Variable architectures of Zinc coordination polymers modeled by tetra-pyridine ligands with different anions

Abstract

Solvothermal reactions of tetrakis(4-pyridyloxymethyl)methane (TPOM) and tetrakis(3-pyridyloxymethyl)methane (TPOM2) with different counter-anions (Cl -, deprotonated benzoate (L1) and 1,4-benzenedicarboxylic acid (L2)) in the presence of zinc ions under different synthesis temperatures produced six new coordination polymers (CPs), namely, {[Zn 2 (TPOM2) 2 (Cl) 4 ]} n (1), {[Zn 2 (TPOM2)(L1) 4 ]·4H 2 O} n (2), {[Zn 4 (TPOM2) (L2) 4 ]·DMF·4H 2 O} n (3), {[Zn(TPOM)(Cl) 2 ]} n (4), {[Zn 2 (TPOM)(L1) 4 ]·2H 2 O} n (5), and {[Zn 2 (TPOM)(L2) 2 ]·4H 2 O} n (6). These complexes were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Complexes 1, 2 and 4 reveal 1D crystal structures with novel 2,2,4-connected 3-nodal, 2 2,4-connected 2-nodal and 2,2-unidonal topology constructed from the connection of Zn centers and tetra-pyridine ligands, which were further neutralized by the mono-dentate Cl - and L1 ligands coordinated to the Zn ions. In contrast, complex 5 exhibits a two-fold interpenetrating 2D structure with a novel 2,2,4-connected 3-nodal net. Interestingly, complex 3 exhibits a distinct 3D framework constructed by the connection of typical neutral {Zn 2 (L2) 2 } n square-grid and 4-connected TPOM2 ligands, compared to the distinct 3D structure of 6. Structural results for these complexes show that the different counter-anions play an important role in constructing CPs with flexible ligands. © The Royal Society of Chemistry 2012.