A theoretical study on 2-chloro-5-(2-hydroxyethyl)-4-methoxy-6-methylpyrimidine by DFT/ab initio calculations

Quantum chemical calculations have been performed to study the molecular geometry, H-1 and C-13 NMR chemical shifts, conformational, natural bond orbital (NBO) and nonlinear optical (NLO) properties of the 2-chloro-5-(2-hydroxyethyl)-4methoxy-6-methylpyrimidine molecule in the ground state using DFT and HF methods with 6-311++G(d,p) basis set. The optimized geometric parameters and H-1 and C-13 NMR chemical shifts have been compared with the experimental values of the title molecule. The results of the calculations show excellent agreement between the experimental and calculated frequencies at B3LYP/6-311++G(d,p) level. In order to provide a full understanding of the properties of the title molecule in the context of molecular orbital picture, the highest occupied molecular energy level (E-HOMO), the lowest unoccupied molecular energy level (E-LUMO), the energy difference (Delta E) between EHOMO and ELUMO, electronegativity (chi), hardness (eta) and softness (S) have been calculated using B3LYP/6-311++G(d, p) and HF/6-311++G(d,p) levels. The calculated HOMO and LUMO energies show that the charge transfer occurs within the title molecule

Effects of donor-acceptor groups on the structural and electronic properties of 4-(methoxymethyl)-6-methyl-5-nitro-2-oxo-1, 2-dihydropyridine-3-carbonitrile

Quantum chemical calculations on the geometric parameters, harmonic vibrational wavenumbers and H-1 and C-13 nuclear magnetic resonance (NMR) chemical shifts values of 4-(methoxymethyl)-6-methyl-5-nitro-2-oxo-1,2-dihydropyridine-3-carbonitrile [C9H9N3O4] molecule in ground state were performed using the ab initio HF and density functional theory (DFT/B3LYP) methods with 6-311++G(d,p) basis set. The results of optimized molecular structure were presented and compared with X-ray diffraction results. The theoretical vibrational frequencies and H-1 and C-13 NMR chemical shifts values were compared with experimental values of the investigated molecule. The observed and calculated values were found to be in good agreement. Since the title compound contains different electron-donor and -acceptor groups as well as lone pair electrons, and multiple bonds, the effects of these groups on the structural and electronic properties are found out. In addition, conformational, natural bond orbital (NBO), nonlinear optical (NLO) analysis, frontier molecular orbital energies, molecular surfaces, Mulliken charges and atomic polar tensor based charges were investigated using HF and DFT methods. (C) 2014 Elsevier B.V. All rights reserved

A Theoretical Study on Structural, Spectroscopic, Electronic and Nonlinear Optical Properties of 1-[(E)-{[4-(Morpholin-4-Yl)Phenyl]Imino}Methyl]Naphthalen-2-Ol

Density functional theory calculations on ground state molecular geometry, stable conformers, and vibrational wavenumbers for 1-[(E)-{[4-(morpholin-4-yl)phenyl]imino}methyl]naphthalen-2-ol (MPIMN) molecule were performed by using B3LYP and B3PW91 functionals for the exchange-correlation energy with the 6-311++G(d,p) basis set. The detailed assignments of vibrational wavenumbers were carried out on the basis of potential energy distribution (PED) analysis. Nonlinear optical (NLO) behavior of MPIMN was investigated by the determining of electric dipole moment (mu), polarizability (alpha), and first hyperpolarizability (beta) by using B3LYP and B3PW91 functionals. Stability of the molecule arising from hyperconjugative interactions and charge delocalization was analyzed using natural bond orbital (NBO) analysis. The frontier molecular orbitals (HOMO and LUMO) were simulated, and the obtained relatively small energy gap confirmed that charge transfer occurs within MPIMN. Finally, molecular electrostatic potential (MEP) surface was simulated to demonstrate reactive sites for the title molecule

Theoretical Investigations on Nonlinear Optical and Spectroscopic Properties of 6-(3,3,4,4,4-Pentafluoro-2-hydroxy-1-butenyl)-2,4-pyrimidinedione: An Efficient NLO Material

In this study, quantum chemical calculations of geometric parameters, conformational, natural bond orbital (NBO) and nonlinear optical (NLO) properties, vibrational frequencies, H-1 and C-13 NMR chemical shifts of the title molecule [C9H7F5N2O3] in the ground state have been calculated with the help of Density Functional Theory (DFT-B3LYP/6-311++G(d, p)) and Hartree-Fock (HF/6-311++G(d, p)) methods. The optimized geometric parameters, vibrational frequencies, H-1 and C-13 NMR chemical shifts values are compared with experimental values of the investigated molecules. Comparison between experimental and theoretical results showed that B3LYP/6-311++G(d, p) method is able to provide more satisfactory results. In order to understand this phenomenon in the context of molecular orbital picture, we examined the molecular frontier orbital energies (HOMO, HOMO-1, LUMO, and LUMO + 1), the energy difference (Delta E) between E-HOMO and E-LUMO, electronegativity (chi), hardness (eta), softness (S) calculated by HF/6-311++G(d, p) and B3LYP/6-311++G(d, p) levels. The molecular surfaces, Mulliken, NBO, and Atomic polar tensor (APT) charges of the investigated molecule have also been calculated by using the same methods