JournalTOCs

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

[7 followers] Follow
Full-text available via subscription

Subscription journal
ISSN (Print) 1386-1425
Published by Elsevier

[2565 journals]

Dynamic quenching study of 2-amino-3-bromo-1,4-naphthoquinone by titanium dioxide nano particles in solution (methanol)
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): S. Pushpam , M. Kottaisamy , V. Ramakrishnan
  The dependence of fluorescence emission of 2-amino-3-bromo-1,4-naphthoquinone on titanium dioxide (TiO2) in methanol has been investigated. The increase in TiO2 concentration causes a decrease in the fluorescence intensity of 2-amino-3-bromo-1,4-naphthoquinone. A linear Stern–Volmer plot in this study indicates the presence of dynamic quenching. The quenching and association constants have been calculated. The quenching process is due to the electron transfer from 2-amino-3-bromo-1,4-naphthoquinone to TiO2.
  Graphical abstract
  
  PubDate: 2013-06-15T13:49:42Z
Charge transfer complexes of quinones in aqueous medium: Spectroscopic and theoretical studies on interaction of cimetidine with novel substituted 1,4-benzoquinones and its application in colorimetric sensing of anions
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): C. Balraj , A. Satheshkumar , K. Ganesh , Kuppanagounder P. Elango
  For the first time, the charge transfer (CT) complexes of quinones in aqueous medium have been reported. A series of novel water soluble 1,4-benzoquinones possessing variable number of chloro and methoxy substituents has been employed as electron acceptors (MQ1−4) in the CT complexation with cimetidine (CTD) drug. The mechanism of the interaction has been investigated using various spectral techniques such as UV–Vis, 1H NMR and FT-IR spectra. The rate of the CT interaction was observed to decrease with progressive replacement of chloro by methoxy substituent in the quinone and this variation is well supported by the formation constant and enthalpy of activation values. Ab initio DFT calculations predicted that the variation in the bond lengths of the carbonyl moieties and the charge densities on the carbonyl oxygen atoms depend largely on the nature of the substituent present in the quinone ring. Also, the HOMODonor–LUMOAcceptor energy gaps correlate linearly with the formation constants of the CT complex. The equilibrium, kinetic, electrochemical and theoretical investigations of the CT interaction of these quinones indicated that progressive replacement of electron withdrawing chlorine atom (−I effect) by an electron releasing methoxy group (+M effect) makes these acceptors progressively weaker. The charge-transfer complex, formed between CTD and monomethoxy quinone derivative, has been employed as a new class of chromogenic sensor for the colorimetric sensing of fluoride and acetate ions.
  Graphical abstract
  
  PubDate: 2013-06-15T13:49:42Z
Use of vibrational spectroscopy to study 2-[4-(N-dodecanoylamino)phenyl]-5-(4-nitrophenyl)-1,3,4-oxadiazole: A combined theoretical and experimental approach
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Saba Bee , Parag Agarwal , Archana Gupta , Poonam Tandon
  Quantum chemical calculations of geometric structure and vibrational wavenumbers of 2-[4-(N-dodecanoylamino)phenyl]-5-(4-nitrophenyl)-1,3,4-oxadiazole (AF51) were carried out by using density functional theory (DFT/B3LYP/6-311G(d,p) method. The fundamental vibrational modes were characterized depending on their potential energy distribution (PED). In order to predict the reactive sites for electrophilic and nucleophilic attacks of the title molecule, electrostatic potential surface has been plotted. The UV absorption spectrum was examined in chloroform solvent and compared with the calculated one in gas phase as well as in solvent environment using TD-DFT/ PCM approach. The 1H NMR spectra was recorded. Comparison between the experimental and the theoretical results is satisfactory. The thermodynamic properties of the title compound at different temperatures have been calculated. A relationship between molecular structural features, non-linear responses and hyperpolarizability of AF51 has been established using vibrational spectra with emphasis on the role of intramolecular charge transfer mechanism in such organic NLO materials.
  Graphical abstract Highlights
  
  PubDate: 2013-06-15T13:49:42Z
Rapid differentiation of Ghana cocoa beans by FT-NIR spectroscopy coupled with multivariate classification
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Ernest Teye , Xingyi Huang , Huang Dai , Quansheng Chen
  Quick, accurate and reliable technique for discrimination of cocoa beans according to geographical origin is essential for quality control and traceability management. This current study presents the application of Near Infrared Spectroscopy technique and multivariate classification for the differentiation of Ghana cocoa beans. A total of 194 cocoa bean samples from seven cocoa growing regions were used. Principal component analysis (PCA) was used to extract relevant information from the spectral data and this gave visible cluster trends. The performance of four multivariate classification methods: Linear discriminant analysis (LDA), K-nearest neighbors (KNN), Back propagation artificial neural network (BPANN) and Support vector machine (SVM) were compared. The performances of the models were optimized by cross validation. The results revealed that; SVM model was superior to all the mathematical methods with a discrimination rate of 100% in both the training and prediction set after preprocessing with Mean centering (MC). BPANN had a discrimination rate of 99.23% for the training set and 96.88% for prediction set. While LDA model had 96.15% and 90.63% for the training and prediction sets respectively. KNN model had 75.01% for the training set and 72.31% for prediction set. The non-linear classification methods used were superior to the linear ones. Generally, the results revealed that NIR Spectroscopy coupled with SVM model could be used successfully to discriminate cocoa beans according to their geographical origins for effective quality assurance.
  Graphical abstract Highlights
  
  PubDate: 2013-06-15T13:49:42Z
Study on the proteins–luminol binding by use of luminol as a fluorescence probe
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Xili He , Zhenghua Song
  In this paper, a new mathematical equation of lg(F 0 − F)/F =1/nlg[P]+1/nlgKa , which was used to obtain interaction parameters (the binding constant Ka and the number of binding sites n) between the protein and the small molecule ligand by using the ligand as a fluorescence (FL) probe, was constructed for the first time. The interaction parameters between myoglobin, catalase, lysozyme, bovine serum albumin (BSA) and luminol were obtained by this equation with luminol used as a FL probe, showing that the binding constants Ka were 8.78×105, 4.47×105, 4.21×104 and 3.95×104 respectively, and the number of binding sites n approximately equaled to 1.0 for myoglobin, catalase, and 2.0 for lysozyme, BSA. The interactions of ferritin, ovalbumin, aldolase, chymotrypsinogen and ribonuclease with luminol were also studied by this method. The binding constants Ka were at 104–105 level, and the number of binding sites n mostly approximately equaled to 2.0. The binding ability of luminol to the studied proteins followed the pattern: myoglobin>aldolase>ferritin>ovalbumin>catalase>ribonuclease>lysozyme>BSA>chymotrypsinoge.
  Graphical abstract
  
  PubDate: 2013-06-15T13:49:42Z
DNA binding properties and biological evaluation of dihydropyrimidinones derivatives as potential antitumor agents
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Gongke Wang , Xiangrong Li , Yaping Gou , Yuhan Chen , Changling Yan , Yan Lu
  The binding properties of two medicinally important dihydropyrimidinones derivatives 5-(Ethoxycarbonyl)-6-methyl-4-phenyl-3,4-dihydropyrimidin-2(1H)-one (EMPD) and 5-(Ethoxycarbonyl)-6-methyl-4-(4-chlorophenyl)-3,4-dihydropyrimidin-2(1H)-one (EMCD) with calf-thymus DNA (ctDNA) were investigated by spectroscopy, viscosity, isothermal titration calorimetry (ITC) and molecular modeling techniques. Simultaneously, their biological activities were evaluated with MTT assay method. The binding constants determined with spectroscopic titration and ITC were found to be in the same order of 104 M−1. According to the results of viscosity studies, fluorescence competitive binding experiment and ITC investigations, intercalative binding was evaluated as the dominant binding modes between the two compounds and ctDNA. Furthermore, the results of molecular modeling corroborated those obtained from spectroscopic, viscosimetric and ITC investigations. Evaluation of the antitumor activities of the two derivatives against different tumor cell lines proved that they exhibited significant tumor cell inhibition rate, accordingly blocking DNA transcription and replication. The present results favor the development of potential drugs related with dihydropyrimidinones derivatives in the treatment of some diseases.
  Graphical abstract
  
