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  Subjects -> CHEMISTRY (Total: 843 journals)
    - ANALYTICAL CHEMISTRY (47 journals)
    - CHEMISTRY (594 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (26 journals)
    - INORGANIC CHEMISTRY (42 journals)
    - ORGANIC CHEMISTRY (45 journals)
    - PHYSICAL CHEMISTRY (67 journals)

CHEMISTRY (594 journals)            First | 1 2 3 4 5 6 | Last

Journal of Analytical Methods in Chemistry     Open Access  
Journal of Analytical Sciences, Methods and Instrumentation     Open Access   (Followers: 2)
Journal of AOAC International     Full-text available via subscription   (Followers: 9)
Journal of Applied Chemistry     Open Access   (Followers: 4)
Journal of Applied Solution Chemistry and Modeling     Hybrid Journal  
Journal of Applied Spectroscopy     Hybrid Journal   (Followers: 8)
Journal of Argentine Chemical Society     Open Access  
Journal of Biomaterials and Nanobiotechnology     Open Access   (Followers: 6)
Journal of Carbohydrate Chemistry     Hybrid Journal   (Followers: 5)
Journal of Catalysis     Hybrid Journal   (Followers: 7)
Journal of Catalyst & Catalysis     Full-text available via subscription   (Followers: 1)
Journal of Catalysts     Open Access  
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 10)
Journal of Chemical and Biological Interfaces     Full-text available via subscription   (Followers: 1)
Journal of Chemical Education     Full-text available via subscription   (Followers: 21)
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: 6)
Journal of Chemical Science and Technology     Open Access   (Followers: 3)
Journal of Chemical Sciences     Partially Free   (Followers: 17)
Journal of Chemical Theory and Computation     Full-text available via subscription   (Followers: 14)
Journal of Chemical Thermodynamics     Hybrid Journal   (Followers: 4)
Journal of Cheminformatics     Open Access   (Followers: 2)
Journal of Chemistry     Open Access   (Followers: 5)
Journal of Chemometrics     Hybrid Journal   (Followers: 10)
Journal of Chromatography A     Hybrid Journal   (Followers: 60)
Journal of Clinical Toxicology     Open Access   (Followers: 2)
Journal of Colloid and Interface Science     Hybrid Journal   (Followers: 14)
Journal of Computational Chemistry     Hybrid Journal   (Followers: 17)
Journal of Coordination Chemistry     Hybrid Journal   (Followers: 3)
Journal of Dispersion Science and Technology     Hybrid Journal  
Journal of Encapsulation and Adsorption Sciences     Open Access   (Followers: 4)
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: 5)
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: 2)
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: 3)
Journal of Mass Spectrometry     Hybrid Journal   (Followers: 27)
Journal of Materials Chemistry A : Materials for Energy and Sustainability     Full-text available via subscription   (Followers: 27)
Journal of Materials Chemistry B : Materials for Biology and Medicine     Full-text available via subscription   (Followers: 6)
Journal of Materials Chemistry C : Materials for Optical, Magnetic and Electronic Devices     Full-text available via subscription   (Followers: 9)
Journal of Materials Physics and Chemistry     Open Access   (Followers: 1)
Journal of Materials Research     Full-text available via subscription   (Followers: 10)
Journal of Mathematical Chemistry     Hybrid Journal   (Followers: 6)
Journal of Medicinal Chemistry     Full-text available via subscription   (Followers: 74)
Journal of Membrane and Separation Technology     Hybrid Journal   (Followers: 1)
Journal of Membrane Science     Hybrid Journal   (Followers: 14)
Journal of Metastable and Nanocrystalline Materials     Full-text available via subscription  
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: 1)
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: 3)
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  
Journal of Organometallic Chemistry     Hybrid Journal   (Followers: 14)
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: 7)
Journal of Polymer and Biopolymer Physics Chemistry     Open Access   (Followers: 3)
Journal of Polymer Science Part A: Polymer Chemistry     Hybrid Journal   (Followers: 110)
Journal of Polymers     Open Access   (Followers: 3)
Journal of Porphyrins and Phthalocyanines     Hybrid Journal   (Followers: 2)
Journal of Pure and Applied Chemistry Research     Open Access   (Followers: 1)
Journal of Raman Spectroscopy     Hybrid Journal   (Followers: 12)
Journal of Research Updates in Polymer Science     Hybrid Journal  
Journal of Saudi Chemical Society     Open Access  
Journal of Solid State Chemistry     Hybrid Journal   (Followers: 15)
Journal of Solution Chemistry     Hybrid Journal   (Followers: 3)
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: 4)
Journal of Taibah University for Science     Open Access   (Followers: 1)
Journal of the American Chemical Society     Full-text available via subscription   (Followers: 215)
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  
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: 9)
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: 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]   [7 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1386-1425
   Published by Elsevier Homepage  [2801 journals]
  • Extensive theoretical studies on the low-lying electronic states of BBr+
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): Xianghong Niu, Huabing Shu, Zunlue Zhu, Qian Chen
      The potential energy curves (PECs) of two lowest dissociation channels of BBr+ have been thoroughly investigated using the internally contracted multireference configuration interaction method with Davidson correction and relativistic correction. All PECs are extrapolated to complete basis set limit. Several quasibound excited states caused by avoided crossings are found. Based on the PECs, the spectroscopic parameters of bound and quasibound states are obtained. The transition dipole moments and radiative lifetimes are predicted for all possible transitions. Finally, the spin–orbit coupling matrix elements are computed using the states interaction approach with the full Breit–Pauli Hamiltonian to analyze the interactions in PECs crossing regions. We propose that the 22Σ+–X2Σ+ and 22Π–X2Σ+ transitions which cannot be observed in experiments are attributed to the intricate couplings among 12Π, 22Π, 22Σ+, 14Σ+, 14Δ, 14Σ−, 12Δ and 12Σ− states.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • Joint analyses model for total cholesterol and triglyceride in human serum
           with near-infrared spectroscopy
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): Lijun Yao, Ning Lyu, Jiemei Chen, Tao Pan, Jing Yu
      The development of a small, dedicated near-infrared (NIR) spectrometer has promising potential applications, such as for joint analyses of total cholesterol (TC) and triglyceride (TG) in human serum for preventing and treating hyperlipidemia of a large population. The appropriate wavelength selection is a key technology for developing such a spectrometer. For this reason, a novel wavelength selection method, named the equidistant combination partial least squares (EC-PLS), was applied to the wavelength selection for the NIR analyses of TC and TG in human serum. A rigorous process based on the various divisions of calibration and prediction sets was performed to achieve modeling optimization with stability. By applying EC-PLS, a model set was developed, which consists of various models that were equivalent to the optimal model. The joint analyses model of the two indicators was further selected with only 50 wavelengths. The random validation samples excluded from the modeling process were used to validate the selected model. The root-mean-square errors, correlation coefficients and ratio of performance to deviation for the prediction were 0.197mmolL−1, 0.985 and 5.6 for TC, and 0.101mmolL−1, 0.992 and 8.0 for TG, respectively. The sensitivity and specificity for hyperlipidemia were 96.2% and 98.0%. These findings indicate high prediction accuracy and low model complexity. The proposed wavelength selection provided valuable references for the designing of a small, dedicated spectrometer for hyperlipidemia. The methodological framework and optimization algorithm are universal, such that they can be applied to other fields.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • Simultaneous determination of benznidazole and itraconazole using
           spectrophotometry applied to the analysis of mixture: A tool for quality
           control in the development of formulations
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): Ludmila A.G. Pinho, Lívia C.L. Sá-Barreto, Carlos M.C. Infante, Marcílio S.S. Cunha-Filho
