Bimetallic Au₂Cu₆ Nanoclusters: Strong Luminescence Induced by the Aggregation of Copper(I) Complexes with Gold(0) Species

Abstract

The concept of aggregation-induced emission (AIE) has been exploited to render non-luminescent Cu(I) SR complexes strongly luminescent. The Cu(I) SR complexes underwent controlled aggregation with Au(0) . Unlike previous AIE methods, our strategy does not require insoluble solutions or cations. X-ray crystallography validated the structure of this highly fluorescent nanocluster: Six thiolated Cu atoms are aggregated by two Au atoms (Au2 Cu6 nanoclusters). The quantum yield of this nanocluster is 11.7 %. DFT calculations imply that the fluorescence originates from ligand (aryl groups on the phosphine) to metal (Cu(I) ) charge transfer (LMCT). Furthermore, the aggregation is affected by the restriction of intramolecular rotation (RIR), and the high rigidity of the outer ligands enhances the fluorescence of the Au2 Cu6 nanoclusters. This study thus presents a novel strategy for enhancing the luminescence of metal nanoclusters (by the aggregation of active metal complexes with inert metal atoms), and also provides fundamental insights into the controllable synthesis of highly luminescent metal nanoclusters.

Isomer Structural Transformation in Au–Cu Alloy Nanoclusters: Water Ripple‐Like Transfer of Thiol Ligands

“…The overall nanocluster displays a trigonal axis (C 3 ), three polar axes (C 2 ), three planes of symmetry ( ð d ), and one symmetric center. The high symmetric leads to the achiral arrangement of the Au 2 Cu 6 nanocluster . By comparison, when using the bis(diphenylphosphino)methane (L 1 ) ligand instead of the initial PPh 3 ligand, the Au 4 Cu 4 nanocluster is prepared, which contains a Cu 4 (SR) 5 semiring inlayed by an Au 4 kernel.…”

Observation of a new type of aggregation-induced emission in nanoclusters

“…Several strategies have been developed to enhance the PL QY of NCs, and they can be mainly classified into the following three categories: (1) tailoring the capping ligands of NCs (in terms of controlling the ligand to metal charge transfer (LMCT) process); 8 , 35 – 37 (2) controlling the metal composition in the NC kernel; 21 , 22 , 26 , 28 , 29 , 38 and (3) aggregation-induced emission (AIE) from non- or weakly luminescent metal NCs (or complexes). 19 , 20 , 25 , 39 , 40 Nowadays, the AIE strategy is being expanded to the hydrocarbon, metal complex, metal NC, and macromolecular research fields. 41 The corresponding AIEgens have been widely applied in biological probing, chemical sensing, and organic light-emitting diodes, to name a few.…”

“… 19 , 25 Furthermore, the previously reported enhancements of fluorescence in NCs have mostly been achieved by the restriction of intramolecular motion (RIM, a general mechanism in AIE materials). 19 , 25 This raises some interesting questions: are there any other patterns (other than RIM) of AIE that exist in the NC field? If so, how can we enhance the QY of fluorescent NCs with new patterns?…”

Facile modulation of optical properties of octagold clusters through the control of ligand-mediated interactions

“…1 One of the prominent features of such cluster species is their molecule-like behaviour offering structured visible electronic absorptions, which are closely related to the nature of their intrinsic electronic structures and also apparent colors. [2][3][4][5] Furthermore, it has been also reported that some clusters are photoluminescence active, [6][7][8][9][10][11][12][13] which sometimes extend to the near-IR region, [14][15][16][17][18] expanding the scope of the potential application of this class of compounds. [19][20][21] Recent advances in the crystal structure determination have enabled precise structure-based inspection of the factors affecting their electronic and optical properties, which revealed that the overall trends are mostly governed by the nuclearity and geometries of inorganic moieties.…”