Solid-State Dendrimer Sensors: Probing the Diffusion of an Explosive Analogue Using Neutron Reflectometry

TitleSolid-State Dendrimer Sensors: Probing the Diffusion of an Explosive Analogue Using Neutron Reflectometry
Publication TypeJournal Article
Year of Publication2009
AuthorsCavaye, Hamish, Smith Arthur R. G., James Michael, Nelson Andrew, Burn P. L., Gentle Ian R., Lo S. C., and Meredith Paul
JournalLangmuir
Volume25
Start Page12800
Issue21
Pagination12805
Date Published07/2009
Abstract

Determining how analytes are sequestered into thin films is important for solid-state sensors that detect the presence of the analyte by oxidative luminescence quenching. We show that thin (230 ± 30 Å) and thick (750 ± 50 Å) films of a first-generation dendrimer comprised of 2-ethylhexyloxy surface groups, biphenyl-based dendrons, and a 9,9,9′,9′-tetra-n-propyl-2,2′-bifluorene core, can rapidly and reversibly detect p-nitrotoluene by oxidative luminescence quenching. For both the thin and thick films the photoluminescence (PL) is quenched by p-nitrotoluene by ∼90% in 4 s, which is much faster than that reported for luminescent polymer films. Combined PL and neutron reflectometry measurements on pristine and analyte-saturated films gave important insight into the analyte adsorption process. It was found that during the adsorption process the films swelled, being on average 4% thicker for both the thin and thick dendrimer films. At the same time the PL was completely quenched. On removal of the analyte the films returned to their original thickness and scattering length density, and the PL was restored, showing that the sensing process was fully reversible.

URLhttp://dx.doi.org/10.1021/la9017689