Manganese(II) and cobalt(II) complexes based on pyridyl diimide: in situ ligand formation, crystal structures, and sorption properties

Two complexes, namely {[Mn(L1)2(H2O)2]·0.5H2O} n (1) and {[Co(L2)(H2O)2]·4H2O} n (2), (L1,1,3-dioxo-2-pyridin-3-ylmethyl-6-[(pyridin-3-ylmethyl)-carbamoyl]-2,3-dihydro-1H-isoindole-5-carboxylic acid; L2,2,5-bis-[(pyridine-3-yl methyl)-carbamoyl]-terephthalic acid), were synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and X-ray single-crystal structure analysis. The ligands HL1 and HL2 were formed in situ by the hydrolysis of N,N′-bis(3-pyridylmethyl)-pyromellitic diimide (L). Apparently, Mn2+ acts as an asymmetric catalyst, such that a new asymmetric pyridinecarboxylate derivative ligand L1 is formed, while Co2+ acts as a symmetric catalyst, giving the pyridinedicarboxylate derivative ligand L2. Complex 1 has a 1D double-chain structure, in which the adjacent chains are arranged in parallel arrays through π···π interactions, resulting in a 2D supramolecular framework. Complex 2 has a grid (4,4)-sql net structure in an edge-to-edge arrangement through hydrogen bonds between adjacent layers, forming a 3D supramolecular framework containing 1D channels to accommodate water guest molecules. The thermal stabilities of both complexes and ethanol adsorption properties of complex 2 were investigated. 1D double-chain Mn(II) complex (1) and 2D (4,4) net Co(II) complex (2) were synthesized. The Mn2+ ions have the asymmetric catalysis property, and a new asymmetric pyridinecarboxylates derivative ligand is formed; the Co2+ ions have symmetric catalysis property, giving the pyridinedicarboxylates derivative ligand. The complex 2 allows for stepwise sorption of ethanol.