d-Penicillamine-coated Cu/Ag alloy nanocluster superstructures: aggregation-induced emission and tunable photoluminescence from red to orange

Abstract

The aggregation-induced emission (AIE) behavior of metal nanoclusters has attracted much attention owing to their extensive application prospects in bio-imaging and chemical sensors. However, the intrinsic mechanism of metal nanoclusters' aggregation-induced emission is still not very clear. Herein, Cu nanoclusters S1 and Ag(i)-doped Cu/Ag nanoclusters S2 and S3 coated with d-penicillamine are designed and synthesized by a self-assembly strategy. S1-S3 show strong luminescence properties with luminescence quantum yields as high as 11.4%-14.2%. Moreover, their luminescence peak position shows an obvious hypsochromic shift from 615 (S1) to 570 nm (S3). With the introduction of Ag(i) ions, the assembly morphology also shows clear changes from the irregular assembly structure (S1) to large spherical particles with the average size of 0.18 μm for S2 and 0.47 μm for S3. A detailed investigation of high-resolution transmission electron microscopy (HRTEM) images, X-ray diffraction (XRD) patterns, ESI-TOF-mass spectra, UV-vis absorption spectra, photoluminescence spectra and luminescence lifetimes of Cu/Ag nanoclusters S2 and S3 indicates that Cu/Ag nanoclusters are actually a Cu/Ag alloy nanocluster superstructure and the microscopic arrangement of S2 and S3 is more compact and ordered relative to S1. The more compact and ordered Cu/Ag alloy nanocluster superstructure enhances the metal-metal interaction of inter-nanoclusters and intra-nanoclusters and facilitates the radiative transition of ligand-to-metal charge transfer (LMCT) and/or ligand-to-metal-metal charge transfer (LMMCT), which results in the aggregation-induced emission phenomenon. In addition, an enhanced metal-metal interaction increases the average metal-metal distance of the Cu/Ag nanocluster superstructure, leading to a hypsochromic shift of emission spectra. Furthermore, the Cu/Ag alloy nanoclusters show good stability and reversibility on pH cycling between pH = 3 and 7 and temperature cycling between 5 °C and 48 °C. The Cu/Ag alloy nanoclusters can be used as probes for Ag(i) ion and halide anion detection in real water samples by the ratiometric PL method (I/I).

Using G‐Rich Sequence to Enhance the Peroxidase‐Mimicking Activity of DNA‐Cu/Ag Nanoclusters for Rapid Colorimetric Detection of Hydrogen Peroxide and Glucose

“…For Ag in the Cu/Ag NCs, there are two relatively strong peaks at 368.1 eV for Ag 3d 5/2 and 374.1 eV for Ag 3d 3/2 , indicating that Ag (0) is the main form of existence (Figure b) . In Figure c, since the electron binding energy difference between Cu (0) and Cu (I) species is only 0.1 eV, the peak at 932.8 eV indicates the presence of Cu (0) and/or Cu (I) in NCs, while the peak at 952.4 eV is thought to contain Cu (0) in NCs . The peak positions of 564.6 eV and 572.9 eV in the auger spectrum of Cu (inset in Figure c) were similar to those of 564.6 eV and 572.7 eV in the literature, indicating the simultaneous existence of Cu (0) and Cu (I).…”

Stimuli‐Responsive Fluorescent Nanoswitches: Solvent‐Induced Emission Enhancement of Copper Nanoclusters

“…The interlayer spacing d corresponding to the thickness of the GSH ligandsa nd metal core slabs can be calculated from the scattering factor of the first peak (d = 2p/q 1 ). For aC u slab thickness of approximately 1 , [18] the length of GSH is cal- culated to be 9a nd 7 ,r espectively.T he theoretically estimated layer spacing of 1.7 nm is consistent witht he calculated values of about 1.7 and 1.9 nm. This can be achieved by a combination of ligand density redistribution and ligand bending.…”

Ligand functionalized copper nanoclusters for versatile applications in catalysis, sensing, bioimaging, and optoelectronics

“…Among these sensing schemes, the detection based on absorption and emission properties has been employed more frequently, and included in situ synthesis of fluorescent Cu NCs (through the turn on/turn-off mechanism), fluorescent quenching through the inner filter effect (IFE), FRET, and electron transfer, and enhanced fluorescent intensity (mostly due to AIE mechanisms). Accordingly, a lot of studies have recently been conducted on potential applications of Cu NCs as a fluorescent sensor for detection of various compounds such as anions, namely, halides (Cl À , Br À and I À ), 63,201 S 2À , 28,153,165,202,203 64 and phosphate; 204 cations, such as Ag + , 63,205 This journal is © The Royal Society of Chemistry and the Chinese Chemical Society 2019…”