  PubDate: 2013-06-15T13:49:42Z
The prototropic tautomerism and substituent effect through strong electron-withdrawing group in (E)-5-(diethylamino)-2-[(3-nitrophenylimino)methyl]phenol
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Çiğdem Albayrak , Gökhan Kaştaş , Mustafa Odabaşoğlu , Rene Frank
  The prototropic tautomerism in o-Hydroxy Schiff bases results in two forms called phenol-imine and keto-amine. The preference of a particular form by the compound changes in the solid and solvent media. The choice can also be regulated by a substituent with a different electron-donating or withdrawing group. In the present study, the above-mentioned factors are considered in the investigation of (E)-5-(diethylamino)-2-[(3-nitrophenylimino)methyl]phenol compound (an o-Hydroxy Schiff basis) by experimental (XRD, FT-IR and UV–vis) and computational (DFT and TD-DFT) methods. The results show that the title compound adopts only phenol-imine form in the solid and solvent media. This was attributed to the substituent effect through strong electron-withdrawing nitro group.
  Graphical abstract Highlights
  
  PubDate: 2013-06-15T13:49:42Z
Interaction of acriflavine with pyrimidines: A spectroscopic approach
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): C. Manivannan , S. Sambathkumar , R. Renganathan
  The interaction of acriflavine with uracils was investigated by using spectroscopic tools viz., UV–Vis absorption, steady state and time resolved fluorescence measurements. The spectroscopic data were analyzed using Stern–Volmer equation to determine the quenching process. The bimolecular quenching rate constant (k q), binding constant (K) and number of binding sites (n) were calculated at different temperature from the relevant fluorescence data. The experimental results obtained from life-time measurement indicate that the quenching mechanism was static via the formation of ground state complex. The free energy change (ΔG et) for electron transfer process was calculated by Rehm–Weller equation. The existence of binding forces and the interactions of acriflavine with uracils were examined.
  Graphical abstract
  
  PubDate: 2013-06-15T13:49:42Z
Vibrational spectroscopy of the phosphate mineral kovdorskite – Mg2PO4(OH)⋅3H2O
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Ray L. Frost , Andrés López , Yunfei Xi , Amanda Granja , Ricardo Scholz , Rosa Malena Fernandes Lima
  The mineral kovdorskite Mg2PO4(OH)⋅3H2O was studied by electron microscopy, thermal analysis and vibrational spectroscopy. A comparison of the vibrational spectroscopy of kovdorskite is made with other magnesium bearing phosphate minerals and compounds. Electron probe analysis proves the mineral is very pure. The Raman spectrum is characterized by a band at 965cm−1 attributed to the PO 4 3 - ν1 symmetric stretching mode. Raman bands at 1057 and 1089cm−1 are attributed to the PO 4 3 - ν3 antisymmetric stretching modes. Raman bands at 412, 454 and 485cm−1 are assigned to the PO 4 3 - ν2 bending modes. Raman bands at 536, 546 and 574cm−1 are assigned to the PO 4 3 - ν4 bending modes. The Raman spectrum in the OH stretching region is dominated by a very sharp intense band at 3681cm−1 assigned to the stretching vibration of OH units. Infrared bands observed at 2762, 2977, 3204, 3275 and 3394cm−1 are attributed to water stretching bands. Vibrational spectroscopy shows that no carbonate bands are observed in the spectra; thus confirming the formula of the mineral as Mg2PO4(OH)⋅3H2O.
  Graphical abstract
  
  PubDate: 2013-06-15T13:49:42Z
A theoretical systematic study of a series of isocyanopolyynes
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): R.M. Vichietti , R.L.A. Haiduke
  Several isocyanopolyynes, HC n NC (n =0, 2,…,16), are analyzed in this theoretical work. We performed calculations at MP2/cc-pVTZ (n =0–16), CCSD/cc-pVDZ (n =0–12) and CCSD/cc-pVTZ (n =0–6) levels. The dipole moments from the best treatment, CCSD/cc-pVTZ, are in much closer agreement with those obtained in CCSD/cc-pVDZ calculations (deviations up to 0.05 Debye) than with the results from MP2/cc-pVTZ (discrepancies that can reach 0.55 Debye). Moreover, the CCSD/cc-pVTZ level yields values in excellent accordance with experimental dipole moments for HNC and HC2NC. Hence, this allows concluding that the correct treatment of electron correlation is more important than increments in basis sets for this electric property in isocyanopolyynes and CCSD/cc-pVDZ values are indicated as the best estimates available for large isocyanopolyynes. The findings from infrared intensities of fundamental vibrational bands are also similar (mean deviations of 3.1kmmol−1 for CCSD/cc-pVDZ and 12.6kmmol−1 for MP2/cc-pVTZ with respect to CCSD/cc-pVTZ results). Thus, we decided to use the charge – charge flux – dipole flux (CCFDF) model from multipoles given by the Quantum Theory of Atoms in Molecules (QTAIM), which were obtained at the CCSD/cc-pVDZ level, to investigate the variations in infrared intensities of some selected modes along these systems. The intensity of the band associated with CH stretching shows an increase with the size of these molecules (from 96 to 146kmmol−1 between n =4 and 12) that is readily explained by variations in the charge flux contribution to this mode, in a similar way as found before for cyanopolyynes. Furthermore, the degenerate CH bending vibrations present almost constant intensities in these isocyanopolyynes (around 37–38kmmol−1 from n =4 up to n =12) and this pattern is supported by CCFDF/QTAIM contributions. The band mostly assigned to stretching of the NC triple bond, which can also be described as asymmetric stretching mode of all pairs of adjacent triple bonds, shows an increase of intensity up to n =6 and is associated to values around 96–102kmmol−1 in the remaining larger members. Another important mode detected is a symmetric stretching of NC and CC triple bonds belonging to the isonitrile end (between 66 and 101kmmol−1 when n =6–12) for which the charge contribution is nearly constant and dynamic contributions change in a more complicated way. The most intense fundamental band in each isocyanopolyyne from n =4 to 12 is assigned to vibrations of triple bonds in both ends of these systems (from 129 to 164kmmol−1) and an alternating behavior according with even or odd numbers of CC triple bonds is observed for these values and also for respective CCFDF/QTAIM contributions. Finally, this work also brings values derived from regressions that are indicated as the best estimates of rotational constants and dipole moments to be used for detection of large isocyanopolyynes in the interstellar medium.
  Graphical abstract
  
  PubDate: 2013-06-15T13:49:42Z
A novel colorimetric and fluorescent sensor based on calix[4]arene possessing triphenylamine units
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Serkan Erdemir , Sait Malkondu , Ozcan Kocyigit , Onder Alıcı
  A novel colorimetric and fluorometric calix[4]arene probe (CTP) bearing triphenylamine units was synthesized in good yield and characterized by combination of 1H, 13C, APT, COSY, FTIR, HRMS, and UV–vis spectral data. Ion-binding studies of CTP were investigated in acetonitrile with a wide range of cations and anions and the recognition process was monitored by luminescence, UV–vis and 1H NMR spectral changes. CTP exhibited naked eye detection for Hg2+ ion. Also it showed a significant fluorescence quenching towards F− ion.
  Graphical abstract
  
  PubDate: 2013-06-15T13:49:42Z
Synthesis, spectroscopic (FT-IR/NMR) characterization, X-ray structure and DFT studies on (E)-2-(1-phenylethylidene) hydrazinecarboximidamide nitrate hemimethanol
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Namık Özdemir , Ersin İnkaya , Emin Sarıpınar , Lale Akyüz , İlhan Özer İlhan , Semiha Aydın , Muharrem Dinçer , Orhan Büyükgüngör
  The title molecular salt, (E)-2-(1-phenylethylidene) hydrazinecarboximidamide nitrate hemimethanol C 9 H 13 N 4 + · NO 3 - · 0.5 CH 4 O , was synthesized and characterized by elemental analysis, FT-IR and NMT spectroscopies, and single-crystal X-ray diffraction technique. Quantum chemical calculations were performed to study the molecular and spectroscopic properties of the title compound, and the results were compared with the experimental findings. The calculated results show that the optimized geometry can well reproduce the crystal structure parameters, and the theoretical vibrational frequencies and GIAO 1H and 13CNMR chemical shifts show good agreement with experimental values. The dipole moment, linear polarizability and first hyperpolarizability values were also computed. The linear polarizabilities and first hyper polarizabilities of the studied molecule indicate that the compound is a good candidate of nonlinear optical materials. On the basis of the thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between standard heat capacities (C) standard entropies (S), and standard enthalpy changes (H) and temperatures.
  Graphical abstract
  
