Selective Metal Cation Capture by Soft Anionic Metal–Organic Frameworks via Drastic Single-Crystal-to-Single-Crystal Transformations

Flexible anionic metal–organic frameworks (MOFs)
are transformed
into neutral heterobimetallic systems via single-crystal-to-single-crystal
processes invoked by cation insertion. These transformations are directed
by cooperative bond breakage and formation, resulting in expansion
or contraction of the 3D framework by up to 33% due to the flexible
nature of the organic linker. These MOFs displays highly selective
uptake of divalent transition-metal cations (e.g., Co2+ and Ni2+) over alkali-metal cations (Li+ and
Na+).