Effect of Specific Heavy Doping of Silver Atoms into the Icosahedral Au13 on Electronic Structure and Catalytic Performance.

The exploration of specific heavy doping of silver atoms into icosahedral Au13 clusters and their electronic structures and properties has been somewhat limited. Herein, we report two heavily Ag doped nanoclusters, [Au7Ag6(C7H4NOS)4(Dppf)3Cl]0 and [Au7Ag6(C7H4NOS)3(Dppf)3Cl](SbF6) (Au7Ag6-0 and Au7Ag6-1, respectively) [C7H4NOSH = 2-mercaptobenzoxazole, and Dppf = 1,1'-bis(diphenylphosphino)ferrocene]. The electronic structures and superatomic orbitals of nanoclusters were determined by density functional theory (DFT) calculations, and the energy degeneracy of the superatomic orbitals of Au7Ag6-1 is higher than that of Au7Ag6-0. Transient absorption spectroscopy was performed, revealing that Au7Ag6-0 significantly extends the excited-state lifetime. Both nanoclusters were supported on activated carbon for the oxygen reduction reaction. DFT calculations confirm that the catalytic activities mainly stem from the carbon atom of ferrocene rather than the iron atom. This study not only sheds light on the preparation of icosahedral alloy clusters but also provides insights into the regulation of icosahedral superatomic structure and electrocatalytic properties.

Evolution of Electrocatalytic CO2 Reduction Activity Induced by Charge Segregation in Atomically Precise AuAg Nanoclusters Based on Icosahedral M13 Unit 3D Assembly.

The precise self-assembly of building blocks at atomic level provides the opportunity to achieve clusters with advanced catalytic properties. However, most of the current self-assembled materials are fabricated by 1/2D assembly of blocks. High dimensional (that is, 3D) assembly is widely believed to improve the performance of cluster. Herein, the effect of 3D assembly on the activity for electrocatalytic CO2 reduction reaction (CO2 RR) is investigated by using a range of clusters (Au8 Ag55 , Au8 Ag57 , Au12 Ag60 ) based on 3D assembly of M13 unit as models. Although three clusters have almost the same sizes and geometric structures, Au8 Ag55 exhibits the best CO2 RR performance due to the strong CO2 adsorption capacity and effective inhibition of H2 evolution competition reaction. The deep insight into the superior activity of Au8 Ag55 is the unique electronic structure attributed to the charge segregation. This study not only demonstrates that the assembly mode greatly affects the catalytic activity, but also offers an idea for rational designing and precisely constructing catalysts with controllable activities.

Overall structure of Au12Ag60(S-c-C6H11)31Br9(Dppp)6: achieving a stronger assembly of icosahedral M13 units.

Precise atomically assembled nanoclusters provide a great platform to elucidate the evolution of the assembly of building blocks. Herein, a large icosahedral (M13)-based silver-gold alloy nanocluster [Au12Ag60(S-c-C6H11)31Br9(Dppp)6]Br2 (dppp = 1,3-bis(diphenylphosphino)propane) is reported. Structurally, Au12Ag60 consists of an Au12Ag40 kernel, which is viewed as the interpenetration of ten twisted complete icosahedrons (M13) and two missing icosahedrons (M12), and this is surrounded by a complex metal-organic shell. Benefiting from the extra doping of eight to twelve Au atoms, the octameric assembly was increased to a twelve-mer assembly. The time-dependent density functional theory (TDDFT) method with a Tamm-Dancoff approximation (TDA) was performed to investigate the difference in the optical properties of Au12Ag60 and Au8Ag57. The results indicate that the difference in the amount of Au atoms results in different optical properties. Furthermore, transient absorption spectroscopy (TA) was also performed, revealing that a twelve-mer assembly greatly enhances the excited-state lifetime. The [Au12Ag60(S-c-C6H11)31Br9(Dppp)6]Br2 alloy nanocluster has provided a breakthrough in the number of icosahedral M13 assemblies, i.e., achieving a twelve-mer assembly, helping to elucidate the fusion growth of M13-based assembled nanoclusters as well as their geometric/electronic structure correlations, which will promote further research on the assembly of M13 nano-building blocks, especially on their optical properties.

Biomimetic non-classical crystallization drives hierarchical structuring of efficient circularly polarized phosphors.

