| Abstract: 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 1×10-6 to 1×10-2 mol·L-1. |
