M. Ezz-Eldin
      The paper deals with the structure, morphology and magnetic properties of two different iron concentrations (20 and 33mol.%) of Fe2O3−SiO2 nanocomposites, prepared by sol–gel technique and exposed to different gamma-irradiation doses (0, 30 and 60kGy). The nanocomposites were investigated through XRD, TEM, SEM, FTIR and EPR measurements. Superparamagnetic iron (III) oxide nanoparticles with a narrow size distribution, dispersed over the amorphous silica matrix, are assumed to be present in all the samples before and after irradiation. Before irradiation, a lot of γ-Fe2O3 crystalline ferromagnetic nanoparticles are assumed to be formed particularly for sample containing 33mol.% Fe2O3, while exposing the samples to irradiation results in the transformation of γ- to α-Fe2O3. Iron concentrations and/or irradiation of the samples are assumed to cause changes in the bond angles and/or bond lengths of the structural silicate units within network, as well, the increase of more defect centers induced by irradiation as evident through the variations of the IR bands intensity. The EPR results show both intensity and line width increase with increasing Fe2O3 concentration. The EPR signals for the samples consist of a well defined symmetrical broad signal at g ≈2.0 ascribed to antiferromagnetic interactions between the Fe2+ and Fe3+ clusters. Condensed clusters of Fe3+ ions are observed to give rise to a resonance line at g ∼2 whose position and width do not depend on the Fe2O3 concentrations. The EPR signal intensity is observed to be significantly decreased in the sample 33mol.% or stabilized in the sample 20mol.% by γ-irradiation. This reflects simultaneous spin transformation from the high-spin state of Fe III to the low-spin state of Fe II. As a final point, an effort has been given to found the possibility to use one of these studied nanocomposite materials as candidate for radiation shielding purposes.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Determination of dexamethasone by flow-injection chemiluminescence method
           using capped CdS quantum dots
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Alireza Khataee , Aliyeh Hasanzadeh , Roya Lotfi , Rahmatollah Pourata , Sang Woo Joo
      l-Cysteine capped CdS quantum dots (QDs) were synthesized through a facile hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and UV–Vis spectroscopy. The light emitted from KMnO4–l-cysteine capped CdS QDs reaction in acidic medium was applied as a simple and sensitive chemiluminescence (CL) system for determination of dexamethasone. The CL intensity of KMnO4–l-cysteine capped CdS QDs CL system was remarkably enhanced in the presence of dexamethasone. Under optimum experimental conditions, the enhanced CL intensity was related to dexamethasone concentration in the range of 0.004–25.0mgL−1, with the detection limit (3σ) of 0.0013mgL−1. The analytical applicability of the proposed CL system was assessed by determining dexamethasone in spiked environmental water samples and pharmaceutical formulation. The analytical performances of proposed flow-injection CL method for the determination of dexamethasone were compared with those obtained by corona discharge ionization ion mobility spectrometry (CD-IMS) method. The proposed CL system exhibits a higher sensitivity and precision than the CD-IMS method for the determination of dexamethasone.
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      PubDate: 2015-06-27T11:43:00Z
       
  • Raman analysis of complex pigment mixtures in 20th century metal knight
           shields of the Order of the Elephant
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Clara Bratt Lauridsen , Jana Sanyova , Kim Pilkjær Simonsen
      The pigment composition of six painted metal knight shields of the Order of the Elephant dating from the second half of the 20th century belonging to the Danish royal collection were studied using Raman microscopy. By focusing a 785nm laser with a 50× objective on particles in paint cross sections, it was possible to identify the following 20 compounds: hematite, goethite, chrome red/orange, chrome yellow, zinc chrome yellow, carbon black, toluidine red PR3, chlorinated para red PR4, dinitroaniline orange PO5, phthalocyanine blue PB15, indanthrone blue PB60, ultramarine, Prussian blue, lead white, anatase, rutile, calcium carbonate, barium sulphate, gypsum and dolomite. The components were frequently present in complex pigment mixtures. Additional information was obtained by elemental analysis with scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX) to identify cobalt blue, zinc white and cadmium red, as well as to indicate the presence of zinc white in some pigment mixtures. The study allowed a comparison between the industrially applied preparation layers and the artistic paint layers applied by the heraldic painter. Differences in the choice of paint and pigment types were observed on the earliest knight shields, demonstrating a general delay of industrial materials into artist paints.
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      PubDate: 2015-06-27T11:43:00Z
       
