Jinsong Chai

The Magic Au60 Nanocluster: A New Cluster‐Assembled Material with Five Au13 Building Blocks

Herein, we report the synthesis and atomic structure of the cluster-assembled [Au60Se2(Ph3P)10(SeR)15](+) material. Five icosahedral Au13 building blocks from a closed gold ring with Au-Se-Au linkages. Interestingly, two Se atoms (without the phenyl tail) locate in the center of the cluster, stabilized by the Se-(Au)5 interactions. The ring-like nanocluster is unprecedented in previous experimental and theoretical studies of gold nanocluster structures. In addition, our optical and electrochemical studies show that the electronic properties of the icosahedral Au13 units still remain unchanged in the penta-twinned Au60 nanocluster, and this new material might be a promising in optical limiting material. This work offers a basis for deep understanding on controlling the cluster-assembled materials for tailoring their functionalities.

Crystallization-induced emission enhancement: A novel fluorescent Au-Ag bimetallic nanocluster with precise atomic structure

Crystallization-induced emission enhancement was achieved in metal nanoclusters for the first time. We report the first noble metal nanocluster with a formula of Au4Ag13(DPPM)3(SR)9 exhibiting crystallization-induced emission enhancement (CIEE), where DPPM denotes bis(diphenylphosphino)methane and HSR denotes 2,5-dimethylbenzenethiol. The precise atomic structure is determined by x-ray crystallography. The crystalline state of Au4Ag13 shows strong luminescence at 695 nm, in striking contrast to the weak emission of the amorphous state and hardly any emission in solution phase. The structural analysis and the density functional theory calculations imply that the compact C–H⋯π interactions significantly restrict the intramolecular rotations and vibrations and thus considerably enhance the radiative transitions in the crystalline state. Because the noncovalent interactions can be easily modulated via varying the chemical environments, the CIEE phenomenon might represent a general strategy to amplify the fluorescence from weakly (or even non-) emissive nanoclusters.

Controlling the selectivity of catalytic oxidation of styrene over nanocluster catalysts

Atomically precise Au25 and Ag44 as well as alloy nanoclusters (Au25−xAgx and Au12Ag32) are investigated for catalytically selective oxidation of styrene. Distinct synergistic effects of Au–Ag bimetallic nanoclusters are identified. In addition, the addition of H2O (a few vol%) to the reaction solvent is found to drastically affect the product selectivity. Based upon Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) measurements, a possible mechanism for the nanocluster-catalyzed styrene selective oxidation is proposed. Specifically, H2O could change the surface composition of Au on the Au25 nanocluster and the valence state of Ag on the Ag44 nanocluster. Such effects are also present on the bimetallic Au25−xAgx, but not on the bimetallic Au12Ag32 nanocluster because for the latter Au exclusively acts as kernel atoms. This work provides insights into the different functional roles of water in the nanoclusters based upon their different atomic structures.

Crystal Structures of Two New Gold–Copper Bimetallic Nanoclusters: CuxAu25–x(PPh3)10(PhC2H4S)5Cl22+ and Cu3Au34(PPh3)13(tBuPhCH2S)6S23+

Herein, we report the synthesis and atomic structures of the cluster-assembled CuxAu25-x(PPh3)10(PhCH2CH2S)5Cl22+ and Cu3Au34(PPh3)13(tBuPhCH2S)6S23+ nanoclusters (NCs). The atomic structures of both NCs were precisely determined by single-crystal X-ray crystallography. The CuxAu25-x(PPh3)10(PhC2H4S)5Cl22+ NC was assembled by two icosahedral M13 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 Cu3Au34(PPh3)13(tBuPhCH2S)6S23+ 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 Cu3Au34 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.

Fluorescence Signal Amplification of Gold Nanoclusters with Silver Ions

The introduction of Ag+ results in significant amplification of the fluorescence signal of water-soluble gold nanoclusters (NCs) capped by BSA (short for bull serum albumin) associated with a blueshift of the emission maximum by about 35 nm. In contrast, all other metal ions and anions (Au3+, Ca2+, Mn2+, NO2−, F−, Cl−, etc.) induce comparable emission intensities, and Hg2+ completely quenches the emission of gold NCs. The amplified fluorescence is used to recover the fluorescence in sensing systems of Hg2+ based on gold nanoclusters, amplifying the emission signal and improving the detection limits.

CCDC 1567807: Experimental Crystal Structure Determination

Related Article: Sha Yang, Jinsong Chai, Yongbo Song, Jiqiang Fan, Tao Chen, Shuxin Wang , Haizhu Yu , Xiaowu Li, Manzhou Zhu|2017|J.Am.Chem.Soc.|139|5668|doi:10.1021/jacs.7b00668

CCDC 1494985: Experimental Crystal Structure Determination

Related Article: Jiqiang Fan, Yongbo Song, Jinsong Chai, Sha Yang, Tao Chen, Bo Rao, Haizhu Yu, Manzhou Zhu|2016|Nanoscale|8|15317|doi:10.1039/C6NR04255D