Syntheses, Characterizations And Properties Of Metal (Ⅱ) 2-Hydroxyacetophosphonate Coordination Polymers

Metal phosphonate coordination polymers have attracted a great deal of research interest due to their structural diversities and many potential applications in catalysis, ion exchange, intercalation chemistry, absorption, proton conduction, photochemistry, and so on.In this work, we have devoted effort toward hydrothermal synthesis of metal phosphonate coordination polymers by using 2-hydroxyphosphonoacetic acid with chiral groups as chiral building units to obtain possible new types of materials with potential applications. Sixteen novel metal phosphonate coordination polymers are hydrothermally synthesized by using direct reaction or organic-amine as template agent, and characterizally characterized by using X-ray single-crystal diffraction, X–ray powder diffraction, IR spectroscopy and thermogravimetric analysis. Meanwhile, surface photovoltage and magnetic properties of compound 16 have also been studied.Ten kinds of metal and three kinds of organic templates, including ethylenediamine (en), 1,4-butylenediamine (bn) and pyrazine (pz) were used in the synthesis of metal phosphonate coordination polymers. In the structure of these compounds, the MOn (M = metal, n = the number of oxygen atoms) polyhedral are bridged and chelated by the oxygen atoms from the functional groups of the 2-hydroxyphosphonoacetic acid ligands, resulting in the formation of one-dimensional chain, two-dimensional layer and three-dimensional open-framework. The chemical constitution formulas are listed as follow: (1) Ni[(HO₃PCH(OH)CO₂)(H₂O)₂] (2) Cu[(HO₃PCH(OH)CO₂)(H₂O)]·2H₂O (3) Mg[(HO₃PCH(OH)CO₂)(H₂O)₂] (4) Sr[(HO₃PCH(OH)CO₂)(H₂O)₂] (5) Cd2[(HO₃PCH(OH)CO₂)₂(H₂O)₃]·4H₂O (6) [pzH₂]_0.5Co[(O₃PCH(OH)CO₂)(H₂O)]·1.5H₂O (7) [pzH₂]_0.5Ni[(O₃PCH(OH)CO₂)(H₂O)]·1.5H₂O (8) [pzH₂]_0.5Zn[(O₃PCH(OH)CO₂)(H₂O)]·1.5H₂O (9) [enH₂]_0.5Zn[(O₃PCH(OH)CO₂)(H₂O)]·H₂O (10) Ca_2.5[(HO₃PCH(OH)CO₂)(O₃PCH(OH)CO₂)(H₂O)]·2H₂O (11) Ba[HO₃PCH(OH)CO₂] (12) [enH₂]_0.5Zn₅[(HO₃PCH(OH)CO₂)(O₃PCH(OH)CO₂)3(H₂O)₂]·3H₂O (13) [bnH₂]_0.5Zn_2.5[(O₃PCH(OH)CO₂)₂(H₂O)] (14) [bnH₂]_0.5Mn_2.5[(O₃PCH(OH)CO₂)₂(H₂O)] (15) [enH₂]_0.5Cd₂[(HO₃PCH(OH)CO₂)(O₃PCH(OH)CO₂)] (16) [enH₂]_0.5Mn₂[(HO₃PCH(OH)CO₂)(O₃PCH(OH)CO₂)]Compounds 1–5, 10, 11 are obtained by the direct reaction, and the single-crystal X-ray diffraction analysis shows that the compounds 1, 2 are one-dimensional chain structure, compounds 3–5 form two-dimensional layer structure, and compounds 10, 11 feature three-dimensional open-framework structure. Compounds 6–9 and 12–16 are synthesized by using organic-amine as template agent, X-ray diffraction analysis shows that the compounds 6–9 are a two-dimensional layer structure, and compounds 12–16 feature a three-dimensional open-framework structure. Notably, compounds 12–14 can be described as a 3D open–framework with nano–channels, compound 15 can be described as a 3D open–framework with double helical channels, while compound 16 can be described as a 3D heterochiral coordination polymer with double helical channels, which can be obtained by spontaneous resolution from the racemic phosphonic acid.X–ray powder diffraction analysis shows that compound 16 is a pure phase. Surface photovoltage spectroscopy (SPS) of compound 16 indicates that it possesses positive SPV response in the range of 300–600 nm and shows p–type semiconductor characteristic. Magnetic susceptibility studies of compound 16 reveal that there exist weak antiferromagnetic interactions between the metal centers.