  PubDate: 2013-06-15T13:49:42Z
Benzimidazole derivative vs. different phases of TiO2-physico-chemical approach
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): C. Karunakaran , J. Jayabharathi , K. Jayamoorthy
  1-Benzyl-2-phenyl-1H-benzo[d]imidazole (BPBI) has been synthesized by simple steps and characterized by spectral studies. Absorption and fluorescence spectral studies have been employed to investigate the interaction of BPBI with the anatase, hombikat, P25 and rutile phases of TiO2. The emission of the BPBI is efficiently quenched by anatase, hombikat and P25 TiO2 nanoparticles owing to charge injection from the excited singlet state of BPBI to the conduction band of the TiO2 nanoparticles. Surprisingly, rutile phase enhances the fluorescence which is likely due to lowering of LUMO and HOMO levels of the ligand on ducking of the benzimidazole moiety of the BPBI molecule into the void space of rutile TiO2. Electron injection from photoexcited BPBI to the TiO2 conduction band (S∗ →S+ + e − CB) is likely to enhance the fluorescence.
  Graphical abstract
  
  PubDate: 2013-06-15T13:49:42Z
Biological synthesis of silver nanoparticles using the fungus Humicola sp. and evaluation of their cytoxicity using normal and cancer cell lines
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Asad Syed , Supriya Saraswati , Gopal C Kundu , Absar Ahmad
  Nanoscience is a new born science of the modern era and taps into the potential of particles at nanoscale. Bulk materials reduced to nanoscale dimensions thus obtain unique properties such as electronic, optical, magnetic and chemical. As far as synthesis of nanoparticles is concerned, biological synthesis has recently sparked a great interest as compared to other available chemical and physical methods on account of its eco-friendliness and cost-effectiveness. Here we report, for the first time, the biosynthesis of silver nanoparticles by the thermophilic fungus Humicola sp. The fungus when reacted with Ag+ ions reduces the precursor solution and leads to the formation of extracellular nanoparticles as monitored by ultra violet visible spectroscopy (UV–Vis). The morphology of nanoparticles is found to be spherical with good dispersity as revealed by transmission electron microscopy (TEM). Cell viability assays were carried out to assess the cytotoxicity of silver nanoparticles on NIH3T3 mouse embryonic fibroblast cell line and MDA-MB-231 human breast carcinoma cell line.
  Graphical abstract Highlights The thermophilic fungus Humicola sp. was successfully employed first time in the laboratory for the biosynthesis of extracellular protein capped, water dispersible and well dispersed silver nanoparticles.
  
  PubDate: 2013-06-15T13:49:42Z
Experimental and theoretical investigations of nonlinear optical properties of 1,4-Diamino-9,10-Anthraquionone
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Sana Zafar , Zahid H. Khan , Mohd. Shahid Khan
  Nonlinear optical properties of 1,4-Diamino-9,10-Anthraquinone dye in solution at different concentrations are investigated by utilizing single beam Z-scan technique using a low power continuous wave laser (λ =532nm). The anthraquinone dye is found to exhibit self-defocusing and reverse saturable absorption behavior. Effect of concentration on nonlinear refractive index and nonlinear absorption coefficient are also studied. The nonlinear absorption coefficient (β) and nonlinear refractive index (n 2) have been evaluated from the open aperture and closed aperture Z-scan data and are found to increase with increase in concentration. The order of magnitude obtained for nonlinear refractive index and nonlinear absorption coefficient are found to be 10−6 esu and 10−4 m/W, respectively. The optical limiting behavior and induced self-diffraction patterns are also observed. To have a theoretical insight of nonlinear optical properties of 1,4-Diamino-9,10-Anthraquinone, first hyperpolarizability (β) is also evaluated by using quantum chemical calculations employing DFT method using 6-311G basis set. The results obtained confirm the nonlinear optical behavior of 1,4-Diamino-9,10-Anthraquinone dye.
  Graphical abstract
  
  PubDate: 2013-06-15T13:49:42Z
Interaction of Schiff base ligand with tin dioxide nanoparticles: Optical studies
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): J. Suvetha Rani , V. Ramakrishnan
  Interaction between 1,4 Bis ((2-Methyl) thio) Phenylamino methyl benzene (BMTPMB) Schiff base with tin dioxide nanoparticles (SnO2 NPs) of various concentrations in methanol have been studied using UV–Visible and Fluorescence spectroscopic techniques. The low value of Stern–Volmer quenching constant and non-linear plot of Benesi–Hildebrand equation suggests the less affinity of SnO2 NPs towards the adsorption of BMTPMB Schiff base. The Scott equation has been employed to determine molar absorptivity of the Schiff base-NPs system.
  Graphical abstract Highlights Scott plot.
  
  PubDate: 2013-06-15T13:49:42Z
IR vibrational assignments for 1,3,5-triamine-2,4,6-trinitrobenzene (TATB) based on the temperature-dependent frequency shifts
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Heliang Sui , Fachun Zhong , Kemei Cheng , Xueyong Liu , Xin Ju
  IR spectra of TATB at different temperature were investigated for vibrational assignments. The results showed that the hydrogen bonding interaction of TATB was significantly weakened with increasing the temperature. Based on the frequency shifts of the hydrogen bonding interaction to several vibrational modes, 12 absorbance bands in the region 600–1700cm−1 were assigned to corresponding vibrational modes. In addition, Fermi resonance effect between NO2 and NH2 scissors was observed, and the enhancement of Fermi resonance effect caused the intensity of v3 (at 1545cm−1) to grow during heating.
  Graphical abstract Highlights
  
  PubDate: 2013-06-15T13:49:42Z
Luminescent pH sensor of a novel imidazole-containing hexanuclear Ru(II) polypyridyl complex
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Feixiang Cheng , Ning Tang , Jishu Chen , Guang Chen
  Hexapodal ligand H6L containing imidazole rings has been prepared by the reaction of 1,10-phenanthroline-5,6-dione with 1,2,3,4,5,6-hexakis[(3-formylphenoxy)methyl]benzene. The Ru(II) polypyridyl complex [{Ru(bpy)2}6(μ6-H6L)](PF6)12 (bpy=2,2′-bipyridine) has been synthesized by the reaction of Ru(bpy)2Cl2·2H2O with ligand H6L. The pH effects on the UV–vis absorption and emission spectra of the complex have been studied. The ground- and excited-state ionization constants of the acid–base equilibria have been calculated according to the absorbance and emission data. The complex acts as an off–on–off luminescent pH sensor through two successive deprotonation processes of imidazole rings, with a maximum on–off ratio of 5 in buffer solution.
  Graphical abstract Highlights One novel hexanuclear Ru(II) complex with imidazole units uncoordinated to the Ru(II) center has been synthesized. The complex acts as an “off–on–off” luminescent pH sensor through two successive deprotonation processes of imidazole units.
  
