Discrete Molecular Aggregates Based on ZnII and SbIII/V Ions Displaying Efficient Antibacterial and Antioxidant Properties

The reactions of [Zn3Cl2(3,5-Me2PzH)4(t-BuPO3)2] with organostibonic acid in varying reaction conditions have been investigated. Single-crystal X-ray diffraction studies reveal the formation of [Zn2(p-ClC6H4Sb)2(O)2(OCH3)2(t-BuPO3)3(py)2] (1), [Zn2(p-ClC6H4SbV)4(SbIII)2(O)8(t-BuPO3H)4(t-BuPO3)2(py)2Cl2] (2), and [Zn2(RSb)4(O)4(OCH3)4(t-BuPO3)4(py)2], where R = p-ClC6H4 (3) and R = p-iPrC6H4 (4), respectively. Interestingly, in the synthesis of 2, complete dearylation of organoantimony moieties followed by C–F bond formation, a reduction from Sb (V) to Sb (III), and Sb···Cl weak intermolecular interactions have been observed. ESI-MS studies suggested that clusters 1–4 maintained their structural integrity in the solution state also. Solution NMR studies (1H, 31P, and 13C) support well the observed solid-state structures. 1–4 were tested for antibacterial activity using a microdilution assay. 1 and 4 showed the best activity with lower MIC values (0.78–6.25 μg/mL) against all the tested pathogens. The total antioxidant activity of 1–4 was evaluated through the phosphomolybdenum assay, which showed a total antioxidant activity ranging from 28.96 to 86.46 mg AAE/g compound with the ascorbic acid standard.