Lateral diffusion of thiol ligands on the surface of Au nanoparticles: an electron paramagnetic resonance study

TY - JOUR

T1 - Lateral diffusion of thiol ligands on the surface of Au nanoparticles

T2 - an electron paramagnetic resonance study

AU - Ionita, Petre

AU - Volkov, Aleksei

AU - Jeschke, Gunnar

AU - Chechik, Victor

PY - 2008/1/1

Y1 - 2008/1/1

N2 - The lateral mobility of the thiolate ligands on the surface of Au nanoparticles was probed by EPR spectroscopy. This was achieved by using bisnitroxide ligands, which contained a disulfide group (to ensure attachment to the Au surface) and a cleavable ester bridge connecting the two spin-labeled branches of the molecule. Upon adsorption of these ligands on the surface of Au nanoparticles, the two spin-labeled branches were held next to each other by the ester bridge as evidenced by the spin-spin interactions. Cleavage of the bridge removed the link that kept the branches together. CW and pulsed EPR (DEER) experiments showed that the average distance between the adjacent thiolate branches on the Au nanoparticle surface only marginally increased after cleaving the bridge and thermal treatment. This implies that the lateral diffusion of thiolate ligands on the nanoparticle surface is very slow at room temperature and takes hours even at elevated temperatures (90 degrees C). The changes in the distance distribution observed at high temperature are likely due to ligands hopping between the nanoparticles rather than diffusing on the particle surface.

AB - The lateral mobility of the thiolate ligands on the surface of Au nanoparticles was probed by EPR spectroscopy. This was achieved by using bisnitroxide ligands, which contained a disulfide group (to ensure attachment to the Au surface) and a cleavable ester bridge connecting the two spin-labeled branches of the molecule. Upon adsorption of these ligands on the surface of Au nanoparticles, the two spin-labeled branches were held next to each other by the ester bridge as evidenced by the spin-spin interactions. Cleavage of the bridge removed the link that kept the branches together. CW and pulsed EPR (DEER) experiments showed that the average distance between the adjacent thiolate branches on the Au nanoparticle surface only marginally increased after cleaving the bridge and thermal treatment. This implies that the lateral diffusion of thiolate ligands on the nanoparticle surface is very slow at room temperature and takes hours even at elevated temperatures (90 degrees C). The changes in the distance distribution observed at high temperature are likely due to ligands hopping between the nanoparticles rather than diffusing on the particle surface.

KW - SELF-ASSEMBLED MONOLAYERS

KW - PLACE-EXCHANGE-REACTIONS

KW - GOLD CLUSTER MOLECULES

KW - ALKANETHIOL MONOLAYERS

KW - METAL NANOPARTICLES

KW - PHASE-SEPARATION

KW - STABILITY

KW - KINETICS

KW - AU(111)

KW - DISULFIDES

UR - http://www.scopus.com/inward/record.url?scp=41349099823&partnerID=8YFLogxK

U2 - 10.1021/ac071266s

DO - 10.1021/ac071266s

M3 - Article

SN - 0003-2700

VL - 80

SP - 95

EP - 106

JO - Analytical Chemistry

JF - Analytical Chemistry

IS - 1

ER -