Tripodal imidazole frameworks: reversible vapour sorption both with and without significant structural changes

A series of tripodal imidazole frameworks (TIFs) are reported based on a tripodal, cavity-containing tris(imidazole) derivative. In the case of [Co3Cl6(1)(2)]center dot n(solvent) (TIF-1) which possesses a doubly interpenetrated framework structure, the material exhibits rigid, permanent porosity and selectively absorbs CO2. The non-interpenetrated [Co(1)(2)(H2O)(2)]Cl-2 center dot 4H(2)O (TIF-2) also absorbs gases and vapours fully reversibly exhibiting a reversible phase change in the process and considerable conditioning and hysteresis. The very highly hydrated [Co(1)(2)]Cl-2 center dot 22H(2)O (TIF-3) irreversibly dehydrates to the layered structure [Co(1)(2)]Cl-2 center dot H2O (TIF-4). A nickel analogue [Ni(1)(2)]Cl-2 center dot 22H(2)O (TIF-5) closely related to TIF-3 is also reported along with two isostructural, non-porous materials [MCl2(1)] (M = Mn, TIF-6; M = Cd, TIF-7) based on d(5) and d(10) Mn(II) and Cd(II). Some of the materials may be prepared by mechanochemical as well as solution based methods. We liken TIF-1 to a gas cylinder, TIF-2 to a sponge and TIF-3 to a fragile soda can that is crushed on emptying to give TIF-4.