The steric effect of peripheral functional groups on the [4+ 4]-photocycloaddition between substituted anthracene derivatives was examined. The reactivity of 2, 3, 6, 7- tetraphenylanthracene (TPA) with 2-phenylanthracene (PA), 2, 9, 10-trimethylanthracene (TMA) and 9, 10-dimethyl-2, 3-diphenylanthracene (DMDPA) was investigated. In all cases, the photodimers were formed in high yield despite the steric bulk of the peripheral ...