[摘要]：Organic Pigments, Fluorescent Brighteners, and Photographic Two (one purple and one blue) 3-(2-phenyl-4H-thiochromen-4-ylidene)-3H-chromene-2,4-dione derivs. were synthesized and evaluated as reversible redox switches. The prepd. purple compd. and blue compd. instantly changed to colorless when treated with sodium borohydride in methanol. The corresponding reduced compds. can be reverted to their original colors via DDQ oxidn. or by air. While no fluorescence of the N,N-dimethylamino-substituted blue compd. was detected prior to redn., the reduced form emitted blue fluorescence in methanol with a quantum yield value of 0.19.