  PubDate: 2013-06-15T13:49:42Z
Synthesis of Cu/CuO nanoparticles in mesoporous material by solid state reaction
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Sh. Sohrabnezhad , A. Valipour
  The Mobil Composition of Matter No. 41 (MCM-41) containing 1.0 and 5.0wt.% of Cu was synthesized under solid state reaction. The calcinations of samples were done at two different temperatures, 500 and 300°C. X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) were used for samples characterization. Powder X-ray diffraction showed that when Cu(CH3COO)2 content is about 1.0wt.% in Cu/MCM-41, the guest CuO-NPs and copper ions is formed on the silica channel wall, and more exists in the crystalline state. When Cu(CH3COO)2 content exceeds this value (5.0wt.%), CuO nanoparticles and Cu2+ ions can be observed in low crystalline state. From the diffuse reflectance spectra it was confirmed that 5wt.% Cu/MCM-41 sample calcined at 500°C show plasmon resonance band due to Cu nanoparticles in the range between 500 and 600nm and small copper clusters Cu n in 450nm. It also shows that some of the Cu2+ ions are present octahedrally in extraframework position in all samples. Both fourier transform infrared and diffuse reflectance spectra indicate that some of Cu2+ ions are tetrahedrally within the framework position in 1wt.% Cu/MCM-41 samples. TEM images indicated that nanoparticles size of CuO is in range of 30–40nm.
  Graphical abstract Highlights
  
  PubDate: 2013-06-15T13:49:42Z
A facile channel for D-glucose detection in aqueous solution
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Zhijun Wang , Haiying Lei , Liheng Feng
  Three facile ensembles for sensing D-glucose are designed and constructed. The ensembles are comprised of fluorescent dye (NAHBDS) and boronic acid substituted viologens (BBVs) quenchers/receptors. The sensing processes of three ensembles (NAHBDS/o-BBV, NAHBDS/m-BBV and NAHBDS/p-BBV) to D-glucose were determined by fluorescence spectra at pH 7.4 buffer solution. The results show that NAHBDS/o-BBV and NAHBDS/m-BBV ensembles embody higher sensitivity for D-glucose with reversible “on–off” fluorescence response. More importantly, the recovery of relative intensity has good linear relation to low concentration of D-glucose. The action between the ensemble with D-glucose is dynamically reversible equilibrium process. The research results provide a new mode to design highly selective probe.
  Graphical abstract Highlights
  
  PubDate: 2013-06-15T13:49:42Z
Density functional theory, restricted Hartree – Fock simulations and FTIR, FT-Raman and UV–Vis spectroscopic studies on lamotrigine
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): T. Ramya , S. Gunasekaran , G.R. Ramkumaar
  The Fourier Transform Infrared (FTIR) and FT Raman spectra of lamotrigine have been recorded in the region 4000–450cm−1 and 4000–50cm−1, respectively. The title compound is used as Antiepileptic drug. The optimized geometry, frequency, and intensities of the vibrational bands of the lamotrigine were obtained by Density Functional Theory (DFT) using B3LYP/631G** basis set and ab initio method at the restricted Hartree Fock/6-31** level. The harmonic vibrational frequencies, Natural population analysis, HOMO–LUMO energy gap, infra red intensities and Raman scattering activities, force constant were calculated by DFT and RHF methods. The quality of lamotrigine under different storage containers were analyzed using UV–Vis spectral technique.
  Graphical abstract Highlights
  
  PubDate: 2013-06-15T13:49:42Z
Spectroscopic properties of Eu3+ doped RbLaP4O12 powders
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): M. Mesfar , K. Horchani-Naifer , M. Abdelhedi , M. Dammak , M. Ferid
  Monophasic RbLaP4O12 possessing monoclinic symmetry with varied Eu3+ concentrations was synthesized by flux method. The obtained cyclotetraphosphate exhibits very small crystals and the dopant Eu3+ ions were successfully incorporated into the sites of La3+ ions of the host lattice. These compounds were characterized by infrared and Raman spectroscopy, X-ray diffraction (XRD) and luminescence spectroscopy. The spectroscopy properties confirm the potentiality of present RbLaP4O12 doped with Eu3+ ions as luminophore host materials to produce an intense red luminescence at 616nm corresponding to 5D0 → 7F2 emission level and have significant importance in the development of emission optical systems.
  Graphical abstract Highlights Excitation and emission spectra of Eu3+ doped RbLaP4O12 host lattice with 1, 2 and 3mol%.
  
  PubDate: 2013-06-15T13:49:42Z
Polymeric cyanide azo compounds dipole moments and photo-physical properties in solvents media
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): M.S. Zakerhamidi , Sh. Golghasemi Sorkhabi , S. Ahmadi-Kandjani , M. Moghadam , E. Ortyl
  A quantitative study of solvent environment effects on the photo-physical properties of a group of polymeric cyano azo benzene compounds was carried out at room temperature. Absorption and emission spectra of this group of azo matter with similar structure and different statistical weight of azo block have been studied in different solvents. The solvatochromic method was used to estimate the dipole moments in ground and excited states. The nature and degree of solvent–solute interactions were characterized using Kamlet–Abboud–Taft multi-parameter polarity scale.
  Graphical abstract Highlights
  
  PubDate: 2013-06-15T13:49:42Z
Targeting triple negative breast cancer cells by N3-substituted 9,10-Phenanthrenequinone thiosemicarbazones and their metal complexes
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Zahra Afrasiabi , Preston Stovall , Kristen Finley , Amitava Choudhury , Charles Barnes , Aamir Ahmad , Fazlul Sarkar , Alok Vyas , Subhash Padhye
  Novel N3-substituted 9,10-Phenanthrenequinone thiosemicarbazones and their copper, nickel and palladium complexes are structurally characterized and reported along with the single crystal X-ray structures of three ligands and one nickel complex. All compounds were evaluated for their antiproliferative potential against Triple Negative Breast Cancer (TNBC) cells which have poor prognosis and no effective drugs to treat with. All compounds exhibited antiproliferative activity against these cells. Among the metal complexes evaluated, redox active copper complexes were found to be more potent. The possible mechanism for such enhanced activity can be attributed to the generation of oxidative stress, which was amenable for targeting through metal complexation.
  Graphical abstract Highlights Novel N3-substituted 9,10-Phenanthrenequinone thiosemicarbazones and their copper, nickel and palladium complexes are reported along with the single crystal X-ray structures of the three ligands and one nickel complex. All compounds were evaluated for their antiproliferative potential against Triple Negative Breast Cancer (TNBC) cells which have poor prognosis and no effective drugs to treat. All compounds exhibited antiproliferative activity against these cells. Among the metal complexes evaluated, redox active copper complexes were found to be more potent and warrant further mechanistic studies.
  
  PubDate: 2013-06-15T13:49:42Z
IR, Raman and SERS spectral analysis and DFT calculations on the Herbicide O,S-Dimethyl phosphoramidothioate, metamidophos
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Guillermo Diaz Fleming , Joao Villagrán , Rainer Koch
  Infrared, Raman and SERS spectra of O,S-Dimethyl phosphoramidothioate, metamidophos, MAP, have been recorded. Density Functional Theory, DFT, with the B3LYP functional was used for the optimization of the ground state geometry and simulation of the infrared and Raman spectra of this molecule. Calculated geometrical parameters fit very well with the experimental ones. Combining the recorded data, the DFT results and a Normal Coordinate Analysis based on a scaled quantum mechanical (SQM) force field approach, a complete vibrational assignment was made for the first time. The comparison of SERS spectra obtained by using colloidal silver nanoparticles, with the corresponding Raman spectrum reveals enhancement and shifts in bands as well as information about the orientation of MAP on the nm-sized metal structures and the importance of the S atom on the SERS effect. DFT modelling of the SERS effect and Molecular Electrostatic Potentials (MEP) confirms the experimental information.
  Graphical abstract Highlights Infrared, Raman and SERS spectra of O,S-Dimethyl phosphoramidothioate, metamidophos, MAP, have been recorded. A DFT calculation was used for the optimization of the ground state geometry, simulation of the vibrational spectra and interaction MAP-metal surface. The comparison of SERS spectra obtained by using colloidal silver nanoparticles, with the corresponding Raman spectrum reveals enhancement and shifts in bands as well as information about the orientation of MAP on the nm-sized metal structures and the importance of the S atom on the SERS effect. DFT modelling of the SERS effect and Molecular Electrostatic Potentials (MEP) confirms the experimental information.
  
