Syntheses And Properties Of Metal-Organic Coordination Cages Constructed From Resorcin[4]arenes

In this paper,a series of new metal-organic coordination cages were constructed by3-?2-pyridinyl?pyrazol modified resorcin[4]arene?TPC4R-I?and methyl imidazole functionalized resorcin[4]arene?MTR4A?.The assembly rules of these cages also have been investigated.We can infer that the formation of these compounds is highly dependent on the additional negative charges of the ancillary acid ligands used.When the ancillary acid ligands5-sulfoisophthalic acid monosodium salt and 5-hydroxyisophthalic acid were used,compounds 1-SO₃H and 1-OH were assembled,respectively.Compound 2 was always obtained,when ancillary acid ligand 1,3-benzenedicarboxylate was applied.A large[Co₈]coordination cage was self-assembled by MTR4A,[?-SiW₁₂O₄₀]^4-and Co?II?cations.The crystal structures were determined by the single crystal X-ray diffractometer.And they were characterized by infrared spectra and powder X-ray diffraction spectra.The proton conductivity for compounds 1-SO₃H and 1-OH was studied.The catalytic performance of cycloaddition of CO₂ to epoxides was investigated for compound 2.In addition,we discussed the electrochemical properties of[Co₈]coordination cage.1.A new ligand was synthesized by introducing 3-?2-pyridinyl?pyrazol into the upper of calix[4]resorcinarene?TPC4R-I?.Then two novel metal-organic coordination cages were constructed from TPC4R-I,two isomorphous isophthalic acid derivatives with different acid groups and Co?II?cations under solvothermal conditions,namely,[Co₁₆?TPC4R-I?₂-?HL?₄?L?₈?H₂O?₂₄]?12DMF?4H₂O?1-SO₃H?and[Co₁₆?TPC4R-I?₂-?HL₁?₄?L₁?₈?H₂O?₁₆]?17DMA?H₂O?1-OH??NaO₃S-H₂L=5-sulfoisophthalic acid monosodium salt,H₃L1=5-hydroxyisophthalic acid,DMF=N,N'-dimethylformamide,DMA=N,N'-dimethylacetamide?.Single-crystal X-ray diffraction reveals that 1-SO₃H and 1-OH are isostructural.1-SO₃H and 1-OH,composed of twelve isophthalic acid derivatives,two calix[4]resorcinarenes and sixteen Co?II?cations,show remarkable nanosized[Co₁₆]coordination cage structures.Due to the introduction of–SO₃H and–OH,the properties of compounds 1-SO₃H and 1-OH in proton conduction were significantly improved.Further the nature of proton conductivity can be controlled by these way.Markedly,1-SO₃H,featuring–SO₃H sites on the surface of each cage,displays a higher proton conductivity than 1-OH with–OH sites,reaching 1.35×10^-2 S cm^-1 under 98%RH at 90?.The proton conductivity of 1-SO₃H increased about 1 order of magnitude relative to that of its counterpart 1-OH.Therefore,this kind of material represents one of the most high-performance proton-conductive materials.2.A new polynuclear metal cluster-based coordination cage with[Co₄O₄]cubanes was constructed from calix[4]resorcinarenes?TPC4R-I?,1,3-benzenedicarboxylates and Co?II?cations under solvothermal conditions,namely,[Co₁₂?TPC4R-I?₂?1,3-BDC?₁₀?₃-OH?₄?H₂O?₁₀?DMF?₂]·7DMF·23H₂O?1,3-BDC=1,3-benzenedicarboxylate??2?.Notably,2 features a[Co₁₂]coordination cages structure,composed of two calix[4]resorcinarenes,twelve Co?II?cations and ten 1,3-BDC anions.2 represents a unique example of[Co₁₂]coordination cages with[Co₄O₄]cubanes.Then 2 was activated to remove the coordinated water and DMF molecules.The exposed Co?II?Lewis acid active sites make2 available for catalyzing the cycloaddition of CO₂ to epoxides.We have performed subsequent studies on cycloadditions of CO₂ with different substrates at 60? and 1 atm.The catalytic results demonstrate that 2 has excellent catalytic capability for cycloadditions of CO₂and still retains the high catalytic performance after cycling tests.3.A new polyoxometalate-resorcin[4]arene-based supramolecular coordination cage was constructed from methyl imidazole functionalized resorcin[4]arene ligand?MTR4A?,Keggin-type polyoxometalate?POM?and Co?II?cations under solvothermal conditions,namely,[Co₈Cl₈?MTR4A?₆][Si O₄?W₃O₉?₄]₂·Xsolvents?3?.Single-crystal X-ray diffraction measurement revealed that 3 features an unusual cationic porous coordination cage assembled with six calix[4]resorciarenes,eight Co?II?cations and eight Cl^-counter anions,namely,[Co₈Cl₈?MTR4A?₆]⁸⁺.Two[?-SiW₁₂O₄₀]^4-anions are free and balance the negative charge as a counteranion.And 3 exhibits a charming 3D supramolecular architecture sandwiched by POM anions via the weak C-H···O hydrogen bonds.Because POMs functionalized materials have good energy storage effects.Hence,we tested the performance of 3 as anode material for lithium ion batteries?LIBs?.The results demonstrate that 3 has excellent stability and reversibility.Moreover,they also may be employed as bifunctional electrocatalysts for the oxidation of AA and reduction of NO₂^-.