TY - JOUR
T1 - Entropy-Driven Reversible Agglomeration of Crown Ether Capped Gold Nanoparticles
AU - Hill, Alexander P.
AU - Kunstmann-Olsen, Casper
AU - Grzelczak, Marcin P.
AU - Brust, Mathias
PY - 2018/3/2
Y1 - 2018/3/2
N2 - It is shown that plasmonic gold nanoparticles functionalised with a thiolated 18-crown-6 ligand shell agglomerate spontaneously from aqueous dispersion at elevated temperatures. This process takes place over a narrow temperature range, is accompanied by a colour change from red to purple-blue and is fully reversible. Moreover, the temperature at which it occurs can be adjusted by the degree of complexation of the crown ether moiety with appropriate cations. More complexation leads to higher transition temperatures. The process has been studied by UV/Vis spectroscopy, electron microscopy, dynamic light scattering and zeta potential measurements. A thermodynamic rationale is provided to suggest an entropy-driven endothermic agglomeration process based on attractive hydrophobic interactions of the complexed crowns that are competing against electrostatic repulsion of the charged ligand shells.
AB - It is shown that plasmonic gold nanoparticles functionalised with a thiolated 18-crown-6 ligand shell agglomerate spontaneously from aqueous dispersion at elevated temperatures. This process takes place over a narrow temperature range, is accompanied by a colour change from red to purple-blue and is fully reversible. Moreover, the temperature at which it occurs can be adjusted by the degree of complexation of the crown ether moiety with appropriate cations. More complexation leads to higher transition temperatures. The process has been studied by UV/Vis spectroscopy, electron microscopy, dynamic light scattering and zeta potential measurements. A thermodynamic rationale is provided to suggest an entropy-driven endothermic agglomeration process based on attractive hydrophobic interactions of the complexed crowns that are competing against electrostatic repulsion of the charged ligand shells.
KW - aggregation
KW - crown ether
KW - nanoparticles
KW - thermoresponsive
UR - https://doi.org/10.1002/chem.201705820
U2 - 10.1002/chem.201705820
DO - 10.1002/chem.201705820
M3 - Journal article
SN - 1521-3765
VL - 24
SP - 3151
EP - 3155
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 13
ER -