A Class of Nonplanar Conjugated Compounds with Aggregation-Induced Emission: Structural and Optical Properties of 2,5-Diphenyl-1,4-distyrylbenzene Derivatives with All Cis Double Bonds
文摘
We have studied the structural and optical properties of four 2,5-diphenyl-1,4-distyrylbenzene derivativeswith all cis double bonds. These compounds belong to a class of nonplanar conjugated compounds possessinga typical Aggregation-Induced Emission (AIE) property that has no emission in solution but intense emissionin crystal. The four molecules are packed in different stacking modes with different intermolecular interactions,resulting in different crystalline state photoluminescence (PL) efficiency. The torsional molecular configurationincreases the intermolecular distances effectively in the crystalline state, which decreases the difference ofthe optical properties from the frozen isolated molecules to the crystalline state. The Stokes shifts of thesecompounds are very large and the PL spectra have only one broad emission band with poor structure, due tothe relatively large configuration difference between the ground state and the first singlet excited state, andthe abundant vibration energy levels of the torsional molecule with changeable conformation.