Polarity and Structure of BODIPYs: A Semiempirical and Chemoinformation Analysis

A simple phenomenological substantiation was presented for a method to determine the polarity of BODIPYs using the spectral characteristics of the absorption and emission of the fluorophores in various solvents. This method is a new tool to experimentally estimate the effect of a solvent on the sensitivity of fluorophores to the polarity of the medium. A fragment approach was used to make a chemoinformation analysis of a library of BODIPY compounds, which has been collected from the literature data and encompasses a wide range of solvatochromic effects from negative to positive. The most significant fragments of molecules, which are responsible for the sensitivity of the compounds to the polarity of the medium, were determined. It was found that the positive and negative solvatochromic effects are enhanced with increasing molecular polarizability of the compounds, which agrees with the parameters of the determined fragments of BODIPYs as chains of conjugated unsaturated bonds. By and large, the semiempirical method to determine the polarity of fluorophores and the results of the chemoinformation analysis gave an extended insight into the effect of solvents on the spectral behavior of fluorescent dyes and on the design of new compounds.