Synthesis, Characterization and Antimicrobial Activity Evaluation of the Polybenzimidazole Derivatives with Different Dicarboxylic Acid Moieties

A series of polybenzimidazole were synthesized by the solution polycondensation reaction of 3,3´-diaminobenzidine (DAB) with dicarboxylic acid derivatives. The synthesized polybenzimidazoles were characterized by using IR, 1H-NMR, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA and DSC studies showed that the polybenzimidazoles have good thermal stability and are generally amorphous in nature. Glass transition temperature (Tg) values were found to be in the range of 300-410 °C. This is the first detailed study to investigate antimicrobial activities of the polybenzimidazoles. The synthesized polybenzimidazoles have high antimicrobial activity compared to benzimidazole molecule. It was also found that they are more effective against bacterial species than fungal species. The polymers 2, 5, 6 and 7 showed remarkable activity against tested bacterial species (MIC = 32-500 μg/mL). Among these polymers, the polymers 6 and 7 having additional electronegative moiety have the highest activity against tested bacterial species.

一系列聚苯并咪唑通过3,3'-二氨基联苯胺（DAB）与二羧酸衍生物的溶液聚合缩合反应合成。所合成的聚苯并咪唑通过红外光谱（IR）、核磁共振氢谱（1H-NMR）、热重分析（TGA）和差示扫描量热法（DSC）进行表征。TGA和DSC研究表明，聚苯并咪唑具有良好的热稳定性，在本质上通常为非晶态。玻璃化转变温度（Tg）值发现处于300-410°C之间。这是首次对聚苯并咪唑的抗菌活性进行详细研究的文献。与苯并咪唑分子相比，合成的聚苯并咪唑展现出更高的抗菌活性。此外，发现它们对细菌比真菌更为有效。聚合物2、5、6和7对测试的细菌表现出显著活性（最低抑菌浓度MIC = 32-500 μg/mL）。在这些聚合物中，带有额外电子负性基团的聚合物6和7对测试的细菌表现出最高的活性。