An indirect generation of 1D M(II)-2,5-dihydroxybenzoquinone coordination polymers, their structural rearrangements and generation of materials with a high affinity for H2, CO2 and CH4

Abstract

A series of solid-state structural transformations are found to accompany desolvation of relatively simple coordination polymers to yield materials that exhibit unexpected gas sorbing properties. Reaction of 1,2,4,5-tetrahydroxybenzene with M(II) salts (M = Mg, or Zn) in an alcohol/water solution in the presence of air affords cis-M(II)(C6H2O4(-II))(H2O)2·2H2O·xROH, (M = Mg, or Zn), crankshaft-like chains in which the absolute configurations of the chiral metal centres follow the pattern Δ Δ Λ Λ Δ Δ Λ Λ, and are hydrogen bonded together to generate spacious channels. When crystals of the crankshaft chain are air dried the crystals undergo a single crystal-to-powder rearrangement to form linear trans-M(II)(C6H2O4(-II))(H2O)2 chains. Further dehydration yields microporous solids that reversibly sorb H2, CH4 and CO2 with high sorption enthalpies.