Hierarchically structured chiral luminescent materials hold promise for achieving efficient circularly polarized luminescence. However, a feasible chemical route to fabricate hierarchically structured chiral luminescent polycrystals is still elusive because of their complex structures and complicated formation process. We here report a biomimetic non-classical crystallization (BNCC) strategy for preparing efficient hierarchically structured chiral luminescent polycrystals using well-designed highly luminescent homochiral copper(I)-iodide hybrid clusters as basic units for non-classical crystallization. By monitoring the crystallization process, we unravel the BNCC mechanism, which involves crystal nucleation, nanoparticles aggregation, oriented attachment, and mesoscopic transformation processes. We finally obtain the circularly polarized phosphors with both high luminescent efficiency of 32% and high luminescent dissymmetry factor of 1.5 × 10-2, achieving the demonstration of a circularly polarized phosphor converted light emitting diode with a polarization degree of 1.84% at room temperature. Our designed BNCC strategy provides a simple, reliable, and large-scale synthetic route for preparing bright circularly polarized phosphors.

Rapid Conversion of a Au9 Ag12 into a Aux Ag16-x Nanocluster via Bisphosphine Ligand Engineering.

The [Aux Ag16-x (SAdm)8 (Dppe)2 ] nanocluster with aggregation-induced emission (AIE) was synthesized from a non-fluorescent [Au9 Ag12 (SAdm)4 (Dppm)6 Cl6 ](SbF6 )3 nanocluster via a ligand-exchange engineering (Dppe=1,2-Bis(diphenylphosphino)ethane, Dppm=Bis(diphenylphosphino)methane, HSAdm=1-Adamantanethiol). The nanocluster has a Au-doped icosahedral Aux Ag13-x core, capped by two Ag(SR)3 , one Ag(SR)2 and two Dppe ligands. By changing the achiral Dppe ligand into a chiral dbpb ligand ((2S,3S)-(-)-Bis(diphenylphosphino)butane or (2R,3R)-(+)-2,3-Bis(diphenylphosphino)butane), chiral nanoclusters are obtained. ESI-MS and UV-vis spectroscopy were performed to track the reaction. This work provides guidance for the construction of new clusters by etching clusters with multidentate phosphine ligands.

[Ag71(S-tBu)31(Dppm)](SbF6)2: an intermediate-sized metalloid silver nanocluster containing a building block of Ag64.

An intermediate-sized atomically precise metalloid silver nanocluster [Ag71(SR)31(Dppm)](SbF6)2 (Dppm = bis (diphenylphosphino)methane, SR = S-tBu) is reported, which comprises one building block Ag64, six SR5 pentagons, one sole SR ligand, a DppmAg2 handle, and an Ag5 lid. Structurally, a decahedron Ag23 kernel is observed in the metalloid silver nanocluster. Moreover, the Ag64 unit provides insights into the growth of large clusters such as Ag136(SR)64Cl3 and Ag141(SR)40Br12via assembly. The observed decahedron Ag23 provides a deeper understanding on Marks decahedron in larger nanoclusters, and the [Ag71(S-tBu)31(Dppm)](SbF6)2 uses Ag64 as a building block to predict the structure of larger metalloid nanoclusters.

Chiral Phosphine-Copper Iodide Hybrid Cluster Assemblies for Circularly Polarized Luminescence.

Chiral chromophores and their ordered assemblies are intriguing for yielding circularly polarized luminescence (CPL) and exploring intrinsic structure-light emission relationships. With the extensively studied chiral organic molecules and inorganic nanoparticle assemblies for the amplified CPL, the assemblies of copper halide hybrid clusters have attracted intensive attention due to their potential efficient CPL. Here, we report robust chiral phosphine-copper iodide hybrid clusters and their layered assemblies in crystalline states for amplified CPL. We reveal that the intermolecular interactions endow the clusters with the capability of assembling into chiral crystalline CPL materials, including hexagonal platelet-shaped microcrystals (glum ≈ 9.5 × 10-3) and highly oriented crystalline films (glum ≈ 5 × 10-3). Owing to the high crystalline feature of the thin film, we demonstrate an electroluminescent device with bright electroluminescence (1200 cd m-2).

Pharmacokinetics and safety of liposomal bupivacaine after local infiltration in healthy Chinese adults: a phase 1 study.

