烷基桥联双苯并咪唑化合物的合成与表征

Synthesis and characterization of bis-benzimidazole compounds with alkylene linker

在氢化钠存在下,用苯并咪唑与1-溴代烷烃反应生成1-烷基苯并咪唑,然后再与1,6-二碘己烷反应制得双苯并咪唑盐[1,6-二(1’-乙基-3’-苯并咪唑)己烷]二碘化物(Ⅰ)和[1,6-二(1’-正丁基-3’-苯并咪唑)己烷]二碘化物(Ⅱ).化合物Ⅰ和Ⅱ分别与不同比例的Hg I2反应得到阴离子配合物[1,6-二(1’-乙基-3’-苯并咪唑)己烷]四碘合汞酸盐(Ⅲ)和[1,6-二(1’-正丁基-3’-苯并咪唑)己烷]六碘合二汞酸盐(Ⅳ).化合物Ⅲ和Ⅳ的晶体结构通过X-线单晶衍射分析、~1H NMR和^(13)C NMR得到确认.在化合物Ⅲ和Ⅳ的阳离子单元中,每个阳离子上的2个苯并咪唑环形成的二面角分别为70.2(1)°和0°.在化合物Ⅲ的阴离子单元[HgI_4]^(2-)中,汞(Ⅱ)离子与4个碘离子配位形成四面体构型.在化合物Ⅳ的阴离子单元[Hg_2I_6]^(2-)中,2个汞(Ⅱ)离子和2个桥碘离子形成一个平面的四边形结构,另外4个碘离子位于四边形的两侧.在化合物Ⅲ和Ⅳ的晶体堆积中,其二维超分子层和三维超分子建筑是通过分子间弱相互作用形成的(包括C——H···I氢键、I···π作用和π-π作用).对化合物Ⅰ~Ⅳ的荧光特性的研究表明,Ⅰ和Ⅱ中加入汞离子后并未导致配合物Ⅲ和Ⅳ中产生重原子效应.

Benzimidazole was treated with 1-bromoalkane in the presence of Na H to afford 1-alkyl-benzimidazole,and then 1-alkyl-benzimidazole was reacted with 1,6-diiodohexane to give bis-benzimidazolium salts 1,6-bis(1'-ethyl-3'-benzimidazoliumyl)hexane diiodide(Ⅰ)and 1,6-bis(1'-nbutyl-3'-benzimidazoliumyl)hexane diiodide(Ⅱ). Compound ⅠorⅡ was treated with different proportions of Hg I2 to form anionic complexes,1,6-bis(1'-ethyl-3'-benzimidazoliumyl)hexane tetraiodomercurate(Ⅲ)and 1,6-bis(1'-nbutyl-3'-benzimidazoliumyl)hexane hexaiododimercurate(Ⅳ). Compounds Ⅲand Ⅳ were characterized by X-ray diffraction analysis and ~1H NMR and ^(13)C NMR. In each cationic unit of compounds Ⅲand Ⅳ,two benzimidazole rings form the dihedral angles of 70.2(1)° for Ⅲ and 0° for Ⅳ. In the anionic unit [HgI_4]^(2-) of Ⅲ,the mercury(Ⅱ)ion was coordinated by four iodide ions to afford a tetrahedral geometry. In the anionic unit [Hg_2I_6]^(2-) of Ⅳ,two mercury(Ⅱ) ions and two bridging iodide ions form a coplanar quadrangle,the other four iodide ions are located on the both side of the coplanar quadrangle. In the crystal packings of compounds Ⅲ and Ⅳ,2D supramolecular layers and 3D supramolecular frameworks are formed via intermolecular weak interactions(including C—H···I hydrogen bonds,I···π interactions and π-π interactions). Additionally,the fluorescence emission spectra of compounds Ⅰ-Ⅳ showed that the heavy atom effects were not found in compound Ⅲ or Ⅳ after the addition of mercury(Ⅱ)ions into compound Ⅰ or Ⅱ.