Theoretical Calculation of UV-Vis, IR Spectra and Reactivity Properties of Tamoxifen Drug: A Methodology Comparison

Abstract

Some theoretical properties were analyzed and compared with the experimental data for Tamoxifen molecule, a drug commonly used as complementary therapy for breast cancer. The molecular structure and some chemical reactivity parameters were calculated through Density Functional Theory using different functionals, including B3LYP, PBE0, PBEPBE, TPSS, TPSSh and the M05 and M06 density functionals of Minnesota family, all of them combined with a 6-31G (d) basis set. The theoretical IR and ultraviolet-visible (V-Vis) spectra were compared with experimental data. Reactivity parameters are of great importance in the pharmacological testing. For this reason, a correlation between the different chemical models was carried out using the electron affinity and ionization potential calculations. According to the outcomes, the methodology that had a better correlation with the experimental data is M06/6-31G (d).Keywords: DFT, tamoxifen the theoretical spectroscopic analysis of Riluzole, using FT-IR, FT--Raman and UV-Vis techniques were obtained with three functionals (B3LYP, MPWLYP and M06-2X) and 6-311++G(d,p) basis set having agreement between experimental and the calculated. 25 According of the study reported by Soto-Rojo et al. 26 the M06 functional presents the best alternative to obtain the UV-Vis spectra with good accuracy. 26 The theoretical determination of chemical model for TAM can be very useful in the design and development of new and better drugs, allowing so that other researchers have the facility to use the chemical model in other derivatives of the drug tamoxifen without validate the chemical model. Computational detailsAll calculations were performed using the Gaussian 09 software. 27The Density Functional Theory (DFT) was used, [28][29][30] which has been proven to be a key method for drug design and specifically in the field of transition metals with medicinal applications, and has been successful in terms of accuracy and reliability. 31 The used functio- 21 for the geometrical optimizations, followed by a frequency calculation to confirm that the structure is at the minimum energy state. The theoretical Infrared spectra (IR) were also plotted with the results obtained by the different chemical model frequency calculations and compared with the experimental IR spectrum.Ultraviolet-visible spectra (UV-Vis) were calculated by solving the time-dependent density functional theory (TD-DFT) equations [42][43][44] approach and analyzed through the SWizard program;45 theoretical UV-Vis spectra were obtained with different chemical model in the presence of methanol as solvent, using the conductor-like polarizable continuum model (CPCM) 46 which defines the cavities as envelopes of spheres centered on atoms or atomic groups. Inside the cavity the dielectric constant is the same as in vacuum, outside it takes the value of the desired solvent; 47 the equations were solved for 20 exited states.The conceptual aspect of the density functional method has been amply used to understand the chemical reactivity, t...

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First-principles density functional theoretical study on the structures, reactivity and spectroscopic properties of (NH) and (OH) Tautomer's of 4-(methylsulfanyl)-3[(1Z)-1-(2-phenylhydrazinylidene) ethyl] quinoline-2(1H)-one

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