Structural Diversity and Magnetic Properties of Seven Coordination Polymers Based on the 2,2′-Phosphinico-dibenzoate Ligand

Seven novel coordination polymers based on 2,2'-phosphinico-dibenzoic acid (H3L), namely, {[Zn3L2(H2O)(4)]center dot 2H(2)O}(n) (1), [Zn3L2(4,4'-bipy)(2)](n) (2), [Zn(HL)(2,2'-bipy)(H2O)](n) (3), {[Cd9L6(H2O)(8)]center dot 4H(2)O}(n) (4), [Cd8L4(OH)(2)(OAc)(2)(4,4'-bipy)](n) (5), [Mn3L2(4,4'-bipy)(EtOH)(H2O)(2)](n) (6), and [Mn(HL)(2,2'-bipy)-(H2O)](n) (7), were synthesized under hydro(solvo)thermal conditions. These compounds crystallize in the triclinic P (1) over bar space group for 1, 4, 5, and 6, the monoclinic space group C2/c for 2, and the monoclinic P2(1)/c space group for 3 and 7. The L3- ligand displays versatile binding modes in 1-7. Compound 1 is a one-dimensional (1-D) chain coordination polymer with a three-dimensional (3-D) supramolecular framework. Compound 2 is a 3-D porous metal-organic framework (MOF) with two different 4,4'-bipyridine linkers. Compounds 3 and 7 show 1-D zigzag chain structures. Compound 4 exhibits a sophisticated 3-D MOF constructed from two types of Cd-8 clusters and one Cd-2 dimer, which is the first example exhibiting the coexistence of four coordination modes of L3- ligands and four geometries of Cd(II) ions in one network. Compound 5 displays a two-dimensional (2-D) network containing a ring-like Cd-8 cluster. Compound 6 shows a 2-D layered network with 4,4'-bipyridine linker. Their luminescence and variable-temperature magnetic property were investigated, which indicated ligand-centered emission in 1-5 and weak antiferromagnetic coupling between Mn(II) ions in 6 and 7.