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Journal Cover Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
  [SJR: 0.717]   [H-I: 80]   [17 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1386-1425
   Published by Elsevier Homepage  [3042 journals]
  • The fluorescent property of 3-[(2-hydroxy-1-naphthyl)
           methylideneamino]benzoic acid and its application as fluorescent
           chemosensor for Hg2+ and Al3+ ions
    • Authors: Changyan Sun; Jiayi Sun; Fazheng Qiu; Wenjun Li; Zhidong Chang; Lijun Zhang
      Pages: 1 - 7
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Changyan Sun, Jiayi Sun, Fazheng Qiu, Wenjun Li, Zhidong Chang, Lijun Zhang
      This manuscript studies the fluorescent property of 3-[(2-hydroxy-1-naphthyl)methylideneamino]benzoic acid (H2L). Fluorescent spectra show that in different solvents, H2L displays different fluorescent properties, which can be attributed to the interaction between the solvents and H2L. Further study indicates that H2L exhibits a highly selective and sensitive recognition for Hg2+ ions in dimethylsulfoxide (DMSO), Al3+ ions in methanol and N,N′-dimethylformamide/water (DMF/H2O, 1/1, v/v). The bonding modes and bonding ratio of H2L and metal ions in different solvents are explored by Job's plot, 1H NMR titration, and electrospray ionization mass spectrometry (ESI-MS). The probable mechanisms were discussed.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.061
      Issue No: Vol. 188 (2017)
       
  • The biochemical, nanomechanical and chemometric signatures of brain cancer
    • Authors: Halina Abramczyk; Anna Imiela
      Pages: 8 - 19
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Halina Abramczyk, Anna Imiela
      Raman spectroscopy and imaging combined with AFM topography and mechanical indentation by AFM have been shown to be an effective tool for analysis and discrimination of human brain tumors from normal structures. Raman methods have potential to be applied in clinical practice as they allow for identification of tumor margins during surgery. In this study, we investigate medulloblastoma (grade IV WHO) (n =5) and the tissue from the negative margins used as normal controls. We compare a high grade medulloblastoma (IV grade), and non-tumor samples from human central nervous system (CNS) tissue. Based on the properties of the Raman vibrational spectra and Raman images we provide a real–time feedback that is label-free method to monitor tumor metabolism that reveals reprogramming of biosynthesis of lipids, and proteins. We have found that the high-grade tumors of central nervous system (medulloblastoma) exhibit enhanced level of β-sheet conformation and down-regulated level of α-helix conformation when comparing against normal tissue. We have shown that the ratio of Raman intensities I2930/I2845 at 2930 and 2845cm−1 is a good source of information on the ratio of lipid and protein contents. We have found that the ratio reflects the lipid and protein contents of tumorous brain tissue compared to the non-tumor tissue. Almost all brain tumors have the Raman intensity ratios significantly higher (1.99±0.026) than that found in non-tumor brain tissue, which is 1.456±0.02, and indicates that the relative amount of lipids compared to proteins is significantly higher in the normal brain tissue. Mechanical indentation using AFM on sliced human brain tissues (medulloblastoma, grade IV) revealed that the mechanical properties of this tissue are strongly heterogeneous, between 1.8 and 75.7kPa, and the mean of 27.16kPa. The sensitivity and specificity obtained directly from PLSDA and cross validation gives a sensitivity and specificity of 98.5% and 96% and 96.3% and 92% for cross-validation, respectively. The high sensitivity and specificity demonstrates usefulness for a proper decision for a Raman diagnostic test on biochemical alterations monitored by Raman spectroscopy related to brain cancer development.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.037
      Issue No: Vol. 188 (2017)
       
  • A label-free fluorimetric detection of biothiols based on the oxidase-like
           activity of Ag+ ions
    • Authors: Ru Li; Cuihua Lei; Xian-En Zhao; Yue Gao; Han Gao; Shuyun Zhu; Hua Wang
      Pages: 20 - 25
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Ru Li, Cuihua Lei, Xian-En Zhao, Yue Gao, Han Gao, Shuyun Zhu, Hua Wang
      In this work, a label-free and sensitive fluorimetric method has been developed for the detections of biothiols including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), based on the specific biothiol-induced inhibition of the oxidase-like activity of silver ions (Ag+). It is well established that o-phenylenediamine (OPD) can be oxidized by Ag+ ions to generate fluorescent 2,3-diaminophenazine (OPDox). The introduction of biothiols would inhibit the oxidation of OPD by Ag+ due to the strong coordination between biothiols and Ag+. The changes of fluorescence intensities obtained in the Ag+-OPD system exhibited good linear correlations in the ranges of 0.50–30.0μM for Cys, 1.0–45.0μM for Hcy and 0.50–40.0μM for GSH. The detection limits (S/N=3) of Cys, Hcy and GSH were 110nM, 200nM and 150nM, respectively. Subsequently, the developed fluorimetric method was successfully applied for the detection of biothiols in human serum.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.056
      Issue No: Vol. 188 (2017)
       
  • Anharmonic vibrational spectra and mode-mode couplings analysis of
           2-aminopyridine
    • Authors: Mohd Faizan; Mohammad Jane Alam; Ziya Afroz; Sheeraz Ahmad Bhat; Shabbir Ahmad
      Pages: 26 - 31
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Mohd Faizan, Mohammad Jane Alam, Ziya Afroz, Sheeraz Ahmad Bhat, Shabbir Ahmad
      Vibrational spectra of 2-aminopyridine (2AP) have been analyzed using the vibrational self-consistence field theory (VSCF), correlated corrected vibrational self-consistence field theory (CC-VSCF) and vibrational perturbation theory (VPT2) at B3LYP/6-311G(d,p) framework. The mode-mode couplings affect the vibrational frequencies and intensities. The coupling integrals between pairs of normal modes have been obtained on the basis of quartic force field (2MR-QFF) approximation. The overtone and combination bands are also assigned in the FTIR spectrum with the help of anharmonic calculation at VPT2 method. A statistical analysis of deviations shows that estimated anharmonic frequencies are closer to the experiment over harmonic approximation. Furthermore, the anharmonic correction has also been carried out for the dimeric structure of 2AP. The fundamental vibration bands have been assigned on the basis of potential energy distribution (PED) and visual look over the animated modes. Other important molecular properties such as frontier molecular orbitals and molecular electrostatics potential mapping have also been analyzed.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.054
      Issue No: Vol. 188 (2017)
       
  • Near-near-infrared thermal lens spectroscopy to assess overtones and
           combination bands of sulfentrazone pesticide
    • Authors: M. Ventura; J.R. Silva; L.H.C. Andrade; R.P. Scorza Júnior; S.M. Lima
      Pages: 32 - 36
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): M. Ventura, J.R. Silva, L.H.C. Andrade, R.P. Scorza Júnior, S.M. Lima
      Thermal lens spectroscopy (TLS) in the near-near-infrared region was used to explore the absorptions of overtones and combination bands of sulfentrazone (SFZ) herbicide diluted in methanol. This spectroscopic region was chosen in order to guarantee that only thermal lens effect is noted during the experimental procedure. The results showed that it was possible to detect very low concentrations (~2ng/μL) of SFZ in methanol by determining its thermal diffusivity or the absorption coefficient due to the 3ν(NH)+1δ(CH) combination band. This minimum SFZ concentration is the limit observed by chromatography method. The findings demonstrated that the TLS can be used for precise and accurate assessment of pesticides in ecosystems. Besides, the 3ν(NH)+1δ(CH) combination band at 960nm can be used as a marker for SFZ in methanol.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.043
      Issue No: Vol. 188 (2017)
       
  • ATR-IR study of skin components: Lipids, proteins and water. Part I:
           Temperature effect
    • Authors: S. Olsztyńska-Janus; A. Pietruszka; Z. Kiełbowicz; M.A. Czarnecki
      Pages: 37 - 49
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): S. Olsztyńska-Janus, A. Pietruszka, Z. Kiełbowicz, M.A. Czarnecki
      In this work we report the studies of the effect of temperature on skin components, such as lipids, proteins and water. Modifications of lipids structure induced by increasing temperature (from 20 to 90°C) have been studied using ATR-IR (Attenuated Total Reflectance Infrared) spectroscopy, which is a powerful tool for characterization of the molecular structure and properties of tissues, such as skin. Due to the small depth of penetration (0.6–5.6μm), ATR-IR spectroscopy probes only the outermost layer of the skin, i.e. the stratum corneum (SC). The assignment of main spectral features of skin components allows for the determination of phase transitions from the temperature dependencies of band intensities [e.g. νas(CH2) and νs(CH2)]. The phase transitions were determined by using two methods: the first one was based on the first derivative of the Boltzmann function and the second one employed tangent lines of sigmoidal, aforementioned dependencies. The phase transitions in lipids were correlated with modifications of the structure of water and proteins.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.07.001
      Issue No: Vol. 188 (2017)
       
  • Different molecular organization of two carotenoids, lutein and
           zeaxanthin, in human colon epithelial cells and colon adenocarcinoma cells
           
