Department of Chemistry
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Item Estimation of ground and excited-state dipole moments of synthesized coumarin derivative, (S)-(1-((7-hydroxy-2-oxo-2H-chromen-4-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl 2-(((9H-fluoren-9-yl)methoxy)cabonylamino)-3-phenylpropanoate from a solvatochromic shift and theoretical methods(Elsiever, 2015-09) Sakhuja, Rajeev; Pant, Debi D.The electronic absorption and fluorescence spectra of coumarin derivative, (S)-(1-((7-hydroxy-2-oxo-2H-chromen-4-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl2-(((9H-fluoren-9-yl)methoxy)cabonylamino)-3-phenylpropanoate have been studied in solvents of different polarities, and the data were used to study the solvatochromic properties. The absorption maximum remains almost unchanged with the increase in solvent polarity, whereas a red shift in fluorescence emission maximum was observed. Synthesized compound (S)-(1-((7-hydroxy-2-oxo-2H-chromen-4-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl2-(((9H-fluoren-9-yl)methoxy)cabonylamino)-3-phenylpropanoate was characterized by 1H and 13C NMR, and FT-IR spectral studies. The ground and excited state dipole moments of molecule were obtained from Bakshiev's and Bilot–Kawski's equations by means of solvatochromic shift method. High value of dipole moment is observed for excited state as compared to ground state value and this is attributed to more polar excited state of molecule. Also, fluorescence emission peak undergoes a bathochromic shift with increase in the polarity of the solvent, confirming π → π* transition. Numerical calculations are performed using B3LYP/6-31G(d) level of theory for the ground state using Gaussian 03. Studies in different solvents are also done using IEF-PCM method and UA0 radii. A comparative analysis between the values of dipole moment in gas phase and various solvents is also done for the ground state.Item Experimental and theoretical study: Determination of dipole moment of synthesized coumarin–triazole derivatives and application as turn off fluorescence sensor: High sensitivity for iron(III) ions(Elsiever, 2015-12) Sakhuja, Rajeev; Pant, Debi D.Electronic absorption and fluorescence spectra of two synthesized coumarin–triazole based probes (S)-(1-((7-hydroxy-2-oxo-2H-chromen-4-yl) methyl)-1H-1,2,3-triazol-4-yl)methyl 2-(tert-butoxycabonylamino)-3-phenylpropanoate and (S)-(1-((7-hydroxy-2-oxo-2H-chromen-4-yl)methyl)-1H-1,2,3-triazol-4-yl) methyl 2-(benzyloxycabonylamino)-3-phenylpropanoate have been recorded at room temperature in wide range of solvents of different polarities. Synthesized compounds were characterized by 1H and 13C NMR, and FT-IR spectral studies. The ground and excited state dipole moments of molecules were obtained from Bakshiev's and Bilot–Kawski's equations by means of solvatochromic shift method. A DFT based studies in different solvents are also performed using IEF-PCM method and UA0 radii. A comparative analysis between the values of dipole moment in gas phase and various solvents is also performed for the ground state. The potential sensor behaviors of these compounds to metal ions have also been examined by fluorescence spectroscopy and these compounds exhibited as fluorescence sensor for the determination of Fe3+ ions in solution. Effect of various metal ions on fluorescent behavior was also studied. Both the synthesized compounds act as selective and sensitive sensor for micromolar detection of Fe3+ ions. Binding stoichiometry of Fe3+ ion detection was also investigated. Conventional binding energy calculations are performed to determine the relative stability of Fe(III) complexes.Item Solvatochromic shift and estimation of dipole moment of synthesized coumarin derivative: Application as sensor for fluorogenic recognition of Fe3 + and Cu2 + ions in aqueous solution(Elsiever, 2016-10) Sakhuja, Rajeev; Pant, Debi D.(S)-4-((4-((3-amino-2-oxo-4-phenylbutoxy)methyl)-1H-1,2,3-triazol-1-yl)methyl)-7 hydroxy-2H-chromen-2-one hydrochloride was synthesized and characterized by detailed spectroscopic studies such as 1H, 13C NMR and HRMS. Excited state dipole moment of synthesized compound was obtained using different solvatochromic shift methods. High value of dipole moment is observed for excited state as compared to ground state value and this is attributed to more polar excited state of molecule. Also, fluorescence emission peak undergoes a bathochromic shift with increase in the polarity of the solvent, confirming π → π* transition. The potential sensor behavior of the compound to metal ions has also been examined. Chemosensor shows the sensitivity for Fe3 + and Cu2 + over other metal cations in aqueous solution. The detection limits of Fe3 + and Cu2 + were calculated to be 143 nM and 71.31 μM, respectively. The LC–mass analysis indicated that 1:1 complex was formed between Fe3 + (or) Cu2 + and compound. Binding energy values for the complexation of the compound with