Crystallization-induced emission enhancement was achieved in metal nanoclusters for the first time.

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A structure evolution map of face-centered cubic (fcc)-structured thiolate-ligand protected gold nanoclusters is outlined on the basis of total structure determination of a new 6e Au21(SR)15 (R = tert-butyl, t-Bu) cluster. The structural evolution map described some basic structural evolution patterns such as a triangle-Au3 and tetrahedron-Au4 associated gold-core evolution pattern and the periodic or symmetric growth of gold cores and ligand shells. According to the structural evolution map, a topological structure–electronic structure relationship is also proposed. The delocalized valence electronic properties of any fcc-structured gold clusters may be expressed as the linear combinations of the molecular orbitals of the fragment 2e units (Au3 + and Au4 2+). The structural disciplines and topological structure–electronic structure relationships reported in this work laid a basis for understanding the structural evolution and electronic structure of fcc-structured thiolate-protected gold nanoclusters. Particularly, the established structural evolution map provides a tool to explore new magic-sized clusters and cluster structures. In this work, a new fcc-structured 4e Au17(SR)13 and a new isomer structure of the 8e Au28(SR)20 cluster were predicted. The medium-sized fcc-structured gold clusters locating in the size range from 52 to 92 gold atoms and even larger-sized gold clusters can be also explored from the structural regularities described in the map.

We report the observation of new doping behavior in Au36-xAgx(SR)24 nanoclusters (NCs) with x = 1 to 8. The atomic arrangements of Au and Ag atoms are determined by X-ray crystallography. The new gold-silver bimetallic NCs share the same framework as that of the homogold counterpart, i.e. possessing an fcc-type Au28 kernel, four dimeric AuAg(SR)3 staple motifs and twelve simple bridging SR ligands. Interestingly, all the Ag dopants in the Au36-xAgx(SR)24 NCs are selectively incorporated into the surface motifs, which is in contrast to the previously reported Au-Ag alloy structures with the Ag dopants preferentially displacing the core gold atoms. This distinct doping behavior implies that the previous assignments of an fcc Au28 core with four dimers and 12 bridging thiolates for Au36(SR)24 are more justified than other assignments of core vs. surface motifs. The UV-Vis adsorption spectrum of Au36-xAgx(SR)24 is almost the same as that of Au36(SR)24, indicating that the Ag dopants in the motifs do not change the optical properties. The similar UV-Vis spectra are further confirmed by TD-DFT calculations. DFT also reveals that the energies of the HOMO and LUMO of the motif-doped AuAg alloy NC are comparable to those of the homogold Au36 NC, indicating that the electronic structure is not disturbed by the motif Ag dopants. Overall, this study reveals a new silver-doping mode in alloy NCs.

Herein, we report the synthesis and atomic structures of the cluster-assembled CuAu(PPh)(PhCHCHS)Cl and CuAu(PPh)(BuPhCHS)S nanoclusters (NCs). The atomic structures of both NCs were precisely determined by single-crystal X-ray crystallography. The CuAu(PPh)(PhCHS)Cl NC was assembled by two icosahedral M via a vertex-sharing mode. The Cu atom partially occupies the top and waist sites and is monocoordinated with chlorine or thiol ligands. Meanwhile, the CuAu(PPh)(BuPhCHS)S NC can be described as three 13-atom icosahedra sharing three vertexes in a cyclic fashion. The three Cu atoms all occupy the internal positions of the cluster core. What is more important is that all three Cu atoms in CuAu are monocoordinated by the bare S atoms. The absorption spectra of the as-synthesized bimetallic NCs reveal that the additional metal doping and different cluster assemblies affect the electronic structure of the monometallic NCs.

A novel AuCu(m-MBT) (x = 1-3, m-MBT = 3-methylbenzenethiolate) nanocluster has been prepared. According to the X-ray single crystal diffractometer, the structure of AuCu(m-MBT) is similar to that of Au(SPhBu). The AuCu(m-MBT) nanocluster contains a face-centered cubic (FCC) M core, which is protected by 4 MS (M = Au/Cu) staple motifs and 12 bridging SR ligands. The Cu dopants could possibly occupy 14 sites (six in the sub-surface and eight in the staple motifs). Spectral monitoring indicates that the number of Cu dopants sequentially increased on increasing the amount of Cu precursors (relative to a Au control). Meanwhile, DFT calculations imply that the maximum doping number of Cu is 3, and doping occurs preferentially at the staple sites and sub-surface sites (instead of the centre of the core). Because the atomic orbital of the peripheral locations hardly contributes to the frontier molecular orbitals, the UV-vis of the AuCu alloy is almost the same as that of its homometallic Au counterpart.

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superior to conventional computers as it is highly energy efficient, fault tolerant and has parallel processing capabilities, all this in such a small volume [2,3]. Advancements in both neuroscience and electronics have led to the area of neuromorphic computing, in which attempts are being made to incorporate certain aspects of neurobiological anatomy into the design and implementation of computing systems by implementing hardware neurons and synapses [4]. In a biological system,