In virtue of the sulfurphilic nature of Hg2+, three new sensors RN1, RN2 and RST1 that combine a thiophene group and one or two rhodamine choromophores, or a thiospirolactam rhodamine chromophore, were designed and prepared for the selective detection of Hg2+ in aqueous media, respectively. These sensors all displayed good brightness and fluorescence enhancement following Hg2+ coordination with limits of detection for Hg2+ at the ppb level. Thus, they have the potential for distinguishing between safe and toxic levels of inorganic mercury in drinking water. RN1 exhibited chromogenic and fluorogenic selectivity over alkali, alkaline earth metals, divalent first-row transition metal ions as well as heavy metals, but the presence of Cu2+ had a small but significant influence on the absorption detection of Hg2+. Compared to RN1, the introduction of sufficient sulfur atoms could increase the binding capability of RST1 towards Hg2+ relative to the sensor RN1, but decrease its Hg specific ability. The existence of some heavy and transition metal ions, such as Pb2+, Ag+, Cu2+ enhance the silent absorption spectra of RST1. Spectral evidence and X-ray structural investigations of the mercury complex revealed a possible 1:2 complexation behaviour between the Hg2+ ion and the sensor RN1 or RST1. Sensor RN2 which contains two rhodamine carboxhydrazone arms exhibited better selectivity, compared to those of RN1 and RST1. The addition of Cu2+ only caused a small interference for the absorption detection of Hg2+ under the same conditions, demonstrating the efficiency of the robust bis-chelating mode with regard to the selectivity for Hg2+.
由于Hg2+具有亲
硫性,研究人员设计并制备了三种新型传感器RN1、RN2和RST1,分别用于选择性检测
水介质中的Hg2+。这些传感器在Hg2+与ppb级Hg2+检测限发生配位反应后,均显示出良好的亮度和荧光增强效果。因此,它们有可能区分饮用
水中无机
汞的安全和有毒
水平。RN1对碱、碱土
金属、二价第一过渡族
金属离子以及重
金属具有显色和荧光选择性,但Cu2+的存在对Hg2+的吸收检测有微小但显著的影响。与RN1相比,引入足够的
硫原子可以提高RST1对Hg2+的绑定能力,但会降低其Hg特异性。一些重
金属和过渡族
金属离子(如Pb2+、Ag+、Cu2+)的存在会增强RST1的静默吸收光谱。对
汞络合物的光谱证据和X射线结构研究揭示了Hg2+离子与传感器RN1或RST1之间可能的1:2络合行为。与RN1和RST1相比,传感器RN2含有两个
罗丹明羧
肟臂,具有更好的选择性。在相同条件下,添加Cu2+只会对Hg2+的吸收检测产生轻微干扰,这表明强健的双螯合模式对Hg2+的选择性是有效的。