BACKGROUND: Liposomal bupivacaine (LB) is a long-acting formulation of bupivacaine. The safety and efficacy of LB has been demonstrated across surgical procedures. However, pharmacokinetic (PK) parameters and safety of LB in the Chinese population have not been assessed. METHODS: In this single-arm, single center, phase 1, open-label study, PK and safety of local infiltration with LB 266 mg were assessed in healthy Chinese adults. Eligible participants were aged 18 to 55 years with biologic parents and grandparents of Chinese ethnicity, in generally good health (i.e., no clinically significant abnormalities), and with a body mass index (BMI) 19.0 to 24.0 kg/m2 (inclusive) and body weight ≥ 50 kg. RESULTS: Participants (N = 20) were predominantly men (80 %); mean age was 32 years; and mean BMI was 21.8 kg/m2. After LB administration, mean plasma levels of bupivacaine rapidly increased during the first hour and continued to increase through 24 h; plasma levels then gradually decreased through 108 h followed by a monoexponential decrease through 312 h. Geometric mean maximum plasma concentration was 170.9 ng/mL; the highest plasma bupivacaine concentration detected in any participant was 374.0 ng/mL. Twenty-two treatment-emergent adverse events were reported (mild, n = 21; moderate, n = 1). CONCLUSIONS: After single-dose administration of LB, PK measures were similar to a previously reported profile in US adults. The highest observed peak plasma concentration of bupivacaine was several-fold below the plasma concentration threshold accepted as being associated with neurotoxicity or cardiotoxicity (2000-4000 ng/mL). These data support that LB is well tolerated and safe in individuals of Chinese descent. TRIAL REGISTRATION: NCT04158102 (ClinicalTrials.gov identifier), Date of registration: November 5, 2019.

The geometric and electronic structures of a Ag13Cu10(SAdm)12X3 nanocluster.

Herein, we report the synthesis and total structure of a Cu-rich alloy nanocluster protected by twelve adamantanethiolate ligands, i.e., [Ag13Cu10(SAdm)12]X3 (-SAdm = SC10H15, X = counterion), which was confirmed by single-crystal X-ray structure determination and electrospray ionization mass spectrometry (ESI-MS). X-ray crystallographic analysis indicated that [Ag13Cu10(SAdm)12]X3 consisted of an icosahedral Ag13 core, covered by a cage-like shell of Cu10(SAdm)12. Furthermore, density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations on the geometric and electronic structures and KS orbitals and UV-vis spectroscopy were performed on the model [Ag13Cu10(SMe)12]3+ and its monometallic analog [Ag23(SMe)12]3+. This work will deepen the understanding of core-shell Ag-Cu alloy nanoclusters.

Overall Structures of Two Metal Nanoclusters: Chloride as a Bridge Fills the Space between the Metal Core and the Metal Shell.

In addition to using common ligands (phosphine, thiol, or acetylene ligands) to protect metal nanoclusters, halogens can also be used to participate in the formation of nanoclusters. In this study, we reported the formation of two new nanoclusters promoted by chlorides released from HAuCl4: one [Au1Ag26(SR)18Cl] with an icosahedral Au1Ag12 kernel, which is surrounded by the shell of Ag14(SR)18, and the special chlorine atom fills the space between the metal core and the metal shell; the other [Au6Ag33(Dppf)2(SR)16Cl6]+ with the kernel consisted of two icosahedral Au3Ag10 units by sharing one vertex Ag atom, which is protected by the complicated shell of Ag14(Dppf)2(SR)16Cl4, two special chlorine atoms also fill the space between the metal core and the metal shell. Thus, both two nanoclusters suggest that the chlorine atoms can exist in the space between the metal kernel and out shell, playing a critical role in maintaining the stability of the overall structures. These will deepen the comprehensive understanding of chlorine in constructing the structures of alloy nanoclusters and will also be helpful in mapping out the new strategies for core-shell nanocluster synthesis.

Nanocluster growth via "graft-onto": effects on geometric structures and optical properties.

Atomically precise engineering on the nanocluster surface remains highly desirable for the fundamental understanding of how surface structures of a nanocluster contribute to its overall properties. In this paper, the concept of "graft-onto" has been exploited to facilitate nanocluster growth on surface structures. Specifically, the Ag2(DPPM)Cl2 complex is used for re-constructing the surface structure of Pt1Ag28 (SR)18(PPh3)4 (Pt1Ag28 , SR = 1-adamantanethiolate) and producing a size-growth nanocluster - Pt1Ag31 (SR)16(DPPM)3Cl3 (Pt1Ag31 ). The grafting effect of Ag2(DPPM)Cl2 induces both direct changes on the surface structure (e.g., size growth, structural transformation, and surface rotation) and indirect changes on the kernel structure (from a fcc configuration to an icosahedral configuration). Remarkable differences have been observed by comparing optical properties between Pt1Ag28 and Pt1Ag31 . Significantly, Pt1Ag31 exhibits high photo-luminescent intensity with a quantum yield of 29.3%, which is six times that of the Pt1Ag28 . Overall, this work presents a new approach (i.e., graft-onto) for the precise dictation of nanocluster surface structures at the atomic level.

