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Odd–Even Alternation in Tautomeric Porous Organic Cages with Exceptional Chemical Stability
Author(s) -
Bera Saibal,
Basu Arghya,
Tothadi Srinu,
Garai Bikash,
Banerjee Subhrashis,
Vanka Kumar,
Banerjee Rahul
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201611260
Subject(s) - tautomer , imine , chemistry , chemical stability , amine gas treating , diamine , schiff base , condensation reaction , condensation , alternation (linguistics) , crystallography , computational chemistry , stereochemistry , medicinal chemistry , organic chemistry , catalysis , thermodynamics , physics , linguistics , philosophy
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 −CH 2 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.