Solvent Dependent Fluorescent Properties of a 1,2,3-Triazole Linked 8-Hydroxyquinoline Chemosensor: Tunable Detection from Zinc(II) to Iron(III) in the CH3CN/H2O System
Solvent Dependent Fluorescent Properties of a 1,2,3-Triazole Linked 8-Hydroxyquinoline Chemosensor: Tunable Detection from Zinc(II) to Iron(III) in the CH3CN/H2O System
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1,2,3-三唑连接的 8-羟基喹啉化学传感器的溶剂依赖性荧光特性：CH3CN/H2O 系统中锌 (II) 到铁 (III) 的可调检测
DOI：
10.1021/jp202700s
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发表时间：
2011-07-28
影响因子：
2.9
通讯作者：
Jiao, Lijuan
中科院分区：
文献类型：
--
作者：
Hao, Erhong;Meng, Ting;Jiao, Lijuan
从“点击”策略出发，分两步高效合成了含三唑的8-羟基喹啉(8-HQ)醚2。化合物2在非质子性溶剂CH3CN中有较强的荧光(phi=0.21)，在质子性溶剂(如水)中有微弱的荧光(phi=0.06)。与在CH3CN溶液中相比，化合物2在水中的最大荧光强度红移了100 nm以上。这种荧光差异可能归因于涉及质子溶剂水分子的分子间光诱导质子转移(PPT)过程。同样，在高含水率的CH3CN水溶液(如CH3CN/H2O=5/95；v/v)中也观察到了这种分子间PPT过程；CH3CN/H2O二元混合溶剂中的水含量对荧光强度(如当CH3CN/H2O=5/95和95/5，v/v时，phi分别为0.06和0.25时)和发射波长有很大的影响。利用这一有趣的性质，通过简单地改变CH3CN水溶液中的水含量，化合物2可以从选择性的锌离子荧光传感器(CH3CN/H2O=5/95，v/v)调整为锌离子的比率荧光传感器和Fe3+的选择性“关断”荧光传感器(CH3CN/H2O=95/5，v/v)。在高含水率(CH3CN/H2O=5/95，v/v)的水溶液中，化合物2对锌离子表现出选择性的“开启”响应，其428 nm处的荧光强度增强了10倍，最大发射波长蓝移62 nm(490~428 nm)，这是由于与锌离子的络合抑制了分子间的PPT过程。而在低极性溶剂(CH3CN/H2O=95/5，v/v)中，化合物2具有较高的荧光强度(量子产率为0.25)，其对锌离子的荧光强度在399 nm处持续减弱，在423 nm处增加。更有趣的是，在这种情况下，它还表现出非常灵敏的，选择性的和比率荧光猝灭存在于Fe3+的存在，通过金属配体电荷转移(MLCT)效应，在较宽的pH范围内发射最大值(399到480 nm)红移了81 nm。
A triazole-containing 8-hydroxyquinoline (8-HQ) ether 2 was efficiently synthesized in two steps from the "click" strategy. Compound 2 gave a strong fluorescence (Phi = 0.21) in nonprotic solvent like CH3CN, and a weak fluorescence (Phi = 0.06) in protic solvent like water. In water, a more than 100 nm red shift of the fluorescence maximum was observed for compound 2 in comparison with that in CH3CN. This fluorescence difference may be attributed to the intermolecular photoinduced proton transfer (PPT) process involving the protic solvent water molecules. Similarly, this intermolecular PPT process was also observed in the high-water-content CH3CN aqueous solution (e.g., CH3CN/H2O = 5/95; v/v); The water content in the CH3CN/H2O binary solvent mixture greatly affected the fluorescence intensity (e.g., Phi = 0.06 and 0.25 when CH3CN/H2O = 5/95 and 95/5, v/v, respectively) and emission wavelength. Using this interesting property, by simple variation of the water content in the CH3CN aqueous solution, compound 2 was tuned from a selective "turn-on" fluorescent sensor for Zn2+ (CH3CN/H2O = 5/95, v/v) to a ratiometric one for Zn2+ and a selective "turn-off" one for Fe3+ (CH3CN/H2O = 95/5, v/v) over a wide range of pH value. In high-water-content (CH3CN/H2O = 5/95, v/v) aqueous solution compound 2 shows a selective "turn-on" response toward Zn2+, with a 10-fold enhancement in the fluorescence intensity at 428 nm and a 62 nm blue shift of the emission maximum (490 to 428 nm) due to the inhibition of intermolecular PPT process upon chelating with Zn2+. However, in a less polar solvent (CH3CN/H2O = 95/5, v/v) in which compound 2 has high fluorescence (quantum yield =0.25), it shows a ratiometric response toward Zn2+, with a continuous decrease of the fluorescence intensity at 399 nm and an increase at 423 nm. More interestingly, in this case, it also exhibits a very sensitive, selective, and ratiometric fluorescence quenching in the presence of Fe3+, with an 81 nm red shift of the emission maximum (399 to 480 nm) in a wide range of pH through a metal ligand charge transfer (MLCT) effect.