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.%A novel highly symmetrical compound, N,N'-di[3-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 l×l0-6 to l×l0-2 mol·L-1.
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