Density functional study on spectroscopic properties of meso-phenyl and 3,5-diaryl substituted BODIPY dyes

School of Science, Honghe University, Mengzi, Yunnan 661199, P. R. China

Key Laboratory of Natural Pharmaceutical and Chemical Biology of Yunnan Province, Yunnan 661199,

P. R. China

E-mail : hhxylxyhxx@126.com, liuwei4728@126.com Fax : 86-873-3694919

College of Pharmaceutical Science and Chemistry, Dali University, Dali, Yunnan 671000, P. R. China

Manuscript received online 27 May 2014, accepted 15 October 2016

The molecular structures, infrared and electronic absorption spectra of four meso-phenyl and 3,5-diaryl substituted BODIPY dyes, A to D, were investigated theoretically using the gradient-corrected density functional theory B3LYP method. The dependence of spectra with the molecular and electronic structures was investigated on the basis of time-dependent density functional theory (TD-DFT) computations with the B3LYP hybrid functional under 6-31+G*, 6-31G and 6-31G* in different solvents. The vibrational and transition modes of spectra were explored in terms of their microscopic origin. According to structure analysis, the intersection angles of BODIPY core with meso-phenyl were estimated 59–61º and the angles of BODIPY ring with 3,5-diaryl groups were evaluated 38–62º. The UV-Vis spectra were in good accordance with the experimental values. The maximum wavelengths of BODIPYs arose from S₀→S₁ transition which stemmed from HOMO to LUMO (^πBODIPY core^→πBODIPY core*). However, the maximum absorptions of four BODIPYs increased inconspicuously with magnified the 3,5-diaryl substitution that caused by nonradioactive loss of energy via rotation around the C-Ar bonds to preventing free rotation. The solvation energies of four BODIPYs are –26.26, –30.39, –34.1, –27.58 kJ/mol, respectively.