  • Bivalent transition metal complexes of
           (E)-3-(2-benzylidenehydrazinyl)-3-oxo-N-(p-tolyl)propanamide:
           Spectroscopic, computational, biological activity studies
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): R.R. Zaky , K.M. Ibrahim , H.M. Abou El-Nadar , S.M. Abo-Zeid
      Schiff base complexes of Co(II), Ni(II) and Cu(II) with (E)-3-(2-benzylidenehydrazinyl)-3-oxo-N-(p-tolyl)propanamide (H2BHAH) containing N and O donor sites were synthesized. Both ligand and its metal complexes were characterized by elemental analysis, thermal analysis (TG and DTG), spectroscopy (1H NMR, IR, UV–visible, MS spectra), and physical measurements (magnetic susceptibility and molar conductance). The kinetic and thermodynamic parameters of the different decomposition steps of some complexes were calculated using the Coats–Redfern and Horowitz–Metzger methods. Also, the DFT studying was evaluated to confirm the geometry of the investigated compounds. Moreover, the association and formation constants of Ni(II) and Cu(II) ions in mixed solvent at 290.15K were calculated by using electrical conductance. The antimicrobial activities of the ligand and its complexes were studied against gram positive bacteria Staphylococcus aureus, gram negative bacteria; Escherichia coli and pathogenic fungi; Candida albicans by using minimum inhibition concentrations method. The antioxidant (ABTS-derived free radical method) and cytotoxic (in vitro Ehrlich Ascites) activities of the isolated compounds were estimated.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Synthesis of pyrazolylbisindoles over mesoporous Lewis acidic ZrTUD-1:
           Potential application in selective Cu2+ colorimetric detection
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Karthikeyan Kandasamy , Sivaprasad Ganesabaskaran , Muthusamy Poomalai Pachamuthu , Rajamanickam Maheswari , Anand Ramanathan
      A series of pyrazolylbisindole (PBI) derivatives were prepared by simple condensation of indole and pyrazole aldehyde utilizing amorphous mesoporous ZrTUD-1 having predominant Lewis acid sites. The applicability of pyrazolylbisindolyl derivate as a colorimetric chemosensor with high selectivity toward Cu2+ over other cations were tested. Among heavy and transition metal (HTM) ions in CH3CN solution, the probe only sensed Cu2+ detectable by naked eye. The sensor exhibited a new absorption band at 488nm (a red shift of 206nm from 282nm) with a large colorimetric response and affinity to Cu2+ over other cations tested (Al3+, Pb2+, Cd2+, Mg2+, Mn2+, Zn2+, K+, Fe2+, Ca2+, Cu2+ and Hg2+).
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      PubDate: 2015-06-27T11:43:00Z
       
  • A highly selective fluorescent probe for Al3+ based on quinoline
           derivative
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Guan-qun Wang , Jin-can Qin , Chao-Rui Li , Zheng-yin Yang
      A novel Schiff base fluorescent probe, 1-phenyl-3-methyl-5-hydroxypyrazole-4-carbaldehyde (2′-methylquinoline-4′-formyl) hydrazone (PMHCH), for selective detection of Al3+ has been designed and synthesized. Upon addition of various metal ions, the receptor only shows 286-fold enhancement of fluorescence intensity which might be attributed to a 1:1 stoichiometry between PMHCH and Al3+ and the photo-induced electron transfer progress in the present of Al3+ at 505nm. More importantly, the detection limit of PMHCH for Al3+ could reach at 10−7 M level.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
  • Spectroscopic study on binding of gentisic acid to bovine serum albumin
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Andrés Garzón , Iván Bravo , M. Rosario Carrión-Jiménez , Ángela Rubio-Moraga , José Albaladejo
      The interaction of (gentisic acid) GA with (bovine serum albumin) BSA has been studied by different spectroscopic techniques. GA is a monoanionic specie at the working pH of 7.4, it was determined by combining UV–Vis absorption spectroscopy and theoretical calculations. A set of fluorescence quenching experiments at different temperatures was carried out employing the native fluorescence of BSA. A Stern–Volmer constant (K SV) of (2.07±0.12)×104 mol−1 L and a binding constant (Ka ) of (8.47±4.39)×103 were determined at 310K. The static quenching caused by the BSA–GA complex formation seems to play a significant role in the overall quenching process. A single binding site on BSA for GA was observed. ΔH =−55.6±0.2kJmol−1 and ΔS =−104.3±0.6Jmol−1 K−1 were determined in a set of experiments on the dependence of Ka with the temperature. The binding process is, therefore, spontaneous and enthalpy-driven. Van der Waals forces and hydrogen bonds could also play the major role in the binding mode. The secondary structure changes of BSA in the absence and presence of GA were studied by FTIR and UV–Vis absorption spectroscopy.
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      PubDate: 2015-06-27T11:43:00Z
       
