Structural Modification of Silicon‐Bridged Ladder Stilbene Oligomers and Distyrylbenzenes

Two kinds of the totally alkyl‐substituted ladder π ‐conjugated compounds, the totally hexyl‐substituted silicon‐bridged stilbene trimer 1 and the totally propyl‐substituted silicon‐ and carbon‐bridged distyrylbenzene 2 , were synthesized. X‐ray crystallography revealed that both compounds adopt the all‐parallel‐aligned packing structures through the interpenetration of the alkyl chains with those of the neighboring molecules. The effect of this packing structure on the photophysical properties was investigated. The fluorescence quantum yield measurements showed that both compounds maintained their high quantum yields (Φ F ) even in the crystalline state (Φ F = 0.64 for 1 ; 0.63 for 2 ), suggesting the potential effect of the all‐parallel alignment for attaining the intense emission in the solid state. magnified image