Ultrastable atomically precise chiral silver clusters with more than 95% quantum efficiency

Abstract

Monolayer-protected atomically precise silver clusters display low photoluminescence (PL) quantum yield (QY) and susceptibility under ambient conditions, and their chiroptical activities also remain underdeveloped. Here, we report enantiomers of an octahedral Ag6 cluster prepared via one-step synthesis using designed chiral ligands at ambient temperature. These clusters exhibit a highest PLQY (300 K) >95.0% and retain their structural integrity and emission up to 150°C in air. Atomically precise structural determination combined with photophysical and computational analysis revealed that thermally activated delayed fluorescence, observed in silver cluster systems, is responsible for the high PLQY, which combines chirality in excited states to generate strong circularly polarized luminescence. These unprecedented findings open up horizons of investigation of monolayer-protected silver clusters for future luminescence applications.

Ligand engineering to achieve enhanced ratiometric oxygen sensing in a silver cluster-based metal-organic framework

“…The significant decrease in the ligand-based Fl lifetimes of Ag 12 bpy-NH 2 from 3.59 to 0.37 ns, which is accompanied by a considerable increase in the Ph lifetime from 0.2 μs to 3.12 ms (Table 1), suggested the occurrence of an efficient ISC process from the lowest singlet to the lowest triplet excited states (vide infra). The 15,000-fold enhancement in the Ph lifetime is an unprecedented phenomenon among luminescent MOFs [19][20][21][22][23][24][25][26][27][28][33][34][35][36][37][38] and metal clusters [39][40][41][42][43] , even in metal-containing phosphors 12,13,[44][45][46] , which means that the triplet excited state(s) of Ag 12 bpy-NH 2 is capable of responding to oxygen molecules with a sensitivity of one-15,000th of the original sensitivity of unsubstituted Ag 12 bpy if one merely considers the lifetime factor. Of course, this also presents a challenge for obtaining precise measurements in the range of hypoxia.…”

“…Silver-chalcogenolate-cluster-based metal-organic frameworks (SCC-MOFs) [33][34][35][36][37][38] , in which each SBU consists of tens of silver and chalcogen atoms, have become a new member of the MOF family. SCC-MOFs combine the advantages of silver clusters [39][40][41][42][43] and MOFs [8][9][10][11][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] ; SCC-MOFs have shown remarkably improved luminescent properties relative to discrete silver clusters and unique excellent luminescent responses for sensing gases and volatile organic compounds (VOCs) [33][34][35][36][37] . We previously reported a SCC-MOF, that is, Ag 12 bpy 33 , ([Ag 12 (S t Bu) 8 (CF 3 COO) 4 (bpy) 4 ] n , bpy = 4,4′-bipyridine), whose single green Ph is sensitive to oxygen (Fig.…”

Single‐Pulse‐Induced Ultrafast Spatial Clustering of Metal in Glass: Fine Tunability and Application

“…Clustering offers a new perspective for modulating the properties of metals. [ 1,2 ] The quantum confinement effect and high quantum yield of luminescence endow metal clusters with unusual optoelectronic properties and multifunctionalities. [ 2–4 ] Recently, metal clusters in transparent solids have attracted extensive research attention and served a number of functions in photonic devices, such as light‐emitting diodes, solar cells, flexible screen monitors, and optical information storage.…”

“…[ 1,2 ] The quantum confinement effect and high quantum yield of luminescence endow metal clusters with unusual optoelectronic properties and multifunctionalities. [ 2–4 ] Recently, metal clusters in transparent solids have attracted extensive research attention and served a number of functions in photonic devices, such as light‐emitting diodes, solar cells, flexible screen monitors, and optical information storage. [ 5–13 ] In particular, the spatial‐controllable clustering of metals in transparent solids provides a unique flexibility in the 3D design of micro/nano and high‐capacity optical storage devices.…”

Silver in the Center Enhances Room‐Temperature Phosphorescence of a Platinum Sub‐nanocluster by 18 Times

“…[11][12][13] The use of metal nanoclusters as phosphors in white light-emitting diodes has been receiving much attention due to the nature of aggregation-induced emission. [14][15][16] However, in the early investigations, metal nanoclusters had very weak photoluminescence (PL), with quantum yield typically in the order of 0.1 % or less. [17,18] Designing strategies are needed but the most fundamental issue; the origin of PL remains unclear.…”