Tuning the solid-state emission of the analogous GFP chromophore by varying alkyl chains in the imidazolinone ring

New analogues of green fluorescent protein (GFP) chromophore m GFP-C n (n = 1, 3, 5, 11) with alkyl chains of different lengths in the imidazolinone rings were synthesized and their crystal structures were determined. These GFP-like chromophores are all emissive in the solid state. And the solid-state emission quantum yields of increase by extending the lengths of alkyl chains, owing to the fact that the intermolecular pi-pi interactions are significantly weakened based on their crystal structures.