    • Authors: Wojciech Grudzinski; Mateusz Piet; Rafal Luchowski; Emilia Reszczynska; Renata Welc; Roman Paduch; Wieslaw I. Gruszecki
      Pages: 57 - 63
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Wojciech Grudzinski, Mateusz Piet, Rafal Luchowski, Emilia Reszczynska, Renata Welc, Roman Paduch, Wieslaw I. Gruszecki
      Two cell lines, human normal colon epithelial cells (CCD 841 CoTr) and human colon adenocarcinoma cells (HT-29) were cultured in the presence of exogenous carotenoids, either zeaxanthin or lutein. Both carotenoids demonstrated cytotoxicity with respect to cancer cells but not to normal cells. Cells from both the cell lines were analyzed with application of fluorescence lifetime imaging microscopy and Raman scattering microscopy. Both imaging techniques show effective incorporation of carotenoid molecules into growing cells. Comparison of the Raman scattering and fluorescence lifetime characteristics reveals different molecular organization of carotenoids in the carcinoma and normal cells. The main difference consists in a carotenoid aggregation level which is substantially lower in the carcinoma cells as compared to the normal cells. Different molecular organization of carotenoids was interpreted in terms of a different metabolism of normal and carcinoma cells and has been concluded to provide a possibility of cancer diagnosis based on spectroscopic analyses.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.041
      Issue No: Vol. 188 (2017)
       
  • Φ-order spectrophotokinetic characterisation and quantification of
           trans-cis oxyresveratrol reactivity, photodegradation and actinometry
    • Authors: Mounir Maafi; Mohammed Ahmed Al-Qarni
      Pages: 64 - 71
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Mounir Maafi, Mohammed Ahmed Al-Qarni
      A new Φ-order kinetic method was proposed in this study for the investigation of trans-cis photoisomerization reaction of Oxyresveratrol (ORVT) subjected to non-isosbestic irradiation. In ethanolic media, it has been proven that forward (Φ A → B λ irr ) and reverse (Φ B → A λ irr ) reaction quantum yields were dependent on the monochromatic irradiation wavelength according to sigmoid patterns over the spectral ranges of their electronic absorption (260–360nm). An 11.4- and 6.6-fold increases were recorded for Φ B → A λ irr and Φ A → B λ irr , respectively. The efficiencies of the former (Φ B → A λ irr , ranging between 2.3×10−2 and 26.3×10−2) were 33 to 60% smaller than those of the respective Φ A → B λ irr measured at the irradiation wavelengths selected. Overall, between 57 and 97% degradation of the initial trans-ORVT was observed under relatively weak light intensities, with the highest values recorded at the longest wavelengths. These findings strongly recommend protection from light in all situations of this biologically important phytomolecule that possesses therapeutic value of interest to pharmaceutical applications. The Φ-order kinetics also offered a simple way to develop a reliable actinometric method that proved ORVT to be an efficient actinometer for the dynamic range 295–360nm. The usefulness of Φ-order kinetics for the investigation and quantification of phytoproducts' photodegradation was discussed.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.067
      Issue No: Vol. 188 (2017)
       
  • Air-assisted liquid–liquid microextraction using floating organic
           droplet solidification for simultaneous extraction and spectrophotometric
           determination of some drugs in biological samples through chemometrics
           methods
    • Authors: Farnaz Farahmand; Bahar Ghasemzadeh; Abdolhossein Naseri
      Pages: 72 - 79
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Farnaz Farahmand, Bahar Ghasemzadeh, Abdolhossein Naseri
      An air assisted liquid–liquid microextraction by applying the solidification of a floating organic droplet method (AALLME-SFOD) coupled with a multivariate calibration method, namely partial least squares (PLS), was introduced for the fast and easy determination of Atenolol (ATE), Propanolol (PRO) and Carvedilol (CAR) in biological samples via a spectrophotometric approach. The analytes would be extracted from neutral aqueous solution into 1-dodecanol as an organic solvent, using AALLME. In this approach a low-density solvent with a melting point close to room temperature was applied as the extraction solvent. The emulsion was immediately formed by repeatedly pulling in and pushing out the aqueous sample solution and extraction solvent mixture via a 10-mL glass syringe for ten times. After centrifugation, the extractant droplet could be simply collected from the aqueous samples by solidifying the emulsion at a lower than the melting point temperature. In the next step, analytes were back extracted simultaneously into the acidic aqueous solution. Derringer and Suich multi-response optimization were utilized for simultaneous optimizing the parameters of three analytes. This method incorporates the benefits of AALLME and dispersive liquid–liquid microextraction considering the solidification of floating organic droplets (DLLME-SFOD). Calibration graphs under optimized conditions were linear in the range of 0.30–6.00, 0.32–2.00 and 0.30–1.40μg mL−1 for ATE, CAR and PRO, respectively. Other analytical parameters were obtained as follows: enrichment factors (EFs) were found to be 11.24, 16.55 and 14.90, and limits of detection (LODs) were determined to be 0.09, 0.10 and 0.08μg mL−1 for ATE, CAR and PRO, respectively. The proposed method will require neither a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.069
      Issue No: Vol. 188 (2017)
       
  • A highly sensitive and selective off–on fluorescent chemosensor for
           hydrazine based on coumarin β-diketone
    • Authors: Wei-Na Wu; Hao Wu; Yuan Wang; Xian-Jie Mao; Xiao-Lei Zhao; Zhou-Qing Xu; Yun-Chang Fan; Zhi-Hong Xu
      Pages: 80 - 84
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Wei-Na Wu, Hao Wu, Yuan Wang, Xian-Jie Mao, Xiao-Lei Zhao, Zhou-Qing Xu, Yun-Chang Fan, Zhi-Hong Xu
      A coumarin-based sensor C1, namely 3-acetoacetylcoumarin was designed, synthesized and applied for hydrazine detection. Hydrazinolysis of the chemosensor gives a fluorescent coumarin-pyrazole product C1 −N2H4 [3-(3-methyl-1H-pyrazol-5-yl)coumarin], and thus resulting in a prominent fluorescence off-on response toward hydrazine under physiological conditions. The probe is highly selective toward hydrazine over cations, anions and other biologically/environmentally abundant analytes. The detection limit of the probe is 3.2ppb. The sensing mechanism was supported by 1H NMR, IR, MS and DFT calculation. The application of the fluorescent probe in monitoring intracellular hydrazine in glioma cell line U251 was also demonstrated.
      Graphical abstract image

      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.062
      Issue No: Vol. 188 (2017)
       
  • Electron velocity map imaging and theoretical study on CuXH (X=O and S)
           anions
    • Authors: Zhengbo Qin; Hui Wang; Yangdi Ren; Xianfeng Zheng; Zhifeng Cui; Zichao Tang
      Pages: 85 - 89
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Zhengbo Qin, Hui Wang, Yangdi Ren, Xianfeng Zheng, Zhifeng Cui, Zichao Tang
      Vibrationally resolved photoelectron spectra of CuOH− and CuSH− have been determined via velocity map imaging method to investigate the transitions of X1A′←X2A′ at 532nm. Adiabatic detachment energies of CuOH− and CuSH− are assigned to 0.995(12) and 1.098(12) eV, respectively. Combined theoretical calculations with Franck-Condon simulations, it allows extracting the vibrational frequencies in neutral, which yields 629(32) cm−1 with CuO stretching mode and 387(24) cm−1 with CuS stretching mode for CuXH (X=O and S). Parallel transition properties of photoelectron angular distributions (PADs) for both species are correlated to the photodetachment of SOMO orbitals, which mainly involved in the Cu atom s orbital and partial s orbital in other atoms. Based on chemical bonding analyses (Wiberg, NAO, Mayer, NRT, and ELF), it is suggested that a trend is observed with a subtle variation of covalent component from weak covalent behavior between CuO in CuOH–1/0 to stronger covalent bonding between CuS in CuSH–1/0 (especially for non-ignorable covalent component in CuSH species) though ionic bonding dominates both in CuO and CuS bonds for the two systems.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.039
      Issue No: Vol. 188 (2017)
       
  • Conformation and activity alteration of horseradish peroxidase induced by
           the interaction with gene carrier polyethyleneimines
    • Authors: Aimin Huang; Bangzhi Wei; Junyong Mo; Yajing Wang; Lin Ma
      Pages: 90 - 98
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Aimin Huang, Bangzhi Wei, Junyong Mo, Yajing Wang, Lin Ma
      Polyethyleneimine (PEI) has long been considered as “golden standard” for polymeric gene delivery carriers. However the molecular basis of the cytotoxicity of PEI is poorly understood. Little is known about the effects of PEI on the structure and functions of biomacromolecules. In this work, fluorescence, UV–vis absorption, circular dichroism spectroscopy were conducted to investigate the influence of PEI of average molecular weight 25, 10 and 1.8kDa (denoted as PEI25k, PEI10k and PEI1.8k) on the conformation of horseradish peroxidase (HRP) and its catalytic efficiency. Zeta-potential measurement and isothermal titration calorimetry were used to reveal the mechanism of the interaction between PEIs and HRP. PEIs were found to bind onto the surface of HRP predominantly via hydrophobic interaction and hydrogen bond or van der Waals interaction. The complex formation between HRP and PEI induced a more compact conformation of the enzyme and an increased hydrophobicity of the microenvironment surrounding heme pocket. The conformational change of HRP had little impact on the affinity towards H2O2 and phenol. However, the increase in the non-planarity of porphyrin ring in the heme group led to an increase in the exposure degree of the active center and thus an enhancement of catalytic efficiency of HRP in the presence of high molecular weight PEIs (PEI25k and PEI10k). The polymer size played an important role in PEI-HRP interaction. PEI of low molecular weight (PEI1.8k) was less efficient to alter the conformation and catalytic activity of HRP in aqueous solutions.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.046
      Issue No: Vol. 188 (2017)
       
