An antibacterial Co(II) mononuclear compound containing N,N-bis(3,5-dichlorosalicylidene)hydrazine obtained from 3,5-dichlorosalicylaldehyde thiosemicarbazone in hydrothermal conditions

A mononuclear compound, [Co(L1)₂(H₂O)]·2H₂O (1), where L1 = N,N-bis(3,5-dichlorosalicylidene)hydrazine, was synthesized under hydrothermal conditions. Note that L1 is derived from the hydrothermal in situ reaction of L2 (L2 = 3,5-dichlorosalicylaldehyde thiosemicarbazone). L2 is prepared by reflux using 3,5-dichlorosalicylic aldehyde and thiosemicarbazide. Although 1 is only a mononuclear structure coordinated with L1, intermolecular hydrogen-bonded interactions between two adjacent mononuclear units creates a 1D supramolecular chain. Furthermore, it self-assembles into a fascinating 2D supramolecular layer via π⋅⋅⋅π stacking between benzene rings of adjacent chains. Hirshfeld surfaces and fingerprint maps of 1 were applied to obtain data on non-covalent interactions. Antibacterial analysis shows that 1 is a potential antibacterial material and the bacteriostasis rate is higher than that of L1 (E. coli: 89.41% for 1, 29.09% for L1; MRSA: 93.17% for 1, 38.54% for L1). The solid and liquid photoluminescence properties of 1 and L1 were also investigated.