Wu Dayu, Huang Wei, Lin Zhihua, Duan Chunying, He Cheng, Wu Shuo, Wang Dehui
State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, China.
Inorg Chem. 2008 Aug 18;47(16):7190-201. doi: 10.1021/ic8004344. Epub 2008 Jul 19.
A new chemosensor RF1 that combines a ferrocene unit and a rhodamine block via the linkage of a carbohydrazone binding unit was designed and prepared for the highly selective detection of Hg (2+) in natural water. This chemosensor displays great brightness and fluorescence enhancement following Hg (2+) coordination within the limit of detection for Hg (2+) at 1 parts per billion (ppb). The fluorescence intensities are nearly proportional to the amount of Hg (2+) at the ppb level. It is capable of distinguishing between the safe and the toxic levels of inorganic mercury in drinking water. Hg (2+)-binding also arouses the absorption of the rhodamine moiety in RF1 significantly with the chromogenic detection limit for Hg (2+) at 50 ppb. The conventional UV-vis spectroscopic method thus has the potential to provide the critical information about the mercury hazard assessment for industrial wastewater discharging. The obvious and characteristic color change of the titration solution from colorless to pink upon the addition of Hg (2+) demonstrates that RF1 can be used for "naked-eye" detection of Hg (2+) in water. The Hg (2+) complexation also causes a significant shift of the redox potential about the ferrocene/ferrocenium couple. The electrochemical responses provide the possibility to quantitative analysis of Hg (2+) at the parts per million (ppm) level. Preliminary investigations in natural water samples including seawater and freshwater indicate that RF1 offers a direct and immediate Hg (2+) detection in complex media, pointing out its potential utility in environment monitoring and assessment. The responses of RF1 are Hg (2+) specific, and the chemosensor exhibits high selectivity toward Hg (2+) over other Group 12 metals, alkali, alkaline earth metals, and most of the divalent first-row transition metals. The RF1-Hg (2+) complex is successfully isolated and the Hg (2+)-binding is reversible. The crystal structure and spectral properties of its congener RF2 that contains one ferrocene group and two rhodamine 6G moieties were also investigated for a comparison.
设计并制备了一种新型化学传感器RF1，它通过腙结合单元将二茂铁单元和罗丹明基团连接起来，用于天然水中汞（2+）的高选择性检测。该化学传感器在汞（2+）的检测限为十亿分之一（ppb）时，与汞（2+）配位后显示出很强的亮度和荧光增强。荧光强度在ppb水平上几乎与汞（2+）的量成正比。它能够区分饮用水中无机汞的安全水平和有毒水平。汞（2+）结合还会显著引起RF1中罗丹明部分的吸收，汞（2+）的显色检测限为50 ppb。因此，传统的紫外-可见光谱法有可能为工业废水排放的汞危害评估提供关键信息。加入汞（2+）后滴定溶液从无色到粉红色的明显且特征性的颜色变化表明，RF1可用于水中汞（2+）的“裸眼”检测。汞（2+）络合还会导致二茂铁/二茂铁离子对的氧化还原电位发生显著变化。电化学响应为百万分之一（ppm）水平的汞（2+）定量分析提供了可能性。对包括海水和淡水在内的天然水样的初步研究表明，RF1能够在复杂介质中直接即时检测汞（2+），指出了其在环境监测和评估中的潜在用途。RF1的响应具有汞（2+）特异性，该化学传感器对汞（2+）的选择性高于其他第IIB族金属、碱金属、碱土金属以及大多数二价第一行过渡金属。成功分离出RF1-汞（2+）络合物，且汞（2+）结合是可逆的。还研究了其同系物RF2（包含一个二茂铁基团和两个罗丹明6G基团）的晶体结构和光谱性质以作比较。
