Dissecting the Role of the Sergeants in Supramolecular Helical Catalysts: From Chain Capping to Intercalation. (21st December 2020)

• Record Type: Journal Article
• Authors: Martínez‐Aguirre, Mayte A.; Li, Yan; Vanthuyne, Nicolas; Bouteiller, Laurent; Raynal, Matthieu
• Is Part Of: Angewandte Chemie. Volume 133:Number 8(2021)
• Page Start: 4229
• Page End: 4237
• Publication Date: 2020-12-21
• Subjects: supramolecular catalysis -- helical catalyst -- sergeants-and-soldiers effect -- supramolecular chirality -- supramolecular copolymerisation; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202012457
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Controlling the properties of supramolecular assemblies requires unveiling the specific interactions between their components. In the present work, the catalytic properties and structure of co‐assemblies composed of a benzene‐1, 3, 5‐tricarboxamide (BTA) ligand coordinated to copper (the soldier) and seven enantiopure BTAs (the sergeants) have been determined. Whatever the sergeant, the enantioselectivity of the reaction is directly proportional to the optical purity of the supramolecular helices. More strikingly, the role played by the sergeant in the co‐assembly process differs significantly: from almost pure intercalator (when it is incorporated in the stacks of the soldier and generates long homochiral helices) to pure chain capper (when it leads to the formation of partly helically biased and short assemblies). The former situation leads to optimal enantioselectivity for the catalytic system under study (58 % ee ) while the latter situation leads to very low selectivity (8 % ee ). The successful rationalization of this high and unexpected difference is crucial for the development of more efficient catalysts and more elaborate supramolecular systems. Abstract : Co‐assemblies between a benzene‐1, 3, 5‐tricarboxamide (BTA) ligand (soldier) and different types of enantiopure BTAs (sergeants) are evaluated as helical catalysts. The selectivity is related to the helicity and structure of the supramolecular helices (length, composition) which strongly depend on the role adopted by the sergeant in the co‐assembly process (from intercalation to pure chain capping).