Syntheses, Structures And Properties Of Functional Clusters Based On Calixarene Derivatives

Calixarenes derivatives are a class of macrocyclic compounds formed by several phenol units and the same number of bridged atoms.The phenolic hydroxyl atoms and bridged hetero atoms in calixarenes derivatives are potential coordination sites which could bond different metal ions.Thus,calixarenes derivatives can be used as a platform for the assembly of several metal centres,and generated novel compounds through bond auxiliary ligands.In this paper,p-tert-butylthiacalix[4]arenes?H₄TC4A?and their derivatives?H₄TC4A-SO₂?or thiacalix[4]arenes?H₄T4A?were selected as main ligands,under solvothermal conditions,metal-calixarene clusters were synthetized with organic ligands or inorganic ions as auxiliary ligands.The structures of the compounds were characterized by single crystal diffraction,thermogravimetry,FT-IR,etc.The effects of different calixarene derivatives and auxiliary ligands on the structures of the compounds were studied,and the electrocatalytic properties of the clusters were also discussed.1.Three high-cluster compounds with different structures were synthesized undersolvothermalconditionsusing1-hydroxy-2-?3-pyridinyl?ethylidene-1,1-diphosphonic acid?H₅L?as auxiliary ligand,Co₂₆,Ni₂₈8 were based on H₄TC4A and Ni₂₄ was based on H₄T4A.Co₂₆features a rod-like Co₂₆ core constructed by six Co₄-TC4A secondary building units?SBUs?and four HL^4-with extra two cobalt ions.Ni₂₈8 cluster represents a flower-like Ni₂₈ core built form six Ni₄-TC4A SBUs,six HL^4-and four additional nickel ions.Ni₂₄ features oval-like clusters constructed by six Ni₄-TC4A SBUs and four HL^4-and two phosphoric acid synthesized in situ.Co₂₆ and Ni₂₈ clusters was directly dispersed on carbon paper?CP?and showed extraordinary oxygen evolution reaction?OER?activity.2.A series of metal clusters?Co-1,Fe-1,Co₁Fe₁-1,Co₃Fe₁-1 and Co₁Fe₃-1?with the similar structure were obtained by assemble of different metals?Fe and/or Co?,H₄TC4A-SO₂,and tetrazole?1,3-di?2H-tetrazol-5-yl?benzene,H₂L?as linkers under the solvothermal conditions.The OER properties of the five clusters indicated that bimetal clusters exhibited better oxygen evolution reaction?OER?activity than monometal clusters,and the cluster Co₁Fe₁-1represented the best electrocatalytic performance among the five compounds.3.Four nuclearity clusters were obtained by the reaction of H₄TC4A or H₄T4A,H₃PO₄ and transition metal ions under solvothermal conditions.The formula are[Co₁₆?TC4A?₄?CH₃OPO₃?₈?Cl?₄?CH₃NH₂CH₃?₄](Co₁₆-1)?[Co₁₆?T4A?₄?HPO₄?₈?Cl?₄?CH₃NH₂CH₃?₄]?+solvent?(Co₁₆-2 and Co₁₆-2')?[Co₂₀?T4A?₅?CH₃OPO₃?₈?HPO₄?₈?Cl?₅?CH₃NH₂CH₃?](Co₂₀-2).Co₁₆-1,Co₁₆-2,Co₁₆-2'have similar window-like structures,which are constructed by four Co₄-calixarene SBUs?calixarene=TC4A or T4A?and eight auxiliary ligands.Co₂₀-2 was built by five Co₄-T4A SBUs and four H₃PO₄,four in situ synthesized CH₃OPO₃,represented an open nanocage structure.By comparing the compounds formed by different calixarene derivatives with same ligand,it is found that the modification of the upper rim of calixarene did not change the coordination modes between metals and calixarenes in essence,however the coordination of different metal ions with calixarenes or synthesis conditions change the way that the clusters are stacked.