Solvent-controlled elongation and mechanochemical strain in a metal-organic framework

Under high pressure, crystals of [Zn(m-btcp)₂(bpdc)₂]·2DMF·H₂O, referred to as DMOF are particularly sensitive to the type of pressure-transmitting media (PTM) employed: large PTM molecules seal the pores and DMOF is compressed as a closed system, whereas small PTM molecules are pushed into the pores, thereby altering the stoichiometry of DMOF. Compression in glycerol and Daphne 7474 leads to negative linear compressibility (NLC), while a mixture of methanol : ethanol : water 'hyperfills' the pores of the chiral framework, adjusting its 3-dimensional strain and resulting in pressure-induced amorphization around 1.2 GPa. The uptake of the small-molecule PTM strongly increases the dimensions of DMOF in the direction perpendicular to that of the NLC of the crystal.