Huang Wei, Song Chunxia, He Cheng, Lv Guojun, Hu Xiaoyue, Zhu Xiang, Duan Chunying
Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, PR China.
Inorg Chem. 2009 Jun 15;48(12):5061-72. doi: 10.1021/ic8015657.
This work presents the design, syntheses, photophysical properties and Hg(2+)-binding of the red-emitting rhodamine derivatives RS1, RS2, and RS3 with different coordination ability and different spatial effects that derived from rhodamine thiohydrazone chromophores and respective carboxaldehydes (benzaldehyde, pyridine-2-carboxaldehyde, ferrocenecarboxaldehyde). Chemosensors RS2 and RS3 afford turn-on fluorescence enhancement and display high brightness in water with the EC(50) for Hg(2+) of 0.5 ppb. The fluorescence intensities are nearly proportional to the amount of Hg(2+) at ppb level, when employing 100 nM probes in water. The fluorescence responses of these two chemosensors are Hg(II) specific, and the probes are selective for Hg(II) over alkali, alkaline earth metals, divalent first-row transition metal ions, and Group 12 congeners Zn(II) and Cd(II), as well as heavy metals Pb(II) and Ag(I). X-ray crystal structure analyses exhibit the thioether derivative of the spirolactone in these compounds. Hg(II)-specific binding in water would make the opening of the spirolactam ring and consequently causes the appearance of strong absorption at visible range, and the obvious and characteristic color change from colorless to pink. Compared to the thioamides, the improved selectivity for Hg(2+) is attributed to the poorer coordination affinity of the thioether over other interference metal ions.
这项工作展示了具有不同配位能力和不同空间效应的红色发射罗丹明衍生物RS1、RS2和RS3的设计、合成、光物理性质及汞离子（Hg(2+)）结合能力，这些衍生物由罗丹明硫腙发色团和相应的醛（苯甲醛、吡啶 - 2 - 甲醛、二茂铁甲醛）衍生而来。化学传感器RS2和RS3呈现开启型荧光增强，在水中具有高亮度，对Hg(2+)的半数有效浓度（EC(50)）为0.5 ppb。当在水中使用100 nM的探针时，荧光强度在ppb水平上几乎与Hg(2+)的量成正比。这两种化学传感器的荧光响应具有Hg(II)特异性，且探针对Hg(II)的选择性高于碱金属、碱土金属、二价第一行过渡金属离子、第12族同族元素Zn(II)和Cd(II)以及重金属Pb(II)和Ag(I)。X射线晶体结构分析显示了这些化合物中螺内酯的硫醚衍生物。在水中Hg(II)特异性结合会使螺内酰胺环打开，从而导致在可见光范围内出现强烈吸收，以及从无色到粉红色的明显且特征性的颜色变化。与硫代酰胺相比，对Hg(2+)选择性的提高归因于硫醚对其他干扰金属离子的配位亲和力较差。
