A simple and efficient protocol for screening boron-dipyrromethene dyes using TD-DFT and an examination of the aryl-meso position

Abstract

BMK (Boese-Martin for Kinetics) and CAM-B3LYP (coulomb-attenuating method-Becke, 3-parameter, Lee-Yang-Parr) are evaluated as functionals in the calculation of the absorption wavelengths of boron dipyrromethene (BODIPY) fluorescent dyes using time-dependent density functional theory (TD-DFT). We discovered that a computational protocol using CAM-B3LYP/cc-pVTZ//B3LYP/6-31G∗ with a polarization-continuum model (PCM) was able to predict the absorption wavelengths of BODIPY compounds and matched experimental measurements fairly well when an empirical correction was applied with an average error of 7.1nm. Then, using our computational protocol, we synthesized a few novel BODIPY compounds in which we were able to explore the effect of substitution to an aryl-meso ring on BODIPY compounds and confirmed a small effect on the λmax for these compounds which was able to modify the absorbance up to 10nm. Based on these findings, modifications at the aryl-meso position are insufficient to cause large enough bathochromic shifts in the main spectral band to move the absorbance band of BODIPY molecules into the near-IR range.