A fluorescent bis(benzoxazole) ligand: toward binuclear Zn(II)-Zn(II) assembly.
A bis(benzoxazole) ligand (HL) has been synthesized, and its reaction with Zn(OAc)(2) has led to fluorescent complexes via formation of binuclear Zn(II)-Zn(II) cores. The ligand-to-metal ratio of the complexes varies from 1 : 1 to 2 : 1, depending on the reaction conditions. A large binding constant K = 8.3 x 10(20) [M(-3)] has been determined for the reaction L + Zn(2+)-->L(2):Zn(2)(2+). The result indicates that the bis(benzoxazole) ligand is a useful building block to construct a binuclear core. On the basis of X-ray analysis, the binuclear Zn(II)-Zn(II) distance in the complexes is determined to be approximately 3.22 A, which is quite comparable to that found in the enzymes (3.3 A). Absorption and fluorescence study shows that a subtle chemical environmental change within the binuclear core can induce a large optical response.
Chu
Qinghui
Q
Department of Chemistry & Maurice Morton Institute of Polymer Science, The University of Akron, Akron, OH 44325, USA.
Medvetz
Doug A
DA
Panzner
Matthew J
MJ
Pang
Yi
Y