Studies of the electronic structure and biological activity of chosen 1,4-benzodiazepines by 35Cl NQR spectroscopy and DFT calculations

Selected derivatives of 1,4-benzodiazepine: lorazepam, lormetazepam, oxazepam and temazepam, used as active substances in anxiolytic drugs, have been studied by Cl-35 NQR method in order to find the correlation between electronic structure and biological activity. The Cl-35 NQR resonance frequencies (v(Q)) measured at 77 K have been, correlated with the following parameters characterising their biological activity: biological half-life period (t(0.5)), affinity to benzodiazepine receptor (IC50) and mean dose equivalent. The results of experimental study of some benzodiazepine derivatives by nuclear quadrupole resonance of Cl-35 nuclei are compared with theoretical results based on DFT calculations which were carried out by means of Gaussian '98 W software. (c) 2006 Elsevier B.V. All rights reserved.