Chemical preparation, thermal behavior, magnetic properties and biological activities of a new manganese chloride templated by piperazine (C4H12N2)[MnCl4(H2O)2]

The manganese chloride complex (C4H12N2)[MnCl4(H2O)2] features a unique crystalline structure with hydrogen-bonded anionic and cationic entities. It shows notable thermal stability, paramagnetic behavior, and significant antioxidant and antibacterial activities. The compound’s ability to inhibit pathogenic bacteria highlights its potential as a novel antimicrobial agent. [Display omitted] •(C4H12N2)[MnCl4(H2O)2] crystallizes in P-1 space group.•It decomposes in three steps giving rise to Mn2O3 and Mn3O4.•It is paramagnetic with weak antiferromagnetic interactions.•It exhibits significant biological activities. In this work, we study a new manganese chloride templated by piperazine with the general formula (C4H12N2)[MCl4(H2O)2] that exhibits interesting properties and biological activities. The crystalline structure of (C4H12N2)[MnCl4(H2O)2] consists of anionic and cationic entities bound together by hydrogen bonds. The anionic part of this complex is formed by the diaquatetrachloromanganate(II) octahedra [MnCl4(H2O)2]2−, while the cationic part is composed of an organic component (protonated piperazine (C4H12N2)2+). The thermal behavior of (C4H12N2)[MnCl4(H2O)2] was studied by TGA (thermogravimetric analysis) between 50 and 860 °C under flowing air and by DSC (differential scanning calorimetry) in the temperature range of 25–400 °C, with a heating rate of 10 °C min−1. The title compound decomposes in three steps leading to the formation of manganese oxides, Mn2O3 and Mn3O4. The magnetic measurements indicate that (C4H12N2)[MnCl4(H2O)2] is predominantly paramagnetic with weak antiferromagnetic interactions between the Mn2+ centers, which presents five single electrons and adopts the high spin state. Regarding its biological activities, (C4H12N2)[MnCl4(H2O)2] exhibited a significant antioxidant capacity as measured by the DPPH assay. Additionally, in response to the urgent need for new antimicrobial drugs due to growing antibiotic resistance, the title compound was further evaluated for its antibacterial activity through the well diffusion test followed by the microdilution method. Bacterial growth inhibition and MBC/MIC determinations demonstrated the efficacy of (C4H12N2)[MnCl4(H2O)2] in killing various pathogenic bacteria. These findings highlight the significant biological activities of the compound, particularly its potential capacity to combat resistant bacteria.