“…Irradiation of cinnamates 8a , 8b , and 8d -8i in the presence of CB [8] in water affords mostly the cis HH photodimers, and, also paralleling the cavity size effects of CDs, smaller CB [7] exclusively leads to the isomerization of the exocyclic double bond. 21 When protonated, azastilbenes are particularly prone to form inclusion compounds with CB [8]. Interestingly, irradiation of aqueous solutions of the inclusion complexes selectively leads to the formation of the syn photodimers in the case of symmetrical 1,2 -dipyridiniumethylenes, whereas unsymmetrical analogs show preference for the anti photodimers ( Fig.…”