Three Ti–O clusters and a Tb–Ti–O cluster capped by p-tert-butylcalix[8]arene (H₈C8A), namely, [Ti₇O₈(C8A)(CH₃O)₄(CH₃OH)₄] (CIAC-262), [Ti₁₃O₁₅(C8A)₂(CH₃O)₆(CH₃OH)₃(H₂O)₂] (CIAC-263), [Ti₂₄O₂₈(OH)₈(C8A)₄(DMF)₂(H₂O)₂] (CIAC-264) and [Tb₂Ti₁₃O₁₅(OH)₄(H₃C8A)(C8A)₂(HCOO)₃(DMF)₄(H₂O)] (CIAC-265), were prepared by controlling the amount of methanol in the reaction system under solvothermal conditions. The amount of methanol is reduced from 4 mL to 2 mL and then to 0 mL, resulting in a {Ti₇} cluster with Ti₇–C8A unit, a {Ti₁₃} cluster constructed by two perpendicular tail-to-tail Ti₇–C8A units with a vertex-shared mode, and a {Ti₂₄} cluster assembled by linking two Ti₁₀–(C8A)₂ units generated by the symmetric operation with a Ti₄ entity, respectively. To replace the Ti₄ linker in the {Ti₂₄} cluster, Tb ions were incorporated in the methanol-free system. Then a {Tb₂Ti₁₃} cluster constructed by linking a Ti₁₀–(C8A)₂ unit and a Ti₂–C8A entity with a Tb₂Ti linker was obtained. Catalytic sulfoxidation experiments were performed to evaluate the structure–property relationships in these calixarene-based clusters. Driven by Ti atoms and active Ti sites with higher steric hindrance, compound CIAC-264 efficiently catalyzes the selective oxidation of methyl phenyl sulfide to methyl phenyl sulfoxide (96.00% for conversion and 98.28% for selectivity) using 30% H₂O₂ under mild conditions (298 K). Calixarene molecules in CIAC-264 protect the Ti–O cluster from decomposition during the catalytic reaction, which could be directly observed from MALDI-TOF MS spectra. This work not only opens a new insight for preparing high-nuclearity Ti–calixarene clusters with interesting assemblies but also provides new stable titanium oxide candidates for selective oxidation of organic sulfides.

中文翻译：

---

多核钛-杯芳烃配合物的溶剂极性控制组装：构建孤立的{Ti7}、{Ti13}、{Ti24}和{Tb2Ti13}簇

三个Ti–O簇和一个被对叔丁基杯[8]芳烃(H 8 C8A)封端的Tb–Ti–O簇，即_[ Ti ₇ O ₈ (C8A)(CH ₃ O) ₄ (CH ₃ OH) ) ₄ ] ( CIAC-262 ), [Ti ₁₃ O ₁₅ (C8A) ₂ (CH ₃ O) ₆ (CH ₃ OH) ₃ (H ₂ O) ₂ ] ( CIAC-263 ), [Ti ₂₄ O ₂₈ (OH) ) ₈ (C8A) ₄ (DMF) ₂ (H ₂ O) ₂ ] ( CIAC-264 ) 和 [Tb ₂ Ti ₁₃ O ₁₅ (OH) ₄ (H ₃ C8A)(C8A) ₂ (HCOO) ₃ (DMF) ₄ (H ₂ O)]( CIAC-265 )，通过在溶剂热条件下控制反应体系中甲醇的量来制备。甲醇量从4 mL减少到2 mL，然后减少到0 mL，得到具有Ti ₇ –C8A单元的{ Ti ₇ }团簇，即由两个垂直尾对尾的Ti ₇构建的{ Ti ₁₃ }团簇–具有顶点共享模式的C8A单元，以及通过将对称操作生成的两个Ti ₁₀ –(C8A) _{2单元分别与Ti 4}实体链接而组装而成的{ Ti ₂₄ }簇。为了替换{ Ti _{24 }簇中的Ti 4}连接体，将Tb离子掺入无甲醇系统中。然后获得通过用Tb ₂ Ti连接体连接Ti ₁₀ –(C8A) ₂单元和Ti ₂ –C8A实体而构建的{ Tb ₂ Ti ₁₃ }簇。进行催化磺氧化实验来评估这些基于杯芳烃的簇中的结构-性质关系。在Ti原子和具有较高空间位阻的活性Ti位点驱动下，化合物CIAC-264在温和条件下使用30% H ₂ O ₂有效催化甲基苯基硫醚选择性氧化为甲基苯基亚砜（转化率96.00%，选择性98.28%）。条件（298 K）。CIAC-264中的杯芳烃分子保护Ti-O团簇在催化反应过程中不被分解，这可以从MALDI-TOF MS谱中直接观察到。这项工作不仅为制备具有有趣组装的高核钛-杯芳烃簇提供了新的见解，而且还为有机硫化物的选择性氧化提供了新的稳定的氧化钛候选物。