  • Studies on the structural changes during curing of epoxy and its blend
           with CTBN
    • Authors: Kavita Srivastava; Ashwani Kumar Rathore; Deepak Srivastava
      Pages: 99 - 105
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Kavita Srivastava, Ashwani Kumar Rathore, Deepak Srivastava
      Cashew nut shell liquid (CNSL), an agricultural renewable resource material, produces natural phenolic distillates such as cardanol. Cardanol condenses with formaldehyde at the ortho- and para-position of the phenolic ring under acidic or alkaline condition to yield a series of polymers of novolac- or resol-type phenolic resins. These phenolic resins may further be modified by epoxidation with epichlorohydrin to duplicate the performance of such phenolic-type novolacs (CFN). The structural changes during curing of blend samples of epoxy and carboxyl terminated poly (butadiene-co-acrylonitrile) (CTBN) were studies by Fourier-transform infrared (FTIR) spectrophotometer. The epoxy samples were synthesized by biomass material, cardanol. Blend sample was prepared by physical mixing of CTBN ranging between 0 and 20weightpercent CTBN liquid rubber into cardanol-based epoxidized novolac (CEN) resin. The FTIR spectrum of uncured blend sample clearly indicated that there appeared a band in the region of 3200–3500cm−1 which might be due to the presence of phenolic hydroxyl group and OH group of the opened epoxide. Pure epoxy resin showed peaks near 856cm−1 which might be due to oxirane functionality of the epoxidized novolac resin. Both epoxy and its blend sample was cured with polyamine. The cure temperature of CEN resin was found to be decreased by the incorporation of CTBN. The decomposition behavior was also studied by thermogravimetric analyzer (TGA). Two-step decomposition behavior was observed in both epoxy and its blend samples.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.066
      Issue No: Vol. 188 (2017)
       
  • Influence of spectral resolution, spectral range and signal-to-noise ratio
           of Fourier transform infra-red spectra on identification of high explosive
           substances
    • Authors: Krzysztof Banas; Agnieszka M. Banas; Sascha P. Heussler; Mark B.H. Breese
      Pages: 106 - 112
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Krzysztof Banas, Agnieszka M. Banas, Sascha P. Heussler, Mark B.H. Breese
      In the contemporary spectroscopy there is a trend to record spectra with the highest possible spectral resolution. This is clearly justified if the spectral features in the spectrum are very narrow (for example infra-red spectra of gas samples). However there is a plethora of samples (in the liquid and especially in the solid form) where there is a natural spectral peak broadening due to collisions and proximity predominately. Additionally there is a number of portable devices (spectrometers) with inherently restricted spectral resolution, spectral range or both, which are extremely useful in some field applications (archaeology, agriculture, food industry, cultural heritage, forensic science). In this paper the investigation of the influence of spectral resolution, spectral range and signal-to-noise ratio on the identification of high explosive substances by applying multivariate statistical methods on the Fourier transform infra-red spectral data sets is studied. All mathematical procedures on spectral data for dimension reduction, clustering and validation were implemented within R open source environment.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.048
      Issue No: Vol. 188 (2017)
       
  • Biothiols induced colour change of silver nanoparticles: A colorimetric
           sensing strategy
    • Authors: Ambily Thomas; Unni Sivasankaran; Krishnapillai Girish Kumar
      Pages: 113 - 119
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Ambily Thomas, Unni Sivasankaran, Krishnapillai Girish Kumar
      A sensor for the detection and determination of bio-thiols (glutathione (GSH) and cysteamine (Cyste)) has been developed by integrating the distinguished distance related optical characteristics of silver nanoparticles with the simplicity of colorimetric technique. In presence of these analytes, shift in surface plasmon resonance (SPR) absorption of silver nanoparticles (AgNPs) with change in its colour was observed. Yellow coloured AgNPs solution becomes colourless in presence of GSH and changes to red in presence of Cyste. FTIR, TEM and DLS studies were used to confirm the mechanism. The difference in absorption of AgNPs in the absence and presence of GSH was found to vary linearly in the range 1.00×10−5 M to 5.00×10−7 M concentration range with limit of detection at 3.68×10−7 M. The method can also be applied to quantify Cyste in the range 1.10×10−6 M to 5.00×10−8 M with limit of detection at 1.80×10−8 M. The utility of the proposed colorimetric assay is validated by determination of GSH and Cyste in artificial blood serum.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.040
      Issue No: Vol. 188 (2017)
       
  • A molecular rotor based ratiometric sensor for basic amino acids
    • Authors: Aafrin M. Pettiwala; Prabhat K. Singh
      Pages: 120 - 126
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Aafrin M. Pettiwala, Prabhat K. Singh
      The inevitable importance of basic amino acids, arginine and lysine, in human health and metabolism demands construction of efficient sensor systems for them. However, there are only limited reports on the ‘ratiometric’ detection of basic amino acids which is further restricted by the use of chemically complex sensor molecules, which impedes their prospect for practical applications. Herein, we report a ratiometric sensor system build on simple mechanism of disassociation of novel emissive Thioflavin-T H-aggregates from heparin surface, when subjected to interaction with basic amino acids. The strong and selective electrostatic and hydrogen bonding interaction of basic amino acids with heparin leads to large alteration in photophysical attributes of heparin bound Thioflavin-T, which forms a highly sensitive sensor platform for detection of basic amino acids in aqueous solution. These selective interactions between basic amino acids and heparin allow our sensor system to discriminate arginine and lysine from other amino acids. This unique mechanism of dissociation of Thioflavin-T aggregates from heparin surface provides ratiometric response on both fluorimetric and colorimetric outputs for detection of arginine and lysine, and thus it holds a significant advantage over other developed sensor systems which are restricted to single wavelength detection. Apart from the sensitivity and selectivity, our system also provides the advantage of simplicity, dual mode of sensing, and more importantly, it employs an inexpensive commercially available probe molecule, which is a significant advantage over other developed sensor systems that uses tedious synthesis protocol for the employed probe in the detection scheme, an impediment for practical applications. Additionally, our sensor system also shows response in complex biological media of serum samples.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.035
      Issue No: Vol. 188 (2017)
       
  • Some observations on the greenhouse effect at the Earth's surface
    • Authors: J.W. Akitt
      Pages: 127 - 134
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): J.W. Akitt
      It is shown that the greenhouse gases carbon dioxide and water vapour reflect back to the surface, all IR radiation originating at the surface within their respective spectral bands. This reflection occurs in a very thin layer at the surface, not much over 12cm in thickness. Heat is lost from the surface by heat exchange with the atmosphere and by loss of radiation. About 52% of radiation leaves the surface in two principal window regions but this is not enough to account for the earth's equilibrium temperature. This window radiation seems to disappear quite quickly and is replaced by black body radiation. It is this which eventually contributes to the earth's radiation balance, and has to originate approximately between 40 and 50km altitude where the temperature is about correct, near 255K. Doubling the CO2 concentration increases the surface temperature by about 0.9°C and this need not have any influence higher up in the atmosphere. The surface temperature seems indeed to have no direct influence on the earth's external radiation balance.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.051
      Issue No: Vol. 188 (2017)
       
  • Multimodal nonlinear microscope based on a compact fiber-format laser
           source
    • Authors: Francesco Crisafi; Vikas Kumar; Antonio Perri; Marco Marangoni; Giulio Cerullo; Dario Polli
      Pages: 135 - 140
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Francesco Crisafi, Vikas Kumar, Antonio Perri, Marco Marangoni, Giulio Cerullo, Dario Polli
      We present a multimodal non-linear optical (NLO) laser-scanning microscope, based on a compact fiber-format excitation laser and integrating coherent anti-Stokes Raman scattering (CARS), stimulated Raman scattering (SRS) and two-photon-excitation fluorescence (TPEF) on a single platform. We demonstrate its capabilities in simultaneously acquiring CARS and SRS images of a blend of 6-μm poly(methyl methacrylate) beads and 3-μm polystyrene beads. We then apply it to visualize cell walls and chloroplast of an unprocessed fresh leaf of Elodea aquatic plant via SRS and TPEF modalities, respectively. The presented NLO microscope, developed in house using off-the-shelf components, offers full accessibility to the optical path and ensures its easy re-configurability and flexibility.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.055
      Issue No: Vol. 188 (2017)
       
