Design,Synthesis And Application Of Functional Compounds Containing Imidazole Ring

Imidazole derivative with a five-membered ring containing two different types of nitrogen atoms can be introduced functional groups in many positions and has been widely used in many fields.Imidazole molecule is used to produce coordination chemical reaction with specific metal by the intermolecular or intramolecular hydrogen bond,because it contains highly conjugated?bond,multiple nitrogen atoms and the active sites of identifying and integrating metal ions.Therefore,imidazole derivative can be used as a probe to effectively detect the concentration of heavy metal ions in water and industrial sewage.In addition,benzimidazole as a derivative of imidazole is the important component of many biomolecules.Benzimidazole contains imidazole ring and benzene ring,so that it has strong rigid plane and large conjugate structure,which is widely used in medicine,pesticide,etc.fields.Because its structure is similar to purine,benzimidazole can be used as an important competition inhibitor to substitute purine and block its biosynthesis to kill/inhibit the growth of bacteria.Therefore benzimidazole has good activity of antibacterial.The metal probes of imidazole analogues as an effective detection reagent can not only be used in daily life,but also be used to detect metal ions in vivo.In this paper,a metal probe of 1,2,4,5-tetrasubstituted imidazole?probe 2?was synthesized by solvent-free Debus one-pot reaction in which 4-bromobenzaldehyde,1,2-bis?4-bromophenyl?-ethane-1,2-dione,p-phenylenediamine and ammonium acetate were used as the starting materials and phosphotungstic acid was used as a catalyst.Probe 2 could effectively identify Fe³⁺ions under the conditions of absorption and fluorescence.At the same time,The stoichiometry ratio between probe2 and Fe³⁺ion was determined to 1:1 by Job's curve and TOF-MS.The absorption and fluorescence detection limits for detecting Fe³⁺in the solution were calculated.And on this basis Probe 2 was applied to the detection of of Fe³⁺ions concentration in the reservoir water and the lake water.The results showed that Probe 2 possessed highly selectivity and sensitivity.The infections caused by bacterial and fungal resulted in the high probability of death all the time.It was reported that benzimidazole analogues have good biological and drug activity.Especially,the antibacterial activity of 2-substituted benzimidazole is very well.Therefore,2,5-disubstituted benzimidazoles containing bromide substituent,thiophene ring and naphthalene ring were designed and synthesized in this paper,and obtained the excellent bactericidal effect.Firstly,the model compound2-pyridine-5-methyl-1H-benzimidazole was synthesized from 4-methyl-o-phenyl-enediamine and 3-pyridine formaldehyde,and the optimal reaction condition was determined.Seventeen 2,5-disubstituted benzimidazoles were synthesized under these conditions.As a result,it was found that the electron-donating group on o-phenylenediamine was beneficial to the nucleophilic addition of the amino groups to produce benzimidazole and resulted in the yield was increased.The synthesized 17benzimidazole compounds were characterized by FT-IR,HRMS,¹H NMR and ¹³C NMR.The antifungal and antibacterial activities of 17 benzimidazoles were tested by the 96 well plate dilution method with ciprofloxacin,itraconazole and fluconazole as positive controls.The results showed that benzimidazole substituted by naphthalene ring and thiophene ring had broad spectrum of antibacterial activity.In addition,the antibacterial ability of the compounds is highly significant when both thiophene ring and benzene ring contain bromosubstituted groups,which will provide a new idea for the development of antibiotics in the future.