One-pot protocol for J-aggregated anthraimidazolediones catalyzed by phosphotungstic acid in PEG-400 under aerobic condition

A precise and productive one pot green protocol has been developed for the chemoselective synthesis of anthra[1,2-d]imidazole-6,11-diones using phosphotungstic acid (PTA) as a reusable catalyst on polyethylene glycol-400 (PEG-400) support under aerobic condition. It involves a simple synthetic procedure for a wide range of anthraimidazolediones from 1,2-diaminoanthraquinone and various aldehydes possessing π-enriched aromatic/heteroaromatic rings and lipophilic alkyl chains. In inert atmosphere, the reaction followed a different pathway, yielding a unique naphtho-quinoxaline derivative. Synthesized anthraimidazoledione derivatives had shown different self-aggregation morphologies influenced by the substitution pattern. A nice agreement between crystal packing pattern and photophysical properties with J-aggregation morphology was also observed. Representative derivatives exhibited contrasting fluorescence behaviors in transition from solution state to nanostructured solid state.