Amine-Controlled Assembly of Metal Sulfite Architecture from 1-D Chains to 3-D Framework

摘要

While open-framework materials have been made in a variety of chemical compositions, few are known in which three-connected SO3²⁻ anions serve as basic building units. Here we report four new metal sulfite polymeric structures, (ZnSO3)Py (>1, py = pyridine), (ZnSO3)2(2,2′-bipy)H2O (>2, 2,2′-bipy = 2,2′-bipyridine), (ZnSO3)2(TMDPy) (>3, TMDPy = 4,4′-trimethylenedipyridine), and (MnSO3)2en (>4, en = ethylenediamine) that have been synthesized by hydrothermal method and structurally characterized. In these compounds, low-dimensional 1-D and 2-D inorganic subunits are assembled into higher 2- or 3-D covalent frameworks by organic ligands. In addition to the structure-directing effect of organic ligands, the flexible coordination chemistry of Zn²⁺ and SO3²⁻ also contributes to the observed structural diversity. In compounds >1–>3, Zn²⁺ sites alternate with trigonal pyramidal SO3²⁻ anions to form three types of [ZnSO3]n chains, whereas in compound >4, a 2-D corrugated [MnSO3]n layer is present. Compound >1 features a rail-like chain with pendant pyridine rings. The π-π interaction between 2,2′-bipy ligands is found between adjacent chains in compound >2, resulting in 2-D sheets that are further stacked through interlayer hydrogen bonds. Compound >3 exhibits a very interesting inorganic [(ZnSO3)₂]_n chain constructed from two chair-like subunits, and such chains are bridged by TMDPy ligands into a 2-D sheet. In compound >4, side-by-side helical chains permeate through 2-D corrugated [MnSO₃]_n layers, which are pillared by neutral ethylenediamine molecules into a 3-D framework that can be topologically represented as a (3, 6)-connected net. The results presented here illustrate the rich structural chemistry of metal sulfites and the potential of sulfite anions as a unique structural building block for the construction of novel open-framework materials, in particular, those containing polymeric inorganic subunits that may have interesting physical properties such as low-dimensional magnetism or electronic properties.