A novel nonplanar fused pentacycle dual-state emission (DSE) fluorophore

Novel nonplanar fused pentacycles (ITPBs) without excited-state intramolecular proton transfer (ESIPT), which can be corrupted by the hydrogen-bond (H-bond) broken factors (e.g., solvents, temperature) in some practices, have been designed employing the RIR strategy and synthesized using the concept of frustrated Lewis pair (FLP) synergetic catalysis of Sc(OTf)3 and (PhSe)2 as a key step. Photophysical investigation showed that the penta-cycles (ITPBs) exhibited effective DSE PL efficiency. Being the best example, ITPB1 exhibited dual-state emission (DSE) PL efficiency in benzene, THF, and the solid state with high quantum yields of 77%, 68%, and 34%, respectively. Single crystal X-ray diffraction analysis indicated that the effective DSE PL efficiency would result from both the RIR of the ortho-chlorophenyl group and the aggregating mode in the solid state. Additionally, the large Stokes shift and their good thermal stability (Tm > 210 degrees C, T05 > 290 degrees C) make them practical for opto-electronic and biological applications.