Browsing by Author "Sidir, Isa"

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The Solvatochromism and Electronic Structure of (e)-2
(Tubitak Scientific & Technological Research Council Turkey, 2019) Gumus, Aysegul; Gulseven Sidir, Yadigar; Sidir, Isa; Gumus, Selcuk
The (E)-2-(2-hydroxystyryl)quinolin-8-ol (abbreviated as HSQ) molecule was synthesized and characterized. The ESIPT, solvatochromism properties, electronic structure, and ground and excited electric dipole moments of this molecule were measured using absorption and fluorescence spectra recorded in 13 different solvents. Its electronic structure via electronic transitions was investigated to find the quantitative values of solvatochromism properties by LSER calculations. The ESIPT mechanism was clarified; ground and excited dipole moments were determined using solvatochromic shift methods. The DFT (B3LYP)/6-311 ++ G(d,p) method and basis set with potential energy surface (PES) calculations of proton transfer were used to explain the ESIPT mechanism. NBO analysis, NLO properties, and behavior under an electric field were also determined.
Synthesis, Solvatochromism, Electronic Structure and Nonlinear Optic Properties of Quinolin-8 2-Hydroxybenzoate
(Soc Chemists Technologists Madeconia, 2018) Gumus, Aysegul; Sidir, Yadigar Gulseven; Sidir, Isa; Gumus, Selcuk
Quinolin-8-yl 2-hydroxybenzoate (QHB) was synthesized and its physical and electronic properties were investigated both experimentally and theoretically. The electronic structure and spectral behavior were determined by using UV-vis absorption and fluorescence spectra in 11 different polarity solvent media. The absorption band observed at 306-308 nm is attributed to pi-pi* and n-pi* electronic transitions due to its geometric structure in the solution phase. Solvatochromism of QHB was investigated by using Kamlet-Taft and Catalan methods based on the linear solvation energy relationships (LSER). The Kamlet-Taft solvatochromic model indicates that spectral shifts of absorption and fluorescence spectra are effectively controlled by dispersion-polarization forces which describe the non-specific interactions. The solvatochromic model of Catalan states that solute-solvent interaction is governed by solvent polarity in the absorption spectra and by solvent acidity in the fluorescence spectra. Non-specific interactions have a greater effect on fluorescence spectra compared to absorption spectra. Computational calculations were performed by the application of the B3LYP/6-311+(d,p) level of theory. Conformational analysis performed for QHB showed five staggered conformers on torsional potential energy surfaces. Accordingly, the most stable conformer was found to be the one involving infra-molecular hydrogen bonding. The geometry of the other conformers indicated that the absence of hydrogen bonding gave rise to relatively higher energy. Frontier molecular orbitals (HOMO, LUMO) and non-linear optical (NLO) parameters were calculated by B3LYP/6-311+(d,p) level of theory. Theoretical UV spectra both in gas and solution phases were also investigated by TDDFT-CAM-B3LYP/6-311+(d,p) level of theory.