      The aim of this work was the development of an analytical procedure using spectrophotometry for simultaneous determination of benznidazole (BNZ) and itraconazole (ITZ) in a medicine used for the treatment of Chagas disease. In order to achieve this goal, the analysis of mixtures was performed applying the Lambert–Beer law through the absorbances of BNZ and ITZ in the wavelengths 259 and 321nm, respectively. Diverse tests were carried out for development and validation of the method, which proved to be selective, robust, linear, and precise. The lower limits of detection and quantification demonstrate its sensitivity to quantify small amounts of analytes, enabling its application for various analytical purposes, such as dissolution test and routine assays. In short, the quantification of BNZ and ITZ by analysis of mixtures had shown to be efficient and cost-effective alternative for determination of these drugs in a pharmaceutical dosage form.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • A case study of energy transfer mechanism from uranium to europium in
           ZnAl2O4 spinel host by photoluminescence spectroscopy
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): Mithlesh Kumar, M. Mohapatra
      Zinc aluminate (ZAO), a member of spinel class of inorganic compounds has been of much interest of late due to its wide range of use in catalysis, optical, electronic and ceramic industries. When doped with several lanthanides, this material has proved to be a potential host matrix for phosphors. As lanthanides suffer from poor (direct) excitation and emission cross sections, the use of a co-dopant ion can help to circumvent this and extract better emission from a lanthanide doped ZAO system. In this connection, energy transfer mechanism from uranium to europium in the ZAO host was investigated by photoluminescence spectroscopic technique. It was seen that uranium gets stabilized in the hexavalent state as UO6 6− (octahedral uranate) where as the lanthanide ion, Eu is stabilized in its trivalent state in the ZAO host. In the co-doped system, an efficient energy transfer pathway from the uranate to europium ion was observed. Based upon emission and life time data a suitable mechanism was proposed for the energy transfer (quenching) process. It was proposed that after excitation by photons, the uranate ions transfer their energy to nearby 5D1 level of Eu3+ ions which non-radiatively de-excites to the corresponding lower levels of 5D0. Further this 5D0 level decays in a radiative mode to the 7F manifold giving the characteristic emission profile of trivalent Eu. It was proposed that both static and dynamic types of energy transfer mechanism were responsible for this process.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • Temperature-dependent IR and Raman studies of metal–organic
           frameworks [(CH3)2NH2][M(HCOO)3], M=Mg and Cd
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): K. Szymborska-Małek, M. Trzebiatowska-Gusowska, M. Mączka, A. Gągor
      Two metal–organic frameworks of [(CH3)2NH2][M(HCOO)3], where M=Mg and Cd, have been investigated by temperature-dependent IR and Raman methods in order to determine the nature of the phase transition. Our results indicate that phase transition in the Mg-compound is driven by ordering of the dimethylammonium cations. Additional X-ray diffraction and spectroscopic studies on Cd-compound as the function of temperature reveal that this compound does not undergo any structural phase transition. We attribute this behavior to the large size of the cavity occupied by the dimethylammonium cations and thus weak hydrogen bonding between these cations and formate ions.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • Theoretical investigation on ESIPT mechanism of a new fluorescent sensor
           in different solvents
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): Dapeng Yang, Rui Zheng, Yusheng Wang, Jian Lv
      In the present work, a new phenylbenzimidazole derivatized fluorescent sensor (L) (J. Lumin. 147 (2014) 179), has been investigated on the excited state proton transfer (ESPT) based on the time-dependent density functional theory (TDDFT) method. The calculated absorption and fluorescence spectra based on the TDDFT method are in agreement with the experimental results. Two kinds of structures of L chromophore are found in the first excited (S1) state, which may be due to the proton transfer reactive. Hydrogen bond strengthening has been testified in the S1 state based on comparing staple bond lengths and bond angles involved in hydrogen bonding between the S0 state and the S1 state. In addition, the calculated infrared spectra at the N–H stretching vibrational region and calculated hydrogen bond energy also declare the phenomenon of hydrogen bond strengthening. The frontier molecular orbitals (MOs) and Mulliken's charge distribution analysis method as well as natural bond orbital (NBO) demonstrate the charge distribution, which provides the tendency of ESIPT reaction. The potential energy surfaces of the S0 and S1 states are constructed to explain the mechanism of the proton transfer in the excited state in detail. In addition, the ESIPT process of sensor L is dependent on different solvents.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • A micro-Raman spectroscopic investigation of leukemic U-937 cells in aged
           cultures
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): Enza Fazio, Sebastiano Trusso, Domenico Franco, Marco Sebastiano Nicolò, Alessandro Allegra, Fortunato Neri, Caterina Musolino, Salvatore P.P. Guglielmino
      Recently it has been shown that micro-Raman spectroscopy combined with multivariate analysis is able to discriminate among different types of tissues and tumoral cells by the detection of significant alterations and/or reorganizations of complex biological molecules, such as nucleic acids, lipids and proteins. Moreover, its use, being in principle a non-invasive technique, appears an interesting clinical tool for the evaluation of the therapeutical effects and of the disease progression. In this work we analyzed molecular changes in aged cultures of leukemia model U937 cells with respect to fresh cultures of the same cell line. In fact, structural variations of individual neoplastic cells on aging may lead to a heterogeneous data set, therefore falsifying confidence intervals, increasing error levels of analysis and consequently limiting the use of Raman spectroscopy analysis. We found that the observed morphological changes of U937 cells corresponded to well defined modifications of the Raman contributions in selected spectral regions, where markers of specific functional groups, useful to characterize the cell state, are present. A detailed subcellular analysis showed a change in cellular organization as a function of time, and correlated to a significant increase of apoptosis levels. Besides the aforementioned study, Raman spectra were used as input for principal component analysis (PCA) in order to detect and classify spectral changes among U937 cells.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • Stability-indicating spectrophotometric methods for determination of the
           anticoagulant drug apixaban in the presence of its hydrolytic degradation
           product
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): Mahmoud A. Tantawy, Nariman A. El-Ragehy, Nagiba Y. Hassan, Mohamed Abdelkawy
      Apixaban (a novel anticoagulant agent) was subjected to a stress stability study including acid, alkali, oxidative, photolytic, and thermal degradation. The drug was found to be only liable to acidic and alkaline hydrolysis. The degradation product was then isolated and identified by IR and GC–mass spectrometry. Four spectrophotometric methods, namely; first derivative (D1), derivative ratio (DR), ratio difference (RD) and mean centering of ratio spectra (MCR), have been suggested for the determination of apixaban in presence of its hydrolytic degradation product. The proposed methods do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined, and the methods were validated as per ICH guidelines and the specificity was assessed by analyzing synthetic mixtures containing different percentages of the degradation product with the drug. The developed methods were successfully applied for the determination of apixaban in bulk powder and its tablet dosage form.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • A simple and highly sensitive assay of perfluorooctanoic acid based on
           resonance light scattering technique
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): Fang Zhang, Yonghong Zheng, Jiaman Liang, Sha Long, Xianping Chen, Kejun Tan
      A simple, highly sensitive resonance light scattering (RLS) method for the detection of perfluorooctanoic acid (PFOA) has been developed based on the interaction with crystal violet (CV). It was found that PFOA can form complexes with CV in acid medium resulting in remarkable enhancement of the RLS intensity of the system. And the enhanced RLS intensities are in proportion to the concentration of PFOA in the range of 0.1–25.0μmol/L (R2 =0.9998), with a detection limit of 11.0nmol/L (S/N=3). In this work, the optimum reaction conditions and the interferences of foreign substances were investigated. The reaction mechanism between CV and PFOA was also studied by the absorption spectrum and scanning electron microscope (SEM). This method is successfully applied to the determination of PFOA in tap water and Jialing river water samples with RSD≤4.04%.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • Penalized discriminant analysis for the detection of wild-grown and
           cultivated Ganoderma lucidum using Fourier transform infrared spectroscopy
           
