Department of Chemistry, Wuhan University, Wuhan, Hubei 430072, People's Republic of China.
Dalton Trans. 2010 Dec 21;39(47):11344-52. doi: 10.1039/c0dt00737d. Epub 2010 Nov 1.
N,N'-((5,5'-(quinoxaline-2,3-diyl)bis(1H-pyrrole-5,2-diyl))bis(methanylylidene))bis(4-methoxyaniline) 4 and N,N'-((5,5'-(quinoxaline-2,3-diyl)-bis(1H-pyrrole-5,2-diyl))bis(methanylylidene))dianiline 5 have been prepared and structurally characterized. The X-ray crystal structures of compounds 4 and 4a have been determined. These compounds displayed good sensitivity toward transition metal ions with Cd(II), Zn(II) turn-on and Cu(II), Hg(II) turn-off in fluorescence. It is an elegant example of on/off behavior like a lamp. When Cd(II) or Zn(II) is added into compounds 4 or 5, the lamp will switch on, and then when Cu(II) or Hg(II) is added into the mixture, the lamp will switch off. The binding properties of 4 and 5 for cations were examined by fluorescence spectroscopy. The fluorescence data and crystal structure indicate that a 1:1 stoichiometry complex is formed between compound 4 (or 5) and metal ions, and the binding affinity is very high. The recognition mechanism between compound 4 (or 5) and metal ion was discussed based on the their chemical constructions and the CHEF/CHEQ effect when they interacted with each other.
N,N'-((5,5'-(喹喔啉-2,3-二基)双(1H-吡咯-5,2-二基))双(亚甲基亚胺基))双(4-甲氧基苯胺)4 和 N,N'-((5,5'-(喹喔啉-2,3-二基)-双(1H-吡咯-5,2-二基))双(亚甲基亚胺基))二苯胺5 已经被制备并进行了结构表征。化合物 4 和 4a 的 X 射线晶体结构已经被确定。这些化合物对过渡金属离子具有很好的灵敏度，Cd(II)、Zn(II) 为荧光开启，而 Cu(II)、Hg(II) 为荧光关闭。这是一个类似于灯的开/关行为的优雅示例。当 Cd(II)或 Zn(II)加入到化合物 4 或 5 中时，灯会打开，然后当 Cu(II)或 Hg(II)加入到混合物中时，灯会关闭。通过荧光光谱法研究了化合物 4 和 5 对阳离子的结合性质。荧光数据和晶体结构表明，化合物 4（或 5）与金属离子形成 1:1 化学计量比的配合物，并且结合亲和力非常高。基于化合物 4（或 5）和金属离子的化学结构以及它们相互作用时的 CHEF/CHEQ 效应，讨论了化合物 4（或 5）与金属离子之间的识别机制。
