Two halogen-bridged di-nuclear Cu-based 3D porous metal–organic frameworks (MOFs), {[Cu2Cl(OH)(L)2]·(CH3OH)4}n (1) and {[Cu2Br(OH)(L)2]·(CH3OH)4}n (2), have been obtained via solvothermal methods with the bi-functional ligand (HL = 4,2′:6′,4′′-terpyridine-4′-carboxylic acid). These Cu-based frameworks exhibit similar two-interpenetrating frameworks, and 1D channels were left in the packing structures. These MOF materials were then applied as electrode active materials in supercapacitors. Compound 1 presents a high specific capacitance and good cycling stability in 6 M KOH electrolyte compared to 2. The maximum specific capacitance of electrode 1 could reach 1148 F g−1 at a current density of 0.5 A g−1, along with a high capacitance of 90% retained after 2000 cycles at a current density of 10 A g−1 in a 6 M KOH solution. The successful introduction of halogen and hydroxyl ions into the final structures might be responsible for the high performance of the supercapacitor, which makes these Cu MOFs a candidate for an electrode active material for electrochemical energy storage.

The hydrothermal reaction of CoCl2 and 4-((1-carboxy-2-(1H-imidazol-4-yl)ethylamino)methyl)benzoic acid (H2L) generated a {Co2(H2O)}-based 2D coordination framework, {(Co(L)(H2O))2(H2O)}n (1). Heterogeneous catalytic experiments on the allylic oxidation of cyclohexene show that activated 1 exhibits high catalytic activity using tert-butylhydroperoxide (t-BuOOH) as the oxidant toward the formation of tert-butyl-2-cyclohexenyl-1-peroxide. The activation energy for the oxidation of cyclohexene with catalyst 1 was approximately calculated as 91.98 kJ mol−1. This work demonstrates that a degree of creativity in the coordinatively unsaturated metal sites in CPs could significantly enhance their heterogeneous catalytic activity and selectivity.

•One mono-nuclear iron(III) complex was synthesized.•An incomplete spin transition is exhibited.•The tripodal ligand plays the important role in affecting the SCO behavior.A new mononuclear Fe(III)–catecholate complex, which exhibits an incomplete spin transition without hysteresis, had been synthesized and structurally characterized. Analyzed from the structural characteristics, the tripodal ligand must play the important role in affecting the spin crossover (SCO) behavior. The larger steric strain effect and weak cooperativity existed in the crystal lattice are inclined to favor the incomplete transition.A new mononuclear Fe(III)–catecholate complex, which exhibits an incomplete spin transition without hysteresis, had been synthesized and structurally characterized. Analyzed from the structural characteristics, the tripodal ligand must play the important role in affecting the SCO behavior.

•A new di-nuclear valence tautomeric complex was formed.•Valence tautomeric transition with a small hysteresis around room temperature and photo-excited phenomenon is exhibited.•Temperature-dependent hs–ls relaxation of the converted high-spin fraction after irradiation was also studied.A di-nuclear compound, [(CoTPA)2(1,4-BQ)][AsF6]3 (1) (TPA = tris(2-pyridylmethyl)amine, 1,4-BQ = deprotonated 2,5-dihydroxy-1,4-benzoquinone), was formed by one electron oxidation of [(CoTPA)2(1,4-BQ)]2+ cations. The compound was characterized by X-ray diffraction, electrochemistry, ESR, thermal- and photo-induced magnetic measurements. Variable temperature magnetic measurements have demonstrated that valence tautomeric transition with a small hysteresis around room temperature and photo-excited phenomenon is exhibited. In addition, temperature-dependent hs–ls relaxation of the converted high-spin fraction after irradiation was also studied.A new di-nuclear valence tautomeric complex was formed and characterized by X-ray diffraction, electrochemistry, ESR, thermally and photo-induced magnetic measurements. Variable temperature magnetic measurements have demonstrated that valence tautomeric transition with a small hysteresis around room temperature and photo-excited phenomenon is exhibited. In addition, temperature-dependent hs–ls relaxation of the converted high-spin fraction after irradiation was also studied.