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): Ying Zhu, Tuck Lee Tan
      An effective and simple analytical method using Fourier transform infrared (FTIR) spectroscopy to distinguish wild-grown high-quality Ganoderma lucidum (G. lucidum) from cultivated one is of essential importance for its quality assurance and medicinal value estimation. Commonly used chemical and analytical methods using full spectrum are not so effective for the detection and interpretation due to the complex system of the herbal medicine. In this study, two penalized discriminant analysis models, penalized linear discriminant analysis (PLDA) and elastic net (Elnet),using FTIR spectroscopy have been explored for the purpose of discrimination and interpretation. The classification performances of the two penalized models have been compared with two widely used multivariate methods, principal component discriminant analysis (PCDA) and partial least squares discriminant analysis (PLSDA). The Elnet model involving a combination of L 1 and L 2 norm penalties enabled an automatic selection of a small number of informative spectral absorption bands and gave an excellent classification accuracy of 99% for discrimination between spectra of wild-grown and cultivated G. lucidum. Its classification performance was superior to that of the PLDA model in a pure L 1 setting and outperformed the PCDA and PLSDA models using full wavelength. The well-performed selection of informative spectral features leads to substantial reduction in model complexity and improvement of classification accuracy, and it is particularly helpful for the quantitative interpretations of the major chemical constituents of G. lucidum regarding its anti-cancer effects.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • High-throughput prediction of tablet weight and trimethoprim content of
           compound sulfamethoxazole tablets for controlling the uniformity of dosage
           units by NIR
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): Yanhong Dong, Juan Li, Xiaoxiao Zhong, Liya Cao, Yang Luo, Qi Fan
      This paper establishes a novel method to simultaneously predict the tablet weight (TW) and trimethoprim (TMP) content of compound sulfamethoxazole tablets (SMZCO) by near infrared (NIR) spectroscopy with partial least squares (PLS) regression for controlling the uniformity of dosage units (UODU). The NIR spectra for 257 samples were measured using the optimized parameter values and pretreated using the optimized chemometric techniques. After the outliers were ignored, two PLS models for predicting TW and TMP content were respectively established by using the selected spectral sub-ranges and the reference values. The TW model reaches the correlation coefficient of calibration (R c) 0.9543 and the TMP content model has the R c 0.9205. The experimental results indicate that this strategy expands the NIR application in controlling UODU, especially in the high-throughput and rapid analysis of TWs and contents of the compound pharmaceutical tablets, and may be an important complement to the common NIR on-line analytical method for pharmaceutical tablets.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • The development of a new optical sensor based on the Mn doped ZnS quantum
           dots modified with the molecularly imprinted polymers for sensitive
           recognition of florfenicol
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): Susan Sadeghi, Moslem Jahani, Foroogh Belador
      The Mn doped ZnS quantum dots (Mn:ZnS QDs) capped with the florfenicol molecularly imprinted polymer (Mn:ZnS QDs@MIP) were prepared via the sol–gel surface imprinting approach using 3-aminopropyltriethoxysilane (APTES) as the functional monomer and tetraethoxysilane (TEOS) as the cross-linker for the optosensing of the florfenicol. Transmission electron microscopy (TEM), X-ray diffractometer, IR spectroscopy, UV–Vis absorption spectrophotometry, and spectrofluorometry were used to elucidate the formation, morphology, and identification of the products. To illustrate the usefulness of the new imprinted material, the non-imprinted coated Mn:ZnS QDs (Mn:ZnS QDs@NIP) were synthesized without the presence of the florfenicol. It was revealed that the fluorescence (FL) intensity of the Mn:ZnS QDs@MIP increased with increasing the FF concentration. Under the optimal conditions, changes in the FL intensity in the presence of the target molecule showed a linear response in the concentration range of 30–700μmolL−1 with a detection limit of 24μmolL−1. The developed method was finally applied successfully to the determination of FF in different meat samples with satisfactory recoveries.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • Delafossite structure of heterogenite polytypes (HCoO2) by Raman and
           infrared micro-spectroscopy
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): C. Burlet, H. Goethals, Y. Vanbrabant
      Heterogenite is commonly referred in mineralogy literature as a cobalt oxy-hydroxide CoO(OH). However, detailed analysis of Raman and infrared spectra acquired on particularly well-crystallized natural samples of heterogenite suggests that the mineral can be characterized by a delafossite-type structure, with a general chemical formula ABO2. Indeed, the Raman spectrum of heterogenite, along the one with grimaldiite (HCrO2), lacks visible free OH-group vibrational modes, while the infrared spectrum shows strong hydrogen bond absorption bands. HCoO2 is thus a better formulation of heterogenite that describes more clearly its vibrational behavior and avoids the confusion in literature. Electronic backscattered diffraction (EBSD) is then used to distinguish and map the 2H and 3R heterogenite natural polytypes for the first time. The comparison of EBSD and Raman mappings clearly indicates that the 2H polytype is characterized by an additional peak at 1220cm−1. The presence/absence is therefore an efficient tool to distinguish both polytypes.
      Graphical abstract image

      PubDate: 2016-01-30T20:02:48Z
       
  • Editorial Board
    • Abstract: Publication date: 5 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 158




      PubDate: 2016-01-30T20:02:48Z
       
  • Publisher's Note
    • Abstract: Publication date: 5 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 158




      PubDate: 2016-01-30T20:02:48Z
       
  • Editorial Board
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157




      PubDate: 2016-01-25T19:03:27Z
       
  • Free variable selection QSPR study to predict 19F chemical shifts of some
           fluorinated organic compounds using Random Forest and RBF-PLS methods
    • Abstract: Publication date: 5 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 158
      Author(s): Nasser Goudarzi
      In this work, two new and powerful chemometrics methods are applied for the modeling and prediction of the 19F chemical shift values of some fluorinated organic compounds. The radial basis function-partial least square (RBF-PLS) and random forest (RF) are employed to construct the models to predict the 19F chemical shifts. In this study, we didn't used from any variable selection method and RF method can be used as variable selection and modeling technique. Effects of the important parameters affecting the ability of the RF prediction power such as the number of trees (nt) and the number of randomly selected variables to split each node (m) were investigated. The root-mean-square errors of prediction (RMSEP) for the training set and the prediction set for the RBF-PLS and RF models were 44.70, 23.86, 29.77, and 23.69, respectively. Also, the correlation coefficients of the prediction set for the RBF-PLS and RF models were 0.8684 and 0.9313, respectively. The results obtained reveal that the RF model can be used as a powerful chemometrics tool for the quantitative structure–property relationship (QSPR) studies.
      Graphical abstract image

      PubDate: 2016-01-25T19:03:27Z
       
  • Moles quantification in liquid samples by Raman spectroscopy
    • Abstract: Publication date: 5 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 158
      Author(s): R.Y. Sato-Berrú, E.A. Araiza-Reyna, A.R. Vazquéz-Olmos
      The mole is a unit of measurement that expresses amounts of a chemical substance. Its importance lies in that the mass and the number of molecules of a substance can be determined with this value. In this work, we suggest a mathematical expression that relates the number of moles of the sample studied with the Raman signal and the experimental parameters used. In other words, with this mathematical expression it is possible to obtain quantitative information in a simple manner from Raman spectra. We have applied this method to different samples and we have observed an excellent correlation between the experimental and expected data.
      Graphical abstract image

      PubDate: 2016-01-25T19:03:27Z
       
  • Stability indicating methods for the analysis of cefprozil in the presence
           of its alkaline induced degradation product
    • Abstract: Publication date: 15 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 159
      Author(s): Khalid A.M. Attia, Mohammed W.I. Nassar, Mohamed B. El-Zeiny, Ahmed Serag
      Three simple, specific, accurate and precise spectrophotometric methods were developed for the determination of cefprozil (CZ) in the presence of its alkaline induced degradation product (DCZ). The first method was the bivariate method, while the two other multivariate methods were partial least squares (PLS) and spectral residual augmented classical least squares (SRACLS). The multivariate methods were applied with and without variable selection procedure (genetic algorithm GA). These methods were tested by analyzing laboratory prepared mixtures of the above drug with its alkaline induced degradation product and they were applied to its commercial pharmaceutical products.
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      PubDate: 2016-01-25T19:03:27Z
       
