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-G2 BDS). p-G2 BDS is obtained from its acetone solvate, AcMe@G2 BDS, by single-crystal-to-single-crystal (SC-SC) desolvation, and exhibits a Type I low-temperature/pressure N2 sorption isotherm (SABET =408.7(2) m2  g-1 , 77 K). SC-SC sorption of N2 , CO2 , Xe, and AcMe by p-G2 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-G2 BDS is formally metastable relative to the "collapsed", nonporous polymorph, np-G2 BDS, a sample of p-G2 BDS survived for almost two decades under ambient conditions. np-G2 BDS reverts to zCO2 @p-G2 BDS or yXe@p-G2 BDS (y,z=variable) when pressure of CO2 or Xe, respectively, is applied.