A cobalt redox switch driving alcohol dehydrogenation by redox coupled molecular swing

Developing redox switches that not only perform specific mechanical movements but also drive important chemical reactions is important but a great challenge.Herein,we report a redox pair of cobalt species(Co^(Ⅲ)/Co^(Ⅱ))that switches through photo-dehydrogenation of alcohol and hydrogenation of azo-ligand.The cobalt species is equipped with a flexible azo-ligand containing two bulky planar substituents.A planar oxidated sate(Co^(Ⅲ)species)can be photo-reduced to a saddle-like reduced state(Co^(Ⅱ))with alcohol molecules as electron donors,and in turn the Co^(Ⅲ)species can be recovered with azo-ligand as oxidant under acidic surrounding.Both the redox states of the pair are isolated and characterized by single crystal X-ray diffraction.In the switching cycle,alcohol is oxidized to aldehyde by azo-ligand through proton coupled electron transfer and the cobalt complex acts as a redox catalyst.These results provide important insights into alcohol dehydrogenation catalyzed by redox complexes.

Successive magnetic ordering in two Co^(Ⅱ)-ladder metal-organic frameworks

Metal-organic frameworks showing successive magnetic ordering are far less common than inorganic compounds.Here,we report two metal-organic frameworks[Co^Ⅱ(ox)(bphy)·0.1(DMF)·0.1(Me OH)]n(1)and[Co3^Ⅱ(ox)3(bphy)2(DMF)2]n(2)comprised of zigzag and necklace Co^Ⅱ-ladders,respectively.Together with a previously reported compound[Co^Ⅱ(ox)(bphy)·0.2(DMF)]n(3)consisting of spiraling zigzag Co^Ⅱ-ladders,these three compounds provide a good system for comparative structural and magnetic studies.Comprehensive magnetic analysis reveals that the three compounds undergo long-range magnetic ordering at^2.6 K but exhibit vastly different short-range magnetic correlations:compound 1 shows short-range spin-canted antiferromagnetism ordering at^14.0 K;compound 2 demonstrates successive short-range antiferromagnetism ordering at^15.5and^12.6 K;compound 3 shows slow magnetic relaxation with Tb≈4.6 K.These results demonstrate long-range magnetic ordering is readily accessible in the frameworks of ox^2-bridging Co^Ⅱ-ladders linked by bphy,where short-range magnetic correlations can be systematicly tuned by the Co^Ⅱ-ladder structures.