BODIPY derivatives with diverse meso-aryl groups – the influence of chemical structure alterations on their electrochemical and optical properties

Electrochemical and optical studies in an organic environment were performed on eight boron-dipyrromethene derivatives with various aromatic meso substituents. The influence of an extended π-electron system and the introduction of alkyl substituents into the pyrrolyl moieties were assessed, revealing significant changes in redox processes. Two redox pairs were observed in compounds with single aromatic meso residues, whereas four or five were found in the case of extended π-electron systems of derivatives 2 and 4–6. Applying a negative potential resulted in the formation of anionic species only in one studied BODIPY 8 with methoxy‑phenyl groups, as observed by UV–Vis. The optical properties of the BODIPY derivatives were also investigated, revealing that structural modifications induced the redshift of S0→S1 transition bands. Experimental UV–Vis spectra and electrochemical band gaps were compared with the theoretical results derived from time-dependent density functional theory (TD-DFT) calculations using IEFPCM and SMD models. The computed data were in good agreement with the experimental ones, indicating the highest band gap values in compounds 1–3, along with the lowest for derivative 4 with pyrene moiety. Moreover, the computational studies identified B3LYP and PW6B95D3 as the most accurate functionals for predicting band gaps. These findings provide valuable insights into the structure-property relationships of BODIPY derivatives, offering a predictive framework for tuning their electronic and optical properties through targeted structural modifications. By elucidating how meso‑substituents influence the electrochemical and optical properties of BODIPY derivatives, this study advances the rational design of functional materials for optoelectronic and sensing applications.