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Catalysis by Dynamically Formed Defects in a Metal–Organic Framework Structure: Knoevenagel Reaction Catalyzed by Copper Benzene‐1,3,5‐tricarboxylate
Author(s) -
Položij Miroslav,
Rubeš Miroslav,
Čejka Jiří,
Nachtigall Petr
Publication year - 2014
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201402411
Subject(s) - knoevenagel condensation , catalysis , chemistry , deprotonation , lewis acids and bases , metal organic framework , aldehyde , benzene , copper , brønsted–lowry acid–base theory , methylene , photochemistry , organic chemistry , adsorption , ion
The high catalytic activity and selectivity of the metal–organic framework (MOF) copper benzene‐1,3,5‐tricarboxylate (CuBTC) that are observed experimentally in the Knoevenagel reaction are explained on the basis of computational investigations by employing a periodic model and density functional theory. Three factors are responsible for the unusually high activity of CuBTC: One, CuBTC can act as a base, and the active methylene reactant is deprotonated, whereas a temporary defect in the framework is formed; two, the thus‐formed defect, a Brønsted acid site, simultaneously activates the aldehyde; three, the reaction takes place on two adjacent Cu 2+ sites (Lewis acid sites) that are separated by 8.2 Å. The results reported herein show the great versatility of the CuBTC MOF catalyst, including its amphiphilic character and the concerted effect of nearby framework metal cations.