Aggregation induced emission enhancement and chromism properties of a vinyl bridged naphthalene diimide dimer

A vinyl bridged 1,4,5,8-Naphthalenetetracarboxylic diimide (NDI) dimer, DNV was synthesized, which exhibits relatively strong Aggregation Induced Emission Enhancement (AIEE) behaviour with absolute quantum yield of 13.6%, as well as wide Aggregation Induced Chromism (AIC) phenomenon (over 100 nm), from green to orange emission. The density functional theory (DFT) and coupled cluster calculations reveal a unique twisted packing mode of DNV in its aggregated state, and mild intermolecular CT between the stacked DNV molecules was also observed. This J-aggregation like molecular arrangement and the net CT might contribute to the long wavelength emission. The bio-imaging capability of DNV is also examined by a living cell experiment.