Nanocluster Transformation Induced by SbF₆^– Anions toward Boosting Photochemical Activities

Abstract

The interactions between SbF6 – and metal nanoclusters are of significance for customizing clusters from both structure and property aspects; however, the whole-segment monitoring of this customization remains challenging. In this work, by controlling the amount of introduced SbF6 – anions, the step-by-step nanocluster evolutions from [Pt1Ag28(S-Adm)18(PPh3)4]Cl2 (Pt1Ag28–Cl) to [Pt1Ag28(S-Adm)18(PPh3)4](SbF6)2 (Pt1Ag28–SbF6) and then to [Pt1Ag30Cl1(S-Adm)18(PPh3)3](SbF6)3 (Pt1Ag30–SbF6) have been mapped out with X-ray crystallography, with which atomic-level SbF6 – counterion effects in reconstructing and rearranging nanoclusters are determined. The structure-dependent optical properties, including optical absorption, photoluminescence, and electrochemiluminescence (ECL), of these nanoclusters are then explored. Notably, the Pt1Ag30–SbF6 nanocluster was ultrabright with a high phosphorescence quantum yield of 85% in N2-purged solutions, while Pt1Ag28 nanoclusters were fluorescent with weaker emission intensities. Furthermore, Pt1Ag30–SbF6 displayed superior ECL efficiency over Pt1Ag28–SbF6, which was rationalized by its increased effectively exposed reactive facets. Both Pt1Ag30–SbF6 and Pt1Ag28–SbF6 demonstrated unprecedented high absolute ECL quantum efficiencies at sub-micromolar concentrations. This work is of great significance for revealing the SbF6 – counterion effects on the control of both structures and luminescent properties.

Structurally Flexible Au–Cu Alloy Nanoclusters Enabling Efficient Triplet Sensitization and Photon Upconversion

“…Ligand-protected noble-metal nanoclusters (NCs) are ultrasmall organic–inorganic hybrid nanoparticles (1–3 nm in diameter) with well-defined chemical compositions and geometric structures. Over 100 NCs with stable compositions have hitherto been discovered. − They are widely recognized as an important class of light-harvesting and -emitting materials that can be easily tuned with single-atom precision by doping heteroatoms into the metal core, − functionalizing the surface ligands, − selecting counterions, , or aggregation of NCs. − Many of them exhibit a wide absorption band ranging from ultraviolet to visible and/or near-infrared regions. In addition, NCs comprise plural heavy-metal elements (Au, Ag, Cu, etc.)…”

“…Over 100 NCs with stable compositions have hitherto been discovered. 1−4 They are widely recognized as an important class of light-harvesting and -emitting materials 5 that can be easily tuned with single-atom precision by doping heteroatoms into the metal core, 6−10 functionalizing the surface ligands, 11−13 selecting counterions, 14,15 or aggregation of NCs. 16−18 Many of them exhibit a wide absorption band ranging from ultraviolet to visible and/or near-infrared regions.…”

Elucidation of an Aggregate Excited State in the Electrochemiluminescence and Chemiluminescence of a Thermally Activated Delayed Fluorescence (TADF) Emitter

“…Numerous classes of ECL and CL luminophores have since been studied, including organic molecules, , phosphorescent metallic complexes, , nanomaterials, ,,,, and their emulsion droplets like PL of luminophore aggregate at liquid/liquid interfaces . Thermally activated delayed fluorescent (TADF) emitters are a new class of luminophores in ECL able to utilize thermally activated upconversion of triplet to singlet states, thus enabling theoretical internal quantum efficiencies of up to 100% .…”

“…Electrochemiluminescence (ECL) involves the electro-generation of radical species that subsequently undergo electron transfer reactions to form excited states, which release photons upon relaxation. , ECL has many analytical applications including biological immunoassays, − analyte detection, , single-molecule detection, ,− and various imaging application, , along with various luminophores. ,,− Since ECL does not require an incident light source, detection can be achieved with excellent signal-to-noise ratio and sensitivity . There are two general pathways by which ECL can occur.…”

“… 1 , 2 ECL has many analytical applications including biological immunoassays, 3 − 5 analyte detection, 6 , 7 single-molecule detection, 5 , 8 − 10 and various imaging application, 11 , 12 along with various luminophores. 1 , 2 , 13 − 19 Since ECL does not require an incident light source, detection can be achieved with excellent signal-to-noise ratio and sensitivity. 17 There are two general pathways by which ECL can occur.…”