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Synthesis of superacid-functionalized mesoporous nanocages with tunable pore diameters and their application in the synthesis of coumarins.
MedLine Citation:
PMID:  20087913     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
Here we demonstrate for the first time the preparation of a triflic acid (TFA)-functionalized mesoporous nanocage with tunable pore diameters by the wet impregnation method. The obtained materials have been unambiguously characterized by XRD, N(2) adsorption, FTIR spectroscopy, and NH(3) temperature-programmed desorption (TPD). From the characterization results, it has been found that the TFA molecules are firmly anchored on the surface of the mesoporous supports without affecting their acidity. We also demonstrate the effect of the pore and cage diameter of the KIT-5 supports on the loading of TFA molecules inside the pore channels. It has been found that the total acidity of the materials increases with an increase in the TFA loading on the support, whereas the acidity of the materials decreases with an increase in the pore diameter of the support. The acidity of the TFA-functionalized mesoporous nanocages is much higher than that of the zeolites and metal-substituted mesoporous acidic catalysts. The TFA-functionalized materials have also been employed as the catalysts for the synthesis of 7-hydroxy-4-methylcoumarin by means of the Pechmann reaction under solvent-free conditions. It has been found that the catalytic activity of the TFA-functionalized KIT-5 is much higher than that of zeolites and metal-substituted mesoporous catalytic materials in the synthesis of coumarin derivatives. The stability of the catalyst is extremely good and can be reused several times without much loss of activity in the above reaction.
Authors:
Pranjal Kalita; B Sathyaseelan; Ajayan Mano; S M Javaid Zaidi; Murugulla A Chari; Ajayan Vinu
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Chemistry (Weinheim an der Bergstrasse, Germany)     Volume:  16     ISSN:  1521-3765     ISO Abbreviation:  Chemistry     Publication Date:  2010 Mar 
Date Detail:
Created Date:  2010-03-03     Completed Date:  2010-05-28     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9513783     Medline TA:  Chemistry     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  2843-51     Citation Subset:  -    
Affiliation:
International Center for Materials Nanoarchitectonics, World Premier International (WPI) Research Initiative, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.
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