Physicochemical and computational insight of 19F NMR and emission properties of meso-(o-aryl)-BODIPYs

Abstract

A series of electronic and physicochemical parameters were explored to determine their effect on experimental spectroscopic and photophysical data. Through a systematic obtention of a series of meso-(o-aryl)-BODIPYs, ¹⁹F NMR spectra were analyzed and their fluorescence quantum yields in several solvents were measured. Experimental values of ¹⁹F chemical shift difference Δδ_F correlate well with σ-Hammett constants, which is indicative of the inductive nature of the functional groups on the fluorine atoms. A computational DFT exploration of rotational energy barriers, electrostatic potential maps, group electronegativity, charge partitions and hardness/softness provided insight into how those traits can be directly related to the measured features. Expanded understanding of such characteristics provides design arguments and a structure–property relationship, which in a more advantageous way, would help to understand the properties of the synthesized molecules and of future attempts that are structurally related.