3-/3,5-Pyrrole-substituted BODIPY derivatives and their photophysical and electrochemical studies

Abstract

Nucleophilic substitution on 3-bromo/3,5-dibromo-4,4′-difluoro-8-(aryl)-4-bora-3a,4a-diaza-s-indacene (BODIPY), substituted with anisyl or thienyl at meso positions, with neat pyrrole afforded the mono and di-pyrrole substituted BODIPYs 1–4 in good yields. Large bathochromic shifts, upto ∼180 nm in absorption maxima (581–682 nm), and fluorescence maxima (606–695 nm) were observed for these BODIPYs. Absorption and fluorescence properties were studied in different solvents to compare the effect of mono and di substitution on BODIPY. The Lippert-Mataga equations were used which predict strong polarization of mono substituted BODIPYs. Electrochemical studies were carried out to find the oxidation potential and HOMO energy levels were calculated. Theoretical studies of 1–4 provide the insight on the electron density distribution in 1–4. Theoretical and experimental photo-physical studies in different solvents were correlated to find the substituent effects on BODIPY. [Figure not available: see fulltext.]