A Nonarchetypal 5,6-Dihydro-2H-pyrano[3,2-g]indolizine-Based Solution-Solid Dual Emissive AIEgen with Multicolor Tunability.

Screening of a chemical library of pyranones and their ring transformed fluorophores led to the discovery of a novel 5,6-dihydro-2H-pyrano[3,2-g]indolizine (DPI) class of the luminogen DPI 7, which exhibited unique solution-solid dual emission (SSDE) behavior with an emission color shift from bright-green in solution to a strong red emission in the solid state. The AIE mechanism of these luminogens revealed a well-defined set of noncovalent interactions (CH⋅⋅⋅O and CH⋅⋅⋅N) that block the motion of C2 -flexure leading to restriction of intramolecular vibrations (RIV) in the solid state. DPI-7 is the first example of solution-solid dual emissive RIV-based AIEgen, which has great potential both in biomedical imaging and optoelectronic fields.