Three-dimensional Octameric Assembly of Icosahedral M13 Units in [Au8 Ag57 (Dppp)4 (C6 H11 S)32 Cl2 ]Cl and its [Au8 Ag55 (Dppp)4 (C6 H11 S)34 ][BPh4 ]2 Derivative.

The high-dimensional (that is, three-dimensional (3D)) assembly of nanomaterials is an effective means of improving their properties; however, achieving this assembly at the atomic level remains challenging. Herein, we obtained a novel nanocluster, [Au8 Ag57 (Dppp)4 (C6 H11 S)32 Cl2 ]Cl (Dppp=1,3-bis(diphenylphosphino)propane) showing a 3D octameric assembly mode involving the kernel penetration of eight complete icosahedral Au@Ag10 Au2 units for the first time. The atomically precise structure was determined by single-crystal X-ray diffraction, and further confirmed by thermogravimetric analysis, X-ray photoelectron spectroscopy, and electrospray ionization mass spectrometry measurements. Furthermore, ligand-induced transformation prompted the conversion of [Au8 Ag57 (Dppp)4 (C6 H11 S)32 Cl2 ]Cl, with complete octameric fusion into [Au8 Ag55 (Dppp)4 (C6 H11 S)34 ][BPh4 ]2 , with incomplete octameric fusion. These observations will hopefully facilitate further research on the assembly of M13 nanobuilding blocks.

Total structural determination of [Au1Ag24(Dppm)3(SR)17]2+ comprising an open icosahedral Au1Ag12 core with six free valence electrons.

Herein, we report the first silver-rich nanocluster containing an open icosahedral Au1Ag12 core. This nanocluster is determined to be [Au1Ag24(Dppm)3(SR)17]2+ (where Dppm is short for bis-(diphenylphosphino)methane and SR is short for cyclohexyl mercaptan) by single-crystal X-ray diffraction and electrospray ionization mass spectrometry (ESI-MS). The Au1Ag24 consists of an open icosahedral Au1Ag12, which contains six free valence electrons surrounded by a big ring motif Ag12(Dppm)3(SR)15 and two SR groups. Density Functional Theory (DFT) provided insight into the relationship between the structure and its performance.

[Different treatment modes for cerebral microlesions: a comparison of clinical efficacy].

OBJECTIVE: To tentatively establish a diagnosis and treatment mode for effectively controlling the progress of cerebral microlesions (CM) and preventing the incidence of cerebral infarction (CI) by comparing different intervention modes for treating CM. METHODS: Using a prospective, nonrandomized, controlled trial, 408 subjects with multiple CM were assigned to the Chinese medical pharmacy intervention group (Group A, 100 case), the aspirin intervention group (Group B, 104 cases), the negative control group (Group C, 100 cases), and the non-intervention group (Group D, 104 cases). No intervention was given to those in Group D. Patients in the other 3 groups were intervened by life style and routine therapies of vasculogenic risk factors. Those in Group A took Guizhi Fuling Pill (GFP) and earthworm powder additionally. Those in Group B took aspirin additionally. They were routinely followed-up. The CM, the changes of vasculogenic risk factors, and the incidence rate of CI were compared among the 4 groups. RESULTS: The total effective rate of CM was 66.67% in Group A, obviously higher than that of Group B (52.32%), Group C (42.86%), and Group D (37.04%), respectively. It was obviously higher in Group B than in Group D, showing statistical difference (P <0.01, P <0.05). After treatment, the serum levels of LDL-C, TC, and TG were obviously lower in Group A than in Group B (P <0.05); the serum levels of LDL-C and TC were obviously lower in Group A than in Group C (P <0.01); the systolic pressure was obviously lower in Group A than in Group D (P <0.05). The systolic pressure and the serum TC level were obviously lower in Group C than in Group D (P <0.05). The incidence rate of CI was 2.17% (2/92 cases) in Group A, obviously lower than that of Group C (11.36% ,10/88 cases) and Group D (14.44%, 13/90 cases), showing statistical difference (P <0.05). But there was no statistical difference between Group A and Group B (6.74% ,6/89 cases) (P >0.05). CONCLUSIONS: GFP combined earthworm powder could treat CM, control vasculogenic risk factors, and finally prevent the incidence of CI. Standard Chinese medical intervention mode showed the optimal effects in treating CM and preventing the incidence of CI, and perhaps it could be spread clinically.