RESUMEN
Varying the length of phenanthrene-derived ligands switches the selective assembly of MIInLn metal-organic cages (MOCs, n = 6 or 8) between tetrahedral, square, or triangular architectures. The limit of this approach is explored for both Cu2 and Rh2 paddlewheel MOCs, and supported by solution, solid-state and computational analysis.
RESUMEN
Stimuli-responsive metal-organic frameworks (MOFs) exhibit dynamic, and typically reversible, structural changes upon exposure to external stimuli. This process often induces drastic changes in their adsorption properties. Herein, we present a stimuli-responsive MOF, 1·[CuCl], that shows temperature dependent switching from a rigid to flexible phase. This conversion is associated with a dramatic reversible change in the gas adsorption properties, from Type-I to S-shaped isotherms. The structural transition is facilitated by a novel mechanism that involves both a change in coordination number (3 to 2) and geometry (trigonal planar to linear) of the post-synthetically added Cu(i) ion. This process serves to 'unlock' the framework rigidity imposed by metal chelation of the bis-pyrazolyl groups and realises the intrinsic flexibility of the organic link.