  • Theoretical investigations of electronic, optical and mechanical
           properties for GaSb and AlSb semiconductors under the influence of
           temperature
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Elkenany B. Elkenany
      In this paper we explore the effects of temperature on the electronic and mechanical properties of GaSb and AlSb semiconductors by using the local empirical pseudo-potential method. Our results show that the band gaps, refractive index, optical dielectric constant, elastic constants (C 11, C 12, C 44), bulk modulus, shear modulus and Young modulus of these compounds vary with the change in temperature. The comparison of some of our results with the available experimental data confirms the accurateness of our theoretical approach, which also infers the reliability of our other theoretical results. As, for some of the present calculations a little experimental data is available for comparison, therefore these results can be used as a reference work in the future studies.
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      PubDate: 2015-06-27T11:43:00Z
       
  • Temperature dependent Raman and DFT study of creatine
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Debraj Gangopadhyay , Poornima Sharma , Ranjan K. Singh
      Temperature dependent Raman spectra of creatine powder have been recorded in the temperature range 420–100K at regular intervals and different clusters of creatine have been optimized using density functional theory (DFT) in order to determine the effect of temperature on the hydrogen bonded network in the crystal structure of creatine. Vibrational assignments of all the 48 normal modes of the zwitterionic form of creatine have been done in terms of potential energy distribution obtained from DFT calculations. Precise analysis gives information about thermal motion and intermolecular interactions with respect to temperature in the crystal lattice. Formation of higher hydrogen bonded aggregates on cooling can be visualized from the spectra through clear signature of phase transition between 200K and 180K.
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      PubDate: 2015-06-27T11:43:00Z
       
  • A combined experimental and theoretical study of the tautomeric and
           conformational properties of (5-phenyl-tetrazol-2-yl)-acetic acid methyl
           ester
    • Abstract: Publication date: 5 November 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 150
      Author(s): Aamer Saeed , Muhammad Qasim , Majid Hussain , Ulrich Flörke , Mauricio F. Erben
      The tautomeric and conformational properties of a new tetrazole derivative are studied in a combined approach that includes the analysis of the experimental vibrational data together with theoretical calculation methods, especially in terms of natural bond orbital (NBO) population analysis. Moreover, the molecular and crystal structure was determined by single crystal X-ray diffraction. The compound crystallized as the 2-tautomeric form, monoclinic space group P21/c with Z =4, a =10.0630(14), b =8.2879(11), c =12.8375(18)Å, β =105.546(3)°, V =1031.5(2)Å3. The tetrazole and phenyl rings are coplanar with the acetate group oriented perpendicular to the plane. The NBO analysis showed that delocalizing interactions of the lpp(N2) lone pair orbital contributes to a strong resonance interactions with both adjacent π∗(N3N4) and π∗(N1C5) antibonding orbitals of the tetrazole group.
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      PubDate: 2015-06-27T11:43:00Z
       
  • Interaction of γ-Fe2O3 nanoparticles with fibrinogen
    • Abstract: Publication date: 5 December 2015
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 151
      Author(s): Hongmei Zhang , Peirong Wu , Zhaohua Zhu , Yanqing Wang
      In this article, an attempt is made to analysis the binding mechanism of γ-Fe2O3 nanoparticles with fibrinogen by using a combination of circular dichroism, UV–vis, fluorescence spectroscopic and computational methods. The multi-spectroscopic data revealed that the complex easily formed between γ-Fe2O3 nanoparticles and fibrinogen by mainly hydrogen bonding forces. The binding constants of fibrinogen with γ-Fe2O3 nanoparticles were 2.24×107, 1.15×107 and 0.72×107 Lmol−1 at 298, 304, and 310K, respectively. Furthermore, the results from circular dichroism, UV–vis, synchronous fluorescence, and three-dimensional fluorescence studies showed that the strong binding interaction of γ-Fe2O3 nanoparticles with fibrinogen induced an obvious perturbation in the protein secondary and tertiary structure. Moreover, the results of molecular modeling indicated the existence of the preferable binding site on fibrinogen for γ-Fe2O3 NPs model.
      Graphical abstract image

      PubDate: 2015-06-27T11:43:00Z
       
 
 
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