Experimental and DFT Studies on the FT-IR, NMR and UV/Vis Spectra of a Xanthene Derivative: The Case of 9-benzoyl-3,4,5,6,7,9-hexahydro-1h-xanthene-1,8(2h)-dione

Abstract

9-benzoyl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione was synthesized and studied uing FT-IR, NMR and UV/Vis spectra both experimentally and using density functional theory (DFT) methods. The absoulte average deviation (AAD) between experimental NMR chemical shifts and DFT results calculated at B3LYP/6-311+g(d,p) level was 3.9 % and 4.8 % for 1H and 13C-NMR, respectively. Scaled quantum mechanical (SQM) method was implemented to scale the calculated harmonic frequencies, and it was found that, the experimental and SQM frequencies are in acceptable agreement with AAD of ∼7 cm−1. UV/Vis spectra in water, ethanol, acetonitrile and n-hexane solvents measured experimentally and calculated using time-dependent CAM-B3LYP/6-311+g(d,p) method. Bathochromic shift of some electronic excitations are also discussed based on the linear solvation energy relationships. Molecular orbital, natural transition orbital and hole-electron analyses were used to further analyze the nature of the electron transitions. In Uv/Vis spectra, only S0→S19 excitation is a charge transfer transition, where the other excitations are local electron transitions.