Qin Ze, Wang Li, Chen Liyu, Li Yingwei, Shen Kui
Guangdong Provincial Key Lab of Green Chemical Product Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, China.
Guangdong Provincial Key Laboratory of Fuel Cell Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, China.
Small. 2024 Nov;20(45):e2403517. doi: 10.1002/smll.202403517. Epub 2024 Jul 24.
The cyclization of 3-hydroxy alkynes and the carboxylation of terminal alkynes both with CO are two attractive strategies to simultaneously reduce CO emission and produce value-added chemicals. Herein, the differential activation of alkynes over atomically precise Ag nanoclusters (NCs) supported on Metal-organic framework-derived highly-open mesoporous CeO (HM-CeO) by reserving or removing their surface captopril ligands is reported. The ligand-capped Ag NCs possess electron-rich Ag atoms as efficient π-activation catalytic sites in cyclization reactions, while the naked Ag NCs possess partial positive-charged Ag atoms as perfect σ-activation catalytic sites in carboxylation reactions. Impressively, via coupling with HM-CeO featuring abundant basic sites and quick mass transfer, the ligand-capped Ag NCs afford 97.9% yield of 4,4-dimethyl-5-methylidene-1,3-dioxolan-2-one for the cyclization of 2-methyl-3-butyn-2-ol with CO, which is 4.5 times that of the naked Ag NCs (21.7%), while the naked Ag NCs achieve 98.5% yield of n-butyl 2-alkynoate for the carboxylation of phenylacetylene with CO, which is 15.6 times that of ligand-capped Ag NCs (6.3%). Density functional theory calculations reveal the ligand-capped Ag NCs can effectively activate alkynyl carbonate ions for the intramolecular ring closing in cyclization reaction, while the naked Ag NCs are highly affiliative in stabilizing terminal alkynyl anions for the insertion of CO in carboxylation reaction.
3-羟基炔烃的环化反应以及末端炔烃与一氧化碳的羧化反应，都是减少一氧化碳排放同时生产高附加值化学品的极具吸引力的策略。本文报道了通过保留或去除负载在金属有机框架衍生的高度开放介孔氧化铈（HM-CeO）上的原子精确银纳米团簇（NCs）表面的卡托普利配体，实现炔烃在其上的差异活化。配体封端的银纳米团簇在环化反应中拥有富电子的银原子作为有效的π-活化催化位点，而裸银纳米团簇在羧化反应中拥有部分带正电荷的银原子作为完美的σ-活化催化位点。令人印象深刻的是，通过与具有丰富碱性位点和快速传质特性的HM-CeO耦合，配体封端的银纳米团簇在2-甲基-3-丁炔-2-醇与一氧化碳的环化反应中，4,4-二甲基-5-亚甲基-1,3-二氧戊环-2-酮的产率达到97.9%，是裸银纳米团簇（21.7%）的4.5倍，而裸银纳米团簇在苯乙炔与一氧化碳的羧化反应中，正丁基2-炔酸酯的产率达到98.5%，是配体封端的银纳米团簇（6.3%）的15.6倍。密度泛函理论计算表明，配体封端的银纳米团簇在环化反应中能有效活化碳酸炔根离子以进行分子内环合，而裸银纳米团簇在羧化反应中对稳定末端炔基阴离子以插入一氧化碳具有高度亲和力。
