Structural diversity of Cu(II) compounds of Schiff bases derived from 2-hydroxy-1-naphthaldehyde and a series of aminobenzoic acid

Five novel Cu(II) metal–organic coordination polymers, [(CuL1)n] (1), [Cu2L22(Py)4] (2), [Cu(HL3)(DMF)2] (3), [Cu6L43(Py)6·H2O]n (4), [Cu6L43(Py)8(C10H8N2)2·8CH3OH]n (5) (H2L1 = N-2-hydroxy-naphthaldehyde-1-alkenyl-o-amino acid, H2L2 = N-2-hydroxy-naphthaldehyde-1-alkenyl-m-amino acid, H2L3 = N-2-hydroxy-naphthaldehyde-1-alkenyl-o-amino-terephthalic acid), have been synthesized and characterized by IR, elemental analysis, UV spectroscopy and single-crystal X-ray diffraction analyses. Complex 1 possesses helical chain structure, which are further assembled to form three-dimensional frameworks by π⋯π stacking interactions. Complex 2 and 3 exhibit dimeric and monomeric structure. Complex 4 is a novel two-dimensional layer structure based on two kinds of binuclear Secondary Building Units (SBUs), Cu2O2 and Cu2(CO2)4. Complex 5 exhibits a distorted zigzag chain by the alternate connectivity of L and bpy molecules. This result shows that the position of carboxylate groups play an important role in the formation of supramolecular networks.

► Five Cu(II) coordination compounds based on three novel Schiff bases were reported.
► They exhibit interesting structural diversity.
► The positions of carboxylate groups play an important role.