Syntheses,crystal Structures And Catalytic :properties Of Calix[4,6,8]Arene-Protected Titanium-Oxo Clusters

Calixarene is an ideal ligand for constructing metal clusters due to its variable conformation and rich phenolic hydroxyl sites.Otherwise,the aromatic hydrocarbon of the calixarene molecule provides protection for metal clusters.Therefore,Titanium–oxo（Ti–O）clusters coordinated by calixarene molecules have received more and more attentions in recent years.However,there is still a lack of systematic research on the related work,and the corresponding protective mechanism is unclear.In this dissertation,16 titanium oxo clusters were constructed with the p–tert–butylthiacalix[4]arene（H₄TC4A）,the p–tert–butylcalix[6]arene（H₆C6A）and the p–tert–butylcalix[8]arene（H₈C8A）as the ligands.The stabilizing effect of calixarene molecules with different size on Ti–O clusters and the catalytic activity of Ti–O clusters with different structure were studied.The main contents are as follows:（1）A spherical{Ti₇}cluster（1）,a triangular{Ti₆}cluster（2）,a quadrilateral{Ti₈}cluster（3）and a tetrahedral{Ti₆}cluster（4）were constructed with the H₄TC4A as the main ligand.Compound 2–4 were obtained from the system containing phenylphosphonic acid（Ph PO₃H₂）.However,only compound 4 contains both calixarene molecules and Ph PO₃^2–molecules.The coordination of the Ph PO₃^2–molecules decreases the number of the Ti atoms under calixarene molecule from 2 to 1,which also slightly affects the conformation of the calixarene molecules.In catalytic sulfoxidation reaction,compound 4 showed a higher catalytic activity,which can be attributed to the Ti active sites coordinated by N,N–dimethylformamide molecules.[Ti₇（TC4A）₆（μ₂–O）₆（H₂O）₆Cl₈]^10–（1）[Ti₆（TC4A）₃（μ₂–O）₃（Oi Pr）₆]·2CH₂Cl₂（2）[Ti₈（TC4A）₄（μ₂–O）₄（Oi Pr）₈]（3）H₂[Ti₆（H₂TC4A）₄（C₆H₅PO₃）₄（μ₂–O）₅（DMF）₂]·DMF·2CH₂Cl₂（4）（2）Sandwich–like{Ti₄}cluster（5）and windmill–like{Ti₈}cluster（6）were obtained in the system containing H₆C6A molecules and Ph PO₃H₂ molemcules.The Ph PO₃^2–molecule does not participate in the coordination of the compound 5 but participates in the construction of compound 6.The coordination of the Ph PO₃^2–molecule leds to the reduction of the Ti atoms under the calixarene molecule from 2 to 1and leds to the change of the calixarene molecules from double–cone conformation to1,2,3–alternate conformation.Compound 5 with the Ti active sites selectively catalyzes all the thioanisole（MPS）molecules in the catalytic system to methyl phenyl sulfoxide（MPSO）molecules.Compound 5 was deposited on the surface of honeycomb–like graphene aerogel TCGA–1 to form a photocatalyst with good removal behavior for rhodamine B.[Ti₄（C6A）₂（μ₃–O）₂（DMF）₂]·9HOi Pr（5）H₄[Ti₈（H₃C6A）₄（C₆H₅PO₃）₈（μ₂–O）₄]·9DMF·29HOi Pr（6）（3）For the H₈C8A system,compound 7–12 with integrated assembly of H₈C8A molecules and Ti–O cluster were obtained in the solvothermal reaction.The p H and the polarity of the solvent are crucial for the construction of the complexes.Conpound 7 was constructed by two tail–to–tail calixarene molecules and two Ti₂ units.Compound 8contains two calixarene molecules interlaced with a Ti₂ unit and two Ti atoms.The calixarene molecule in{Ti₇}cluster（9）,{Ti₁₃}cluster（10）and{Ti₂₄}cluster（11）adopts a double–cone conformation.The calixarene molecules in{Ti₁₄}cluster（12）adopt a pinched conformation and a double–cone conformation.Compound 9 can be regarded as a Ti₇–C8A unit,while compound 10 can be regarded as two Ti₇–C8A units with shared vertices.Compound 11 can be seen as four Ti₅–C8A units linked by a centrally symmetric Ti₄ unit,while compound 12 can be seen as two Ti₅–C8A units linked by a Ti₄–C8A unit.Compound 8,11 and 12 with Ti active sites expressed a good catalytic behavior for the selective oxidation of MPS to MPSO.[Ti₄（H₂C8A）₂（HCOO）₂（CH₃O）₄][（（C₂H₅）₃NH）₂]·9DMF（7）[Ti₄（HC8A）₂（CH₃O）₂（DMF）₆]·DMF（8）[Ti₇（C8A）（μ₂–O）₄（μ₃–O）₂（μ₄–O）₂（CH₃O）₄（CH₃OH）₄]·DMF·CH₃OH（9）[Ti₁₃（C8A）₂（μ₂–O）₅（μ₃–O）₆（μ₄–O）₄（CH₃O）₇（CH₃OH）₂（H₂O）₂]·2DMF（10）[Ti₂₄（C8A）₄（μ₂–O）₁₆（μ₃–O）₁₀（μ₄–O）₁₀（DMF）₂（H₂O）₂]（11）[Ti₁₄（C8A）₃（μ₂–O）₈（μ₃–O）₈（μ₄–O）₂（CH₃O）₂（DMF）₄][（（C₂H₅）₃NH）₄]·DMF·2CH₂Cl₂（12）（4）The Ln³⁺ions with small size and luminescence properties were instructed as linkers and functional ions into the H₈C8A–Ti system with methanol and the H₈C8A–Ti system without methanol.And finally,the{Ln Ti₂₁}clusters（13,Ln=Tb,14,Ln=Eu）based on Ti₇–C8A unit and the{Ln₂Ti₁₃}clusters（15,Ln=Tb,16,Ln=Eu）based on Ti₅–C8A unit were constructed in the methanol system and the methanol–free system,respectively.The four Ln–Ti–O clusters did not exhibit luminescent properties and magnetic relaxation behavior.Compound 15 with Ti active sites exhibited a higher catalytic activity for MPS.[Eu Ti₂₁（C8A）₃（μ₃–O）₁₃（μ₄–O）₆（CH₃O）₂₄（H₂O）₂][NO₃]·CH₂Cl₂·10CH₃OH（14）[Tb₂Ti₁₃（H₃C8A）（HC8A）（C8A）（HCOO）₃（μ₂–O）₇（μ₃–O）₆（μ₄–O）₆（H₂O）（DMF）₄]·2DMF（15）[Eu₂Ti₁₃（H₃C8A）（HC8A）（C8A）（HCOO）₃（μ₂–O）₇（μ₃–O）₆（μ₄–O）₆（H₂O）（DMF）₁₀]（16）...