Oxidative cyclization of N-acylhydrazones. Development of highly selective turn-on fluorescent chemodosimeters for Cu<sup>2+</sup>
作者:Ai-Fang Li、Hui He、Yi-Bin Ruan、Zhen-Chang Wen、Jin-Song Zhao、Qiu-Ju Jiang、Yun-Bao Jiang
DOI:10.1039/b811612a
日期:——
A series of N-acylhydrazones were synthesised and found to be “turn-on” fluorescent chemodosimeters for Cu2+. Among the tested transition metal ions such as Cu2+, Pb2+, Zn2+, Cd2+, Hg2+, and Ni2+, a prominent fluorescence enhancement of up to 1000-fold was only observed for Cu2+ in acetonitrile (CH3CN). This was indicated by an onset of unprecedented structured emission. Detailed experiments established that the highly Cu2+ selective fluorescence enhancement resulted from an oxidative cyclization by Cu2+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 Cu2+ at nM levels in CH3CN and sub-µM 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.
合成了一系列N-酰肼酮,并发现其作为Cu2+的“开启型”荧光化学传感器。在测试的过渡金属离子中,如Cu2+、Pb2+、Zn2+、Cd2+、Hg2+和Ni2+,只有Cu2+在乙腈(CH3CN)中显示出高达1000倍的显著荧光增强。这表现为一种前所未有的结构化发射的开始。详细的实验确定,Cu2+的高度选择性荧光增强源于Cu2+对原本非荧光的N-酰肼酮进行的氧化环化反应,转变为具有高荧光性的刚性1,3,4-噁二唑,这些结构是光电材料中的n型掺掺剂。这些化学传感器可用于在CH3CN中检测nM级别的Cu2+,以及在中性水相环境中检测亚µM级别的Cu2+,尽管后者的反应较慢。预计这些基于氧化还原的化学传感器可能具有广泛的适用性。