Structural and spectroscopic properties of voriconazole and fluconazole – Experimental and theoretical studies

Abstract

Abstract The article compares the experimental Fourier transform-infrared, Ultraviolet-visible (UV-vis), and proton nuclear magnetic resonance (1H NMR) spectra of voriconazole and fluconazole with the density functional theory (DFT) calculations using five different functionals. The results were compared with previously reported data related to its analogue – posaconazole. The analysis of calculated infrared (IR) spectra with the use of PBE1PBE (voriconazole) or APF (fluconazole) functionals shows good accordance with the experimental IR spectrum. The best compatibility between the experimental and theoretical UV spectra was observed with the use of PBE1PBE or B3LYP functionals for voriconazole or fluconazole, respectively. The reason for the difference in the UV-vis spectra of voriconazole and fluconazole was discussed based on linear response time-dependent DFT and natural bond orbital methods. The calculated 1H NMR spectrum shows that the DFT formalism, particularly the M06L or B3LYP functionals, gives an accurate description of the voriconazole and fluconazole chemical shifts.