Synthesis And Antifungal/antibacterial Activities Of Benzotriazole Azo Derivatives

Benzotriazole heterocycles containing nitrogen atom exhibit a variety of biological properties,including medicinal,insecticidal and fungicidal activities.In addition,phenol and aniline derivatives show good antifungal activities.In the present paper,we wanted to prepare a series of benzotriazole-azo derivatives by combination of the phenol or aniline moiety with benzotriazole together.Their antifungal and antibacterial activities were tested against phytopathogenic fungi and bacteria.Some results were obtained as follows:1.By using 4-nitro-o-phenylenediamine as a starting material,5-aminobenzotriazole was obtained through the cyclization and reduction reactions.Then in the presence of hydrochloric acid and sodium nitrite,the corresponding diazonium salt was produced from5-aminobenzotriazole.Finally,twenty-six benzotriazole-azo derivatives were given by coupling reaction of the phenol or aniline moiety with the diazonium salt.Among them,twenty-two derivatives were new compounds,and the target compounds were all confirmed by ¹H NMR,IR and melting points.2.The antifungal activities of twenty-eight compounds?including two intermediates?were tested at 100?g/mL against six phytopathogenic fungi,such as Valsa mali,Fusarium graminearum,Fusarium solani,Botrytis cinerea,Alternaria alternate and Curvularia lunata.The results showed that compounds 9f,9o,9p,and 9s exhibited significant antifungal activities;especially against A.alternate and C.lunata,the above four compounds showed more potent antifungal activities than the positive control carbendazim.Particularly,compound 9f showed the significant inhibitory effect on B.cinerea with the EC₅₀0 value of21.25?g/mL.3.The inhibitory activity of twenty-eight compounds against C.lunata was also evaluated by using inhibition of spore germination.The results showed that compounds 9f,9j,9k,9m,9o,9p,9r and 9s had significant inhibitory activity.And their EC₅₀0 values were all less than 30?g/mL;especially compound 9k showed the most promising activity with the EC₅₀0 value of 8.91?g/mL.4.The bacterial inhibitory activities of twenty-eight compounds were determined by the tube disc method.However,all compounds had no significant inhibitory activities against the tested bacteria.5.The control efficiency of some compounds against B.cinerea on tomato at 200?g/mL were further investigated.The protective effects of compounds 9m and 9s were all 72.8%,and the therapeutical effect of compound 9c was 70.7%.The preliminary SARs indicated that introduction of the tert-butyl into the benzotriazole-azo skeleton could lead to the potent compound;introduction of the electron-donating groups?e.g.,methyl,ethyl,methoxy,and hydroxyl?into the benzotriazole-azo skeleton could give potent compounds,which showed the excellent antifungal activity against C.lunata.It will pave the way for further research and development of these compounds as antifungal agents.