Crowdsourcing hypothesis tests: Making transparent how design choices shape research results

To what extent are research results influenced by subjective decisions that scientists make as they design studies? Fifteen research teams independently designed studies to answer fiveoriginal research questions related to moral judgments, negotiations, and implicit cognition. Participants from two separate large samples (total N > 15,000) were then randomly assigned to complete one version of each study. Effect sizes varied dramatically across different sets of materials designed to test the same hypothesis: materials from different teams renderedstatistically significant effects in opposite directions for four out of five hypotheses, with the narrowest range in estimates being d = -0.37 to +0.26. Meta-analysis and a Bayesian perspective on the results revealed overall support for two hypotheses, and a lack of support for three hypotheses. Overall, practically none of the variability in effect sizes was attributable to the skill of the research team in designing materials, while considerable variability was attributable to the hypothesis being tested. In a forecasting survey, predictions of other scientists were significantly correlated with study results, both across and within hypotheses. Crowdsourced testing of research hypotheses helps reveal the true consistency of empirical support for a scientific claim.</div

Combining the Single-Atom Engineering and Ligand-Exchange Strategies: Obtaining the Single-Heteroatom-Doped Au₁₆Ag₁(S-Adm)₁₃ Nanocluster with Atomically Precise Structure

Obtaining cognate single-heteroatom doping is highly desirable but least feasible in the research of nanoclusters (NCs). In this work, we reported a new Au₁₆Ag₁(S-Adm)₁₃ NC, which is synthesized by the combination of single-atom engineering and ligand-exchange strategies. This new NC is so far the smallest crystallographically characterized Au-based NC protected by thiolate. The Au₁₆Ag₁(S-Adm)₁₃ exhibited a tristratified Au₃–Au₂Ag₁–Au₁ kernel capped by staple-like motifs including one dimer and two tetramers. In stark contrast to the size-growth from Au₁₈(S–C₆H₁₁)₁₄ to Au₂₁(S-Adm)₁₅ via just the ligand-exchange method, combining single Ag doping on Au₁₈(S–C₆H₁₁)₁₄ resulted in the size-decrease from Au₁₇Ag₁(S–C₆H₁₁)₁₄ to Au₁₆Ag₁(S-Adm)₁₃. DFT calculations were performed to both homogold Au₁₈ and single-heteroatom-doped Au₁₇Ag₁ to explain the opposite results under the same ligand-exchange reaction. Our work is expected to inspire the synthesis of new cognate single-atom-doped NCs by combining single-atom engineering and ligand-exchange strategies and also shed light on extensive understanding of the metal synergism effect in the NC range

How a Single Electron Affects the Properties of the “Non-Superatom” Au₂₅ Nanoclusters

In this study, we successfully synthesized the rod-like [Au₂₅(PPh₃)₁₀(SePh)₅Cl₂]^<i>q</i> (<i>q</i> = +1 or +2) nanoclusters through kinetic control. The single crystal X-ray crystallography determined their formulas to be [Au₂₅(PPh₃)₁₀(SePh)₅Cl₂]­(SbF₆) and [Au₂₅(PPh₃)₁₀(SePh)₅Cl₂]­(SbF₆)­(BPh₄), respectively. Compared to the previously reported Au₂₅ coprotected by phosphine and thiolate ligands (i.e., [Au₂₅(PPh₃)₁₀(SR)₅Cl₂]²⁺), the two new rod-like Au₂₅ nanoclusters show some interesting structural differences. Nonetheless, each of these three nanoclusters possesses two icosahedral Au₁₃ units (sharing a vertex gold atom) and the bridging “Au–Se­(S)–Au” motifs. The compositions of the two new nanoclusters were characterized with ESI-MS and TGA. The optical properties, electrochemistry, and magnetism were studied by EPR, NMR, and SQUID. All these results demonstrate that the valence character significantly affects the properties of the “non-superatom” Au₂₅ nanoclusters, and the changes are different from the previously reported “superatom” Au₂₅ nanoclusters. Theoretical calculations indicate that the extra electron results in the half occupation of the highest occupied molecular orbitals in the rod-like Au₂₅⁺ nanoclusters and, thus, significantly affects the electronic structure of the “non-superatom” Au₂₅ nanoclusters. This work offers new insights into the relationship between the properties and the valence of the “non-superatom” gold nanoclusters

