Metal−Organic Coordination Polymers Generated from Chiral Camphoric Acid and Flexible Ligands with Different Spacer Lengths: Syntheses, Structures, and Properties

A new family of coordination polymers, [{Cd(d-ca)(bte)}·H2O]n (1, d-H2ca = d-camphor acid, bte = 1,2-bis(1,2,4-triazol-1-yl)ethane), [Cd4(d-ca)4(btp)2(H2O)4]n (2, btp = 1,3-bis(1,2,4-triazol-1-yl)propane), [{Cd(d-ca)(btb)1.5}·3H2O]n (3, btb = 1,4-bis(1,2,4-triazol-1-yl)butane), [{Cd4(d-ca)4(bth)4}·2H2O]n (4, bth = 1,6-bis(1,2,4-triazol-1-yl)hexane), and [{Cd(d-Hca)2(bth)(H2O)}·H2O]n (5), have been prepared under hydrothermal conditions and characterized by elemental analyses, IR, thermogravimetric and X-ray structural analyses. The bis(triazole) ligands with different spacer lengths exhibit conformational flexibility and lead to the generation of diversified architectures. Complex 1 shows a two-dimensional (2D) rectangular network with (4,4) topology. Complex 2 displays the chiral three-dimensional (3D) framework with (32·4) (3·84·12) (83) (4·8·10) topology. The 2D honeycomb motif with one-dimensional (1D) nanosized channels is found in compound 3. Compound 4 is a 2D parallelogram sheet with (4,4) topology. Compound 5 shows a chiral 1D fish-bone chain, and the chains are further connected through hydrogen-bonding interactions to form a 3D supramolecular framework. Their luminescent, second-order nonlinear optical and ferroelectric properties have been investigated in the solid state.