  • Determination of structural elements on the folding reaction of mnemiopsin
           by spectroscopic techniques
    • Abstract: Publication date: 5 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 158
      Author(s): Forough Hakiminia, Khosrow Khalifeh, Reza H. Sajedi, Bijan Ranjbar
      Mnemiopsin 1 is a member of photoprotein family, made up of 206 amino acid residues. These Ca2+-regulated photoproteins are responsible for light emission in a variety of marine cnidarians and ctenophores. They composed of an apoprotein, a single polypeptide chain of 25kDa, molecular oxygen and the non-covalently bound chromophore. In this study, we examined whether three mutations, namely R39K, S128G and V183T affect the thermodynamic stability as well as refolding and unfolding kinetics of mnemiopsin 1. Conformational stability measurements using fluorescence and far-UV CD spectroscopies revealed that all variants unfold in multi-step manner in which the secondary and tertiary structures are lost in different steps. However kinetic studies showed that point mutation S128G destabilizes both kinetic intermediate and native conformation; while, these structural elements are stabilized in V183T. We also found that the stability of folded and intermediate states increases in R39K. We concluded that the initial packing of helical segments within the protein structure is more facilitated when Lys with smaller side chain is present in the protein chain.
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      PubDate: 2016-01-21T18:33:31Z
       
  • Enhanced energy transfer between Co-dopants Pyronin-Y and Thionine
           incorporated into modified polymethyl methacrylate with addition of ZnO
           nanoparticles
    • Abstract: Publication date: 5 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 158
      Author(s): G.V. Vijayaraghavan, M. Basheer Ahamed
      Using a prism dye cell arrangement, the study investigated spectral energy transfer between co-dopants Pyronin-Y and Thionine incorporated into ethanol-modified polymethyl methacrylate. The spectral parameters of the absorption and fluorescence spectra of the donor and acceptor dyes in the so designed solid-state dye laser were calculated theoretically. Fluorescence lasing properties and slope efficiency of the solid-state dye laser were investigated both with and without addition of ZnO nanoparticles. The dye pair generally improved lasing efficiency and tunability in the range from 582 to 689nm.
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      PubDate: 2016-01-21T18:33:31Z
       
  • Fluorescence sensing of phosdrin pesticide by the luminescent Eu(III)- and
           Tb(III)-bis(coumarin-3-carboxylic acid) probes
    • Abstract: Publication date: 5 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 158
      Author(s): Belal H.M. Hussein, Gasser M. Khairy, Rasha M. Kamel
      Luminescence quenching of the Eu(III)- and Tb(III)-bis (coumarin-3-carboxylic acid) (Ln(III)-(CCA)2) probes has been studied in the presence of organophosphorus or organochlorine pesticides; Phosdrin (P1), Malathion (P2), Profenofos (P3), Formothion (P4), Heptachlor (P5), and Endosulfan (P6). The luminescence intensity of lanthanide complex probes Ln(III)-(CCA)2 decreases as the concentration of the Phosdrin pesticide increases, while the other investigated pesticides have no significant influence on the lanthanide fluorescent intensities. It is observed that the quenching of Eu(III) and Tb(III)-coumarin-3-carboxylic acid by Phosdrin proceeds via static quenching processes according to Stern–Volmer plot. The binding constants (K) and the thermodynamic parameters of the interaction of Ln(III)-(CCA)2 with Phosdrin have been determined. A direct method for the determination of the Phosdrin in ethanol has been developed based on the luminescence changes of the Ln(III)-(CCA)2-phosdrin ternary complexes. The detection limits of P1 were 6.28 and 1.07μM in case of Eu(III) and Tb(III)-complex, respectively. The influence of various interfering species on the detection of P1 has been investigated to assess the analytical applicability of the method. The new method was applied to determine the Phosdrin pesticide in different types of water samples.
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      PubDate: 2016-01-21T18:33:31Z
       
  • Spectra, energy levels, and energy transition of lanthanide complexes with
           cinnamic acid and its derivatives
    • Abstract: Publication date: 5 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 158
      Author(s): Kaining Zhou, Zhongshan Feng, Jun Shen, Bing Wu, Xiaobing Luo, Sha Jiang, Li Li, Xianju Zhou
      High resolution spectra and luminescent lifetimes of 6 europium(III)–cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L=cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF=N, N-dimethylformamide, C3H7NO) were recorded from 8K to room temperature. The energy levels of Eu3+ in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu3+ ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p–π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of 5D0 and triplet state contracts.
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      PubDate: 2016-01-21T18:33:31Z
       
  • Selective sensing of submicromolar iron(III) with
           3,3′,5,5′-tetramethylbenzidine as a chromogenic probe
    • Abstract: Publication date: 5 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 158
      Author(s): Lufeng Zhang, Jianxiu Du
      The development of highly selective and sensitive method for iron(III) detection is of great importance both from human health as well as environmental point of view. We herein reported a simple, selective and sensitive colorimetric method for the detection of Fe(III) at submicromolar level with 3,3,′5,5′-tetramethylbenzidine (TMB) as a chromogenic probe. It was observed that Fe(III) could directly oxidize TMB to form a blue solution without adding any extra oxidants. The reaction has a stoichiometric ratio of 1:1 (Fe(III)/TMB) as determined by a molar ratio method. The resultant color change can be perceived by the naked eye or monitored the absorbance change at 652nm. The method allowed the measurement of Fe(III) in the range 1.0×10−7–1.5×10−4 molL−1 with a detection limit of 5.5×10−8 molL−1. The relative standard deviation was 0.9% for eleven replicate measurements of 2.5×10−5 molL−1 Fe(III) solution. The chemistry showed high selectivity for Fe(III) in contrast to other common cation ions. The practically of the method was evaluated by the determination of Fe in milk samples; good consistency was obtained between the results of this method and atomic absorption spectrophotometry as indicated by statistical analysis.
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      PubDate: 2016-01-17T18:31:52Z
       
  • Temperature-dependent μ-Raman investigation of struvite crystals
    • Abstract: Publication date: 5 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 158
      Author(s): Jolanta Prywer, D. Kasprowicz, T. Runka
      The effect of temperature on the vibrational properties of struvite crystals grown from silica gels was systematically studied by μ-Raman spectroscopy. The time-dependent Raman spectra recorded in the process of long time annealing of struvite crystal at 353K do not indicate structural changes in the struvite crystal with the time of annealing. The temperature-dependent Raman spectra recorded in the range 298–423K reveal a phase transition in struvite at about 368K. Above this characteristic temperature, some of bands assigned to vibrations of the PO4 and NH4 tetrahedra and water molecules observed in the Raman spectra in low temperatures (orthorhombic phase) change their spectral parameters or disappear, which indicates a transition to a higher symmetry structure of struvite in the range of high temperatures.
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      PubDate: 2016-01-17T18:31:52Z
       
