Formation of a new CuII-triazole ester complex from 1,2-cyclohexanedione-bis(p-bromobenzohydrazone) compound as a consequence of copper(II)-catalyzed click reaction

Reaction of 1,2-cyclohexanedione-bis(p-bromobenzohydrazone) (CBB) as a bis-aroyl-hydrazone derivative with copper(II) nitrate trihydrate in acetonitrile under ambient conditions produced a mononuclear Cu(II) complex [Cu(TE)(NO3)(2)] (TE: triazole-ester) (1). TE is an intermediate which is formed in situ during the oxidation of CBB by Cu(II) ion based on so-called copper(II)-catalyzed click reaction. CBB and 1 are characterized with various techniques. On the basis of single-crystal X-ray crystallography, compound 1 is confirmed as a 4-coordinate mononuclear Cu(II) complex with a distorted square planner geometry. In this compound, copper is bound to the 1-N of two monodentate triazole ester molecules and two monodentate nitrate ions. Moreover, the antimicrobial activity of CBB and 1 against some selected pathogenic bacteria was investigated. Due to this study, these compounds showed a good antibacterial activity. In addition, the Hirshfeld surface analysis (d(norm) surface and two-dimensional fingerprint plots) was performed to reveal the nature of intermolecular interactions in CBB and 1. The most important contributions for the crystal packing of CBB are mainly from H horizontal ellipsis H (28.8%), Br horizontal ellipsis H/H horizontal ellipsis Br (23.2%) and C horizontal ellipsis H/H horizontal ellipsis C (19.5%) interactions, while the most important contributions for the crystal packing of 1 are found to be from H horizontal ellipsis H (27%), O horizontal ellipsis H/H horizontal ellipsis O (23.7%) and Br horizontal ellipsis H/H horizontal ellipsis Br (19%) interactions.

Automated summary

In this study, reaction between 1,2-cyclohexanedione-bis(p-bromobenzohydrazone) (CBB) and copper(II) nitrate trihydrate in acetonitrile at ambient conditions resulted in a mononuclear Cu(II) complex with distorted square planner geometry. The synthesized compound showed good antimicrobial activity against selected pathogenic bacteria. Analysis of crystal packaging using Hirshfeld surface analysis revealed the nature of intermolecular interactions in CBB and the Cu(II) complex.