New Heterometallic Hybrid Polymers Constructed with Aromatic Sulfonate-Carboxylate Ligands: Synthesis, Layered Structures, and Properties

Three novel alkali metal–cadmium coordination polymers [K₂Cd­(Hsb)₄(H₂O)₆]_3<i>n</i> <b>1</b>, [NaCd­(sip)­(DMF)₂(H₂O)₂]_2<i>n</i> <b>2</b>, and [NaCd₂(sip)₂(DMF)₂(H₂O)₂]_2<i>n</i>·2<i>n</i>Hdeta·2<i>n</i>H₂O <b>3</b> (H₂sb = 4-sulfobenzoic acid, H₃sip = 5-sulfoisophthalic acid) have been synthesized and characterized by single crystal X-ray diffraction and spectroscopic and thermogravimetric methods. The solid state structure of <b>1</b> consists of inorganic layers, formed from Na₂O₁₀ and CdO₆, polyhedral units, bridged via the sulfonate site of the ligand. The layers are pillared by the organic portions of the ligands to form a three-dimensional framework classified as I²O¹. Compounds <b>2</b> and <b>3</b> display inorganic–organic hybrid layers arranged in 3D via nonspecific (hydrophobic) interactions between the DMF ligands. The two-dimensional frameworks of the layers are classified as I¹O¹ (in <b>2</b>) and I⁰O² (in <b>3</b>). The guest diethylammonium ions in <b>3</b> are arranged in hydrophobic channels along the [011] crystallographic direction and circumvented by the DMF ligands