Donor–acceptor phenothiazine functionalized BODIPYs

Abstract

A set of unsymmetrical and symmetrical phenothiazine functionalized BODIPYs of type D–A, D–π–A and A–D–A, A–π–D–π–A were synthesized by condensation and Pd-catalyzed Sonogashira cross-coupling reactions. Their photophysical and electrochemical properties were investigated. The electronic absorption spectra shows that the acetylene linked phenothiazine functionalized BODIPYs 7a and 7b exhibit bathochromic shift as compared to directly linked phenothiazine functionalized BODIPYs 4a and 4b. The density functional theory (DFT) calculation show that the incorporation of acetylene linkage between phenothiazine and BODIPYs induces coplanarity and results lower HOMO–LUMO gap which leads to red shifted absorption. The unsymmetrical phenothiazine functionalized BODIPYs exhibits higher thermal stability as compared to symmetrical analogous and follow the order 7a > 4a > 4b > 7b.