title: "Shine & Click" Photo-Induced Interfacial Unmasking of Strained Alkynes on Small Water-Soluble Gold Nanoparticles.
abstract: In this study, we report the design, synthesis, and characterization of small 3 nm water soluble gold nanoparticles (AuNPs) that feature cyclopropenone-masked strained alkyne moieties capable of undergoing interfacial strain-promoted cycloaddition (i-SPAAC) with azides after exposure to UV-A light. A strained alkyne precursor was incorporated onto AuNPs by direct ligand exchange of a thiol-modified cyclopropenone-masked dibenzocyclooctyne (photoDIBO) ligand. These photoDIBO-AuNPs were characterized by1H NMR, IR, and UV/Vis spectroscopy, as well as transmission electron microscopy (TEM) and thermogravimetric analysis (TGA), and the extent of modification was quantified. Upon irradiation with UV-A light, photoDIBO-AuNPs underwent efficient and quantitative regeneration of the parent strained alkyne by photochemical decarbonylation to afford DIBO-derivatized AuNPs. DIBO-AuNPs were found to react cleanly and rapidly (k=5.3×10-2m-1s-1) by an interfacial strain-promoted alkyne-azide cycloadditon (i-SPAAC) with benzyl azide, which served as a simple model system. Furthermore, DIBO-AuNPs were reacted with various azides and a nitrone (interfacial strain-promoted alkyne-nitrone cycloaddition, i-SPANC) to showcase the generality of this approach for the facile modification of AuNP surfaces and their properties. The cyclopropenone-based photo-triggered click chemistry at the interface of water-soluble AuNPs offers exciting opportunities for the atom-by-atom control and assembly of functional materials for applications in materials and biomaterials science as well as in chemical biology.
authors.affiliation: Department of Chemistry and Centre for Materials and Biomaterials Research, Western University, 1151 Richmond St., London, ON, N6A 5B7, Canada.
authors.forename: Wilson
authors.initials: W
authors.lastname: Luo
authors.affiliation: Department of Chemistry and Centre for Materials and Biomaterials Research, Western University, 1151 Richmond St., London, ON, N6A 5B7, Canada.
authors.forename: Pierangelo
authors.initials: P
authors.lastname: Gobbo
authors.affiliation: Department of Chemistry, University of Georgia, Athens, GA, 30602, United States.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: McNitt
authors.affiliation: Department of Chemistry, University of Georgia, Athens, GA, 30602, United States.
authors.forename: Dewey A
authors.initials: DA
authors.lastname: Sutton
authors.affiliation: Department of Chemistry, University of Georgia, Athens, GA, 30602, United States.
authors.forename: Vladimir V
authors.identifier: http://orcid.org/0000-0001-9112-3935
authors.initials: VV
authors.lastname: Popik
authors.affiliation: Department of Chemistry and Centre for Materials and Biomaterials Research, Western University, 1151 Richmond St., London, ON, N6A 5B7, Canada.
authors.forename: Mark S
authors.identifier: http://orcid.org/0000-0001-8517-6483
authors.initials: MS
authors.lastname: Workentin
keywords: click chemistry; gold nanoparticles; photochemistry; stained alkynes; surface modification