Comparative Analysis of Molecular Structure, Vibrational Spectral Studies and Nlo Properties of 3-Hydroxy-4methoxy-Benzaldehyde and 4-Hydroxy-3-Methoxy-Benzaldehyde by DFT

Abstract

Benzaldehyde is best known as being artificial essential oil of almond and it has many other uses such as; the manufacturing of dyes, perfumes, flavourings, cinnamic and mandelic acids, and it is also used as a solvent. Some more recent developments in the use of benzaldehyde are for the health and agriculture industries. Due to these basic reasons there exist a vast field of study of substituted benzaldehydes. In the present study a comparative analysis is done between 3-hydroxy-4-methoxy-benzaldehyde and 4-hydroxy-3-methoxy-benzaldehyde. The spectral studies were performed for FTIR, IR (KBr and Nuzol) and Raman. Quantum mechanical calculations of geometries, energies, vibrational wave numbers and thermodynamic constants have been performed with Gaussian 09W program package using the Becke-3Lee-Yang-Parr (B3LYP) functional supplemented with the standard 6-31G (DP). The optimised geometrical parameters obtained by computational method used shows good agreement with the experimental data. The thermodynamic properties as heat capacity, entropy, enthalpy and Gibb’s free energy of the titled compounds at different temperatures were also calculated along with dipole moment, polarisability and hyperpolarisability.