Self-assembled carboxylate complexes of zinc, nickel and copper

A metallo-organic hybrid acid namely tetra-aquo bis-4-carboxy-N-phthaloylglycinato zinc(II) dihydrate is prepared and characterised. In this complex the hydrogen bonding by free carboxylic acid group and π–π interactions between the rings in crystal lattice contributes to the formation of self-assembled structure. A monomeric nickel complex from 2-carbomethoxy benzoic acid (L2H) and pyridine [Ni(L2)(py)3(H2O)2]L2 is prepared (where py = pyridine). This complex has ionic as well as monodentate carboxylates. It forms self-assembly by C–H⋯π as well as hydrogen-bonding interactions. The 2-carbomethoxy benzoic acid (L2H) forms dimeric copper complex [Cu2(L2)4(H2O)2]2H2O which has an extended chain structure through hydrogen-bond interactions.