title: Visible-light photocatalyzed cross-linking of diacetylene ligands by quantum dots to improve their aqueous colloidal stability.
abstract: Ligand cross-linking is known to improve the colloidal stability of nanoparticles, particularly in aqueous solutions. However, most cross-linking is performed chemically, in which it is difficult to limit interparticle cross-linking, unless performed at low concentrations. Photochemical cross-linking is a promising approach but usually requires ultraviolet (UV) light to initiate. Using such high-energy photons can be harmful to systems in which the ligand-nanoparticle bond is fairly weak, as is the case for the commonly used semiconductor quantum dots (QDs). Here, we introduce a novel approach to cross-link thiolated ligands on QDs by utilizing the photocatalytic activity of QDs upon absorbing visible light. We show that using visible light leads to better ligand cross-linking by avoiding the problem of ligand dissociation that occurs upon UV light exposure. Once cross-linked, the ligands significantly enhance the colloidal stability of those same QDs that facilitated cross-linking.
authors.affiliation: Department of Chemistry, Whitman College , 345 Boyer Avenue, Walla Walla, Washington 99362, United States.
authors.forename: Marion G
authors.initials: MG
authors.lastname: Götz
authors.forename: Hiroko
authors.initials: H
authors.lastname: Takeuchi
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Goldfogel
authors.forename: Julia M
authors.initials: JM
authors.lastname: Warren
authors.forename: Brandon D
authors.initials: BD
authors.lastname: Fennell
authors.forename: Colin D
authors.initials: CD
authors.lastname: Heyes
mesh_terms: D000114:Acetylene / Q000737:chemistry*; D002384:Catalysis; D003102:Colloids / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D008024:Ligands; D008027:Light; D049449:Luminescence; D045663:Quantum Dots / Q000737:chemistry*; D012666:Semiconductors; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D003102:Colloids; D003432:Cross-Linking Reagents; D008024:Ligands; D013438:Sulfhydryl Compounds; D014867:Water; D000114:Acetylene