Chemical Computations and Vibrational Spectral Studies of 2,3-Pyrazinedicarboxylic Acid

Density functional theory calculations at B3PW91 with 6-311G(d) level basis set were carried out for 2,3-Pyrazinedicarboxylic acid (PDCA) to study about the equilibrium geometries and vibrational spectra. Calculations reveal that the optimized geometry closely resembles the experimental XRD data. Vibrational spectra were analyzed on the basis of the potential energy distribution (PED) of each vibrational mode, which allowed us to obtain a quantitative as well as qualitative interpretation of IR and Raman spectra. Information about size, shape, charge density distribution and site of chemical reactivity of the molecules were obtained by mapping electron density isosurface with electrostatic potential surface (ESP). Based on optimized ground state geometries, NBO analysis has been performed to study donor-acceptor (bond-antibond) interactions.