Conformational analysis and vibrational study of sulfanilamide

The possible stable conformers of sulfanilamide molecule were searched by potential energy surface scan at both semi-empirical PM3 and DFT/B3LYP-3-21G levels of theory. Both the harmonic and anharmonic vibrational modes, the corresponding wavenumbers and IR and Raman intensities of the conformers were calculated by DFT method at B3LYP/6-31++G(d,p) level. The assignments of the fundamentals were proposed on the basis of total energy distribution (TED) calculations. The IR and Raman spectra of solid sulfanilamide were recorded and compared with the calculated ones. The dimer of the title compound were studied at DFT/B3LYP/6-31++G(d,p) level to investigate the intermolecular hydrogen bonding interactions of sulfanilamide molecule.