Characterization and properties of layered tetragonal metal phosphonates with Sulfoethyl and Sulfophenyl groups

Abstract

A set of five layered tetravalent metal phosphonates, zirconium 2-sulfoethylphosphonate, titanium and tin 4-sulfophenylphosphonates, and mixed titanium and tin 4-sulfophenylphosphonate-phosphates, were prepared and characterized. All compounds are layered, their inorganic part is similar to that of α‑zirconium hydrogen phosphate with the sulfophenyl or sulfoethyl groups jutting out of the layers into the interlayer space. Their basal spacing and the amount of water in the interlayer space depends on the relative humidity of the atmosphere. All these compounds are able to interact with basic compounds. Ionic conductivity of zirconium 2-sulfoethylphosphonate, titanium and tin 4-sulfophenylphosphonate strongly depends on relative humidity. The charge carriers are protons and their movement is governed by a Grotthuss mechanism.