Issue 20, 2007

Surface-modified nanoparticlesvia thermal and Cu(i)-mediated “click” chemistry: Generation of luminescent CdSe nanoparticles with polar ligands guiding supramolecular recognition

Abstract

A new, simple and highly versatile method for the surface modification of luminescent cadmium selenide nanoparticles (CdSe NPs) based on 1,3-dipolar cycloaddition reactions is described. Uniform, trioctylphosphine oxide (TOPO)-covered CdSe NPs were prepared and subjected to two ligand-exchange reactions: first, ligand exchange was accomplished with pyridine, fully removing the TOPO ligand from the CdSe surface. In a second step, either 1-[(3-azidopropyl)octylphosphinoyl]octane or hex-5-ynoic acid 3-(dioctylphosphinoyl)propyl ester were added, attaching an azido or an acetylene moiety to the NP surface. Further thermal or Cu(I)-mediated 1,3-dipolar cycloaddition reactions on the residual azido/acetylene moieties with a variety of acetylenes/azides furnished the modified CdSe NPs with supramolecular receptors (i.e. barbituric acid, thymine, oligoethyleneglycol) on their surface. Photoluminescence measurements reveal a ∼50% residual quantum yield (relative to TOPO-covered CdSe NPs) after ligand modification, thus presenting an efficient pathway towards luminescent, surface modified CdSe NPs. The presence of the different functional groups was proven by 1H-NMR, 31P-NMR spectroscopy and by use of a nanoparticle-bound spiropyran dye and subsequent fluorescence quenching experiments. In order to further exploit the ligands on the CdSe NP surfaces, supramolecular recognition via binding to self-assembled monolayers (SAMs) presenting the matching receptor was investigated, leading to dense layers of CdSe NPs on planar surfaces as verified by AFM measurements. The concept offers a simple method for guiding the binding and recognition of luminescent CdSe NPs and related NPs onto surfaces.

Graphical abstract: Surface-modified nanoparticles via thermal and Cu(i)-mediated “click” chemistry: Generation of luminescent CdSe nanoparticles with polar ligands guiding supramolecular recognition

Supplementary files

Article information

Article type
Paper
Submitted
18 Dec 2006
Accepted
14 Feb 2007
First published
06 Mar 2007

J. Mater. Chem., 2007,17, 2125-2132

Surface-modified nanoparticles via thermal and Cu(I)-mediated “click” chemistry: Generation of luminescent CdSe nanoparticles with polar ligands guiding supramolecular recognition

W. H. Binder, R. Sachsenhofer, C. J. Straif and R. Zirbs, J. Mater. Chem., 2007, 17, 2125 DOI: 10.1039/B618510J

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