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

Abstract9‐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.