  • Interaction of 6-methoxyquinoline with anionic sodium dodecylsulfate
           
    • Abstract: Publication date: 5 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 158
      Author(s): Y. Tej Varma, Debi D. Pant
      Interactions of different species of 6-methoxyquinoline (6MQ) with anionic micelles have been studied at different pre-micellar, micellar and post-micellar concentrations using steady state, time resolved fluorescence and fluorescence anisotropy techniques. The sensitivity of fluorescence of 6MQ to change in its local environment was used to probe sodium dodecylsulfate (SDS) micelles. At post-micellar concentrations of SDS, the observed blue shift in the fluorescence spectrum and increase in quantum yield are attributed to the incorporation of solute molecule to micelles. 6MQ has been found to bind to the surface of the anionic micelles instead of penetrating inside the core of micelles. The binding constant (Kb) calculated for 6MQ revealed that the electrostatic forces mediate charged probe–micelle association, whereas, hydrophobic interaction allowed neutral 6MQ to associate with SDS micelles. The charged 6MQ gets inserted deeper into the micelle surface than its neutral form. The fluorescence anisotropy decay of 6MQ in SDS micelles studied at different pH allowed determination of restriction of motion of the fluorophore. The location of the probe molecule in micellar systems is justified by a variety of spectral parameters such as refractive index, dielectric constant, ET(30), average fluorescence decay time, radiative and non-radiative rate constants, and rotational relaxation time. The micro-environment around the fluorophore reveals that the photophysics of 6MQ is very sensitive to the microenvironment of SDS and probe molecules reside at the water–micelle interface.
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      PubDate: 2016-01-17T18:31:52Z
       
  • Photophysical and photochemical studies of a novel amphiphilic zinc
           phthalocyanine and its interaction with calf thymus DNA
    • Abstract: Publication date: 5 April 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 158
      Author(s): Linxin Yuan, Li Gui, Yue Wang, Quanquan Zhang, Lin Zhou, Shaohua Wei
      β-tetra (aminophenoxy) sulfonic substituted zinc phthalocyanines (SNZnPc), a novel amphiphilic zinc phthalocyanine (Pc), was synthesized. The photophysical, photochemical, and photobiology properties were studied. Results indicated that the synthesized SNZnPc has good amphiphilic property and high reactive oxygen species (ROSs) generation ability. Furthermore, SNZnPc has strong affinity to calf thymus DNA (CT-DNA) through intercalation ways and can effectively cleavage CT-DNA after irradiation by light with appropriate wavelength.
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      PubDate: 2016-01-17T18:31:52Z
       
  • Determination of fragrance content in perfume by Raman spectroscopy and
           multivariate calibration
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Robson B. Godinho, Mauricio C. Santos, Ronei J. Poppi
      An alternative methodology is herein proposed for determination of fragrance content in perfumes and their classification according to the guidelines established by fine perfume manufacturers. The methodology is based on Raman spectroscopy associated with multivariate calibration, allowing the determination of fragrance content in a fast, nondestructive, and sustainable manner. The results were considered consistent with the conventional method, whose standard error of prediction values was lower than the 1.0%. This result indicates that the proposed technology is a feasible analytical tool for determination of the fragrance content in a hydro-alcoholic solution for use in manufacturing, quality control and regulatory agencies.
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      PubDate: 2016-01-08T07:35:21Z
       
  • Optical properties of hydroxyethyl cellulose film treated with nitrogen
           plasma
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): K.H. Mahmoud
      Hydroxyethyl cellulose (HEC) film has been prepared by casting technique. The prepared sample has been treated with nitrogen plasma at different exposure times. The optical absorption was recorded at room temperature in the wavelength range of 200–800nm. Absorbance fitting procedure curves revealed a direct allowed transition with optical band gap, Eopt, of 4.9eV for pristine film, and this value decreases to 4.30eV for 20min plasma treatment time. The band tail values (Ee) were found to be increased under plasma time treatment from 1.74eV in case of the pristine film to 2.20eV for 20min. The dispersion of refractive index and complex dielectric constants under plasma treatment was also studied. Variation of color parameters under effect of the plasma treatment is analyzed in the framework of CIE L*U*V* color space.
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      PubDate: 2016-01-08T07:35:21Z
       
  • Evaluation of portable Raman spectroscopy and handheld X-ray fluorescence
           analysis (hXRF) for the direct analysis of glyptics
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): D. Lauwers, A. Candeias, A. Coccato, J. Mirao, L. Moens, P. Vandenabeele
      In archaeometry, the advantages of a combined use of Raman spectroscopy and X-ray fluorescence spectroscopy are extensively discussed for applications such as the analysis of paintings, manuscripts, pottery, etc. Here, we demonstrate for the first time the advantage of using both techniques for analysing glyptics. These engraved gemstones or glass materials were originally used as stamps, to identify the owner, for instance on letters, but also on wine vessels. For this research, a set of 64 glyptics (42 Roman glass specimens and 22 modern ones), belonging to the collection of the museum ‘Quinta das Cruzes’ in Funchal (Madeira, Portugal), was analysed with portable Raman spectroscopy and handheld X-ray fluorescence (hXRF). These techniques were also used to confirm the gemological identification of these precious objects and can give extra information about the glass composition. Raman spectroscopy identifies the molecular composition as well as on the crystalline phases present. On the other hand, hXRF results show that the antique Roman glass samples are characterised with low Pb and Sn levels and that the modern specimens can be discriminated in two groups: lead-based and non-lead-based ones.
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      PubDate: 2016-01-08T07:35:21Z
       
  • On the roles of close shell interactions in the structure of
           acyl-substituted hydrazones: An experimental and theoretical approach
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Aamer Saeed, M. Ifzan Arshad, Michael Bolte, Adolfo C. Fantoni, Zuly Y. Delgado Espinoza, Mauricio F. Erben
      The 2-(phenyl-hydrazono)-succinic acid dimethyl ester compound was synthesized by reacting phenylhydrazine with dimethylacetylene dicarboxylate at room temperature and characterized by elemental analysis, infrared, Raman, 1H and 13C NMR spectroscopies and mass spectrometry. Its solid state structure was determined by X-ray diffraction methods. The X-ray structure determination corroborates that the molecule is present in the crystal as the hydrazone tautomer, probably favored by a strong intramolecular N–H···OC hydrogen bond occurring between the carbonyl (–CO) and the hydrazone –CN–NH– groups. A substantial fragment of the molecular skeleton is planar due to an extended π-bonding delocalization. The topological analysis of the electron densities (Atom in Molecule, AIM) allows characterization of intramolecular N–H···O interaction, that can be classified as a resonant assisted hydrogen bond (RAHB). Moreover, the Natural Bond Orbital population analysis confirms that a strong hyperconjugative lpO1→σ*(N2–H) remote interaction between the C2O1 and N2–H groups takes place. Periodic system electron density and topological analysis have been applied to characterize the intermolecular interactions in the crystal. Weak intermolecular interactions determine the crystal packing, and the prevalence of non-directional dispersive contributions are inferred on topological grounds. The IR spectrum of the crystalline compound was investigated by means of density functional theory calculations carried out with periodic boundary conditions on the crystal, showing excellent agreement between theory and the experiments. The vibrational assignment is complemented with the analysis of the Raman spectrum.
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      PubDate: 2016-01-08T07:35:21Z
       
  • EPR and impedance spectroscopic investigations on lithium bismuth borate
           glasses containing nickel and vanadium ions
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Arti Yadav, Satish Khasa, Ashima Hooda, Manjeet S. Dahiya, Ashish Agarwal, Prem Chand
      Glasses having composition 7NiO∙23Li2O∙20Bi2O3 ∙50B2O3, 7V2O5 ∙23Li2O∙20Bi2O3 ∙50B2O3 and x(2NiO∙V2O5)∙(30− x)Li2O∙50B2O3 ∙20Bi2O3 (with x =0, 2, 5, 7 & 10mol%) prepared through melt-quench route are explored by analyzing density, impedance spectroscopy and electron paramagnetic resonance (EPR). It is found that both density and molar volume increase with an increase in substitution of 2NiO∙V2O5 in the base glass matrix. Different dielectric parameters viz. dielectric loss (ε), electrical modulus (M), loss tangent (tanδ) etc. are evaluated and their variations with frequency and temperature are analyzed which reveals that these glasses exhibit a non-Debye relaxation behavior. A phenomenal description of the capacitive behavior is obtained by considering the circuitry as a parallel combination of bulk resistance (R b ) and constant phase element (CPE). The conduction mechanism is found to follow Quantum Mechanical Tunneling (QMT) model. Spin Hamiltonian Parameters (SHPs) and covalency rates are calculated from the EPR spectra of vanadyl ion. The observed EPR spectra confirmed that V4+ ion exists as vanadyl ion in the octahedral coordination with tetragonal compression.
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      PubDate: 2016-01-03T06:30:14Z
       
