2-(2-氨基-3-吡啶基)-苯并咪唑的合成、晶体结构和荧光特性研究

在合成2-(2-氨基-3-吡啶基)-苯并咪唑的基础上,利用NMR(1H、13C、COSY、HSQC和HMBC)、MS、IR和UV进行了详细表征;通过X-ray单晶衍射仪测定了该化合物的晶体结构,实验结果表明该晶体属于三方晶系(空间群R3,a=1.833 7(3)nm,b=1.833 7(2)nm,c=1.777 7(4)nm,V=5.176 4(15)nm3,Z=18),很好地支持了波谱表征的结果。同时,结合密度泛函计算,研究了2-(2-氨基-3-吡啶基)-苯并咪唑的荧光光谱。结果表明,化合物的双荧光不是由同一种异构体发射的,而是来源于不同异构体:长波区500~600 nm的荧光由K构型发射,短波区350~450 nm的发射由异构体E1和E2共同产生,理论预测的光谱与实验一致。

Synthesis, Crystal Structure and Fluorescence Characteristics on 2-(2-Amino-3-pyridyl)-benzimidazole

2-(2-amino-3-pyridyl)-benzimidazole was synthesized and characterized by NMR (¹H, ¹³C, COSY, HSQC, and HMBC), MS, IR, and UV techniques. The crystal structure was determined by X-ray singlecrystal diffraction. The diffraction experiment confirmed the results of spectroscopic analysis and showed that the crystal belongs to rhombohedral, space group R3 with unit cell parameter a=1.833 7(3) nm, b=1.833 7(2) nm, c=1.777 7(4) nm, V=5.176 4(15) nm³, Z=18. The emission spectra of the isomers of 2-(2-amino-3-pyridyl)-benzimidazole were calculated by means of the density functional theory. These results show that the dual fluorescence of 2-(2-amino-3-pyridyl)-benzimidazole is produced by its different tautomers, but not by the same isomer: the longwavelength (500~600 nm) emission is from K tautomer, and the short wavelength band (350~450 nm) is produced by E1 and E2. The results of density functional calculations provide a reasonable explanation on the experimental phenomena. CCDC: 760505.