High Inhibition for a CoII Tetrazole Bi‐pyrazole Dinuclear Complex against Fusarium Oxysporum f. sp. Albedinis

Abstract New coordination compounds made of two novel tetrazole and C,N‐bipyrazole ligands, 2‐(3,5,5′‐trimethyl‐1′H‐[1,3′‐bipyrazol]‐1′‐yl)acetonitrile (L1), and 1′‐((1H‐tetrazol‐5‐yl)methyl)‐3,5,5′‐trimethyl‐1′H‐1,3′‐bipyrazole (HL2), were prepared and fully characterized by spectroscopic techniques. Their crystal structures were identified by single‐crystal X‐ray diffraction revealing mononuclear complexes: [Ni(L1)3](ClO4)2 (1), [Cd(L1)2Cl2] (2), [Cu(HL2)(L2)]ClO4 (3), [Cu(L2)2] (4) and a dinuclear complex [Co2(HL2)(L2)Cl3] (5) comprising CoII ions in octahedral and tetrahedral surrounding within the same unit. Noticeably, 3 and 4 show different architectural structures due to ligand deprotonation as well as the effect of the counter anion. All compounds demonstrated antimicrobial activity against Gram (+) bacteria Listeria innocua and Staphylococcus aureus, as well as Gram (−) bacteria such as Escherichia coli and Pseudomonas aeruginosa, and antifungal activity against pathogenic fungi Geotrichum candidum, Aspergillus niger, and Penicillium crustosum. Interestingly, a high inhibition activity of 97 % was reached for 5 with a low concentration of only 81.1 μmol/L against Fusarium oxysporum f. sp. Albedinis, which is commonly damaging palm trees crops.