基于羟苯基苯并咪唑的Zn2+比率荧光探针

通过羰基将两分子2-(4-氨基-2-羟苯基)苯并咪唑(4-AHBI)连接,合成了结构高度对称的新化合物N,N′-二-3-羟基-4-(2-苯并咪唑)苯基]脲(C27H20N6O3,1),测试了不同溶剂条件下1的紫外吸收和荧光发射光谱,研究了1对Zn2+的选择性识别作用。结果表明,随着溶剂极性的增大,1的紫外吸收峰发生蓝移,激发态分子内质子转移(ESIPT)荧光发射峰明显增强。与4-AHBI相比,1在乙腈溶液中的紫外吸收强度增强约3.5倍,最大吸收峰红移8 nm,荧光发射增强8倍多。1在乙腈溶液中的Zn2+荧光响应行为表明1与Zn2+的结合将导致1在445 nm处的荧光强度不断降低,而在395 nm处出现的新峰的荧光强度不断增强,具有比率荧光探针的特点,而且检测范围较宽,可达1×10-6-1×10-2 mol.L-1。

Ratiometric Fluorescent Sensor of Zn2+ by Hydroxyphenyl Benzimidazole

A novel highly symmetrical compound,N,N′-di3-hydroxy-4-(2-benzimidazole)phenyl]-urea(C27H20N6O3,1),was synthesized from 2-(4-amino-2-hydroxyphenyl) benzimidazole(4-AHBI),and its specific response to Zn2+ as well as its UV absorption and fluorescence emission spectra in different solvents were investigated.The observation indicated that with the polarity of solvent(toluene,acetic ester,methanol,acetonitrile) increasing,the UV absorption peak of 1 was a blue-shift,and the intensity of its excited state intramolecular proton transfer(ESIPT) increased significantly.In comparison with the spectral properties of 4-AHBI,the UV absorption intensity of 1 in acetonitrile solvent was enhanced up to 3.5 folds with a red-shift of 8 nm at the maximum absorption peak,the fluorescence intensity of 1 was enhanced up to 8 folds,indicating that 1 possessed better optical property compared to 4-AHBI.Furthermore,with the increase of Zn2+,the fluorescence intensity of 1 at 445 nm decreased,in the meantime,a new peak at 395 nm was shown up,with intensity increasing gradually.The analysis suggested that 1 could behave as a ratiometric fluorescent sensor for the selective detection of Zn2+ with the linear response to a concentration of Zn2+ from 1×10-6 to 1×10-2 mol·L-1.