Synthesis, crystal structures, and photophysical properties of dibromo-2-(2′-pyridyl)imidazole and its corresponding boron–fluorine complex
作者:Miaofu Mao、Ronghua Zhang、Shuzhang Xiao、Kun Zou
DOI:10.1080/00958972.2011.618836
日期:2011.10.10
2-(2'-Pyridyl) imidazole L1 and its corresponding boron-fluorine complex, 1, were synthesized and their crystal structures correlated with their photophysical properties. L1 forms a rigid supramolecular network through hydrogen bonds and halogen bond in the single crystal, which induces amplified spontaneous emission in crystals; it emits rather poor fluorescence in solution and powder states. Its boron chelate 1 emits intense fluorescence in solution since boron chelate is an excellent chromophore, and it exhibits large Stokes shift (136nm in acetonitrile), due to the charge-transfer transition from the electron-donating pi system to the electron-accepting boron moiety. Interestingly, 1 is also highly fluorescent in amorphous powder and crystal states; C-C rotation between pyridyl and imidazole groups is inhibited by the formation of a five-member ring containing BF2, and the formation of intermolecular non-covalent bonds is the key factor. Solid emission with large Stokes shift makes it a valuable chromophore for synthesis of functional materials.