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Controlled Synthesis of Water‐Dispersible Faceted Crystalline Copper Nanoparticles and Their Catalytic Properties
Author(s) -
Wang Yanfei,
Biradar Ankush V.,
Wang Gang,
Sharma Krishna K.,
Duncan Cole T.,
Rangan Sylvie,
Asefa Tewodros
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201000354
Subject(s) - nanoparticle , copper , aniline , catalysis , morpholine , reducing agent , materials science , x ray photoelectron spectroscopy , copper chloride , aqueous solution , inorganic chemistry , chemical engineering , polymer chemistry , chemistry , organic chemistry , nanotechnology , engineering
We report a solution‐phase synthetic route to copper nanoparticles with controllable size and shape. The synthesis of the nanoparticles is achieved by the reduction of copper(II) salt in aqueous solution with hydrazine under air atmosphere in the presence of poly(acrylic acid) (PAA) as capping agent. The results suggest that the pH plays a key role for the formation of pure copper nanoparticles, whereas the concentration of PAA is important for controlling the size and geometric shape of the nanoparticles. The average size of the copper nanoparticles can be varied from 30 to 80 nm, depending on the concentration of PAA. With a moderate amount of PAA, faceted crystalline copper nanoparticles are obtained. The as‐synthesized copper nanoparticles appear red in color and are stable for weeks, as confirmed by UV/Vis and X‐ray photoemission (XPS) spectroscopy. The faceted crystalline copper nanoparticles serve as an effective catalyst for N‐arylation of heterocycles, such as the CN coupling reaction between p ‐nitrobenzyl chloride and morpholine producing 4‐(4‐nitrophenyl)morpholine in an excellent yield under mild reaction conditions. Furthermore, the nanoparticles are proven to be versatile as they also effectively catalyze the three‐component, one‐pot Mannich reaction between p ‐substituted benzaldehyde, aniline, and acetophenone affording a 100 % conversion of the limiting reactant (aniline).