Odd-Even Alternation in Tautomeric Porous Organic Cages with Exceptional Chemical Stability

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• 作者：Saibal Bera ; Dr. Arghya Basu ; Dr. Srinu Tothadi ; Bikash Garai ; Subhrashis Banerjee ; Prof. Dr. Kumar Vanka and Prof. Dr. Rahul Banerjee
• 刊名：Angewandte Chemie
• 出版年：2017
• 出版时间：February 13, 2017
• 年：2017
• 卷：129
• 期：8
• 页码：2155-2158
• 全文大小：2031K
• ISSN：1521-3757

文摘

Amine-linked (C−NH) porous organic cages (POCs) are preferred over the imine-linked (C=N) POCs owing to their enhanced chemical stability. In general, amine-linked cages, obtained by the reduction of corresponding imines, are not shape-persistent in the crystalline form. Moreover, they require multistep synthesis. Herein, a one-pot synthesis of four new amine-linked organic cages by the reaction of 1,3,5-triformylphloroglucinol (Tp) with different analogues of alkanediamine is reported. The POCs resulting from the odd diamine (having an odd number of −CH₂ groups) is conformationally eclipsed, while the POCs constructed from even diamines adopt a gauche conformation. This odd–even alternation in the conformation of POCs has been supported by computational calculations. The synthetic strategy hinges on the concept of Schiff base condensation reaction followed by keto–enol tautomerization. This mechanism is the key for the exceptional chemical stability of cages and facilitates their resistance towards acids and bases.