First Hydrotalcite-like Sulfonate Coordination Network Incorporating Robust Cationic Layers and Flexible Interlayer Interactions

In this paper, a novel coordination network of d,l-homocysteic acid with strontium chloride is reported. This compound exhibits an infinite microporous multilayered structure, describable as one-dimensional coordination-based microtubes cross-linking into cationic layers. Chloride anions are intercalated between layers to neutralize the charge, and the layers further pack into a three-dimensional solid via electrostatic interactions and hydrogen bonding. Thermogravimetric analysis (TGA), variable-temperature Fourier transform infrared spectroscopy (FT-IR), and powder X-ray diffraction (XRD) are presented to extensively study the structure. Results show that the compound is stable up to 326 °C. Below this temperature, the layered structure is sustained in the process of the reversible loss/gain of coordinated water, confirming that the network involves a robust coordination-based cationic layer framework but rather flexible interlayer interactions. This compound and its analogies are expected to have potential applications in anion exchange and gas storage.