From nonconjugation to conjugation: novel meso-OH substituted dipyrromethanes as fluorescence turn-on Zn2+ probes
作者:Yubin Ding、Tong Li、Xin Li、Weihong Zhu、Yongshu Xie
DOI:10.1039/c3ob40121a
日期:——
Most reported Zn2+ probes suffer from the interference of background fluorescence originated from the conjugated structures of commonly utilized fluorophores. In this work, three novel meso-hydroxyl group substituted dipyrromethanes DPMOH1–DPMOH3 were synthesized and found to be colourless and nonfluorescent due to the interruption of the conjugated π system by an sp3 carbon between the two pyrrolic units. Interestingly, only the addition of Zn2+ to the solutions of DPMOH1–DPMOH3 promoted their oxidation to dipyrrin forms, and bright fluorescence “turn on” was observed due to the formation of corresponding dipyrrin complexes with the dipyrrin : zinc stoichiometry of 2 : 1. Zn2+ detection mechanism was investigated by UV-Vis, fluorescence, 1H NMR and HRMS analyses, which can be ascribed to the CHEF type fluorescence enhancement, resulting from good rigidity of the dipyrrin complexes. Hence, DPMOH1–DPMOH3 can be used as fluorescence turn-on Zn2+ probes with the advantage of no background fluorescence.
大多数已报道的 Zn2+ 探针都受到来自常用荧光团共轭结构的背景荧光的干扰。在这项工作中,合成了三种新型介羟基取代的二吡咯甲烷 DPMOH1-DPMOH3,并发现由于两个吡咯单元之间的 sp3 碳打断了共轭 π 系统,因此它们是无色无荧光的。有趣的是,只有在 DPMOH1-DPMOH3 溶液中加入 Zn2+ 才能促进它们氧化成二吡咯啉形式,并观察到明亮的荧光 "开启",这是因为形成了相应的二吡咯啉配合物,二吡咯啉与锌的化学计量为 2 :1.通过紫外-可见光、荧光、1H NMR 和 HRMS 分析研究了 Zn2+ 的检测机理,这可归因于二吡咯啉络合物良好的刚性导致的 CHEF 型荧光增强。因此,DPMOH1-DPMOH3 具有无背景荧光的优点,可用作荧光开启型 Zn2+ 探针。