A new heptanuclear compound [{Cu(TPA)CN}6W(CN)2][ClO4]8·14H2O (1) (TPA = tris(2-pyridylmethyl)amine) was synthesized by the reaction of [Cu(TPA)]2 + unit and K4W(CN)8. The cyanometalate core is encapsulated by mononuclear copper moieties via cyano bridges. 1 crystallizes in monoclinic space group P21/c with a = 22.01(2) Å, b = 26.87(3) Å, c = 31.64(2) Å, β = 128.87(2)°, and Z = 4. Variable temperature magnetic measurements have demonstrated that very weak ferromagnetic interaction between the nearest paramagnetic CuII centers is exhibited. Thus weak ferromagnetic coupling might be transferred by NCWCN bridging units.A new heptanuclear compound with octacyanometalates was synthesized. Variable temperature magnetic measurements have demonstrated that very weak ferromagnetic interaction between the nearest paramagnetic CuII centers is exhibited.Highlights► One new hepta-bimetallic complex containing octacyanotungstate(IV) has been synthesized. ► Very weak intercluster ferromagnetic coupling between the nearest paramagnetic Cu(II) ions is exhibited. ► Thus weak coupling might be mediated through the NCWCN bridging units.

Three monomeric cobalt compounds, [Co(PzPy2)(3,5-DBcat)]·PF6 (1), [Co(Pz2Py)(3,5-DBsq)]·BPh4 (2) and [Co(Pz3)(3,5-DBsq)]·PF6 (3), have been synthesized, where PzPy2 = (3,5-dimethyl-1H-pyrazol-1-yl)-N,N-bis(pyridin-2-ylmethyl)methanamine, Pz2Py = (3,5-dimethyl-1H-pyrazol-1-yl)-N-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)-N-(pyridine-2-ylmethyl)methanamine and Pz3 = tris((3,5-dimethyl-1H-pyrazol-1-yl)methyl)amine, respectively. Compound 1 consist of low-spin Co(III) ion and diamagnetic cat2− (Cols-III–DBcat2−) over the temperature regions observed, while compounds 2 and 3 as high-spin cobalt(II) ion and paramagnetic semiquinonate radical (Cohs-II–DBsq−) state are stable in the whole temperature range. No temperature-dependent valence tautomeric transitions were observed in these compounds, and the reason caused the distinct charge distribution on cobalt ion and dioxolene ligands assigned to the natural flexibility and steric hindrance of the tripodal ligands. Magnetic studies indicate that very weak antiferromagnetic interactions are presented between the high-spin Co(II) ion and semiquinonate ligands in 2 and 3. Pressure effects on the magnetic properties were performed, which showed that no pressure-induced valence tautomeric transitions were occurred on 2 and 3. Meanwhile, antiferromagnetic coupling in 2 and 3 are clearly enlarged under external pressure.Graphical abstractThree monomeric cobalt compounds have been synthesized, respectively. The distinct charge distribution on cobalt ion and dioxolene ligands is assigned to the natural flexibility and steric hindrance of the tripodal ligands.Highlights► Three monomeric cobalt compounds containing similar tripodal ligands have been synthesized. ► Weak antiferromagnetic interactions are presented between Co(II) ion and semiquinonate ligands. ► Pressure effects on the magnetic properties were performed.

A new heptanuclear compound [{Cu(DPA)(H2O)CN}4{Cu(DPA)CN}2Fe][PF6]8·4H2O (1) (DPA = bis(pyridin-2-ylmethyl)amine ) was synthesized by the reaction of [Cu(DPA)]2+ unit and K3Fe(CN)6. The cyanometalate core is encapsulated by mononuclear copper moieties via each cyanide, and Fe(III) is reduced to Fe(II). 1 crystallizes in triclinic space group P-1 with a = 13.414(6) Å, b = 16.254(6) Å, c = 16.418(6) Å, α = 117.98(4)°, β = 94.49(3)°, γ = 107.61(4)° and Z = 1. Variable temperature magnetic measurements have demonstrated that very weak ferromagnetic interaction between the nearest paramagnetic CuII centers is exhibited. Thus weak ferromagnetic coupling might be transferred by –NC–Fe–CN– bridging units.The reaction of [Cu(DPA)]2+ moieties with each cyano ligand on ferricyanide results in the self-assembly of hepta-bimetallic complexes, [{Cu(DPA)(H2O)CN}4{Cu(DPA)CN}2Fe][PF6]8·4H2O. Very weak intercluster ferromagnetic coupling between the nearest paramagnetic Cu(II) ions is exhibited, and thus weak coupling might be mediated through the the –NC–Fe–CN– bridging units.Research Highlights► A new hepta-bimetallic complex has been formed. ► Weak intercluster ferromagnetic coupling is exhibited. ► Thus weak coupling might be mediated through the the –NC–Fe–CN– bridging units.