  • Spectroscopic studies of the fish fossils (Cladocyclus gardneri and
           Vinctifer comptoni) from the Ipubi Formation of the Cretaceous Period
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): F.E. Sousa Filho, J.H. da Silva, G.D. Saraiva, B.T.O. Abagaro, O.A. Barros, A.A.F. Saraiva, B.C. Viana, P.T.C. Freire
      Fossils are mineralized remains or traces from animals, plants and other organisms aged to about 108 years. The chemical processes of fossilization are dated back from old geological periods on Earth. The understanding of these processes and the structure of the fossils are one of the goals of paleontology and geology in the sedimentary environments. Many researches have tried to unveil details about special kinds of biological samples; however, a lack of data is noticed for various other specimens. This study reports the investigations through infrared spectroscopy, X-ray fluorescence and X-ray diffraction measurements for two types of fish fossils from the Cretaceous Period. The sample of Cladocyclus gardneri and Vinctifer comptoni fossils were collected from the Ipubi Formation, being one of the less studied, among the formations that constitute the important Santana group in the Araripe Basin, Brazil. The results obtained through different techniques, showed that the C. gardneri fish fossil contains hydroxyapatite and calcite as constituents whereas its rock matrix was formed by calcite, quartz and pyrite. Regarding the V. comptoni, the measurements confirmed the presence of hydroxyapatite in the fossil and its rock matrix gypsum, pyrite, quartz and calcite. The above scientific data contributed to the understanding the fossil formation in the Ipubi Formation, an important environment of the Cretaceous Period, which is rich in well-preserved fossils from different species.
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      PubDate: 2016-01-03T06:30:14Z
       
  • Successive ratio subtraction coupled with constant multiplication
           spectrophotometric method for determination of hydroquinone in complex
           mixture with its degradation products, tretinoin and methyl paraben
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Mohamed R. Elghobashy, Lories I. Bebawy, Rafeek F. Shokry, Samah S. Abbas
      A sensitive and selective stability-indicating successive ratio subtraction coupled with constant multiplication (SRS-CM) spectrophotometric method was studied and developed for the spectrum resolution of five component mixture without prior separation. The components were hydroquinone in combination with tretinoin, the polymer formed from hydroquinone alkali degradation, 1,4 benzoquinone and the preservative methyl paraben. The proposed method was used for their determination in their pure form and in pharmaceutical formulation. The zero order absorption spectra of hydroquinone, tretinoin, 1,4 benzoquinone and methyl paraben were determined at 293, 357.5, 245 and 255.2nm, respectively. The calibration curves were linear over the concentration ranges of 4.00–46.00, 1.00–7.00, 0.60–5.20, and 1.00–7.00μgmL−1 for hydroquinone, tretinoin, 1,4 benzoquinone and methyl paraben, respectively. The pharmaceutical formulation was subjected to mild alkali condition and measured by this method resulting in the polymerization of hydroquinone and the formation of toxic 1,4 benzoquinone. The proposed method was validated according to ICH guidelines. The results obtained were statistically analyzed and compared with those obtained by applying the reported method.
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      PubDate: 2016-01-03T06:30:14Z
       
  • Acetate selective fluorescent turn-on sensors derived using vitamin B6
           cofactor pyridoxal-5-phosphate
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Darshna Sharma, Aman Kuba, Rini Thomas, S.K. Ashok Kumar, Anil Kuwar, Heung-Jin Choi, Suban K. Sahoo
      Two new Schiff base receptors have been synthesized by condensation of pyridoxal-5-phosphate with 2-aminophenol (L 1 ) or aniline (L 2 ). In DMSO, the receptors showed both chromogenic and ‘turn-on’ fluorescence responses selectively in the presence of AcO− and F−. However, in mixed DMSO–H2O medium, the receptors showed AcO− selective ‘turn-on’ fluorescence without any interference from other tested anions including F−. The detection limit for AcO− was found to be 7.37μM and 22.9μM using the receptors L 1 and L 2 , respectively.
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      PubDate: 2016-01-03T06:30:14Z
       
  • Synthesis and spectral characterization of
           bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)propane
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): S. Subashchandrabose, V. Thanikachalam, G. Manikandan, H. Saleem, Y. Erdogdu
      Bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)propane (BAMTP) was synthesized and characterized by FT-IR and FT-Raman spectra. Gas phase structure of BAMTP was examined under density functional theory B3LYP/6-311++G(d, p) level of basis set, wherein the molecule was subjected to conformational analysis. Thus the identified stable structure utilized for the calculations such as geometry optimization, vibrational behavior, hyperpolarizability analysis, natural bond orbital analysis, band gap, chemical hard/softness and stability. Geometry of BAMTP has been discussed elaborately with related crystal data. The results found from experimental and theoretical methods were reported herewith.
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      PubDate: 2015-12-30T05:38:27Z
       
  • A fluorescent sensor based on methyldopa drug modified γ-Fe2O3
           nanoparticles for ultrasensitive detection of calf thymus DNA
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Nahid Shahabadi, Maryam Maghsudi, Soheila Kashanian
      We reported the study of calf thymus DNA (ct-DNA) adsorption by the polymer of methyldopa (2-amino-3-(3,4-dihydroxyphenyl)-2-methyl acid, propanoic) (PMDP), magnetofluorescent PMDP-γ-Fe2O3 nanocrystal. The method is based on the extraordinarily high quenching efficiency of ct-DNA and the specific interaction between ct-DNA and PMDP-γ-Fe2O3 via guanine base and metal coordination, probably. It was found that the designed magnetic nanoparticles can adsorb ct-DNA in nM levels in the presence of NaCl and KCl. In acetate and phosphate buffers DNA were adsorbed completely. Also, we found that pH plays an important role in DNA adsorption onto PMDP-γ-Fe2O3 nanocrystal. PMDP-γ-Fe2O3 nanocrystal is highly hydrophilic and DNA desorption wasn't observed. We believe this study will further stimulate the application of PMDP-γ-Fe2O3 nanocrystal in bioanalytical chemistry and nanotechnology. PMDP-γ-Fe2O3 nanocrystal possesses the ability to interact with ct-DNA via a partial intercalative binding mechanism, as demonstrated by fluorescence displacement experiments and a significant red shift (ca, 10nm) in UV–vis spectra.
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      PubDate: 2015-12-30T05:38:27Z
       
  • Flow-injection chemiluminescence analysis for sensitive determination of
           atenolol using cadmium sulfide quantum dots
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Alireza Khataee, Roya Lotfi, Aliyeh Hasanzadeh, Mortaza Iranifam, Sang Woo Joo
      A sensitive, rapid and simple flow-injection chemiluminescence (CL) system based on the light emitted from KMnO4–cadmium sulfide quantum dots (CdS QDs) reaction in the presence of cetyltrimethylammonium bromide (CTAB) in acidic medium was developed as a CL probe for the sensitive determination of atenolol. Optical and structural features of CdS QDs capped with l-cysteine, which synthesized via hydrothermal approach, were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and UV–Vis spectroscopy. The CL intensity of KMnO4–CdS QDs–CTAB was remarkably enhanced in the presence of trace level of atenolol. Under optimum experimental conditions, there is a linear relationship between the increase in CL intensity of KMnO4–CdS QDs–CTAB system and atenolol concentration in a range of 0.001 to 4.0mgL−1 and 4.0 to 18.0mgL−1, with a detection limit (3σ) of 0.0010mgL−1. A possible mechanism for KMnO4–CdS QDs–CTAB-atenolol CL reaction is proposed. To prove the practical application of the KMnO4–CdS QDs–CTAB CL method, the method was applied for the determination of atenolol in spiked environmental water samples and commercial pharmaceutical formulation. Furthermore, corona discharge ionization ion mobility spectrometry (CD-IMS) technique was utilized for determination of atenolol.
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      PubDate: 2015-12-26T05:17:43Z
       
