Development of non-symmetric thiophene-fused BODIPYs

A series of non-symmetric BODIPYs containing thieno[3,2-b]pyrrole moiety were synthesized in 21–63% yields. The absorption and emission maxima covered from the visible green to red region (λabs=532–647 nm; λem=547–664 nm; Φf=0.19–0.45). X-ray analysis indicated that the S–C bond lengths were shorter than those of thienopyrrole and thienohelicene by 0.03–0.05 Å. The crystal packing pattern suggested that strong π–π interaction, intermolecular C–H⋯F interaction, and weak S⋯π interaction existed. The tunable emission was achieved by structure modifications. Oxidation of BODIPY (λem=547 nm) with m-CPBA generated thiophene-1,1-dioxide derived BODIPY (λem=528 nm). Knoevenagel-type condensation of BODIPY with N,N-dimethylaminobenzaldehyde led to BODIPY (λem=693 nm) with extended conjugation.