Theoretical studies of different tautomers of anti cancer drug: dichloroacetate.

The structure and relative energies of the tautomers of dichloroacetate are predicted using Hartree Fock method. The infrared spectra of two dominant tautomers are calculated in the density functional theory. Good agreement between calculated (DFT) and experimental harmonic vibrational frequencies is found. Assuming Cs point symmetry, vibrational assignments for the observed frequencies have been proposed. The spectra exhibit distinct features originating from low frequency vibrational modes caused by inter-molecular motion. Energy is minimum for DCA-2 tautomer. Dipole moment is large for DCA-1 tautomer and polar surface area is somewhat larger in caso of DCA-2. Local ionization potential map and lowest-unoccupied molecular orbital (LUMO) map has been drawn and analyzed. Linear regression data for both the tautomers has also been calculated, so clearly DCA1 is more correlated to experimental wavenumbers.