metal ions are theoretically computed at M06/6–31 + G(d,p) level. The DFT based binding energy values show good correlation with the experimental observations.Item Design and synthesis of amino acid appended azo dye hybrid: Characterization, solvatochromic and quantum-chemical calculations using experimental and theoretical approach(Elsiever, 2016-09) Sakhuja, Rajeev; Pant, Debi D.Amino acid appended azobenzene hybrid was synthesized and characterized using Spectroscopic techniques like 1H NMR, 13C NMR, FT-IR and Mass spectrometry analysis and its optical properties were investigated using UV–vis absorption and fluorescence spectroscopy in solvents of different polarity. Based on solvent refractive index and relative permittivity, by using the theory of solvatochromism, the excited-state (μe) and ground-state (μg) dipole moments was determined for (E)-4-((4-(heptyloxy)phenyl)diazenyl)benzyl((benzyloxy)carbonyl)glycinate (Gly-Azo-O7) based on the variation of Stokes shift as an effect of various solvent's. A bathochromic shift observed in absorption and emission spectra with increasing solvent polarity, which implied that the transition involved is π → π*. The ground state and excited state dipole moments were also calculated and compared using experimental and DFT calculations.Item Solvent effects on the absorption and emission spectra of novel (E)-4-((4-(heptyloxy)phenyl)diazenyl)benzyl (((9H-fluoren-9-yl)methoxy)carbonyl)-d-alaninate (Fmoc-al-az): Determination of dipole moment by experimental and theoretical study(Elsiever, 2017-02-05) Sakhuja, Rajeev; Pant, Debi D.Amino acid appended azobenzene hybrid has been synthesized (Fmoc-al-az) and its electronic absorbance and fluorescence spectra were recorded at room temperature in a series of polar and non-polar solvents. The ground state and excited state dipole moments were calculated using solvatochromic shift method. A DFT based study was also performed using- Gaussian09 program package. We have observed that the absorption spectra don't show sensitive behavior to the change in the polarity of the solvent, whereas a bathochromic shift was observed in the fluorescence spectra as we moved from non-polar to polar solvents indicating a π→π* transition. It was observed that the dipole moment in the excited state is much higher than the ground state, due to the amino acid containing hydrogen bond acceptor (Osingle bondCdouble bondO) and hydrogen bond donor (single bondNH) in Fmoc-al-az increasing the reorientation tendency of the solvent molecule around the dye therefore enhancing the stabilization of the excited state which is attributed to the high polarity of the excited states. DFT level electronic structure calculations are also performed for a better molecular level understanding of the experimental observations. We obtained a good correlation between the theoretical studies and experimental results.Item Extended coupled cluster through nth perturbation order for molecular response properties: A comparative study(Elsiever, 2013-05-16) Manohar, Prashant UdayIn this paper, we have presented and analyzed the extended coupled cluster (ECC) energy functional, truncated up to nth perturbation order in which expansion is limit to operators of the single and double excitations. The expression for the first order energy derivatives based on the above truncation schemes has been derived and numerically analyzed. We have done a comparative study for dipole moment in various perturbative ECC (n) methods (2 ⩽ n ⩽ 5) for three systems (HF, H2O and BH) at equilibrium geometry. We have particularly studied two variants of ECC (4) and ECC (5∗) method for stretched geometry. We have analyzed the contribution of important terms present in ECC functional based on perturbative argument. We have compared our results with standard coupled cluster (CCSD) as well as cubic truncated ECC and also benchmarked with the full CI results wherever available.Item Extended coupled cluster through nth perturbation order for molecular response properties: A comparative study(Elsiever, 2013-05-16) Manohar, Prashant UdayIn this paper, we have presented and analyzed the extended coupled cluster (ECC) energy functional, truncated up to nth perturbation order in which expansion is limit to operators of the single and double excitations. The expression for the first order energy derivatives based on the above truncation schemes has been derived and numerically analyzed. We have done a comparative study for dipole moment in various perturbative ECC (n) methods (2 ⩽ n ⩽ 5) for three systems (HF, H2O and BH) at equilibrium geometry. We have particularly studied two variants of ECC (4) and ECC (5∗) method for stretched geometry. We have analyzed the contribution of important terms present in ECC functional based on perturbative argument. We have compared our results with standard coupled cluster (CCSD) as well as cubic truncated ECC and also benchmarked with the full CI results wherever available.