Visible-Light Photocatalyzed Cross-Linking of Diacetylene Ligands by Quantum Dots to Improve Their Aqueous Colloidal Stability
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.
Götz, M. G., Takeuchi, H., Goldfogel, M. J., Warren, J. M., Fennell, B. D., & Heyes, C. D. (2014). Visible-light photocatalyzed cross-linking of diacetylene ligands by quantum dots to improve their aqueous colloidal stability. The Journal of Physical Chem