TACN (1,4,7-triazacyclononane) derivatives with three 6-methoxy-2-quinolylmethyl or 1-isoquinolylmethyl moieties were examined as fluorescent zinc sensors. Upon the addition of zinc, 6-MeOTQTACN (5) exhibited a 9-fold fluorescence increase at 420 nm (λex = 341 nm, ϕZn = 0.070). Fluorescence enhancement is specific for zinc and cadmium, although cadmium induces smaller increases (ICd/I0 = 3.6 and ICd/IZn = 40%). The isoquinoline analog 1-isoTQTACN (6) exhibits minimal fluorescence enhancement upon zinc binding. TPEN (N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylene-diamine) does not extract zinc from the 6-MeOTQTACN-Zn complex (5-Zn). The quantum yield, metal ion selectivity and metal binding affinity differences between TACN and ethylenediamine (EN) skeletons in quinoline-based ligands are discussed based on the X-ray crystallographic analysis of zinc and cadmium complexes, demonstrating the superiority of quinoline–TACN conjugates.
TACN(1,4,7-三唑环诺烷)衍
生物中含有三个6-甲氧基-2-
喹啉甲基或1-
异喹啉甲基基团,作为发光
锌传感器进行研究。在加入
锌后,6-甲氧基TQTACN(5)在420 nm处表现出9倍的荧光增强(λex = 341 nm,ϕZn = 0.070)。荧光增强对
锌和
镉是特异的,尽管
镉诱导的增强较小(ICd/I0 = 3.6,ICd/IZn = 40%)。
异喹啉类似物1-异TQTACN(6)在
锌结合时几乎没有荧光增强。TPEN(N,N,N′,N′-四(2-
吡啶甲基)
乙烯二胺)不能从6-甲氧基TQTACN-Zn复合物(5-Zn)中提取
锌。基于
锌和
镉复合物的X射线晶体分析,讨论了TACN和
乙烯二胺(EN)框架在
喹啉基
配体中的量子产率、
金属离子选择性和
金属结合亲和力的差异,显示了
喹啉–TACN共轭物的优越性。