  PubDate: 2013-06-12T07:39:48Z
Vibrational spectroscopic (FT-IR and FT-Raman) studies, natural bond orbital analysis and molecular electrostatic potential surface of Isoxanthopterin
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): N. Prabavathi , A. Nilufer , V. Krishnakumar
  The FTIR and FT-Raman spectra of Isoxanthopterin have been recorded in the region 4000–450 and 4000–100cm−1, respectively. The optimized geometry, frequency and intensity of the vibrational bands of Isoxanthopterin were obtained by the density functional theory (DFT) using 6-311++G(d,p) basis set. The harmonic vibrational frequencies were scaled and compared with experimental values. The observed and the calculated frequencies are found to be in good agreement. The 1H and 13C nuclear magnetic resonance chemical shifts of the molecule were also calculated using the gauge independent atomic orbital (GIAO) method. The UV–visible spectrum was also recorded and compared with the theoretical values. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The first order hyperpolarizability (β 0), related properties (β, α 0 and Δα) and the Mulliken charges of the molecule were also computed using DFT calculations. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ* and π* antibonding orbitals and second order delocalization energies (E2) confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. Information about the charge density distribution of the molecule and its chemical reactivity has been obtained by mapping molecular electrostatic potential surface. In addition, the non-linear optical properties were discussed from the dipole moment values and excitation wavelength in the UV–visible region.
  Graphical abstract Highlights The optimized geometry, frequency and intensity of the vibrational bands. 1H and 13C chemical shifts of Isoxanthopterin were obtained by the density functional theory using 6-311++G** basis set. The electronic properties and NBO analysis are carried out to examine the stability and charge delocalization within the molecule. The non-linear optical properties were also discussed.
  
  PubDate: 2013-06-12T07:39:48Z
Synthesis, spectroscopic and structural characterization of 5-benzoyl-4-phenyl-2-methylthio-1H-pyrimidine with theoretical calculations using density functional theory
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Ersin İnkaya , Muharrem Dinçer , Emine Şahan , İsmail Yıldırım
  In this paper, we will report a combined experimental and theoretical investigation of the molecular structure and spectroscopic parameters (FT-IR, 1H NMR, 13C NMR) of 5-benzoyl-4-phenyl-2-methylthio-1H-pyrimidine. The compound crystallizes in the triclinic space group P-1 with Z =2. The molecular geometry was also optimized using density functional theory (DFT/B3LYP) method with the 6-311G(d,p) and 6-311++G(d,p) basis sets in ground state and compared with the experimental data. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecules has been obtained by mapping electron density isosurface with electrostatic potential (ESP). Also, non-linear optical properties of the title compound were performed at B3LYP/6-311++G(d,p) level. The theoretical results showed an excellent agreement with the experimental values.
  Graphical abstract
  
  PubDate: 2013-06-12T07:39:48Z
Characterization of the sulphate mineral amarantite – Fe23+(SO4)O·7H2O using infrared, Raman spectroscopy and thermogravimetry
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Ray L. Frost , Andrés López , Ricardo Scholz , Yunfei Xi , Aléssio J. da Silveira , Rosa Malena Fernandes Lima
  The mineral amarantite Fe 2 3 + ( SO 4 ) O · 7 H 2 O has been studied using a combination of techniques including thermogravimetry, electron probe analyses and vibrational spectroscopy. Thermal analysis shows decomposition steps at 77.63, 192.2, 550 and 641.4°C. The Raman spectrum of amarantite is dominated by an intense band at 1017cm−1 assigned to the SO 4 2 - ν 1 symmetric stretching mode. Raman bands at 1039, 1054, 1098, 1131, 1195 and 1233cm−1 are attributed to the SO 4 2 - ν 3 antisymmetric stretching modes. Very intense Raman band is observed at 409cm−1 with shoulder bands at 399, 451 and 491cm−1 are assigned to the ν 2 bending modes. A series of low intensity Raman bands are found at 543, 602, 622 and 650cm−1 are assigned to the ν 4 bending modes. A very sharp Raman band at 3529cm−1 is assigned to the stretching vibration of OH units. A series of Raman bands observed at 3025, 3089, 3227, 3340, 3401 and 3480cm−1 are assigned to water bands. Vibrational spectroscopy enables aspects of the molecular structure of the mineral amarantite to be ascertained.
  Graphical abstract
  
  PubDate: 2013-06-12T07:39:48Z
Dispersive liquid–liquid microextraction of thiram followed by microvolume UV–vis spectrophotometric determination
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Saadat Rastegarzadeh , Nahid Pourreza , Arash Larki
  A novel and simple method for the sensitive determination of trace amounts of fungicide thiram is developed by combination of dispersive liquid–liquid microextraction (DLLME) and microvolume UV–vis spectrophotometry. The method is based on the conversion of thiram to a yellow product in the presence of ethanolic potassium hydroxide and copper sulfate, and its extraction into CCL4 using DLLME technique. In this method the ethanol existing in ethanolic KOH plays as disperser solvent and a cloudy solution is formed by injection of only CCl4 as extractant solvent into sample solution. Under the optimum conditions, the calibration graph was linear over the range of 25–1000ngmL−1 of thiram with limit of detection of 11.5ngmL−1. The relative standard deviation (RSD) for 100 and 500ngmL−1 of thiram was 2.7 and 1.1% (n =8), respectively. The proposed method was successfully applied to determination of thiram in water and plant seed samples.
  Graphical abstract
  
  PubDate: 2013-06-12T07:39:48Z
High performance B doped BiVO4 photocatalyst with visible light response by citric acid complex method
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Min Wang , Haoyan Zheng , Qiong Liu , Chao Niu , Yinsheng Che , Mingyan Dang
  A B-doped BiVO4 photocatalyst was synthesized by citric acid complex method and using H3BO3 as the dopant source, and the photocatalyst was characterized with XPS, XRD, SEM, BET and UV–Vis DRS. The photocatalytic activity was evaluated by the photocatalytic degradation of a methyl orange (MO) solution under visible light. This assay revealed that both the pure BiVO4 and all of the B doped samples were the monoclinic phase. Doping the BiVO4 with B increased the number of V4+ and oxygen vacancies, which led to the red shift of the absorbing boundary of the B-doped BiVO4 but had little influence on the morphology and crystal size. The B doping improved the photocatalytic activity, and the highest photocatalytic degradation rate of 98% occurred with a B dopant concentration of 0.04.
  Graphical abstract Highlights The figure shows the photocatalytic activity of BiVO4 and B-doped BiVO4 with different B doping content. The photocatalytic activities increased with increased B doping amount, when the initial molar ratio of B/Bi below 0.04. On the other hand, the activities decreased when the B doping amount was above 0.04. The optimum molar ratio of B to Bi was 0.04.
  
  PubDate: 2013-06-12T07:39:48Z
Comparative studies by IR, Raman, and surface-enhanced Raman spectroscopy of azodicarbonamide, biurea and semicarbazide hydrochloride
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Yunfei Xie , Pei Li , Jin Zhang , Heya Wang , He Qian , Weirong Yao
  Azodicarbonamide is widely applied in the food industry as a new flour gluten fortifier in China, Canada, the United States, and some other countries, whose metabolites of biurea and semicarbazide hydrochloride are reaction products during baking. In this study, IR, Raman and surface-enhanced Raman scattering (SERS) spectra of azodicarbonamide, biurea, and semicarbazide hydrochloride have been studied, and vibrational bands have been assigned on the basis of density functional theory (DFT) calculations. The calculated Raman spectra were in good agreement with experimental Raman spectra. The SERS method coupled with active gold substrates has also been applied for detection of the three chemicals with pure water as solvent, with the limit of detection of this method being as low as 10μg/mL (less than 45μg/mL). These results showed that azodicarbonamide and its metabolites could be detected by the vibrational spectra technique, which might be applied as a powerful tool for the rapid detection on these species derived from agents added to flour.
  Graphical abstract Highlights
  
  PubDate: 2013-06-12T07:39:48Z
FT-IR, dispersive Raman, NMR, DFT and antimicrobial activity studies on 2-(Thiophen-2-yl)-1H-benzo[d]imidazole
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Arslan Ünal , Bilge Eren
  2-(Thiophen-2-yl)-1H-benzo[d]imidazole (TBI) was synthesized under microwave conditions and was characterized by FT-IR, dispersive Raman, 1H-, 13C-, DEPT-, HETCOR-NMR spectroscopies and density functional theory (DFT) computations. The FT-IR and dispersive Raman spectra of TBI were recorded in the regions 4000–400cm−1 and 4000–100cm−1. The experimental vibrational spectra were interpreted with the help of normal coordinate analysis based on DFT/B3LYP/6-311++G(d,p) theory level for the more stable tautomeric form (Tautomer 1). The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. A satisfactory consistency between the experimental and theoretical findings was obtained. The frontier molecular orbitals (FMOs), atomic charges and NMR shifts of the two stable tautomeric forms were also obtained at the same theory level without any symmetry restrictions. In addition, the title compound was screened for its antimicrobial activity and was found to be exhibit antifungal and antibacterial effects.
  Graphical abstract Highlights
  
