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Highly Loaded Multi‐Walled Carbon Nanotubes Non‐Covalently Modified with a Bis‐Imidazolium Salt and their Use as Catalyst Supports
Author(s) -
Salvo Anna Maria Pia,
La Parola Valeria,
Liotta Leonarda F.,
Giacalone Francesco,
Gruttadauria Michelangelo
Publication year - 2016
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.201600023
Subject(s) - catalysis , phenylboronic acid , carbon nanotube , covalent bond , chemistry , pyrene , derivative (finance) , bromide , salt (chemistry) , high resolution transmission electron microscopy , carbon fibers , ion exchange , inorganic chemistry , polymer chemistry , organic chemistry , materials science , ion , nanotechnology , composite number , composite material , transmission electron microscopy , financial economics , economics
The surfaces of multi‐walled carbon nanotubes (MWCNTs) were non‐covalently modified using two bis‐imidazolium dibromide derivatives having phenyl or pyrene groups. Due to the presence of the two pyrene groups the bis(pyren‐1‐ylmethylimidazolium) dibromide derivative was immobilised at a loading of about 15–16 wt %, whereas only <3 wt % of the phenyl derivative was immobilised. The presence of the two imidazolium cations helped the immobilisation of tetrachloropalladate ions after exchange with bromide ions. Tetrachloropalladate was used as pre‐catalyst in several Suzuki–Miyaura carbon–carbon cross‐coupling reactions in water or water/ethanol at 50 °C in only 0.1 mol % and compared with the non‐supported pre‐catalyst. The MWCNT‐supported material was used in five consecutive cycles of the Suzuki–Miyaura reaction. Recycling using phenylboronic acid and 4‐bromobenzaldehyde in water/ethanol was achieved with only a minor loss in activity. HRTEM images clearly showed the presence of the bis(pyren‐1‐ylmethylimidazolium) derivative on the sidewalls of MWCNTs.