The Quantum Mechanical Computations of the Conformational, Structural, Electronic and Spectroscopic Properties of 3-Cyanophenylboronic Acide

Abstract

Abstract In the present study, Conformational analysis of 3-cyanophenylboronic acid (3-CyBA) molecule have been carried by calculating potential energy surface (PES) as a function of two dihedral angles, C1-B-O1-H and C1-B-O2-H, using DFT/B3LYP/6-31G (d) level of theory. As a result of PES, molecular conformers corresponding to low energy of title molecule, anti-syn, syn-anti, syn-syn, anti-anti, respectively, have been determined according to the orientations of the hydroxyl groups attached to the boron atom. The geometries of anti-syn, syn-anti, syn-syn, anti-anti, conformers of studied molecule were fully optimized at the Hartree-Fock (HF) and DFT/B3LYP levels of the theory with 6-311++G(d,p) basis set, and compared with its crystal structure in the literature. The vibrational frequencies, infrared (FT-IR) intensities Raman (FT-Raman) scattering activities of all the conformers of the title molecule were calculated both methods, and vibrational assignments were performed by means of potential energy distribution (PED). Also, frontier molecular orbitals, the linear and nonlinear optics parameters, such as the polarizability (α) ground state dipole moment (µ) and the first-order hyperpolarizability (β) of 3-CyBA molecule, were calculated the same methods. The anti-syn conformer is found to be more stable than the syn-anti, syn-syn and anti-anti-conformers by 0.227, 1.078 and 4.577 kcal/mol in HF/6-311++G(d,p) and 0.248, 1.465 and 3.855 kcal/mol in DFT/B3LYP/6-311++G(d,p) level of theory, respectively. UV-visible absorption spectra such as excitation energies, absorption wavelengths (λ) and oscillator power (f) and stimulation contributions of all examined conformers were examined using TD-DFT/B3LYP and TD-HF methods, and transitions were determined.