Methyl-substituted 2-aminothiazole--based cobalt(II) and silver(I) complexes: synthesis, X-ray structures, and biological activities

Authors : Ezzat KHAN, Tufail AHMAD, Zarif GUL, Farhat ULLAH, Muhammad Nawaz TAHIR, Awal NOOR

Pages : 857-868

View : 13 | Download : 8

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :2-Aminothiazole derivatives bear three nucleophilic centers, i.e. endocyclic N, exocyclic NH$_{2}$, and S atom in the ring system. In addition to these centers there are $\pi$-electrons in the ring system which can also expectedly be involved in some sort of coordination. To the best of our knowledge the solid state coordination chemistry of such ligands has not been fully presented in the literature. These ligands insert ignore into journalissuearticles values(2-amino-4-methylthiazole and 2-amino-5-methylthiazole); were coupled with CoCl$_{2}$ under aerobic conditions to form tetrahedral complexes, bisinsert ignore into journalissuearticles values(2-amino-4-methylthiazole);dichlorocobaltinsert ignore into journalissuearticles values(II); insert ignore into journalissuearticles values(1); and bisinsert ignore into journalissuearticles values(2-amino-5-methylthiazole);dichlorocobaltinsert ignore into journalissuearticles values(II); insert ignore into journalissuearticles values(2);. Reaction of 2-amino-5-methylthiazole with AgNO$_{3}$ led to an expected two-coordinated, bisinsert ignore into journalissuearticles values(2-amino-5-methylthiazole);silverinsert ignore into journalissuearticles values(I); nitrate insert ignore into journalissuearticles values(3); as crystalline material. In all complexes the coordination behavior of the aminothiazole derivatives was identical, coordinating to the metal center through endocyclic N atom. The structures of these complexes were confirmed by single-crystal X-ray analysis. Compounds insert ignore into journalissuearticles values(1-3); were screened for their antimicrobial potency against gram-negative insert ignore into journalissuearticles values(E. sakazkii, E. coli, K. pneumoniae); and a gram-positive bacteria insert ignore into journalissuearticles values(S. aurus);. Additionally, their role as enzyme inhibitors insert ignore into journalissuearticles values(acetylcholinesterase, AChE, and butyrylcholinesterase, BChE); and their free radical scavenging ability insert ignore into journalissuearticles values(2,2-Diphenyl-1-picrylhydrazyl, DPPH, and 2,2`-azino-bisinsert ignore into journalissuearticles values(3-ethylbenzothiazoline-6-sulphonic acid, ABTS); were studied. These ligands bear additional nucleophilic centers insert ignore into journalissuearticles values(S and NH$_{2});$ and can be involved in secondary interactions as confirmed by their solid-state structures. These interactions make the molecules biologically important and thus play a pivotal role in establishing the supramolecular network. We report here the coordination chemistry and selected biological applications of complexes 1-3.
Keywords : 2 Aminomethylthiazole, cobalt complexes, enzyme inhibition, antimicrobial agents, antioxidant agents