Post-synthetic modification (PSM) of the interpenetrated diamondoid metal-organic framework (Me 2 NH 2 )[In-(BDC-NH 2 ) 2 ](BDC-NH 2 = aminobenzenedicarboxylate) SHF-61 proceeds quantitatively in a single-crystal-to-singlecrystal manner to yield the acetamide derivative (Me 2 NH 2 )-[In(BDC-NHC(O)Me) 2 ] SHF-62. Continuous breathing behaviour during activation/desolvation is retained upon PSM, but pore closing now leads to ring-flipping to avert steric clash of amide methyl groups of the modified ligands. This triggers a reduction in the amplitude of the breathing deformation in the two dimensions associated with pore diameter, but a large increase in the third dimension associated with pore length. The MOF is thereby converted from predominantly 2D breathing (in SHF-61) to a distinctly 3D breathing motion (in SHF-62) indicating a decoupling of the pore-width and pore-length breathing motions. These breathing motions have been mapped by a series of single-crystal diffraction studies.

With the recent increase in research into ferroelectric, anti-ferroelectric and piezoelectric materials, studying the solid-state properties in situ under applied electric fields is vital in understanding the underlying processes. Where this behaviour is the result of atomic displacements, crystallographic insight has an important role. This work presents a sample environment designed to apply an electric field to single-crystal samples in situ on the small-molecule single-crystal diffraction beamline I19, Diamond Light Source (UK). The configuration and operation of the cell is described as well as its application to studies of a proton-transfer colour-change material.

Post‐synthetic modification (PSM) of the interpenetrated diamondoid metal–organic framework (Me2NH2)[In(BDC‐NH2)2] (BDC‐NH2=aminobenzenedicarboxylate) SHF‐61 proceeds quantitatively in a single‐crystal‐to‐single‐crystal manner to yield the acetamide derivative (Me2NH2)[In(BDC‐NHC(O)Me)2] SHF‐62. Continuous breathing behaviour during activation/desolvation is retained upon PSM, but pore closing now leads to ring‐flipping to avert steric clash of amide methyl groups of the modified ligands. This triggers a reduction in the amplitude of the breathing deformation in the two dimensions associated with pore diameter, but a large increase in the third dimension associated with pore length. The MOF is thereby converted from predominantly 2D breathing (in SHF‐61) to a distinctly 3D breathing motion (in SHF‐62) indicating a decoupling of the pore‐width and pore‐length breathing motions. These breathing motions have been mapped by a series of single‐crystal diffraction studies.