A combined experimental and theoretical investigation of 2-Thienylboronic acid: Conformational search, molecular structure, NBO, NLO and FT-IR, FT-Raman, NMR and UV spectral analysis

Molecular structure and vibrational assignment of 1-[N-(2-pyridyl) aminomethylidene}-2(1H)-Naphtalenone by density functional theory (DFT) and ab initio Hartree-Fock (HF) calculations

The molecular geometry and vibrational frequencies of 1-[N-(2-pyridyl)aminomethylidene}-2(1H)-Naphtalenone in the ground state have been calculated by using the Hartree-Fock (HF) and density functional method (B3LYP) with 6-311++G(d,p) basis set. The results of the optimized molecular structure are presented and compared with the experimental X-ray diffraction. The computed vibrational frequencies were used to determine the types of molecular motions associated with each of the experimental bands observed. In addition, calculated results are related to the linear correlation plot of computed data versus experimental geometric parameters and IR data. From the results it was concluded that the B3LYP method is superior to the HF method for the vibrational frequencies. Using the time-dependent density functional theory (TD-DFT) and Hartree-Fock (TD-HF) methods, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFT method and experimental ones is determined.

FT-IR, FT-Raman, NMR and UV-Vis spectra and DFT calculations of 5-bromo-2-ethoxyphenylboronic acid (monomer and dimer structures)

In this study, the Fourier Transform Infrared (FT-IR) and Fourier Transform Raman (FT-Raman) spectra of 5-bromo-2-ethoxyphenylboronic acid (5Br2EPBA) are recorded in the solid phase in the region 4000-400 cm(-1) and 3500-10 cm(-1), respectively. The (1)H, (13)C and DEPT nuclear magnetic resonance (NMR) spectra are recorded in DMSO solution. The UV-Vis absorption spectrum of 5Br2EPBA is saved in the range of 200-400 nm in ethanol and water. The following theoretical calculations for monomeric and dimeric structures are supported by experimental results. The molecular geometry and vibrational frequencies in the ground state are calculated by using DFT methods with 6-31G(d,p) and 6-311G(d,p) basis sets. There are four conformers for the present molecule. The computational results diagnose the most stable conformer of 5Br2EPBA as Trans-Cis (TC) form. The complete assignments are performed on the basis of the total energy distribution (TED) of vibrational modes, calculated with scaled quantum mechanics (SQM) method in parallel quantum solutions (PQS) program. The (1)H and (13)C NMR chemical shifts of 5Br2EPBA molecule are calculated by using the Gauge Invariant Atomic Orbital (GIAO) method in DMSO and gas phase for monomer and dimer structures of the most stable conformer. Moreover, electronic properties, such as the HOMO and LUMO energies (by TD-DFT and CIS methods) and molecular electrostatic potential surface (MEPs) are investigated. Stability of the molecule arising from hyper-conjugative interactions, charge delocalization is analyzed using natural bond orbital (NBO) analysis. Nonlinear optical (NLO) properties and thermodynamic features are presented. All calculated results are compared with the experimental data of the title molecule. The correlation of theoretical and experimental results provides a detailed description of the structural and physicochemical properties of the title molecule.