New poly-imidazolium-triazole particles by CuAAC cross-linking of calix[4]arene bis-azide/alkyne amphiphiles - a prospective support for Pd in the Mizoroki-Heck reaction

A new imidazolium amphiphilic calix[4]arene with terminal acetylene fragments in the polar region was synthesized according to a two step scheme including regioselective chloromethylation of distal di- O -butyl calix[4]arene and subsequent interaction with 1-(hex-5-yn-1-yl)-1 H -imidazole. The aggre...

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Bibliographic Details
Published in:RSC advances 2021-01, Vol.11 (1), p.584-591
Main Authors: Burilov, Vladimir, Garipova, Ramilya, Mironova, Diana, Sultanova, Elza, Bogdanov, Ilshat, Ocherednyuk, Evgeny, Evtugyn, Vladimir, Osin, Yuri, Rizvanov, Ildar, Solovieva, Svetlana, Antipin, Igor
Format: Article
Language:English
Subjects:
Acetylene
Alkynes
Chemistry
Crosslinking
Fragments
Imidazole
Infrared spectroscopy
Ions
Light scattering
Polar environments
Synthesis
Triazoles
Zeta potential
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Summary:A new imidazolium amphiphilic calix[4]arene with terminal acetylene fragments in the polar region was synthesized according to a two step scheme including regioselective chloromethylation of distal di- O -butyl calix[4]arene and subsequent interaction with 1-(hex-5-yn-1-yl)-1 H -imidazole. The aggregation properties (CAC, the size and zeta potential of aggregates) of alkynyl calix[4]arene as well as of previously synthesized azidopropyl calix[4]arene and their 1 : 1 mixture were disclosed. Macrocycles with azide and alkyne fragments in the polar region were covalently cross-linked under CuAAC conditions in water. Successful cross-linking of molecules has been proven by IR spectroscopy and MALDI-TOF spectrometry. The obtained polymeric particles were studied both in solution and the solid state and the presence of submicron (∼200 nm) and micron (∼1-5 μm) particles with the prevalence of the latter was found. The average molecular weight of the polymer according to the static light scattering data was found to be 639 ± 44 kDa. The obtained polymeric imidazolium-triazole particles were tested as a support for Pd(OAc) 2 in the Mizoroki-Heck reaction carried out in both organic and water media. In both solvents (especially in water) the addition of imidazolium-triazole particles to Pd(OAc) 2 increased the conversion of 4-iodanisole. It was found that the ratio between the products (1,1 and 1,2-substituted ethylenes) changes drastically on going from DMF to water from 1 : 5 to 1 : 40 when using supported Pd(OAc) 2 . A new supramolecular approach to the formation of polytriazole-imidazolium particles, promising supports for catalysis, based on self-assembly of amphiphilic bis-azides and bis alkynes and their linkage using CuAAC is presented.
ISSN:2046-2069
2046-2069
DOI:10.1039/d0ra09740c