Photochromism of double-bridged viologens in a polar polymer matrix
Abstract
Double-bridged viologens (1 and 2) have been synthesized; in polar polymer films they displayed two distinct colour development and bleaching processes upon UV irradiation. Their photofatigue resistances were apparently better than bisviologens and benzylviologen due to particular intramolecular interactions between their two viologen moieties in the two photochromic stages.