  • Layer-by-layer films and colloidal dispersions of graphene oxide
           nanosheets for efficient control of the fluorescence and aggregation
           properties of the cationic dye acridine orange
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Chaitali Hansda, Utsav Chakraborty, Syed Arshad Hussain, Debajyoti Bhattacharjee, Pabitra Kumar Paul
      Chemically derived graphene oxide (GO) nanosheets have received great deal of interest for technological application such as optoelectronic and biosensors. Aqueous dispersions of GO become an efficient template to induce the association of cationic dye namely Acridine Orange (AO). Interactions of AO with colloidal GO was governed by both electrostatic and π–π stacking cooperative interactions. The type of dye aggregations was found to depend on the concentration of GO in the mixed ensemble. Spectroscopic calculations revealed the formation of both H and J-type dimers, but H-type aggregations were predominant. Preparation of layer-by-layer (LbL) electrostatic self-assembled films of AO and GO onto poly (allylamine hydrochloride) (PAH) coated quartz substrate is also reported in this article. UV–Vis absorption, steady state and time resolve fluorescence and Raman spectroscopic techniques have been employed to explore the detail photophysical properties of pure AO, AO/GO mixed solution and AO/GO LbL films. Scanning electron microscopy was also used for visual evidence of the synthesized nanodimensional GO sheets. The fluorescence quenching of AO in the presence of GO in aqueous solution was due to the interfacial photoinduced electron transfer (PET) from photoexcited AO to GO i.e. GO acts as an efficient quenching agent for the fluorescence emission of AO. The quenching is found to be static in nature. Raman spectroscopic results also confirmed the interaction of AO with GO and the electron transfer. The formation of AO/GO complex via very fast excited state electron transfer mechanism may be proposed as to prepare GO-based fluorescence sensor for biomolecular detection without direct labeling the biomolecules by fluorescent probe.
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      PubDate: 2015-12-26T05:17:43Z
       
  • Non-covalent C–Cl…π interaction in acetylene-carbon
           tetrachloride adducts: Matrix isolation infrared and ab initio
           computational studies
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): N. Ramanathan, K. Sundararajan, K. Vidya, Eluvathingal D. Jemmis
      Non-covalent halogen-bonding interactions between π cloud of acetylene (C2H2) and chlorine atom of carbon tetrachloride (CCl4) have been investigated using matrix isolation infrared spectroscopy and quantum chemical computations. The structure and the energies of the 1:1 C2H2–CCl4 adducts were computed at the B3LYP, MP2 and M05-2X levels of theory using 6–311++G(d,p) basis set. The computations indicated two minima for the 1:1 C2H2–CCl4 adducts; with the C–Cl…π adduct being the global minimum, where π cloud of C2H2 is the electron donor. The second minimum corresponded to a C–H…Cl adduct, in which C2H2 is the proton donor. The interaction energies for the adducts A and B were found to be nearly identical. Experimentally, both C–Cl…π and C–H…Cl adducts were generated in Ar and N2 matrixes and characterized using infrared spectroscopy. This is the first report on halogen bonded adduct, stabilized through C–Cl…π interaction being identified at low temperatures using matrix isolation infrared spectroscopy. Atoms in Molecules (AIM) and Natural Bond Orbital (NBO) analyses were performed to support the experimental results. The structures of 2:1 ((C2H2)2–CCl4) and 1:2 (C2H2–(CCl4)2) multimers and their identification in the low temperature matrixes were also discussed.
      Graphical abstract image

      PubDate: 2015-12-26T05:17:43Z
       
  • Crystal induced phosphorescence from Benz(a)anthracene microcrystals at
           room temperature
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Samir Maity, Prativa Mazumdar, Milan Shyamal, Gobinda Prasad Sahoo, Ajay Misra
      Pure organic compounds that are also phosphorescent at room temperature are very rare in literature. Here, we report efficient phosphorescence emission from aggregated hydrosol of Benz(a)anthracene (BaA) at room temperature. Aggregated hydrosol of BaA has been synthesized by re-precipitation method and SDS is used as morphology directing agent. Morphology of the particles is characterized using optical and scanning electronic microcopy (SEM). Photophysical properties of the aggregated hydrosol are carried out using UV–vis, steady state and time resolved fluorescence study. The large stoke shifted structured emission from aggregated hydrosol of BaA has been explained due to phosphorescence emission of BaA at room temperature. In the crystalline state, the restricted intermolecular motions (RIM) such as rotations and vibrations are activated by crystal lattice. This rigidification effect makes the chromophore phosphorescent at room temperature. The possible stacking arrangement of the neighboring BaA within the aggregates has been substantiated by computing second order Fukui parameter as local reactivity descriptors. Computational study also reveals that the neighboring BaA molecules are present in parallel slipped conformation in its aggregated crystalline form.
      Graphical abstract image

      PubDate: 2015-12-26T05:17:43Z
       
  • Highly sensitive spectrofluorimetric method for determination of doxazosin
           through derivatization with fluorescamine; Application to content
           uniformity testing
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Mahmoud A. Omar, Mohamed A. Hammad, Baher I. Salman, Sayed M. Derayea
      A highly sensitive, simple and selective spectrofluorimetric method has been developed and validated for determination of doxazosin mesylate in pure form, pharmaceutical formulations and human plasma. The method is based on the reaction between doxazosin mesylate and fluorescamine in Teorell buffer solution (pH3) to give highly fluorescent derivative that can be measured at 489nm using excitation wavelength of 385nm. Different experimental parameters affecting the reaction were carefully studied and optimized. The calibration plot was constructed over the concentration range of 16–400ngmL−1 with quantitation limit of 14.3ngmL−1. The developed procedure was validated according to ICH guidelines and the results were satisfactory. The proposed method has been successfully applied to the analysis of the cited drug in its pharmaceutical preparations as well as for content uniformity testing. The results showed excellent agreement with the reported method with respect to precision and accuracy. In addition, the drug concentration was determined in the spiked human plasma by the suggested method with % recovery in the range of 96.2–98.3% (SD; 0.76–0.93, n=5).
      Graphical abstract image

      PubDate: 2015-12-22T04:57:36Z
       
  • Two-dimensional hetero-spectral mid-infrared and near-infrared correlation
           spectroscopy for discrimination adulterated milk
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Renjie Yang, Rong Liu, Guimei Dong, Kexin Xu, Yanrong Yang, Weiyu Zhang
      A new approach for discriminant analysis of adulterated milk is proposed based on two-dimensional (2D) hetero-spectral near-infrared (NIR) and mid-infrared (IR) correlation spectroscopy along with multi-way partial least squares discriminant analysis (NPLS-DA). NIR transmittance spectra and IR attenuated total reflection spectra of pure milk and adulterated milk with level of melamine varying from 0.03 to 3g·L−1 were collected at room temperature. The synchronous 2D hetero-spectral IR/NIR correlation spectra of all samples were calculated to build a discriminant model to classify adulterated milk and pure milk. Also, the NPLS-DA models were built based on synchronous 2D homo-spectral NIR/NIR and IR/IR correlation spectra, respectively. Comparison results showed that the NPLS-DA model could provide better results using 2D hetero-spectral IR/NIR correlation spectra than using 2D homo-spectral NIR/NIR and 2D IR/IR correlation spectra.
      Graphical abstract image