  PubDate: 2013-06-12T07:39:48Z
Electrochemical behavior of N-methyl-N′-carboxydecyl-4,4′-bipyridinium probed by surface-enhanced Raman spectroscopy
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Jian-Fang Xu , Guo-Kun Liu
  Interfacial structure determines the activity and selectivity of a sensor and plays important roles in interfacial electrochemistry, electroanalysis, biosensing, etc. In situ electrochemical Raman spectroscopy appears to be a powerful tool to probe the electrochemical interface and surface process by providing the molecular fingerprint information. Herein, the electrochemical behaviors of N-methyl-N′-carboxydecyl-4,4′-bipyridinium (derivatives of methyl viologens, MV2+) with different alkyl chain lengths (n =2 and 10) on roughened Au electrodes were systematically investigated by the electrochemical surface-enhanced Raman spectroscopy (SERS). Three systems with different interfacial structures were constructed. One is to anchor the MV2+ molecules via esterification with the 2-mercaptoethanol molecule pre-assembled on the Au surface. The second system is similar to the first one but without esterification. The third system is the direct adsorption of MV2+ molecules on the bare roughened Au surfaces. The three systems gave different spectral response upon the change of the electrode potential. A drastically increased relative Raman intensity of 19a/8a modes of the MV2+ molecules was observed at negative potentials. The phenomenon is attributed to the formation of the reduced form of MV2+ molecules, which produces resonant Raman effect to enhanced the signal of 19a mode. The third system showed the highest electrochemical reduction activity towards the reduction of MV2+ molecules, followed by the first and second systems. The result indicates that the interfacial structure can sensitively influence electrochemical activity of the electrode.
  Graphical abstract Highlights
  
  PubDate: 2013-06-12T07:39:48Z
The P-branch and R-branch emission spectral lines in the d1Σ+–A3Σ0- system of NbN
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Qi Wang , Weiguo Sun , Qunchao Fan
  The P and R-branch spectral lines of high-lying rotational quantum states of (0,0), (1,1) bands in d 1 Σ + - A 3 Σ 0 - electronic transition of NbN are obtained in this work by using the analytical formula proposed recently by Sun et al. The formula have generated unknown P and R-branch emission spectral lines up to J =80 those may not be available experimentally for these bands of NbN molecule.
  Graphical abstract Highlights Fig. 1. Experimental (“∗”) and theoretical (“○”) transition line of P-branch emission spectra of (0,0) band of d 1 Σ + – A 3 Σ 0 - system of NbN.
  
  PubDate: 2013-06-12T07:39:48Z
Inhibition in binding between fullerene and a bisporphyrin in presence of silver nanoparticles in solution: UV–Vis, DLS, SEM and TEM studies
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Ratul Mitra , Sumanta Bhattacharya
  The present paper reports the role of silver nanoparticles, i.e., AgNp (having diameter ∼5–15nm), in non-covalent interaction between fullerenes (C60 and C70) and a designed bisporphyrin (1) in toluene. UV–Vis measurement reveals reduction in binding constant (K) values for both C60-1 (K C60 -1 = 18,800dm3 mol−1) and C70-1 systems (K C70- 1 = 27,300dm3 mol−1) in presence of AgNp, i.e., K C60- 1 -AgNp =3700dm3 mol−1 and K C70- 1 -AgNp =1600dm3 mol−1 for C60-1-AgNp and C70-1-AgNp nanocomposite, respectively. Dynamic light scattering study reveals considerable increase in the particle size of C70-1-AgNp nanocomposite, i.e., ∼39nm, compared to C60-1-AgNp, e.g., ∼22nm. Scanning electron microscope measurement reveals that the well arranged and composed structure of uncomplexed 1 is perturbed very much in presence of both C60 and C70, and it ultimately results into formation of nanoaggregate in case of C70-1-AgNp system. Transmission electron microscope study envisages formation of fibrous structure in presence of C60 and C70.
  Graphical abstract
  
  PubDate: 2013-06-08T11:00:55Z
Determination of structural and vibrational spectroscopic features of neutral and anion forms of dinicotinic acid by using NMR, infrared and Raman experimental methods combined with DFT and HF
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): E. Kose , F. Bardak , A. Atac , M. Karabacak , M.A. Cipiloglu
  In this study; the experimental (NMR, infrared and Raman) and theoretical (HF and DFT) analysis of dinicotinic acid were presented. 1H and 13C NMR spectra were recorded in DMSO solution and chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The vibrational spectra of dinicotinic acid were recorded by FT-Raman and FT-IR spectra in the range of 4000–10cm−1 and 4000–400cm−1, respectively. To determine the most stable neutral conformer of molecule, the selected torsion angle was changed every 10° and molecular energy profile was calculated from 0° to 360°. The geometrical parameters and energies were obtained for all conformers form from density functional theory (DFT/B3LYP) and HF with 6-311++G(d,p) basis set calculations. However, the results of the most stable neutral and two anion forms (anion−1 and anion−2 forms) of dinicotinic acid are reported here. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational wavenumbers, calculated with scaled quantum mechanics (SQM) method and PQS program.
  Graphical abstract Highlights
  
  PubDate: 2013-06-08T11:00:55Z
Chemiluminescence determination of trimetazidine via inducing the aggregation of gold nanoparticles
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Jiao Li , Jie Quan , Jianxiu Du , Mei Liu
  A simple, rapid and sensitive chemiluminescence (CL) method combined with flow injection analysis was developed for the determination of trimetazidine. Trimetazidine was found to significantly increase the CL signal arising from N-bromosuccinimide-luminol reaction in the presence of gold nanoparticles. The enhanced CL intensity was proportional to trimetazidine concentration in the range of 0.01–5.0μg/mL, with a limit of detection (3s b) of 6.7ng/mL. The relative standard deviation was 2.8% for 11 repetitive measurements of 0.1μg/mL trimetazidine solution. The practicality of the method was evaluated by determining trimetazidine in pharmaceutical formulations and in spiked human serum samples. Moreover, the possible CL reaction mechanism was also discussed.
  Graphical abstract Highlights Trimetazidine induced the aggregation of gold nanoparticles (AuNPs), resulting in signal amplification in luminol-N-bromosuccinimide-AuNPs chemiluminescence system, providing a simple and sensitive detection method for trimetazidine.
  
  PubDate: 2013-06-08T11:00:55Z
FT-IR, Micro-Raman and UV–vis spectroscopic and quantum chemical investigations of free 2,2′-dithiodipyridine and its metal (Co, Cu and Zn) halide complexes
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Halil Gökce , Semiha Bahçeli
  In this study the elemental analysis results, molecular geometries, vibrational and electronic absorption spectra of free 2,2′-dithiodipyridine(C10H8N2S2), (or DTDP) (with synonym, 2,2′-dipyridyl disulfide) and M(C10H8N2S2)Cl2 (M=Co, Cu and Zn) complexes have been reported. Vibrational wavenumbers of free DTDP and its metal halide complexes have been calculated by using DFT/B3LYP calculation method with 6-31++G(d,p) and Lanl2DZ basis sets, respectively, in the ground state, for the first time. The calculated fundamental vibrational frequencies are in a good agreement with experimental data. The HOMO, LUMO and MEP analyses of all compounds are performed by DFT method.
  Graphical abstract Highlights
  
  PubDate: 2013-06-08T11:00:55Z
Vibrational and spectroscopic investigation on the structure of 5H-dibenzo[b,f]azipine-5-carboxamide
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): S. Muthu , S. Renuga
  Fourier transform Raman and Fourier transform infrared spectra of 5H-dibenzo[b,f]azepine-5-carboxamide were recorded in the regions 4000–100cm−1 and 4000–400cm−1 respectively in the solid phase. 5H-dibenzo[b,f]azepine-5-carboxamide is typically used for the treatment of seizure disorders and neuropathic pain. The equilibrium geometry harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated by density functional B3LYP/6-31G(d,p) method. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated Potential energy distribution (PED). The thermodynamic functions of the title compound were also performed at the above methods and basis set. A detailed interpretation of the infrared and Raman spectra of 5H-dibenzo[b,f]azepine-5-carboxamide is reported. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The linear polarizability (α) and the first order hyperpolarizability (β) values of the investigated molecule have been computed using DFT quantum mechanical calculations. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The observed and calculated wave numbers are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed spectra.
  Graphical abstract
  
