Synthesis, crystal structures and luminescent properties of nickel (II) and copper (II) hexaazamacrocyclic compounds with 1,3,5-benzenetricarboxylate ligands

Two new nickel (II) and copper (II) hexaazamacrocyclic compounds {[Ni(L1)(Hbtc)]·3H2O}n (1) and [Cu(L2)(H2btc)2] (2) (L1 = 1,3,6,9,11,14-hexaazatricyclo [12.2.1.16,9]octadecane, L2 = 3,10-bis(2-hydroxyethyl)-1,3,5,8,10,12-hexaazacycltetradecane, and H3btc = 1,3,5-benzenetricarboxylic acid), have been synthesized and structurally characterized. In 1 and 2, each metal (II) ion is six-coordinated with four nitrogen atoms from the hexaazamacrocycle and two oxygen atoms from the 1,3,5-benzenetricarboxylate ligands. The Ni (II) ions in the complex 1 are bridged by the Hbtc2− anions to form an infinite 1D chain. Hydrogen bonding interactions further link these chains to form a 3D supramolecular architecture. The crystal structure of complex 2 is centrosymmetric and the Cu(II) ion has an axially elongated octahedron geometry. Each [Cu(L2)(H2btc)2] unit extends its structure to form a 3D supramolecular structure based on π–π stacking and hydrogen bonding interactions. In addition, their luminescent properties have been investigated in the solid state.

► Two new hexaazamacrocyclic Ni(II) and Cu(II) compounds containing H3btc ligand have been synthesized.
► Crystal structures of Ni(II) and Cu(II) compounds indicated a distorted octahedral geometry.
► The different metal ions and organic ligands have significant effects on the final complexes.
► The photoluminescent properties of complexes 1 and 2 are measured.