Unusual reaction of (E)-2-[(benzo[d]thia­zol-2-yl­imino)­meth­yl]-5-(di­ethyl­amino)­phenol with tri­phenyl­borane: crystal structures and optical properties

The mol­ecular and crystal structure of (E)-2-[(benzo[d]thia­zol-2-yl­imino)­meth­yl]-5-(di­ethyl­amino)­phenol (C(18)H(19)N(3)O(2)S, Et(2)N-Bz) and its unexpected reaction product with tri­phenyl­borane, 2,2-diphenyl-1,3-dioxa-2-borata-1,2-di­hydro­naphthalene [systematic name: N,N-diethyl-2,2-diphenyl-2H-1,3λ(3),2λ(4)-ben­zodioxaborinin-7-amine, C(23)H(24)BNO(2), (I)] are described. For Et(2)N-Bz, the hydroxyl group is involved in an intra­molecular hydrogen bond with the imino nitro­gen atom and the C=N bond displays an E configuration. The crystal packing is characterized by layers of inversion dimers parallel to the (10 [Image: see text] ) plane and chains of mol­ecule in the a-axis direction formed through C—H⋯O inter­actions. Complex (I) crystallizes with two mol­ecules (A and B) in the asymmetric unit, which differ in the orientation of the ethyl groups. The 1,3-dioxa-2-borata-1,2,3,4-tetra­hydro­naphthalene ring displays a slight envelope conformation with the boron atom as the flap. In the crystal packing, chains of alternating A and B mol­ecules formed by C—H⋯O hydrogen bonds run in the b-axis direction. The UV–vis absorption and emission properties of the compounds are discussed and their aggregation-induced emission properties are further investigated.