Methoxy-substituted isoTQEN family for enhanced fluorescence response toward zinc ion
作者:Yuji Mikata、Azusa Yamashita、Keiko Kawata、Hideo Konno、Saori Itami、Keiko Yasuda、Satoshi Tamotsu
DOI:10.1039/c0dt01617a
日期:——
Previously, we have reported that 1- and 3-isoTQENs (N,N,N′,N′-tetrakis(1- or 3-isoquinolylmethyl)ethylenediamines) exhibit a specific fluorescence enhancement toward zinc ion. In this study, three methoxy-substituted derivatives of 1-isoTQEN were synthesized and their fluorescent response toward zinc ion was studied. The substitution pattern of the methoxy group significantly changes the solubility of compounds in aqueous DMF, λmax in the absorption spectra, excitation/emission wavelengths and fluorescence intensity of zinc complexes. In the presence of zinc ion, 7-MeO-1-isoTQEN exhibits higher fluorescence intensity and longer excitation/emission wavelengths (λex = 342 nm, λem = 526 nm) than 6-MeO-1-isoTQEN (λex = 303 nm, λem = 469 nm) and 5,6,7-triMeO-1-isoTQEN (λex = 340 nm, λem = 504 nm). The fluorescence intensity of a zinc complex of 7-MeO-1-isoTQEN (ϕ = 0.122) is four times higher than the parent 1-isoTQEN (ϕ = 0.034) under the same conditions. The crystal structure of 7-MeO-1-isoTQEN-Zn complex reveals that all six nitrogen atoms participate to the metal coordination with ideal octahedral geometry, affording significantly high metal binding affinity comparable with TPEN (N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine). 7-MeO-1-isoTQEN detects zinc ion concentration change in cells by fluorescence microscopic analysis.
以前,我们曾报道过 1- 和 3-isoTQENs (N,N,N′,N′-四(1- 或 3-异喹啉甲基)乙二胺)对锌离子具有特异性荧光增强作用。本研究合成了 1-isoTQEN 的三种甲氧基取代衍生物,并研究了它们对锌离子的荧光反应。甲氧基的取代模式显著改变了化合物在 DMF 水溶液中的溶解度、锌络合物吸收光谱中的λmax、激发/发射波长和荧光强度。在锌离子存在的情况下,7-MeO-1-isoTQEN 比 6-MeO-1-isoTQEN(λex = 303 nm,λem = 469 nm)和 5,6,7-triMeO-1-isoTQEN(λex = 340 nm,λem = 504 nm)具有更高的荧光强度和更长的激发/发射波长(λex = 342 nm,λem = 526 nm)。在相同条件下,7-MeO-1-isoTQEN 的锌络合物(j = 0.122)的荧光强度是母体 1-isoTQEN (j = 0.034)的四倍。7-MeO-1-isoTQEN-Zn 复合物的晶体结构显示,所有六个氮原子都以理想的八面体几何形状参与了金属配位,因此具有与 TPEN(N,N,N′,N′-四(2-吡啶基甲基)乙二胺)相当的高金属结合亲和力。7-MeO-1-isoTQEN 可通过荧光显微分析检测细胞中锌离子浓度的变化。