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 ](ClO 4 ) 2 ( 1 ), [Cd( L1 ) 2 Cl 2 ] ( 2 ), [Cu( HL2 )( L2 )]ClO 4 ( 3 ), [Cu( L2 ) 2 ] ( 4 ) and a dinuclear complex [Co 2 ( HL2 )( L2 )Cl 3 ] ( 5 ) comprising Co II 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.