Microporosity of a Guanidinium Organodisulfonate Hydrogen-Bonded Framework

Guanidinium organosulfonates (GSs) are a large and well-explored archetypal family of hydrogen-bonded organic host frameworks that have, over the past 25 years, been regarded as nonporous. Reported here is the only example to date of a conventionally microporous GS host phase, namely guanidinium 1,4-benzenedisulfonate (p-G₂BDS). p-G₂BDS is obtained from its acetone solvate, AcMe@G₂BDS, by single-crystal-to-single-crystal (SC-SC) desolvation, and exhibits a Type I low-temperature/pressure N₂ sorption isotherm (SA_BET=408.7(2) m² g⁻¹, 77 K). SC-SC sorption of N₂, CO₂, Xe, and AcMe by p-G₂BDS is explored under various conditions and X-ray diffraction provides a measurement of the high-pressure, room temperature Xe and CO₂ sorption isotherms. Though p-G₂BDS is formally metastable relative to the “collapsed”, nonporous polymorph, np-G₂BDS, a sample of p-G₂BDS survived for almost two decades under ambient conditions. np-G₂BDS reverts to zCO₂@p-G₂BDS or yXe@p-G₂BDS (y,z=variable) when pressure of CO₂ or Xe, respectively, is applied.