Cobalt(II)‐dianthracene Frameworks: Assembly, Exfoliation and Properties

Metal‐organic frameworks containing responsive organic linkers are attractive for potential applications in sensors and molecular devices. Herein we report three cobalt(II) phosphonates incorporating responsive dianthracene linkers, namely, Co2(amp2H2)2(H2O)4 ⋅ 6H2O (MDAF‐1), Co2(amp2)(H2O)4 ⋅ 2H2O (MDAF‐2) and Co(amp2H2) ⋅ 2H2O ⋅ 0.5DMF (MDAF‐3), where amp2H4 is pre‐photodimerized 9‐anthrylmethylphosphonic acid. MDAF‐1 shows a layer structure in which dinuclear Co2(PO3H)2 units are inter‐connected by dianthracene ligands. In MDAF‐2 and MDAF‐3, inorganic chains of corner‐sharing {CoO4} (or {CoO6}) and {PO3C} are cross‐linked by dianthracene ligands into 3D frameworks. All compounds underwent thermo‐induced phase transitions, first the de‐solvation and then the de‐dimerization of dianthracene (as well as the release of the remaining solvent molecules for MDAF‐2 and ‐3), associated with magnetic changes. MDAF‐1 can be exfoliated into single‐layer nanosheets in water which show light‐triggered luminescent changes. Three Co‐MOFs containing dianthracene‐phosphonate linkers are reported showing 2D layer or 3D framework structures. They undergo thermo‐induced transitions, first de‐solvation and then de‐dimerization of dianthracene associated with magnetic changes. The layer compound can be exfoliated in water forming nanosheets which show light‐triggered luminescence changes.