  • The Raman and SERS spectra of indigo and indigo-Ag2 complex: DFT
           calculation and comparison with experiment
    • Authors: Marilena Ricci; Cristiana Lofrumento; Maurizio Becucci; Emilio M. Castellucci
      Pages: 141 - 148
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Marilena Ricci, Cristiana Lofrumento, Maurizio Becucci, Emilio M. Castellucci
      Using time-dependent density functional theory in conjunction with B3LYP functional and LANL2DZ/6-31+g(d,p) basis sets, static and pre-resonance Raman spectra of the indigo-Ag2 complex have been calculated. Structure optimization, excitation energies and pre-resonance Raman spectra of the indigo molecule have been obtained at the same level of theory. The available experimental Raman spectra at 1064, 785 and 514nm and the SERS spectra at 785 and 514nm have been well reproduced by the calculation. Experimental SERS spectra are confronted with the calculated pre-resonance Raman spectra obtained for the indigo-Ag2 complex. The Raman activities calculated under the infinite lifetime approximation show a strong dependence upon the proximity to the energy and the oscillator strength of the excitation electronic transition. The comparison of the integrated EFs for indigo and indigo-Ag2 calculated Raman spectra, gave some hints as to the enhancement mechanisms acting for the different excitation wavelengths. Whereas for excitation at a wavelength corresponding to 785nm, the enhancement mechanism for the Raman spectrum of the metal complex seems the chemical one, the strong increment (ten times) of the integrated EF of the Raman spectra of the complex in the case of 514nm excitation, suggests the onset of other enhancement mechanisms. Assuming that intra-cluster transitions with high oscillator strength can be thought of as to mimic surface plasmons excitations, we suggest the onset of the electromagnetic mechanisms (EM) as the origin of the Raman spectrum enhancement. Nevertheless, other enhancement effects cannot be ruled out, as a new molecular transition gains strength in the proximity of the excitation wavelength, as a consequence of the symmetry lowering of the molecule in the complex. A large variation across vibrational modes, by a factor of at least 104, was found for the EFs. This large variation in the EFs can indicate that B-term Herzberg-Teller scattering, due to metal and/or charge transfer states, can feed intensity to the inactive (in the molecule) and/or non totally symmetric modes.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.036
      Issue No: Vol. 188 (2017)
       
  • Spectroelectrochemical insights into structural and redox properties of
           immobilized endonuclease III and its catalytically inactive mutant
    • Authors: Elin Moe; Filipe Rollo; Célia M. Silveira; Murat Sezer; Peter Hildebrandt; Smilja Todorovic
      Pages: 149 - 154
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Elin Moe, Filipe Rollo, Célia M. Silveira, Murat Sezer, Peter Hildebrandt, Smilja Todorovic
      Endonuclease III is a Fe-S containing bifunctional DNA glycosylase which is involved in the repair of oxidation damaged DNA. Here we employ surface enhanced IR spectroelectrochemistry and electrochemistry to study the enzyme from the highly radiation- and desiccation-resistant bacterium Deinococcus radiodurans (DrEndoIII2). The experiments are designed to shed more light onto specific parameters that are currently proposed to govern damage search and recognition by endonucleases III. We demonstrate that electrostatic interactions required for the redox activation of DrEndoIII2 may result in high electric fields that alter its structural and thermodynamic properties. Analysis of inactive DrEndoIII2 (K132A/D150A double mutant) interacting with undamaged DNA, and the active enzyme interacting with damaged DNA also indicate that the electron transfer is modulated by subtle differences in the protein-DNA complex.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.050
      Issue No: Vol. 188 (2017)
       
  • Pt@Ag and Pd@Ag core/shell nanoparticles for catalytic degradation of
           Congo red in aqueous solution
    • Authors: Mohamed A. Salem; Eman A. Bakr; Heba G. El-Attar
      Pages: 155 - 163
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Mohamed A. Salem, Eman A. Bakr, Heba G. El-Attar
      Platinum/silver (Pt@Ag) and palladium/silver (Pd@Ag) core/shell NPs have been synthesized in two steps reaction using the citrate method. The progress of nanoparticle formation was followed by the UV/Vis spectroscopy. Transmission electron microscopy revealed spherical shaped core/shell nanoparticles with average particle diameter 32.17nm for Pt@Ag and 8.8nm for Pd@Ag. The core/shell NPs were further characterized by FT-IR and XRD. Reductive degradation of the Congo red dye was chosen to demonstrate the excellent catalytic activity of these core/shell nanostructures. The nanocatalysts act as electron mediators for the transfer of electrons from the reducing agent (NaBH4) to the dye molecules. Effect of reaction parameters such as nanocatalyst dose, dye and NaBH4 concentrations on the dye degradation was investigated. A comparison between the catalytic activities of both nanocatalysts was made to realize which of them the best in catalytic performance. Pd@Ag was the higher in catalytic activity over Pt@Ag. Such greater activity is originated from the smaller particle size and larger surface area. Pd@Ag nanocatalyst was catalytically stable through four subsequent reaction runs under the utilized reaction conditions. These findings can thus be considered as possible economical alternative for environmental safety against water pollution by dyes.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.07.002
      Issue No: Vol. 188 (2017)
       
  • Application of Taguchi L16 design method for comparative study of ability
           of 3A zeolite in removal of Rhodamine B and Malachite green from
           environmental water samples
    • Authors: Mashaallah Rahmani; Massoud Kaykhaii; Mojtaba Sasani
      Pages: 164 - 169
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Mashaallah Rahmani, Massoud Kaykhaii, Mojtaba Sasani
      This study aimed to investigate the efficiency of 3A zeolite as a novel adsorbent for removal of Rhodamine B and Malachite green dyes from water samples. To increase the removal efficiency, effecting parameters on adsorption process were investigated and optimized by adopting Taguchi design of experiments approach. The percentage contribution of each parameter on the removal of Rhodamine B and Malachite green dyes determined using ANOVA and showed that the most effective parameters in removal of RhB and MG by 3A zeolite are initial concentration of dye and pH, respectively. Under optimized condition, the amount predicted by Taguchi design method and the value obtained experimentally, showed good closeness (more than 94.86%). Good adsorption efficiency obtained for proposed methods indicates that, the 3A zeolite is capable to remove the significant amounts of Rhodamine B and Malachite green from environmental water samples.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.070
      Issue No: Vol. 188 (2017)
       
  • Using silicon-coated gold nanoparticles to enhance the fluorescence of
           CdTe quantum dot and improve the sensing ability of mercury (II)
    • Authors: Jian Zhu; Hui Chang; Jian-Jun Li; Xin Li; Jun-Wu Zhao
      Pages: 170 - 178
      Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Jian Zhu, Hui Chang, Jian-Jun Li, Xin Li, Jun-Wu Zhao
      The effect of silicon-coated gold nanoparticles with different gold core diameter and silica shell thickness on the fluorescence emission of CdTe quantum dots (QDs) was investigated. For gold nanoparticles with a diameter of 15nm, silica coating can only results in fluorescence recover of the bare gold nanoparticle-induced quenching of QDs. However, when the size of gold nanoparticle is increased to 60nm, fluorescence enhancement of the QDs could be obtained by silica coating. Because of the isolation of the silica shell-reduced quenching effect and local electric field effect, the fluorescence of QDs gets intense firstly and then decreases. The maximum fluorescence enhancement takes place as the silica shell has a thickness of 30nm. This enhanced fluorescence from silicon-coated gold nanoparticles is demonstrated for sensing of Hg2+. Under optimal conditions, the enhanced fluorescence intensity decreases linearly with the concentration of Hg2+ ranging from 0 to 200ng/mL. The limit of detection for Hg2+ is 1.25ng/mL. Interference test and real samples detection indicate that the influence from other metal ions could be neglected, and the Hg2+ could be specifically detected.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.038
      Issue No: Vol. 188 (2017)
       
  • Tunable excited-state intramolecular proton transfer reactions with NH or
           OH as a proton donor: A theoretical investigation
    • Authors: Yuanyuan Li; Keke Wen; Songyan Feng; Huijuan Yuan; Beibei An; Qiuling Zhu; Xugeng Guo; Jinglai Zhang
      Pages: 9 - 14
      Abstract: Publication date: 5 December 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 187
      Author(s): Yuanyuan Li, Keke Wen, Songyan Feng, Huijuan Yuan, Beibei An, Qiuling Zhu, Xugeng Guo, Jinglai Zhang
      Excited-state intramolecular proton transfer (ESIPT) reactions occurring in the S1 state for five molecules, which possess five/six-membered ring intramolecular NH···N or OH···N hydrogen bonds bearing quinoline or 2-phenylpyridine moiety, have been described in detail by the time-dependent density functional theory (TD-DFT) approach using the B3LYP hybrid functional. For the five molecules, the constrained potential energy profiles along the ESIPT reactions show that proton transfer is barrierless in molecules possessing six-membered ring intramolecular H-bonds, which is smoother than that with certain barriers in five-membered ring H-bonding systems. For the latter, chemical modification by a more strong acid group can lower the ESIPT barrier significantly, which harnesses the ESIPT reaction from a difficult type to a fast one. The energy barrier of the ESIPT reaction depends on the intensity of the intramolecular H-bond, which can be measured with the topological descriptors by topology analysis of the bond critical point (BCP) of the intramolecular H-bond. It is found that when the value of electron density ρ(r) at BCP is bigger than 0.025a.u., the corresponding molecule might go through an ultrafast and barrierless ESIPT process, which opens a new scenario to explore the ESIPT reactions.
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      PubDate: 2017-06-22T08:00:04Z
      DOI: 10.1016/j.saa.2017.06.019
      Issue No: Vol. 187 (2017)
       
