Solid-state structure and antimicrobial and cytotoxicity studies of a cucurbit[6]uril-like CuL constructed from 3,5-bis[(1H-tetrazol-5-yl)methyl]-4H-1,2,4-triazol-4-amine.

3,5-Bis[(1H-tetrazol-5-yl)methyl]-4H-1,2,4-triazol-4-amine (HL) associates under deprotonation with CuSO in aqueous medium to form a new waisted barrel-shaped ML cluster, namely hexaaquatetrakis{μ-3,5-bis[(1H-tetrazol-5-yl)methyl]-4H-1,2,4-triazol-4-amine}-μ-sulfato-hexacopper(II) sulfate hydrate, [Cu(SO)(CHN)(HO)]SO·nHO (n = ∼23) (1). Cluster 1 resembles concave cucurbit[6]uril and has one disordered sulfate anion trapped inside the cage, which additionally stabilizes the Cu unit. The Cu ions have either a square-pyramidal or a distorted octahedral geometry. The equatorial positions are filled by N atoms from the L ligand, while the axial positions are occupied by coordinated water molecules and O atoms of the sulfate counter-ion. In the solid state, the Cu clusters are connected through a large number of hydrogen bonds formed by uncoordinated water molecules and an additional sulfate anion. The compound shows good antimicrobial activity against E. coli tested with the Kirby Bauer approach. In addition, the cell viability towards HeLa and L-929 cells was studied.