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Self‐Assembly of ZnO Nanoparticles – An NMR Spectroscopic Study
Author(s) -
Coppel Yannick,
Spataro Grégory,
Collière Vincent,
Chaudret Bruno,
Mingotaud Christophe,
Maisonnat André,
Kahn Myrtil L.
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201200019
Subject(s) - chemistry , carboxylate , amine gas treating , ammonium , nanoparticle , inorganic chemistry , nuclear magnetic resonance spectroscopy , proton nmr , ligand (biochemistry) , colloid , molecule , organic chemistry , chemical engineering , biochemistry , receptor , engineering
The role of ligands (i.e. hexadecylamine, dodecylamine, or octylamine associated with oleic acid) on the formation of ZnO nanoparticle superlattice structures (NSSs) was investigated by NMR spectroscopy in C 7 D 8 . This full study demonstrates that ion‐paired ammonium carboxylates play a crucial role in NSS formation. Using different NMR spectroscopic experiments, such as 1 H NMR, pulsed field gradient spin‐echo (PGSE) NMR, and NOESY, we evidenced that the introduction of long‐alkyl‐chain carboxylic acid molecules into a colloidal solution of ZnO nanoparticles (NPs) stabilized by amine ligands leads to rearrangement of the amines on the surface of the NPs with the formation of ammonium carboxylate. This NMR spectroscopic study evidences the dependence of the nature of the ligands adsorbed on the NP surface on the colloid concentration. At high concentration, several ligand shells with a lot of ion‐paired ammonium carboxylate and inclusion of amine are observed. At low concentration, the ion‐paired ammonium carboxylate shells are replaced by amine shells. This NMR spectroscopic study suggests that the driving force of NSS formation is the presence of ion‐paired ammonium carboxylate shells around the nanoparticle.