Syntheses and characterizations of four mixed-ligand hydrogen bonding supramolecular architectures with different structural motifs

Abstract

The reactions of 4-aminobenzoic acid (4-abaH), 4,4′-bipyridine (4,4′-bipy) and transitional metal ions (Zn II, Mn II and Cu II) gave rise to four supramolecular architectures, namely, [(4-abaH) 2(4,4′-bipy)] ( 1), {[Zn 2(4,4′-bipy) 2(4-aba) 4] (H 2O) 5} n ( 2), {[Mn(4,4′-bipy) 2(H 2O) 4] (4-aba)Br(H 2O) 3} ( 3) and {[Cu 2(4,4′-bipy) 3(H 2O) 2(4-aba) 2](NO 3) 2(H 2O) 4} n ( 4). Their crystal structures were determined by X-ray diffraction and show different structural motifs. 1 is a one-dimensional hydrogen bonding ladder constructed by 4-abaH and 4,4′-bipy. In 2, 4,4′-bipy bridges Zn(4-aba) 2 units forming a one-dimensional zigzag chain, which is extended into a three-dimensional framework by crystalline water molecules through hydrogen bonding interactions. Three-dimensional network of 3 is constructed by mononuclear [Mn(4,4′-bipy) 2(H 2O) 4] 2+ cations, neutral crystalline water molecules, and 4-aba and Br − anions through extensive hydrogen bonding and π–π interactions. However, one-dimensional ladder formed by 4,4′-bipy and Cu(4-aba) units in 4 is extended into a three-dimensional architecture through interpenetration of the lateral 4-aba arms into squares of the adjacent Cu–(4,4′-bipy) ladders and extensive hydrogen bonding interactions.