Existence of α‐mangostin conformers and effects of aprotic and protic solvents on their equilibria, UV–Vis spectra, and chemical descriptors: Density functional theory and time‐dependent density functional theory study

Abstract

AbstractThe physicochemical, thermodynamic, spectroscopic, and electronic properties of α‐mangostin dye (1,3,6‐trihydroxy‐7‐methoxy‐2,8‐bis(3‐methyl‐2‐buten‐1‐yl)‐9H‐xanthen‐9‐one) were investigated. Five conformers of the α‐mangostin dye were obtained using three different polarizable continuum model (PCM)/density functional theory (DFT) methods: wB97XD/6‐31+G(d,p), M06‐2X/6‐31+G(d,p), and B3LYP/6‐31+G(d,p). The species distribution of the five conformers in acetonitrile, water, and the gas phase was derived from the Gibbs free energy changes of their interconversion equilibria. Three dominant conformers (Conformers 2, 3, and 4) were found as coexisting species in solvents. Chemical descriptors of the three dominant conformers of the α‐mangostin in acetonitrile and water were obtained. Simulated UV–Vis spectra of the existing conformers and their mixtures in acetonitrile and water derived from the PCM/TD‐DFT calculations were in good agreement with experimental results. Because the three dominant conformers of α‐mangostin absorb light in the UV region, the application of α‐mangostin dye for UV protection is suggested. The performance of the three dominant α‐mangostin conformers in dye sensitized solar cells was also investigated.