      PubDate: 2015-12-22T04:57:36Z
       
  • Human hemoglobin structural and functional alterations and heme
           degradation upon interaction with benzene: A spectroscopic study
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Reza Hosseinzadeh, Ali Akbar Moosavi-Movahedi
      Here, the effect of benzene on hemoglobin structure, stability and heme prosthetic group integrity was studied by different methods. These included UV–vis absorption spectrophotometry, normal and synchronous fluorescence techniques, and differential scanning calorimetry (DSC). Our results indicated that benzene has high hemolytic potential even at low concentrations. The UV–vis spectroscopic results demonstrated that benzene altered both the globin chain and the heme prosthetic group of hemoglobin increasing met- and deoxy-Hb, while decreasing oxy-Hb. However, with increasing benzene the concentration of all species decreased due to heme destruction. The spectrophotometric results show that benzene has a high potential for penetrating the hydrophobic pocket of hemoglobin. These results were consistent with the molecular docking simulation results of benzene-hHb. Aggregation and thermal denaturation studies show that the increased benzene concentration induced hemoglobin aggregation with a decrease in stability, which is consistent with the DSC results. Conventional fluorescence spectroscopy revealed that the heme degradation species were produced in the presence of benzene. The results of constant wavelength synchronous fluorescence spectroscopy (CWSFS) indicated that at least five heme-degraded species were produced. Together, our results indicated that benzene has adverse effects on hemoglobin structure and function, and heme degradation.
      Graphical abstract image

      PubDate: 2015-12-22T04:57:36Z
       
  • Voigt deconvolution method and its applications to pure oxygen absorption
           spectrum at 1270nm band
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Muhammad A. AL-Jalali, Issam F. Aljghami, Yahia M. Mahzia
      Experimental spectral lines of pure oxygen at 1270nm band were analyzed by Voigt deconvolution method. The method gave a total Voigt profile, which arises from two overlapping bands. Deconvolution of total Voigt profile leads to two Voigt profiles, the first as a result of O2 dimol at 1264nm band envelope, and the second from O2 monomer at 1268nm band envelope. In addition, Voigt profile itself is the convolution of Lorentzian and Gaussian distributions. Competition between thermal and collisional effects was clearly observed through competition between Gaussian and Lorentzian width for each band envelope. Voigt full width at half-maximum height (Voigt FWHM) for each line, and the width ratio between Lorentzian and Gaussian width (Γ L Γ G −1) have been investigated. The following applied pressures were at 1, 2, 3, 4, 5, and 8bar, while the temperatures were at 298K, 323K, 348K, and 373K range.
      Graphical abstract image

      PubDate: 2015-12-22T04:57:36Z
       
  • Spectrophotometric and chemometric methods for determination of imipenem,
           ciprofloxacin hydrochloride, dexamethasone sodium phosphate, paracetamol
           and cilastatin sodium in human urine
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): A.M. El-Kosasy, Omar Abdel-Aziz, N. Magdy, N.M. El Zahar
      New accurate, sensitive and selective spectrophotometric and chemometric methods were developed and subsequently validated for determination of Imipenem (IMP), ciprofloxacin hydrochloride (CIPRO), dexamethasone sodium phosphate (DEX), paracetamol (PAR) and cilastatin sodium (CIL) in human urine. These methods include a new derivative ratio method, namely extended derivative ratio (EDR), principal component regression (PCR) and partial least-squares (PLS) methods. A novel EDR method was developed for the determination of these drugs, where each component in the mixture was determined by using a mixture of the other four components as divisor. Peak amplitudes were recorded at 293.0nm, 284.0nm, 276.0nm, 257.0nm and 221.0nm within linear concentration ranges 3.00–45.00, 1.00–15.00, 4.00–40.00, 1.50–25.00 and 4.00–50.00μgmL−1 for IMP, CIPRO, DEX, PAR and CIL, respectively. PCR and PLS-2 models were established for simultaneous determination of the studied drugs in the range of 3.00–15.00, 1.00–13.00, 4.00–12.00, 1.50–9.50, and 4.00–12.00μgmL−1 for IMP, CIPRO, DEX, PAR and CIL, respectively, by using eighteen mixtures as calibration set and seven mixtures as validation set. The suggested methods were validated according to the International Conference of Harmonization (ICH) guidelines and the results revealed that they were accurate, precise and reproducible. The obtained results were statistically compared with those of the published methods and there was no significant difference.
      Graphical abstract image

      PubDate: 2015-12-22T04:57:36Z
       
  • Periodic model of LTA framework containing various non-tetrahedral cations
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): A. Koleżyński, A. Mikuła, M. Król
      A simplified periodic model of Linde Type A zeolite (LTA) structure with various selected mono- and di-valent extra-framework cations was formulated. Ab initio calculations (geometry optimization and vibrational spectra calculations) using the proposed model were carried out by means of Crystal09 program. The resulting structures and simulated spectra were analyzed in detail and compared with the experimental ones. The presented results show that in most cases the proposed model agrees well with experimental results. Individual bands were assigned to respective normal modes of vibration and the changes resulting from the selective substitution of extra framework cations were described and explained.
      Graphical abstract image

      PubDate: 2015-12-18T04:26:24Z
       
  • Development of a cell permeable red-shifted CHEF-based chemosensor for
           Al3+ ion by controlling PET
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Manjira Mukherjee, Buddhadeb Sen, Siddhartha Pal, Abhishek Maji, Darshita Budhadev, Pabitra Chattopadhyay
      A structurally modified quinazoline derivative (L) acts as highly selective chemosensor for Al3+ ions in DMSO–H2O (1:9, v/v) over the other competitive metal ions. L shows a red shifted fluorescence after the addition of Al3+ ions and later the further fluorescence enhancement is due to chelation enhanced fluorescence (CHEF) through inhibition of photoinduced electron transfer (PET). This probe (L) detects Al3+ ions as low as 9nM in DMSO–H2O (1:9, v/v) at biological pH. The non-cytotoxic probe (L) can efficiently detect the intercellular distribution of Al3+ ions in living cells under a fluorescence microscope to exhibit its sensible applications in the biological systems.
      Graphical abstract image

      PubDate: 2015-12-18T04:26:24Z
       
  • Acridine-based complex as amino acid anion fluorescent sensor in aqueous
           solution
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Yanpeng Dai, Kuoxi Xu, Qian Li, Chaoyu Wang, Xiaoyan Liu, Peng Wang
      Novel acridine-based fluorescence sensors containing alaninol ligands, L1 and D1, were designed and synthesized. The structure of the compound was characterized by IR, 1H NMR, 13C NMR, MS spectra. L1 and D1 possess efficient Cu2+ cation ON–OFF selective signaling behavior based on ligand-to-metal binding mechanism at physiological pH condition. Additionally, the L1–Cu(II) and D1–Cu(II) complexes could further serve as reversible OFF–ON signaling sensing ensemble to allow ratiometric response to amino acid anion in aqueous solution.
      Graphical abstract image

      PubDate: 2015-12-14T04:15:52Z
       
  • A highly selective colorimetric and fluorescent chemosensor for Al(III)
           based-on simple naphthol in aqueous solution
    • Abstract: Publication date: 15 March 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 157
      Author(s): Zhaodi Liu, Huajie Xu, Liangquan Sheng, Shuisheng Chen, Deqian Huang, Jie Liu
      A colorimetric and fluorescent chemosensor (L) for Al(III) was synthesized and fully characterized. L could be both used as a colorimetric and fluorescent chemosensor for the detection of Al3+ ions with low detection limit (8.87×10−7 M) in CH3CN–H2O (1:1, v/v) solution. The binding ratio of L–Al3+ was determined from the Job plot (absorption and fluorescence spectra) and MALDI-TOF MS data to be 1:1. The binding constant (Ka) of Al3+ binding to L was calculated to be 4.8×105 M−1 from a Benesi–Hildebrand plot. Moreover, the binding site of L with Al3+ was determined by 1H NMR titration experiment.
      Graphical abstract image

      PubDate: 2015-12-14T04:15:52Z
       
 
 
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