Non-covalently generated 3D supramolecular crystal structure in a new family of hybrid nitrates templated by piperazine: Thermal behavior and in vitro antimicrobial potential

Three new hybrid nitrate materials based on transition metals and templated by piperazine, (C4H12N2)(3)[M-II(H2O)(6)](NO3)(8) with M-II: Mn (1), Cu (2) and Co (3) have been investigated and crystallo-graphically characterized. The single crystal X-ray diffraction study shows that the three complexes crystallize in the triclinic system, space group P (1) over bar. Within the adopted supramolecular structures, isolated entities [M-II(H2O)(6)](2)(+), NO3- and (C4H12N2)(2+) are held together through an extensive H-bonded system forming a three-dimensional network. The thermogravimetric analysis and temperature-dependent X-ray diffraction (TDXD) were used to follow the thermal behavior of the compounds. The TG analysis shows that, under heating, the precursors decompose into M2O3 via two steps: a dehydration followed by a total decomposition. The nature of the intermediate phases was studied using TDXD analysis. The orientation and strength of the non-covalent interactions binding the crystal, particularly the hydrogen bond network, were examined using density-functional theory (DFT) electron density and the non-covalent interaction (NCI) plot technique. The synthesized compounds were screened for antibacterial and antifungal activities against five Gram-positive, three Gram-negative bacteria and three fungi. (C) 2016 Elsevier Ltd. All rights reserved.