CONTROL OF THE THERMAL CIS TO TRANS ISOMERIZATIONS OF AZOBENZENE AND THIOINDIGO DERIVATIVES BY THE FORMATION OF SUPRAMOLECULAR H-BONDED ASSEMBLIES

摘要

2,3-Bis(aminocyclohexyl)-6-methoxy-1,3,5-triazine (1a) forms intermolecular H-bonded complexes with 3,3′-diacetyl-cis-azobenzene (4b) and 6,6′-diethoxy-cis-thioindigo (5b), (association constants K = 4.9 x 10~4 and 3.5 x 10~5 l mol_(-1), respectively). The thermal cis → trans isomerization of 4b and 5b to 3,3′-diacetyl-trans-azobenzene (4a), and 6,6′-diethoxy-trans-thioindigo (5a), is inhibited in the intermolecular complex 1a-4b and 1a-5b. Molecular mechanics calculations support the formation of the intermolecular H-bonded complexes between 1a and 4b or 5b.