  • Raman spectroscopy differentiates between sensitive and resistant multiple
           myeloma cell lines
    • Authors: Domenico Franco; Sebastiano Trusso; Enza Fazio; Alessandro Allegra; Caterina Musolino; Antonio Speciale; Francesco Cimino; Antonella Saija; Fortunato Neri; Marco S. Nicolò; Salvatore P.P. Guglielmino
      Pages: 15 - 22
      Abstract: Publication date: 5 December 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 187
      Author(s): Domenico Franco, Sebastiano Trusso, Enza Fazio, Alessandro Allegra, Caterina Musolino, Antonio Speciale, Francesco Cimino, Antonella Saija, Fortunato Neri, Marco S. Nicolò, Salvatore P.P. Guglielmino
      Current methods for identifying neoplastic cells and discerning them from their normal counterparts are often nonspecific and biologically perturbing. Here, we show that single-cell micro-Raman spectroscopy can be used to discriminate between resistant and sensitive multiple myeloma cell lines based on their highly reproducible biomolecular spectral signatures. In order to demonstrate robustness of the proposed approach, we used two different cell lines of multiple myeloma, namely MM.1S and U266B1, and their counterparts MM.1R and U266/BTZ-R subtypes, resistant to dexamethasone and bortezomib, respectively. Then, micro-Raman spectroscopy provides an easily accurate and noninvasive method for cancer detection for both research and clinical environments. Characteristic peaks, mostly due to different DNA/RNA ratio, nucleic acids, lipids and protein concentrations, allow for discerning the sensitive and resistant subtypes. We also explored principal component analysis (PCA) for resistant cell identification and classification. Sensitive and resistant cells form distinct clusters that can be defined using just two principal components. The identification of drug-resistant cells by confocal micro-Raman spectroscopy is thus proposed as a clinical tool to assess the development of resistance to glucocorticoids and proteasome inhibitors in myeloma cells.
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      PubDate: 2017-06-22T08:00:04Z
      DOI: 10.1016/j.saa.2017.06.020
      Issue No: Vol. 187 (2017)
       
  • Chiral alkylated-aniline as a noninvasive fluorescence sensor:
           Spectroscopic and molecular modeling studies
    • Authors: Bidisha Sengupta; Chirantan Sen Mukherjee; Sandipan Chakraborty; Maria Jones Muhammad; William Gladney; George Armstrong
      Pages: 23 - 29
      Abstract: Publication date: 5 December 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 187
      Author(s): Bidisha Sengupta, Chirantan Sen Mukherjee, Sandipan Chakraborty, Maria Jones Muhammad, William Gladney, George Armstrong
      Aniline, heterocyclic aromatic amines, and arylamines are known carcinogens. Recently aniline mustard has come into prominence as a novel anticancer agent. In this project, microwave irradiation has been used to synthesize an optically active alkylated aniline namely 2,6-dimethyl-4-(1-(p-tolyl)ethyl)aniline (abbreviated DMPA). The presence of quartet and doublet peaks in NMR and a single chromatogram in HPLC verified that the final product DMPA, prepared from the synthesis reactions, had no major impurities. By using a Lux chiral column in HPLC, two peaks have been detected in the chromatogram, which correspond to two enantiomers of the chiral aniline derivative. Fluorescence spectroscopic measurements on DMPA indicated conspicuous dependence of its emission behavior on the polarity (in terms of the empirical polarity parameter ET(30)) of the homogeneous solvents used, a property important for an optical sensor. The nature of the emission profiles, along with the relevant parameter namely wavelength at emission maximum (λ em max) is used to infer the distribution, binding and microenvironment of the DMPA molecules in human serum albumin protein (HSA). DMPA is weakly fluorescent in aqueous buffer medium, with a dramatic enhancement in the fluorescence emission in the presence of HSA. Molecular modeling studies have been carried out on the two enantiomers (R and S) of DMPA with HSA. The implications of these findings are examined in relation to the potentialities of DMPA as a novel fluorescence sensor for biological systems.
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      PubDate: 2017-07-02T16:35:00Z
      DOI: 10.1016/j.saa.2017.06.008
      Issue No: Vol. 187 (2017)
       
  • Estimation of the molar absorption coefficient of copper salicylate within
           the spectral range 300–350nm
    • Authors: N.L. Lavrik; N.U. Mulloev
      Pages: 36 - 38
      Abstract: Publication date: 5 December 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 187
      Author(s): N.L. Lavrik, N.U. Mulloev
      Additional absorption was detected in absorption spectra within the range 300–350nm after addition of copper sulfate CuSO4(aq) to a solution of sodium salicylate NaНSal (рН=7.8). The additional maximum absorption was observed at 320nm. Assuming that the additional absorption depends on the formation of copper salicylate CuSal, the molar absorption coefficient εCuSal of this complex was determined to be (3.8±0.02)·103 М−1 сm−1. This value is almost equal to that of monoanion HSal−, εHSal− =(3.6±0.04)·103 М−1 сm−1, and is 2.5 times as much as εFe3+HSal− =(1.55±0.05)·103 М−1 сm−1 for iron salicylate. The difference in εCuSal and εFe3+HSal− is due to the difference in the initial electron states of Cu2+ and Fe3+ ions that have the d9 and d5 configurations, respectively.
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      PubDate: 2017-07-02T16:35:00Z
      DOI: 10.1016/j.saa.2017.06.012
      Issue No: Vol. 187 (2017)
       
  • Experimental determination of the absolute infrared absorption intensities
           of formyl radical HCO
    • Authors: Sergey V. Ryazantsev; Daniil A. Tyurin; Vladimir I. Feldman
      Pages: 39 - 42
      Abstract: Publication date: 5 December 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 187
      Author(s): Sergey V. Ryazantsev, Daniil A. Tyurin, Vladimir I. Feldman
      Formyl radical HCO is an important reactive intermediate in combustion, atmospheric and extraterrestrial chemistry. Like in the case of other transients, the lack of knowledge of the absolute IR intensities limits the quantitative spectroscopic studies on this species. We report the first experimental determination of the absorption intensities for the fundamental vibrational bands of HCO. The measurements have been performed using matrix-isolation FTIR spectroscopy. Determination of the values was based on the repeated photodissociation and thermal recovery of the HCO radical using the known value of the absorption coefficient of CO. The experimentally determined values (93.2±6.0, 67.2±4.5, and 109.2±6.6kmmol−1 for the ν1, ν2, and ν3 modes, respectively) have been compared to the calculated IR intensities obtained by DFT and UCCSD(T) computations.
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      PubDate: 2017-07-02T16:35:00Z
      DOI: 10.1016/j.saa.2017.06.018
      Issue No: Vol. 187 (2017)
       
  • Hydrogen bond strengthening induces fluorescence quenching of PRODAN
           derivative by turning on twisted intramolecular charge transfer
    • Authors: Yonggang Yang; Donglin Li; Chaozheng Li; YuFang Liu; Kai Jiang
      Pages: 68 - 74
      Abstract: Publication date: 5 December 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 187
      Author(s): Yonggang Yang, Donglin Li, Chaozheng Li, YuFang Liu, Kai Jiang
      Researchers have proposed different effective mechanisms of hydrogen bonding (HB) on the fluorescence of 6-propionyl-2-dimethylaminonaphthalene (PRODAN) and its derivatives. Herein, excited state transition and dynamics analysis confirm that the fluorescence of PD (a derivative of PRODAN with ethyl replaced by 3-hydroxy-2,2-dimethylpropan) emits from the planar intramolecular charge transfer (PICT) state rather than twist ICT (TICT) state, because the fluorescence emission and surface hopping from the TICT state to the twist ground (T-S0) state is energy forbidden. Nevertheless, the strengthening of intramolecular-HB (intra-HB) and intermolecular-HB (inter-HB) of PD-(methanol)2 smooth the pathway of surface hopping from TICT to T-S0 state and the external conversion going to planar ground state by decreasing the energy difference of the two states. This smoothing changes the fluorescence state of PD-(methanol)2 to the TICT state in which fluorescence emission does not occur but surface hopping, leading to the partial fluorescence quenching of PD in methanol solvent. This conclusion is different from previous related reports. Moreover, the inter-HB strengthening of PD-methanol in PICT state induces the cleavage of intra-HB and a fluorescence red-shift of 54nm compared to PD. This red-shift increases to 66nm for PD-(methanol)2 for the strengthening of the one intra-HB and two inter-HBs. The dipole moments of PD-methanol and PD-(methanol)2 respectively increase about 10.3D and 8.1D in PICT state compared to PD. The synergistic effect of intra-HB and inter-HB induces partial quenching of PD in methanol solvent by turning on the TICT state and fluorescence red-shift. This work gives a reasonable description on the fluorescence red-shift and partial quenching of PD in methanol solvent, which will bring insight into the study of spectroscopic properties of molecules owning better spectral characteristics.
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      PubDate: 2017-07-02T16:35:00Z
      DOI: 10.1016/j.saa.2017.06.029
      Issue No: Vol. 187 (2017)
       
