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A Quantum Chemical Study of Germanium-Substituent Bonding in Complex Compounds of Germanium
摘要： Spatial and electronic structures of six-coordinated germanium compounds are calculated within МР2 and AIM methods using PC GAMESS-Firefly, MORPHY, and AIMALL software packages. Main topological characteristics of germanium-substituent bonds are determined in these molecules.
关键词： AIM method,quantum chemistry
更新于2025-09-23 15:22:29
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Spectroscopic Aspects, Structural Elucidation, Vibrational and Electronic Investigations of 2-Methoxy-1,3-Dioxolane: An Interpretation Based on DFT and QTAIM Approach
摘要： Extensive vibrational spectroscopic investigations along with theoretical quantum chemical studies on 2-methoxy-1,3-dioxolane (MDOL) have been consummated. The experimentally observed spectral data (FT-IR and FT-Raman) of the title compound were compared with the spectral data obtained by DFT/B3LYP method. The 1H and 13C nuclear magnetic resonance (NMR) spectra were simulated by using the gauge independent atomic orbital (GIAO) method and the absolute chemical shifts related to TMS were compared with experimental spectra. The theoretical UV-Visible spectrum of the title compound was measured in different solvent and the electronic properties, such as excitation energies, oscillator strength and wavelengths were performed by time-dependent density functional theory (TD-DFT) approach. The kinetic stability of the molecule has been determined from the frontier molecular orbital (FMO) energy gap. Total density of state (TDOS) and partial density of state (PDOS) of the MDOL in terms of Mulliken population analysis were calculated and analyzed. Reduced density gradient (RDG) of the MDOL was given to investigate interactions of the molecule. Topological parameters at bond critical point have been analyzed in MDOL by Bader’s ‘Atoms in molecules’ (AIM) theory in detail. In addition, the temperature dependence thermodynamic properties and magnetic susceptibility of MDOL were calculated with the help of DFT/B3LYP method using 6-311++G(d,p) basis set.
关键词： DOS,FMO,2-methoxy-1,3-dioxolane,AIM,RDG
更新于2025-09-23 15:21:21
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Synthesis, characterization, optical properties, computational characterizations, QTAIM analysis and cyclic voltammetry of new organic dyes for dye-sensitized solar cells
摘要： In recent years, dye-sensitized solar cells (DSSCs) have regarded as potential solar cells for the next generation of photovoltaic technologies. Many organic compounds are explored and used in DSSCs to produce low-cost devices and improve the cell efficiency. In this work, three new heterocyclic purple dyes are synthesized from the reaction of 3-nitropyrazolo[1,5-a]pyridine with various arylacetonitriles for dye-sensitized solar cells (DSSCs), exhibiting high molar extinction coefficients and a broad absorption range led to the good photovoltaic performance of 6.95e7.18%. Physical spectral, analytical data and optical properties are established the structures of the new dyes. The optimized geometries and relevant frontier orbitals of the dyes are obtained by density functional theory (DFT) at the level of B3LYP/6-311 + G(d,p). Electrostatic potential maps and electron density maps of the dyes were also obtained by atoms in molecules (AIM) analysis. Cyclic voltammetry measurement was performed to evaluate the electrochemical properties of the dyes and reversible oxidation waves were observed for them.
关键词： Dye-sensitized solar cells,DFT,3-Nitropyrazolo[1,5-a]pyridine,AIM,Cyclic voltammetry,Purple dyes
更新于2025-09-12 10:27:22
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Spectroscopic and electronic structure characterization of hydrogen bonding in 2-Bromohydroquinone
摘要： 2-Bromohydroquinone species form both intra- and inter-molecular H-bonds. The evidences for the H-bonds have been observed in the solid-phase Mid IR (4000?400 cm-1) and Near IR (8000?5000 cm-1) absorption spectra with two intensely broad bands near 3263 and 3222 cm-1 and a broad absorption in 7000?5200 cm-1 with a band maximum at 6335 cm-1. Dimer and trimer models with DFT’s B3LYP and BP86 functionals using 6-31G(d) and 6-311++G(d,p) basis sets have been proposed for the ?O?H···O bonding in 2-Bromohydroquinone. Out of the four predicted conformers, one trans and one cis conformers with nearly 1:1 Boltzmann populations, are separated by very small energy difference of 0.03 kcal/mol and this is confirmed by two chemical shifts at 9.0 and 9.3 ppm from an 1H NMR spectrum. On the basis of Quantum Theory of Atoms in Molecules (AIM) and reduced density gradient plots of electron densities and its isosurfaces by non-covalent interactions (NCI) method, the influence of the ?O?H···Br, weak van der Waals and ?O?H···O bond interactions on the stability of dimer and trimer structures have been analysed. From the natural bond orbital (NBO) analysis, it is explained that the formation of H-bonding may be attributed to charge transfer from the lone pair orbital n(O) of the base Oxygen into the vacant antibonding orbital σ*(OH) of the acid OH in the ?O?H···O bonding. The Near IR concentration-dependent spectra demonstrate that the sample of 2-Bromohydroquinone is composed of ?O?H···O bonded species and dissociate into non-bonded species as the mole fraction of the solvent (acetonitrile/1,4-dioxane) is increased. The band observed at 7095 cm-1 at 0.09 M is identified as the first overtone of the ?O?H stretching mode of the weak complex of 2-Bromohydroquinone and acetonitrile. The solvent effects on all the observed solution-phase NIR spectra are not ruled out.
关键词： H-bonding,AIM,NCI,IR spectra,2-Bromohydroquinone,DFT calculations
更新于2025-09-04 15:30:14