Crystalline state photochromism of 3-furylfulgides: impact of size and bond flexibility of the non-aromatic alkylidene group.

3-Furylfulgides are photochromic compounds showing high thermal stability in their closed forms. However, their photochromic properties in the solid state should be improved further to fabricate molecular devices. Understanding how the size and the flexibility of the non-aromatic alkylidene moiety alter the crystalline state photochromic properties is also important here, as the alkylidene group is directly involved in the photochromic ring closing and opening reactions.