Synthesis And Characterization Of Benzimidazole And Their Complexes

The benzimidazole derivatives are special nitrogen-containing heterocyclic compounds, which have found wide application in such fields as catalysis, medicine and materials. In this paper, a series of2-benzoimidazole compounds,1,co-alkylene bis (2-substituted benzimidazole)s and benzimidazolyl-carboxylic acids, were designed and synthesized, and the optimal synthesis method was established. Meanwhile, several coordination complexes were constructed by the reaction of alkyl dicarboxylic acid and1, ω-alkylene bis (2-substituted benzimidazole) compounds with transition metal salts under ambient temperature and hydrothermal condition. These molecules have been characterized by the aid of elemental analysis, IR spectrum, NMR, thermogravimetric analysis. The paper is divided into five parts:1. We make a brief introduction of the synthesis and application research of benzimidazole compounds, as well as their metal complexes applied in the medicine and biological activity. Then, we illustrate the significance of the topic.2. Eight kinds of2-substituted benzimidazole compounds were designed and synthesized. Among them, there are four2-alkyl benzimidazole compounds: benzimidazole (L1),2-methyl benzimidazole (L2),2-chloromethyl benzimidazole (L3),2-ethyl benzimidazole (L4); the others are four2-phenyl benzimidazole group compounds:2-(2’-hydroxy phenyl) benzimidazole (L5),2-(3’-hydroxy phenyl) benzimidazole (L6),2-(4’-hydroxy phenyl) benzimidazole(L7),2-(4’-bromine phenyl) benzimidazole (L8). According to the study of the impact of different reaction conditions on the yield, we established the best synthetic scheme. Finally, we analyzed the experiment results.3. By the reaction of imidazole, L1, L2, L4with1,3-dibromopropane,1,4-dibromobutane, seven benzimidazole compounds were synthesized: 1,3-bis(1H-benzo[d]-imidazol-l-yl)propane(L9),1,3-bis(2-methyl-l H-benzo[d]imid-azol-1-yl)propane(L10),1,3-bis(2-ethyl-1H-benzo[d]imidazol-1-yl)propane(L11),1,4-(2-imidazole-l-yl)butane(L12),1,4-bis(1H-benzo[d]imidazol-l-yl)butane(L13),1,4-bis(2-methyl-1H-benzo[d] imidazol-1-yl)butane(L14),1,4-bis(2-ethyl-1H-imidazol-1-yl)butane(L15). The yield of these seven compounds reached70%. The molecular structures of these compounds were characterized by nuclear magnetic resonance (NMR) spectroscopy.4. Seven benzimidazolyl-carboxylic acid compounds were synthesized and characterized:2-(benzimidazol-l-yl)-acetic acid (L16),2-(2-methyl benzimidazol-l-yl)-acetic acid (L17),3-(benzimidazolyl) propionic acid,3-(imidazole-l-yl) propionic acid (L18),3-(benzimidazol-l-yl) propionic acid (L19),3-(2-methyl benzimidazol-1-yl) propionic acid (L20),3-(2-ethyl benzimidazol-1-yl) propionic acid (L21), and3-(2-methyl benzimidazol-1-yl) propionic acid (L22)-The experiment results were and discussed accordingly.5. The bisbenzimidazole compounds presented good coordination property. Under the room temperature and hydrothermal condition, three metal complexes were obtained by assembling reaction of transition metal salts with1,3-bis(1H-benzo[d]-imidazol-l-yl) propane(L9). The structure of the CoCl2complex with1,3-bis(1H-benzo[d]-imidazol-l-yl) propane (M1) was determined by X-ray diffraction. In the complex M1, the central ion Co(II) was tetrahedral geometry. A ligand molecule connected two Co(II) ion to form ID helix chain structure.