  • Sensitized green emission of terbium with dibenzoylmethane and 1, 10
           phenanthroline in polyvinyl alcohol and polyvinyl pyrrolidone blends
    • Authors: Brijesh Kumar; Gagandeep Kaur; S.B. Rai
      Pages: 75 - 81
      Abstract: Publication date: 5 December 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 187
      Author(s): Brijesh Kumar, Gagandeep Kaur, S.B. Rai
      Tb doped polyvinyl alcohol: polyvinyl pyrrolidone blends with dibenzoylmethane (DBM) and 1, 10 Phenanthroline (Phen) have been prepared by solution cast technique. Bond formation amongst the ligands and Tb3+ ions in the doped polymer has been confirmed employing Fourier Transform Infrared (FTIR) techniques. Optical properties of the Tb3+ ions have been investigated using UV–Vis absorption, excitation and fluorescence studies excited by different radiations. Addition of dimethylbenzoate and 1, 10 Phenanthroline to the polymer blend increases the luminescence from Tb3+ ions along with energy transfer from the polymer blend itself. Luminescence decay curve analysis affirms the non-radiative energy transfer from DBM and Phen to Tb3+ ions, which is identified as the reason behind this enhancement. The fluorescence decay time of PVA-PVP host decreases from 6.02ns to 2.31ns showing an evidence of energy transfer from the host blend to the complexed Tb ions. Similarly the lifetime of DBM and Phen and both in the blend reduces in the complexed system showing the feasibility of energy transfer from these excited DBM and Phen to Tb3+ and is proposed as the cause of the above observations. These entire phenomena have been explained by the energy level diagram.
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      PubDate: 2017-07-02T16:35:00Z
      DOI: 10.1016/j.saa.2017.06.025
      Issue No: Vol. 187 (2017)
       
  • An IR investigation of solid amorphous ethanol — Spectra,
           properties, and phase changes
    • Authors: Reggie L. Hudson
      Pages: 82 - 86
      Abstract: Publication date: 5 December 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 187
      Author(s): Reggie L. Hudson
      Mid- and far-infrared spectra of condensed ethanol (CH3CH2OH) at 10–160K are presented, with a special focus on amorphous ethanol, the form of greatest astrochemical interest, and with special attention given to changes at 155–160K. Infrared spectra of amorphous and crystalline forms are shown. The refractive index at 670nm of amorphous ethanol at 16K is reported, along with three IR band strengths and a density. A comparison is made to recent work on the isoelectronic compound ethanethiol (CH3CH2SH), and several astrochemical applications are suggested for future study.
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      PubDate: 2017-07-02T16:35:00Z
      DOI: 10.1016/j.saa.2017.06.027
      Issue No: Vol. 187 (2017)
       
  • Novel CoIII complexes containing fluorescent coumarin-N-acylhydrazone
           hybrid ligands: Synthesis, crystal structures, solution studies and DFT
           calculations
    • Authors: Esther S. Areas; Bruna Juliana da S. Bronsato; Thiago M. Pereira; Guilherme P. Guedes; Fábio da S. Miranda; Arthur E. Kümmerle; Antônio G.B. da Cruz; Amanda P. Neves
      Pages: 130 - 142
      Abstract: Publication date: 5 December 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 187
      Author(s): Esther S. Areas, Bruna Juliana da S. Bronsato, Thiago M. Pereira, Guilherme P. Guedes, Fábio da S. Miranda, Arthur E. Kümmerle, Antônio G.B. da Cruz, Amanda P. Neves
      A series of new CoIII complexes of the type [Co(dien)(L1−L3)]ClO4 (1–3), containing fluorescent coumarin-N-acylhydrazonate hybrid ligands, (E)-N′-(1-(7-oxido-2-oxo-2H-chromen-3-yl)ethylidene)-4-R-benzohydrazonate [where R=H (L1 2− ), OCH3 (L2 2− ) or Cl (L3 2− )], were obtained and isolated in the low spin CoIII configuration. Single-crystal X-ray diffraction showed that the coumarin-N-acylhydrazones act as tridentate ligands in their deprotonated form (L2−). The cation (+1) complexes contain a diethylenetriamine (dien) as auxiliary ligand and their structures were calculated by DFT studies which were also performed for the CoII (S=1/2 and S=3/2) configurations. The LS CoII (S=1/2) concentrated the spin density on the O–Co–O axis while the HS CoII (S=3/2) exhibited a broad spin density distribution around the metallic center. Cyclic voltammetry studies showed that structural modifications made in the L2− ligands caused a slight influence on the electronic density of the metal center, and the E1/2 values for the CoIII/CoII redox couple increased following the electronic effect of the R-substituent, in the order: 2 (R=OCH3) <1 (R=H) <3 (R=Cl). The theoretical redox potentials (E°) of the process CoIII →CoII were calculated for both CoII spin states (S=1/2 and S=3/2) and a better correlation was found for CoIII →CoII (S=1/2), compared with experimental values vs SHE (E° calc =−0.37, −0.36 and −0.32 V vs E° exp . =−0.371, −0.406 and −0.358 V, for 1–3 respectively). Complexes 1–3 exhibited a very intense absorption band around 470nm, assigned by DFT calculations as π-π* transitions from the delocalized coumarin-N-acylhydrazone system. 1–3 were very stable in MeOH for several days. Likewise, 1–3 were stable in phosphate buffer containing sodium ascorbate after 15h, which was attributed to the high chelate effect and σ-donor ability of the L2− and dien ligands.
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      PubDate: 2017-07-12T01:41:35Z
      DOI: 10.1016/j.saa.2017.06.031
      Issue No: Vol. 187 (2017)
       
  • The nature of hydrogen-bonding interactions in nonsteroidal
           anti-inflammatory drugs revealed by polarized IR spectroscopy
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Barbara Hachuła
      The influence of hydrogen-bonding interactions in the solid phase on the IR spectroscopic pattern of the νOH band of nonsteroidal anti-inflammatory drugs (NSAIDs) was studied experimentally by IR spectroscopy with the use of polarized light at two temperatures (293K and 77K) and in isotopic dilution. The neat and deuterated crystals of (S)-naproxen ((S)-NPX), (R)-flurbiprofen ((R)-FBP), (RS)-flurbiprofen ((RS)-FBP) and (RS)-ketoprofen ((RS)-KTP) were obtained by melt crystallization between the two squeezed CaF2 plates. The vibrational spectra of selected α-aryl propionic acid derivatives (2APAs) reflected the characteristics of their hydrogen-bond networks, i.e., 2APAs were characterized by the chain ((S)-NPX, (R)-FBP) and by dimeric ((RS)-FBP, (RS)-KTP) arrangement of hydrogen bonds in the crystal lattice. Spectroscopic results showed that the interchain (through-space) exciton coupling, between two laterally-spaced hydrogen bonds, dominates in the crystals of four NSAIDs. The same exciton coupled hydrogen bonds were also responsible for the H/D isotopic recognition mechanism in the crystalline spectra of deuterated 2APAs. The presented spectral results may help to predict the hydrogen bond motifs in the crystalline NSAIDs, which structures are not yet known, based on their IR spectra of hydrogen bond in the crystals.
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      PubDate: 2017-07-23T22:09:29Z
       
  • Structure and absolute configuration of some
           5-chloro-2-methoxy-N-phenylbenzamide derivatives
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Alaaeldin M F Galal, Elsayed M. Shalaby, Ahmed Abouelsayed, Medhat A. Ibrahim, Emad Al-Ashkar, Atef G Hanna
      The absolute configuration of 5-chloro-2-methoxy-N-phenylbenzamide single crystal [compound (1)] and the effect of introducing –[CH2]n–, n=1,2 group adjacent to the amide group [compounds (2) and (3)], were studied. Furthermore, the replacement of the methoxy group with a hydroxy group [compound (4)] was defined. Proton and carbon-13 NMR spectrometer were used to record the structural information of the prepared compounds. X-ray single crystal diffractometer were used to elucidate the 3D structural configurations. Intensity data for the studied compounds were collected at room temperature. The X-ray data prove that compound (1) is almost planar, with maximum r.m.s. deviations of 0.210(3)Å corresponds to C13. This planarity starts to disturb by adding –[CH2]n–, n=1,2 groups between the NH group and the phenyl ring in compounds (2) and (3), respectively. By replacing the OCH3 group by an OH group in compound (4), the plane of the chlorophenyl moiety is nearly perpendicular to that of the phenyl ring. Such new structural configurations were further illustrated by the infrared, and ultraviolet-visible spectroscopy measurements in the frequency range 400–4000cm −1 and 190–1100nm, respectively. Spectroscopic analyses were verified with the help of molecular modeling using density functional theory. The estimated total dipole moment for the prepared compounds reflects its ability to interact with its surrounding molecules. The higher dipole moment for a given structures is combined with the higher reactivity for potential use in medicinal applications.
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      PubDate: 2017-07-23T22:09:29Z
       
