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-G(2)BDS). p-G(2)BDS is obtained from its acetone solvate, AcMe@G(2)BDS, by single-crystal-to-single-crystal (SC-SC) desolvation, and exhibits a Type I low-temperature/pressure N-2 sorption isotherm (SA(BET)=408.7(2) m(2) g(-1), 77 K). SC-SC sorption of N-2, CO2, Xe, and AcMe by p-G(2)BDS 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-G(2)BDS is formally metastable relative to the "collapsed", nonporous polymorph, np-G(2)BDS, a sample of p-G(2)BDS survived for almost two decades under ambient conditions. np-G(2)BDS reverts to zCO(2)@p-G(2)BDS or yXe@p-G(2)BDS (y,z=variable) when pressure of CO2 or Xe, respectively, is applied.