Synthesis, characterization and optical properties of merocyanines derived from malononitrile dimer

The reaction between malononitrile dimer and 1,3-dithiole-derived polyenals affords push-pull systems with (Z)-geometry around the newly formed CC bond. In one instance, an unexpected shortening of the merocyanine chain takes place. These push-pull derivatives have weakly alternated structures and moderate optical nonlinearities, which can be modified by functionalization of the amino group.