  • A quinoline-based fluorometric and colorimetric dual-modal pH probe and
           its application in bioimaging
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Qin Zhu, Zhao Li, Lan Mu, Xi Zeng, Carl Redshaw, Gang Wei
      The compound (E)-8-hydroxyl-2-[(E)-2-(2, 4-dihydroxyphenyl)vinyl]-quinoline (1) has been developed as a fluorometric and colorimetric dual-modal probe for pH detection in solution and in vivo. Remarkable changes in the fluorescence intensity with large Stokes shifts and colorimetric responses were observed as a function of pH. The sensing mechanisms involving protonation and deprotonation processes over the acidic and alkaline pH ranges were confirmed by 1H NMR and IR spectroscopic analysis. Furthermore, the application of probe 1 for the imaging of live PC3 cells was successfully achieved. Test strips based on probe 1 were fabricated, and were found to act as a convenient and efficient pH test kits.
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      PubDate: 2017-07-23T22:09:29Z
       
  • Photophysics of a coumarin based Schiff base in solvents of varying
           polarities
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Saptarshi Ghosh, Nayan Roy, T. Sanjoy Singh, Nitin Chattopadhyay
      The present work reports detailed photophysics of a coumarin based Schiff base, namely, (E)-7-(((8-hydroxyquinolin-2-yl)methylene)amino)-4-methyl-2H-chromen-2-one (HMC) in different solvents of varying polarity exploiting steady state absorption, fluorescence and time resolved fluorescence spectroscopy. The dominant photophysical features of HMC are discussed in terms of emission from an intramolecular charge transfer (ICT) excited state. Molecular orbital (MO) diagrams as obtained from DFT based computational analysis confirms the occurrence of charge transfer from 8′-hydroxy quinoline moiety of the molecule to the coumarin part. The notable difference in the photophysical response of HMC from its analogous coumarin (C480) lies in a lower magnitude of fluorescence quantum yield of the former, particularly in the solvents of low polarity, which is rationalized by considering the higher rate of non-radiative decay of HMC in apolar solvents. Phosphorescence emission as well as phosphorescence lifetime of HMC has also been reported in 77K frozen matrix.
      Graphical abstract image

      PubDate: 2017-07-23T22:09:29Z
       
  • Synthesis, physicochemical and optical properties of bis-thiosemicarbazone
           functionalized graphene oxide
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Santosh Kumar, Mohmmad Y. Wani, Claudia T. Arranja, Ricardo A.E. Castro, José A. Paixão, Abilio J.F.N. Sobral
      Fluorescent materials are important for low-cost opto-electronic and biomedical sensor devices. In this study we present the synthesis and characterization of graphene modified with bis-thiosemicarbazone (BTS). This new material was characterized using Fourier transform infrared spectroscopy (FT-IR), Ultraviolet–visible (UV–Vis) and Raman spectroscopy techniques. Further evaluation by X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and atomic-force microscopy (AFM) allowed us to fully characterize the morphology of the fabricated material. The average height of the BTSGO sheet is around 10nm. Optical properties of BTSGO evaluated by photoluminescence (PL) spectroscopy showed red shift at different excitation wavelength compared to graphene oxide or bisthiosemicarbazide alone. These results strongly suggest that BTSGO material could find potential applications in graphene based optoelectronic devices.
      Graphical abstract image

      PubDate: 2017-07-23T22:09:29Z
       
  • Infrared dispersion analysis and Raman scattering spectra of taurine
           single crystals
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Roberto L. Moreira, Ricardo P.S.M. Lobo, Anderson Dias
      A comprehensive set of optical vibrational modes of monoclinic taurine crystals was determined by Raman scattering, and infrared reflectivity and transmission spectroscopies. By using appropriate scattering/reflection geometries, the vibrational modes were resolved by polarization and the most relevant modes of the crystal could be assigned. In particular, we were able to review the symmetry of the gerade modes and to resolve ambiguities in the literature. Owing to the non-orthogonal character of Bu modes in monoclinic crystals (lying on the optic axial plane), we carried out a generalized Lorentz dispersion analysis consisting of simultaneous adjust of infrared-reflectivity spectra at various light polarization angles. The Au modes (parallel to the C 2 -axis) were treated within the classical Lorentz model. The behavior of off-diagonal and diagonal terms of the complex dielectric tensors and the presence of anomalous dispersion were discussed as consequences of the low symmetry of the crystal.
      Graphical abstract image

      PubDate: 2017-07-23T22:09:29Z
       
  • Rhodamine spirolactam sensors operated by sulfur-cooperated metal
           complexation
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Gisuk Heo, Dahye Lee, Chi Gwan Kim, Jung Yun Do
      New rhodamine Schiff base sensors were developed to improve selective sensing by introducing sulfide, ester, and dithiocarbonate groups, as well as using ketones coupled to rhodamine-hydrazine. Metal sensing proceeded through the 1:1 complexation of the metal ion for most sensors in the presence of Cu2+ and Hg2+. A sensor carrying a dithiocarbonate group responded selectively to Hg2+ showing a strong colorimetric change and intense fluorescence. The association constants of the sensors were determined from a linear plot performed at micro-molar concentrations to afford values in the range of 104. Sensing was interrupted at the initial time of Hg2+ exposure due to the isomerization of imine and preferential metal bonding of two dithiocarbonate groups regardless of the main structure of rhodamine. The sensors exhibited the reversible and reproducible performance for Hg2+ sensing.
      Graphical abstract image

      PubDate: 2017-07-23T22:09:29Z
       
  • Highly selective and sensitive fluorogenic ferric probes based on
           aggregation-enhanced emission with −SiMe3 substituted polybenzene
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Xuefeng Wang, Hua Wang, Qin Jiang, Yong-Ill Lee, Shengyu Feng, Hong-Guo Liu
      In this study, thiophene was linked to polybenzene to generate novel fluorescent probes, namely 3,4-diphenyl-2,5-di(2-thienyl)phenyl-trimethylsilane (DPTB-TMS) with a −SiMe3 substituent and 3,4-diphenyl-2,5-di(2-thienyl)phenyl (DPTB) without the −SiMe3 substituent, respectively. Both of the two compounds exhibit aggregation-enhanced emission (AEE) properties in tetrahydrofuran/water mixtures due to restricted intramolecular rotation of the peripheral groups, which make the two compounds good candidates for the detection of Fe3+ ions in aqueous-based solutions. The fluorescence intensity of the two compounds decreases immediately and obviously upon addition of a trace amount of Fe3+, and decreases continuously as the amount of Fe3+ increases. The fluorescence was quenched to 92% of its initial intensity when the amount of Fe3+ ions reached 6μmol for DPTB-TMS and to 80% for DPTB in the systems, indicating that the compound with the −SiMe3 group is a more effective probe. The detection limit was found to be 1.17μM (65ppb). The detection mechanism is proposed to be static quenching. DPTB-TMS is highly efficient for the detection of ferric ions even in the presence of other metal ions. In addition, the method is also successfully applied to the detection of ferric ions in water, blood serum, or solid films. This indicates that these polybenzene compounds can be applied as low-cost, high selectivity, and high efficiency Fe3+ probes in water or in clinical applications.
      Graphical abstract image

      PubDate: 2017-07-23T22:09:29Z
       
  • Selective biosensing of Staphylococcus aureus using chitosan quantum dots
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Hani Nasser Abdelhamid, Hui-Fen Wu
      Selective biosensing of Staphylococcus aureus (S. aureus) using chitosan modified quantum dots (CTS@CdS QDs) in the presence of hydrogen peroxide is reported. The method is based on the intrinsic positive catalase activity of S. aureus. CTS@CdS quantum dots provide high dispersion in aqueous media with high fluorescence emission. Staphylococcus aureus causes a selective quenching of the fluorescence emission of CTS@CdS QDs in the presence of H2O2 compared to other pathogens such as Escherichia coli and Pseudomonas aeruginosa. The intrinsic enzymatic character of S. aureus (catalase positive) offers selective and fast biosensing. The present method is highly selective for positive catalase species and requires no expensive reagents such as antibodies, aptamers or microbeads. It could be extended for other species that are positive catalase.
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      PubDate: 2017-07-23T22:09:29Z
       
  • The design of novel visible light driven Ag/CdO as smart nanocomposite for
           photodegradation of different dye contaminants
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): K. Saravanakumar, V. Muthuraj, M. Jeyaraj
      In this paper, we report a novel visible light driven Ag/CdO photocatalyst, fabricated for the first time via one pot hydrothermal method and further applied for the photodegradation of two important exemplar water contaminants, Malachite green and Acid Orange 7. The microstructure, composition and optical properties of Ag/CdO nanocomposites were thoroughly investigated by various techniques. Scanning electron microscopy clearly shows that Ag NPs were strongly embedded between the CdO nanoparticles. Among the series of synthesized Ag/CdO nanocomposites, (5%) Ag/CdO nanocomposite possesses enhanced photocatalytic activity. This result was attributed to the synergistic effect between Ag and CdO, and mainly Ag NPs can act as an electron trap site, which could reduce the recombination of the electron-hole and induce the visible light absorption. The active species trapping experiments implicate OH and O2 − radicals as the respective primary and secondary reactive species responsible for oxidative photodegradation of organic pollutants. On the basis of the results, a possible photocatalytic mechanism has also been proposed.
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      PubDate: 2017-07-23T22:09:29Z
       
