Abstract
The data on X-ray diffraction analysis for dihetarylethenes with perfluorocyclopentene (F), maleic
anhydride (M) and cyclobutenedione (S) bridges between thienyl fragments were summarized and their photochromic
properties were discussed. It was established that benzoxazole and benzothiazole substituents
in position 5 of thienyl rings are coplanar to the plane of thiophene cycles. Thienyl fragments in A form of
all dithienylethenes are considerably turned relative to the plane of bridging cycle. It means that there is no
conjugation between