Gold and Silver Nanoparticles Functionalized by Luminescent Iridium Complexes: Synthesis and Photophysical and Electrofluorochromic Properties

Abstract

International audienceGold and silver nanoparticles in the 5 nm range functionalized by luminescent and electroactive iridium complexes are synthesized and characterized. Cyclometalated iridium complexes with a modified phenanthroline ligand bearing a pyridine end group are able to cap gold nanoparticles without changing their size and shape, while for silver the size slightly increases and aggregation starts to occur but without any flocculation. The luminescence of iridium is partially quenched by gold nano- particles even when interactions with the complex do not involve surface functionalization (simple mixture). This quenching is much weaker in the case of silver, and capped nanoparticles retain the same luminescence as the free complex. Both iridium complexes display electrofluorochromism, that is, a reversible electrochemically driven luminescence switch when changing the redox state of the metal center

Highly Reversible Electrofluorochromism from Electrochemically Decoupled but Electronically Coupled Molecular Dyads

“…Fluorescence emission can be modulated by facilitating or suppressing excited‐state energy or electron transfer to electrochromic quenchers. Redox‐active molecules, such as ferrocene, were examined for their actions, but inorganic materials, including Prussian blue and polyoxometalates, have been widely employed due to electrochemical robustness . Note that these materials have been used as the forms of multilayer or bulk‐heterojunction films, which attenuated the efficiencies of fluorescence modulation.…”

“…Redox-active molecules, such as ferrocene, were examined for their actions, [3,6,7,[9][10][11][12][13][16][17][18]27,[33][34][35][36][37][38][39][40][41] but inorganic materials, including Prussian blue and polyoxometalates, have been widely employed due to electrochemical robustness. [2,4,5,8,14,42,43] Note that these materials have been used as the forms of multilayer or bulk-heterojunction films, which attenuated the efficiencies of fluorescence modulation. Molecules exhibiting redox-active fluorescence changes are advantageous for their efficiency and tunability ( Figure 1b); however, not all fluorophores display electrofluorochromism.…”

Electroluminochromic Materials and Devices Based on Metal Complexes

“…Gold and silver nanoparticles functionalized by Ir III complex Ir-18 (Figure 2) were reported by utilizing pyridine on the auxiliary ligand as an anchor group. [59] The effects of surfacep lasmon resonance on the electrochemical and photophysical properties of nanoparticles have been explored. The Au nanoparticles capped by complex Ir-18 were in the range of 5nm, and their size and shape were unchanged, whereas the size for the Ir-18-capped Ag nanoparticles slightly increased due to the aggregation effect (Figure 7b,c).…”

Electroluminochromic Materials and Devices

“…The first ELC material was reported by Lehn et al who utilized a quinone redox switching to reversibly turn ON/OFF the luminescence of a ruthenium–bipyridine complex . Since then, many kinds of materials have been developed for ELC applications, including small molecules, , fluorescent polymers, luminescent polyoxometalates, and quantum dots. One pioneering example of ELC device was reported by P. Audebert and E. Kim based on tetrazine small molecules .…”