  • Evidence of anomalous behavior of intermolecular interactions at low
           concentration of methanol in ethanol-methanol binary system
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): K Nilavarasi, Thejus R Kartha, V Madhurima
      At low concentrations of methanol in a binary system of ethanol and methanol, uniquely complex molecular interactions are reported here. Previous studies indicate that ethanol molecules form aggregates held together by hydrogen bonding (O–H–O) and also dispersive forces. Addition of small amount of methanol tends to break the hydrogen bond network of ethanol due to the larger polarity of methanol. This leads to the ethanol molecules becoming somewhat isolated from each other within a scaffolding network of methanol molecules, as seen from the present molecular dynamics simulations. This is an indication of a repulsive force that dominates among the two different alcohols. At higher molar concentration of methanol (Xm > 0.3817), the strength and extent (number) of formation of hydrogen bonds between ethanol and methanol increase. The geometry of molecular structure at high concentration favors the fitting of component molecules with each other. Intermolecular interactions in the ethanol-methanol binary system over the entire concentration range were investigated in detail using broadband dielectric spectroscopy, FTIR, surface tension and refractive index studies. Molecular dynamics simulations show that the hydrogen bond density is a direct function of the number of methanol molecules present, as the ethanol aggregates are not strictly hydrogen-bond constructed which is in agreement with the experimental results.
      Graphical abstract image

      PubDate: 2017-07-23T22:09:29Z
       
  • Deciphering the mechanism of interaction of edifenphos with calf thymus
           DNA
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Ajaz Ahmad, Masood Ahmad
      Edifenphos is an important organophosphate pesticide with many antifungal and anti-insecticidal properties but it may cause potential hazards to human health. In this work, we have tried to explore the binding mode of action and mechanism of edifenphos to calf thymus DNA (CT-DNA). Several experiments such as ultraviolet-visible absorption spectra and emission spectroscopy showed complex formation between edifenphos and CT-DNA and low binding constant values supporting groove binding mode. These results were further confirmed by circular dichroism (CD), CT-DNA melting studies, viscosity measurements, density functional theory and molecular docking. CD study suggests that edifenphos does not alter native structure of CT-DNA. Isothermal calorimetry reveals that binding of edifenphos with CT-DNA is enthalpy driven process. Competitive binding assay and effect of ionic strength showed that edifenphos binds to CT-DNA via groove binding manner. Hence, edifenphos is a minor groove binder preferably interacting with A-T regions with docking score −6.84kJ/mol.
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      PubDate: 2017-07-23T22:09:29Z
       
  • Chemical and spectral behavior of nitric acid in aqueous sulfuric acid
           solutions: Absorption spectrum and molar absorption coefficient of
           nitronium ion
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Boris G. Ershov, Nadezhda M. Panich
      The chemical species formed from nitric acid in aqueous solutions of sulfuric acid (up to 18.0molL−1) were studied by optical spectroscopy method. The concentration region of nitronium ion formation was identified and NO2 + ion absorption spectrum was measured (λ max ≤190nm and ε 190 =1040±50mol−1 Lcm−1).
      Graphical abstract image

      PubDate: 2017-07-23T22:09:29Z
       
  • A DFT study on surface-enhanced Raman spectroscopy of aromatic dithiol
           derivatives adsorbed on gold nanojunctions
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Tingting You, Xiufeng Lang, Anping Huang, Penggang Yin
      A computational study on aromatic dithiol derivatives (HS-Ar-X-Ar-SH, X=O, S, Se, NH, CH2, NN, CHCH, CC) interacting with gold cluster(s) was presented to investigate the chemical enhancement mechanism related to surface-enhanced Raman spectroscopy (SERS) for molecular junctions. Density functional theory (DFT) were performed on derivatives molecules as well as their single-end-linked (SEL) or double-end-linked (DEL) complexes for geometric, spectra, electronic and excitation properties, leading to discussions on dominant factor during SERS process. The resulted enhancement factors of SEL and DEL complexes exhibited specific dependency on linking atom or functional group between two phenyls, which was in accordance with the variation of polarizabilities and molecule-cluster transition energy.
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      PubDate: 2017-07-23T22:09:29Z
       
  • Propping the optical and electronic properties of potential
           photo-sensitizers with different π-spacers: TD-DFT insights
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Basant A. Ali, Nageh K. Allam
      We report density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations on the widely used N3 dye (cis-[Ru(2,2′-bipyridine-4,4′-dicarboxylic acid)2(NCS)2] and its trans isomer with different π-spacers. The study compared the sensitization properties of the two isomers in terms of their electronic properties such as light harvesting efficiency (LHE), absorbed wavelength (λMax) and molecular orbital distribution. Also, charge transfer descriptors, such as the charge transfer distance (DCT), dipole moment (μCT), and the amount of charge transferred (qCT) were investigated. Upon replacing the two “2,2′-bipyridine-4,4′-dicarboxylic acid” ligands of the N3 dye with extended π-spacers of “1,4-benzene and 2,5-thiophene” for both the cis and trans isomers, the LHE of the trans isomer was increased by 70% compared to the cis counterpart. The complexes with thiophene spacers showed the highest LHE. The trans isomers showed wider absorbance range of wavelengths and equal wide distribution of charge density in the excited state along the organic ligands. These findings highlight the importance of using π-spacers between the organic ligands and the carboxylate groups to boost the LHE of DSSCs. Also, our study showed that the trans isomer is superior in its optical and electronic properties than the cis counterpart. However, the trans isomer is yet to be tested experimentally in DSSCs.
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      PubDate: 2017-07-23T22:09:29Z
       
  • Effects of Near Infrared Radiation on DNA. DLS and ATR-FTIR Study
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Katarzyna Szymborska-Małek, Małgorzata Komorowska, Marlena Gąsior-Głogowska
      We presume that the primary effect of Near Infrared (NIR) radiation on aqueous solutions of biological molecules concerns modification of hydrogen bonded structures mainly the global and the hydration shell water molecules. Since water has a significant influence on the DNA structure, we expect that the thermal stability of DNA could be modified by NIR radiation. The herring sperm DNA was exposed to NIR radiation (700–1100nm) for 5, 10, and 20min periods. The temperature dependent infrared measurements were done for the thin films formed on the diamond ATR crystal from evaporated DNA solutions exposed and unexposed to NIR radiation. For the NIR-treated samples (at room temperature) the B form was better conserved than in the control sample independently of the irradiation period. Above 50°C a considerable increase in the A form was only observed for 10min NIR exposed samples. The hydrodynamic radius, (Rh), studied by the dynamic light scattering, showed drastic decrease with the increasing irradiation time. Principal components analysis (PCA) allowed to detect the spectral features correlated with the NIR effect and thermal stability of the DNA films. Obtained results strongly support the idea that the photoionization of water by NIR radiation in presence of DNA molecules is the main factor influencing on its physicochemical properties.
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      PubDate: 2017-07-23T22:09:29Z
       
  • Field-free molecular orientation by delayed elliptically polarised
           laser pulses
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Anjali Maan, Ashish Tyagi, Vinod Prasad
      A theoretical model of NAREX (non-adiabatic rotational excitation) and field-free molecular orientation by a short specific elliptically polarised laser pulses (EPLPs) driving a polar molecule is presented. By choosing the proper value of elliptically polarised field parameters, efficient field-free orientation could be achieved. It is demonstrated that NAREX can be controlled by various laser parameters, out of which pulse shape plays the most significant role. The effect of elliptic parameter on the rotational excitation and orientation dynamics is also under concern.
      Graphical abstract image

      PubDate: 2017-07-23T22:09:29Z
       
  • Quinoline containing acetyl hydrazone: An easily accessible switch-on
           optical chemosensor for Zn2+
    • Abstract: Publication date: 5 January 2018
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 188
      Author(s): Wei-Na Wu, Pan-Dong Mao, Yuan Wang, Xiao-Lei Zhao, Zhou-Qing Xu, Zhi-Hong Xu, Yuan Xue
      A simple chemosensor, namely, N-((quinolin-8-yl)methylene)acetohydrazide (1) was synthesized and used as an off–on fluorescence sensor, which exhibits high selectivity toward Zn2+ in aqueous media. The probe has large Stokes shift of >200nm, and its detection limit for Zn2+ is 89.3nM. The binding process was confirmed through UV–vis absorption analysis, fluorescence measurements, mass spectroscopy study, 1H NMR spectra and density functional theory calculation. The crystal structures of Zn2+, Ni2+, and Cu2+ complexes based on 1 were determined through X-ray crystallographic analysis. The fluorescent probe was then applied to monitor intracellular Zn2+ in HeLa cells.
      Graphical abstract image

      PubDate: 2017-07-23T22:09:29Z
       
 
 
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