  PubDate: 2013-06-08T11:00:55Z
Growth, thermal, dielectric and mechanical properties of L-phenylalanine–benzoic acid: A nonlinear optical single crystal
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): S. Tamilselvan , M. Vimalan , I. Vetha Potheher , S. Rajasekar , R. Jeyasekaran , M. Antony Arockiaraj , J. Madhavan
  An efficient amino acid family nonlinear optical single crystal L-phenylalanine–benzoic acid (LPB) was conveniently grown by slow evaporation technique at room temperature. The crystal system and the lattice parameters were analyzed by single crystal X-ray diffraction studies. The grown crystal has excellent transmission in the entire visible region and its lower cut-off wavelength was found to be 248nm. The SHG efficiency of the grown crystal was found to be 1.6times higher than that of KDP crystal. The Laser damage threshold value of LPB has been found to be 6.5GW/cm2. The sample was thermally stable up to 134°C. Microhardness, dielectric and AC/DC conductivity measurements were made along (001) plane and reported for the first time. Microhardness studies revealed that the sample belongs to hard nature. Frequency dependent dielectric constant was measured for different temperatures and found maximum dielectric constant of 14 for 363K. Photoconductivity studies of LPB divulged its negative photoconducting nature.
  Graphical abstract Highlights Growth, thermal, dielectric and mechanical properties of L-phenylalanine–benzoic acid: A novel nonlinear optical single crystal.
  
  PubDate: 2013-06-08T11:00:55Z
Vibrational spectroscopy of the mineral meyerhofferite CaB3O3(OH)5·H2O – An assessment of the molecular structure
- Abstract: Publication date: October 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 114
  Author(s): Ray L. Frost , Andrés López , Yunfei Xi , Ricardo Scholz , Geraldo Magela da Costa , Fernanda M. Belotti , Rosa Malena Fernandes Lima
  Meyerhofferite is a calcium hydrated borate mineral with ideal formula: CaB3O3(OH)5·H2O and occurs as white complex acicular to crude crystals with length up to ∼4cm, in fibrous divergent, radiating aggregates or reticulated and is often found in sedimentary or lake-bed borate deposits. The Raman spectrum of meyerhofferite is dominated by intense sharp band at 880cm−1 assigned to the symmetric stretching mode of trigonal boron. Broad Raman bands at 1046, 1110, 1135 and 1201cm−1 are attributed to BOH in-plane bending modes. Raman bands in the 900–1000cm−1 spectral region are assigned to the antisymmetric stretching of tetrahedral boron. Distinct OH stretching Raman bands are observed at 3400, 3483 and 3608cm−1. The mineral meyerhofferite has a distinct Raman spectrum which is different from the spectrum of other borate minerals, making Raman spectroscopy a very useful tool for the detection of meyerhofferite in sedimentary and lake bed deposits.
  Graphical abstract Highlights
  
  PubDate: 2013-06-08T11:00:55Z
IR, Raman, SERS and computational study of 2-(benzylsulfanyl)-3,5-dinitrobenzoic acid
- Abstract: Publication date: September 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 113
  Author(s): Asha Raj , Y. Sheena Mary , C. Yohannan Panicker , Hema Tresa Varghese , K. Raju
  FT-IR and FT-Raman spectra of 2-(benzylsulfanyl)-3,5-dinitrobenzoic acid were recorded and analyzed. SERS spectra were recorded in silver colloid, silver electrode and silver substrate. The vibrational wavenumbers were computed using HF and DFT quantum chemical calculation methods. The data obtained from wavenumber calculations are used to assign vibrational bands obtained in infrared and Raman spectra as well as in SERS of the studied molecule. Potential energy distribution was done using GAR2PED program. The geometrical parameters of the title compound are in agreement with the reported similar derivatives. The presence of phenyl ring modes in the SERS spectra suggests a tilted orientation with respect to the metal surface in all cases. In all the three SERS spectra the NO2 moiety shows an enhancement, which indicates the interaction with the metal surface. The first hyperpolarizability is high and the title compound is an attractive object for future studies of nonlinear optics.
  Graphical abstract Highlights FT-IR and FT-Raman spectra of IR, Raman, SERS and computational study of 2-(benzylsulfanyl)-3,5-dinitrobenzoic acid were recorded and analyzed. SERS spectra were recorded in silver colloid, silver electrode and silver substrate. The vibrational wavenumbers were computed using HF and DFT basis sets. The data obtained from wavenumber calculations are used to assign vibrational bands obtained in infrared and Raman spectra as well as in SERS of the studied molecule. Potential energy distribution of the normal modes of vibrations was done using GAR2PED program. The geometrical parameters of the title compound are in agreement with the reported similar derivatives. The presence of phenyl ring modes in the SERS spectra suggests a tilted orientation with respect to the metal surface in all cases. In all the three SERS spectra the NO2 moiety shows an enhancement, which indicates the interaction with the metal surface. The first hyperpolarizability is high and the title compound is an attractive object for future studies of nonlinear optics.
  
  PubDate: 2013-05-26T11:44:37Z
Validated spectrofluorometric method for determination of gemfibrozil in self nanoemulsifying drug delivery systems (SNEDDS)
- Abstract: Publication date: September 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 113
  Author(s): Ana M. Sierra Villar , Ana C. Calpena Campmany , Lyda Halbaut Bellowa , Monserrat Aróztegui Trenchs , Beatriz Clares Naveros
  A spectrofluorometric method has been developed and validated for the determination of gemfibrozil. The method is based on the excitation and emission capacities of gemfibrozil with excitation and emission wavelengths of 276 and 304nm respectively. This method allows de determination of the drug in a self-nanoemulsifying drug delivery system (SNEDDS) for improve its intestinal absorption. Results obtained showed linear relationships with good correlation coefficients (r 2 >0.999) and low limits of detection and quantification (LOD of 0.075μgmL−1 and LOQ of 0.226μgmL−1) in the range of 0.2–5μgmL−1, equally this method showed a good robustness and stability. Thus the amounts of gemfibrozil released from SNEDDS contained in gastro resistant hard gelatine capsules were analysed, and release studies could be performed satisfactorily.
  Graphical abstract
  
  PubDate: 2013-05-26T11:44:37Z
Microalgae associated Brevundimonas sp. MSK 4 as the nano particle synthesizing unit to produce antimicrobial silver nanoparticles
- Abstract: Publication date: September 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 113
  Author(s): Karthic Rajamanickam , S.S. Sudha , Mebin Francis , T. Sowmya , J. Rengaramanujam , Periyasamy Sivalingam , Kandasamy Prabakar
  The biosynthesis of silver nanoparticles and its antimicrobial property was studied using bacteria isolated from Spirulina products. Isolated bacteria were identified as Bacillus sp. MSK 1 (JX495945), Staphylococcus sp. MSK 2 (JX495946), Bacillus sp. MSK 3 (JX495947) and Brevundimonas sp. MSK 4 (JX495948). Silver nanoparticles (AgNPs) were synthesized using bacterial culture filtrate with AgNO3. The initial syntheses of Ag nanoparticles were characterized by UV–vis spectrophotometer (by measuring the color change to intense brown). Fourier Transform Infrared Spectroscopy (FTIR) study showed evidence that proteins are possible reducing agents and Energy-dispersive X-ray (EDX) study showing the metal silver as major signal. The structure of AgNPs was determined by Scanning electron microscopy (SEM) and X-ray diffraction (XRD). Synthesized Ag nanoparticles with an average size of 40–65nm have antimicrobial property against human pathogens like Proteus vulgaris, Salmonella typhi, Vibrio cholera, Streptococcus sp., Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. Among the isolates Brevundimonas sp. MSK 4 alone showed good activity in both synthesis of AgNPs and antimicrobial activity. This work demonstrates the possible use of biological synthesized silver nanoparticles to combat the drug resistant problem.
  Graphical abstract Highlights
  
