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.

Financial support from MEC-FEDER (CTQ2005- 01368 and MAT2005-06373-02) and Gobierno de Aragón-Fondo Social Europeo (E39) is gratefully acknowledged. A predoctoral grant (FPU) to M.A.C. is also acknowledged.

4 pages, 3 schemes, 2 tables.-- Available online 12 July 2007.

Peer reviewed