Electronic structure, charge distribution and vibrational characteristics of glycine/NMDA receptor antagonists

Abstract

Electronic structure, charge distribution and vibrational characteristics in a series of 4-hydroxyquino-2-lone (HQ) derivatives have been derived employing the ab initio Hartree–Fock calculations. Hydrogen bonded interactions in these molecules are analyzed. The strength of intra-molecular O–H ⋯ O interactions is predicted to be: amide > keto > thioamide > ester > acid; which can be explained using the molecular electrostatic potential and electron density topography. Electrostatic potential investigations have shown that the electron-rich regions localized near quinolinic oxygen (O 12) exhibit (3, +3) minima and thus show affinity towards binding of ligand to N-methyl- d-aspartate receptors. Further, the bond critical points for the C O bond in the electron density topography yields a measure of the corresponding bond strength. Both the minimum near O 12 in the electrostatic potentials and the bond critical point in the electron density topography are correlated to the frequency of C O stretching in these derivatives.