Photochromism of triangle terthiophene derivatives as molecular re-routerElectronic supplementary information (ESI) available: analytical data for 1a, 2a and 3a. See http://www.rsc.org/suppdata/cc/b3/b311334e/

2,2[prime or minute]-3,3[double prime]-Terthiophene derivatives undergo photochemically reversible cyclization and cycloreversion reactions. The absorption peak wavelength changed systematically with substitution of the phenyl rings at 5-, 5[prime or minute]- and 5[double prime]-positions of the thiophene rings, which indicates re-routing of the [small pi]-conjugation system.