Mechanistic insight into the Z?E isomerization catalysis of azobenzenes mediated by bare and core?shell gold nanoparticles

SABRINA SIMONCELLI; PEDRO F. ARAMENDÍA

Catalysis Science and Technology

Royal Society of Chemistry

Año: 2015 vol. 5 p. 2110 - 2116

2044-4753

p { margin-bottom: 0.25cm; direction: ltr; color: rgb(0, 0, 0); line-height: 120%; widows: 2; orphans: 2; }p.western { font-family: "Calibri",sans-serif; font-size: 11pt; }p.cjk { font-family: "Calibri",sans-serif; font-size: 11pt; }p.ctl { font-family: "Times New Roman",serif; font-size: 11pt; }a:link { color: rgb(0, 0, 255); } We explored the catalytic effect of 15 nm diameter gold nanoparticles (AuNPs) upon the thermal Z-E isomerization reaction of azobenzene and nine 4 and 4-4´ substituted azobenzenes (ABs). The kinetics follows a first order rate in a range of [ABs] = 5 to 50 µM and [AuNPs] = 50 pM to 1 nM. A kinetic analysis of this compartmentalized system renders the thermal Z-E isomerization rate constant associated to each AuNP. Enhancements of 10 to 106 fold were measured for this rate constant in comparison to the same free ABs in solution. Experiments with selective Au facets coverage, as well as the kinetics studied in gold-silica core-shell nanoparticles (AuNP@SiO2) of different thickness, demonstrate the surface nature of the catalysis and allow to evaluate the diffusion coefficient of azobenzene in the silica layer.