Oxidative cyclization of N-acylhydrazones. Development of highly selective turn-on fluorescent chemodosimeters for Cu2+.
A series of N-acylhydrazones were synthesised and found to be "turn-on" fluorescent chemodosimeters for Cu(2+). Among the tested transition metal ions such as Cu(2+), Pb(2+), Zn(2+), Cd(2+), Hg(2+), and Ni(2+), a prominent fluorescence enhancement of up to 1000-fold was only observed for Cu(2+) in acetonitrile (CH(3)CN). This was indicated by an onset of unprecedented structured emission. Detailed experiments established that the highly Cu(2+) selective fluorescence enhancement resulted from an oxidative cyclization by Cu(2+)of the originally nonfluorescent N-acylhydrazones into highly fluorescent rigid 1,3,4-oxadiazoles, n-dope type blocks in optoelectronic materials. The chemodosimeters can be applied to sense Cu(2+) at nM levels in CH(3)CN and sub-microM levels in neutral aqueous environments, despite a slower response in the latter case. It is expected that these redox-based chemodosimeters might be of general applicability.
Li
Ai-Fang
AF
Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
He
Hui
H
Ruan
Yi-Bin
YB
Wen
Zhen-Chang
ZC
Zhao
Jin-Song
JS
Jiang
Qiu-Ju
QJ
Jiang
Yun-Bao
YB