  PubDate: 2013-05-26T11:44:37Z
XRD and FTIR studies the effect of heat treatment and doping the transition metal oxide on LiNbO3 and LiNb3O8 nano-crystallite phases in lithium borate glass system
- Abstract: Publication date: September 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 113
  Author(s): Ismail Kashif , Ashia A. Soliman , Elham M. Sakr , Asmaa Ratep
  Glasses of various compositions in the system 90 Li2B4O7 10 Nb2O5 mixed with T.M ions (where T.M is the transition metal) were prepared by quenching technique. Heat-treatment of the parent glasses was performed at 540, 570 and 620°C, for 5 and 16h. The glass structure evolution during the controlled crystallization was examined by XRD and FT-IR spectroscopy analysis. The crystalline phases present in the glass ceramics were identified via X-ray diffraction as a function of heat treatment. The FT-IR data propose for these glasses and heat-treated glass network structures mainly built by: di-, tri-, tetra-, penta-and ortho-borate groups. It was found that the quantitative evolution of these various borate species in the glass structures is influenced by the transition metal. A detailed discussion relating to the N4 evolution with the T.M content was made.
  Graphical abstract
  
  PubDate: 2013-05-26T11:44:37Z
Theoretical and experimental study of the vibrational spectra of sarkinite Mn2(AsO4)(OH) and adamite Zn2(AsO4)(OH)
- Abstract: Publication date: September 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 113
  Author(s): Petre Makreski , Stefan Jovanovski , Ljupco Pejov , Gert Kloess , Hans-Joachim Hoebler , Gligor Jovanovski
  The arsenate hydroxyl-bearing minerals sarkinite and adamite were studied with vibrational spectroscopic (IR and Raman) and quantum theoretical methods. The observed IR bands in the higher (1100–600cm−1) and especially lower (600–450cm−1) frequency region of AsO4 vibrations could clearly discriminate between the studied analogues. The differences between their crystal structures are much pronounced in both IR and Raman OH-stretching regions. Namely, a single strong band is found in the case of orthorhombic adamite compared to four weaker bands observed in corresponding IR and Raman spectral regions of monoclinic sarkinite. Essentially all bands in the experimental spectra, collected at both room and liquid nitrogen temperature, were tentatively assigned. To support the tentative assignment of bands in the vibrational spectra of the mentioned minerals, periodic pseudopotential plane wave density functional theory calculations were carried out. Geometry optimizations of the 3D periodic systems included both optimizations of the atomic positions within the unit cell and of the unit cell itself. In most cases, the assignments were either supported or implied by the obtained theoretical data. It is worth mentioning that this is the first experimental and theoretical study of the vibrational spectra of the very-rare sarkinite mineral.
  Graphical abstract
  
  PubDate: 2013-05-26T11:44:37Z
Synthesis, structure and photoresponsive properties of 4-(3-fluorobenzylideneamino)antipyrine
- Abstract: Publication date: September 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 113
  Author(s): Ran Zhang , Ruojing Song , Yuxi Sun , Qingli Hao
  Organic compounds are attracting greater attention largely in the recent years owing to their potential applications in the functional materials. Herein we reported the structural and photophysical properties of 4-(3-fluorobenzylideneamino)antipyrine. The studied molecule adopts a trans configuration about the imine bond, and forms a non-planar molecular device consisted of two effectively conjugated π-electron moieties. The stronger vibrational and nonlinear optical activities are tightly related to the molecular structural characteristics revealed by the analysis on vibrational modes and frontier molecular orbitals. The intramolecular electrons can be separated by the electron-transporting with specified photon-absorbing theoretically. The total molecular dipole moment, mean linear polarizability and first-order hyperpolarizability calculated at B3LYP/6-31G(d) level are 1.5390Debye, 35.6075Å3 and 1.5391×10−29 cm5/esu, respectively. The reported results indicate that the compound is a promising candidate of photoresponsive materials.
  Graphical abstract
  
  PubDate: 2013-05-26T11:44:37Z
Rotational isomers, spectroscopic (FT-IR, FT-Raman) studies and quantum chemical calculations on 2,4,6-tris(dimethylaminomethyl) phenol
- Abstract: Publication date: September 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 113
  Author(s): T. Karthick , V. Balachandran , S. Perumal , A. Lakshmi
  In this work, the spectroscopic characterization of 2,4,6-tris(dimethylaminomethyl) phenol; a novel promoter factor for DNA has been studied primarily. The FT-IR (4000–400cm−1) and FT-Raman (3500–100cm−1) spectra have been recorded on the solid phase of the title molecule. The spectroscopic signature of the title molecule has been found by comparing experimental FT-IR, FT-Raman spectra with the theoretical IR and Raman spectra of the stable isomer geometry at density functional theory (DFT) method with 6-311++G(d,p) basis set. Further, the vibrational assignments were performed on the basis of potential energy distribution (PED). The natural atomic orbital and natural population analysis performed in this study ensures us to know about the delocalization of charge and electron density of atoms within the molecule. Analysis of natural bond orbitals (NBOs) and HOMO–LUMO energy gap of the compound provides information about its chemical stability and intramolecular charge transfer properties. In addition, the reacting electrophilic and nucleophilic sites of the molecule were predicted with the help of molecular electrostatic potential (MEP) surface analysis. Moreover, the intensity of molecular vibrations at different temperatures were examined by applying thermo-chemical analysis. To investigate the solvent effect, the polarizable continuum model was used and the allowed transitions between various HOMO and LUMO levels were found.
  Graphical abstract
  
  PubDate: 2013-05-26T11:44:37Z
Study on different forms and phosphorus distribution in the coastal surface sediments of Southern Caspian Sea by using UV–Vis spectrophotometery
- Abstract: Publication date: September 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 113
  Author(s): A. Samadi-Maybodi , H. Taheri Saffar , S. Khodadoust , H. Nasrollahzadeh Saravi , S. Najafpour
  This paper presents distribution of phosphorus (total P, organic and inorganic P) in the southern of Caspian Sea sediments where collected from four sampling stations in the summer 2009. Several forms of the phosphorus in sediment were separated and extracted according to sequential extraction method. Then extracted phosphorus in each fraction was determined by UV–Vis spectrophotometery. Five forms of phosphorus were studied (i) loosely sorbed phosphorus, (ii) ferric-iron-bound phosphorus, (iii) authigenic phosphorus, (iv) detrital phosphorus, and (v) organic phosphorus. The total P contents were ranged from 124.5 to 328.2μgg−1. It was found that more than 98% of the total P is inorganic phosphorus (IP). Among the four forms of IP, loosely bound P, P–Fe, P–detrital and P–authigenic distribution ranges were 2.70–17.31%, 10.00–44.79%, 0.40–1.70% and 48.35–83.48%, respectively. Result also showed that the most abundant forms of phosphorus were authigenic phosphorus. Relative abundances of other forms of phosphorus follow the order: P–Fe>loosely bound-P>organic P>detrital P.
  Graphical abstract Highlights .
  
  PubDate: 2013-05-26T11:44:37Z
Vibrational spectroscopic investigation of 1-pyrrolidino-1-cyclohexene: A comparative density functional study
- Abstract: Publication date: September 2013
  Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 113
  Author(s): Mehmet Fatih Kaya , Cemal Parlak , Gürkan Keşan , Özgür Alver , Mahir Tursun
  Infrared and Raman spectra of 1-pyrrolidino-1-cyclohexene (1pych) have experimentally been reported in the region of 4000–100cm−1. The conformational analysis, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 1pych (C10H17N) have theoretically been examined by means of the Becke-3–Lee–Yang–Parr (B3-LYP) density functional theory (DFT) method together with the 6-31++G(d,p) basis set. Furthermore, reliable vibrational assignments have been made the basis of potential energy distribution (PED) and the thermodynamics functions, highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of 1pych have been predicted. Angular distribution of the probability density of populations of its conformational isomers is determined by analysis of the potential energy surface (PES). Comparison between the experimental and theoretical results indicates that B3-LYP method is provides satisfactory results for the prediction vibrational wavenumbers and structural parameters and the mixture of envelope and twist conformers is supposed to be the most stable form of 1pych.
  Graphical abstract Highlights
  
  PubDate: 2013-05-19T11:01:03Z