ANALYSIS OF THE STRUCTURAL AND VIBRATIONAL SPECTRAL DATA OF ANTICANCER DRUG FLUTAMIDE ON THE BASIS OF THE DFT AND HARTREE-FOCK CALCULATIONS

Abstract

Flutamide molecule, which is defined as “Androgen hormone blocking” and used in treatment of prostate cancer today, has a variety of pharmacological effects and finds a wide range of usage in medicine. In the first stage of the study, the stable conformers of flutamide, were searched through a “Potential energy surface scanning” accompanied with geometry optimization calculations at B3LYP/6-31G(d) level of theory. Afterwards, geometry optimization + Hessian calculations were carried out for each of the determined conformers at higher levels of theory. The relative energies of the found five stable conformers were determined by these systematic calculations based on HF-SCF and DFTB3LYP methods and Pople-Style and Dunning-Huzinaga style Gaussian basis sets. The relative energies calculated with HF-SCF and DFT-B3LYP methods for these conformers are in the ranges of 0 - 2 kcal/mol and 0 - 1.9 kcal/mol, respectively. The energy values have also shown that the main contribution to the IR and Raman spectra of flutamide at room temperature arises from two of these stable conformers, which are labeled here as conf.1 and conf.2. In the study, the calculated Hessian matrices were transformed into the corresponding force field matrices within the Scaled Quantum Mechanical Force Field (SQM-FF) method and then they were scaled so that the refined theoretical vibrational spectra match the corresponding observed IR and Raman spectra.