How a Single Electron Affects the Properties of the “Non-Superatom” Au₂₅ Nanoclusters

In this study, we successfully synthesized the rod-like [Au₂₅(PPh₃)₁₀(SePh)₅Cl₂]^<i>q</i> (<i>q</i> = +1 or +2) nanoclusters through kinetic control. The single crystal X-ray crystallography determined their formulas to be [Au₂₅(PPh₃)₁₀(SePh)₅Cl₂]­(SbF₆) and [Au₂₅(PPh₃)₁₀(SePh)₅Cl₂]­(SbF₆)­(BPh₄), respectively. Compared to the previously reported Au₂₅ coprotected by phosphine and thiolate ligands (i.e., [Au₂₅(PPh₃)₁₀(SR)₅Cl₂]²⁺), the two new rod-like Au₂₅ nanoclusters show some interesting structural differences. Nonetheless, each of these three nanoclusters possesses two icosahedral Au₁₃ units (sharing a vertex gold atom) and the bridging “Au–Se­(S)–Au” motifs. The compositions of the two new nanoclusters were characterized with ESI-MS and TGA. The optical properties, electrochemistry, and magnetism were studied by EPR, NMR, and SQUID. All these results demonstrate that the valence character significantly affects the properties of the “non-superatom” Au₂₅ nanoclusters, and the changes are different from the previously reported “superatom” Au₂₅ nanoclusters. Theoretical calculations indicate that the extra electron results in the half occupation of the highest occupied molecular orbitals in the rod-like Au₂₅⁺ nanoclusters and, thus, significantly affects the electronic structure of the “non-superatom” Au₂₅ nanoclusters. This work offers new insights into the relationship between the properties and the valence of the “non-superatom” gold nanoclusters

A New Crystal Structure of Au₃₆ with a Au₁₄ Kernel Cocapped by Thiolate and Chloride

This study presents a new crystal structure of a gold nanocluster coprotected by thiolate and chloride, with the formula of Au₃₆(SCH₂Ph-^tBu)₈Cl₂₀. This nanocluster is composed of a Au₁₄ core with two Cl atoms, a pair of pentameric Au₅(SCl₅) staple motifs, and a pair of hexameric Au₆(S₃Cl₄) motifs. It is noteworthy that the “Au–Cl–Au” staple motifs are observed for the first time in thiolate protected gold nanoclusters. More importantly, the formation of the Cl–Au₃ motifs is found to be mainly responsible for the configuration of the gold nanocluster. This work will offer a new perspective to understand how the ligands affect the crystal structure of gold nanocluster

Synthesis and Structure of Self-Assembled Pd₂Au₂₃(PPh₃)₁₀Br₇ Nanocluster: Exploiting Factors That Promote Assembly of Icosahedral Nano-Building-Blocks

The essential force of self-assembly in the nanocluster range is not intrinsically understood to date. In this work, the synergistic effect between metals was exploited to render the self-assembly from the icosahedral M₁₃ (M = Pd, Au) nano-building-blocks. Single-crystal X-ray diffraction analysis revealed that the two Pd₁Au₁₂ icosahedrons were linked by five halogen linkages, and the assembled structure was determined to be Pd₂Au₂₃­(PPh₃)₁₀Br₇. The finding of Au–halogen linkages in the rod-like M₂₅ nanoclusters has not been previously reported. Furthermore, the calculations on Hirshfeld charge analysis were performed, which implied that the reduced electronic repulsion (induced by the synergistic effect of Pd and Au metals) between two icosahedral units promoted the assembly. This study sheds light on the deep understanding of the essential force of self-assembly from icosahedral nano-building-blocks

Molecular-like Transformation from PhSe-Protected Au₂₅ to Au₂₃ Nanocluster and Its Application

In this work, we report a new size conversion from [Au₂₅(SePh)₁₈]⁻ to [Au₂₃(SePh)₁₆]⁻ nanoclusters under the reductive condition (NaBH₄). This novel transformation induced by only reductant has not been reported before in the field of gold nanocluster. The conversion process is studied via MALDI mass spectrometry, and UV–vis spectroscopy. These results demonstrate that the [Au₂₃(SePh)₁₆]⁻ nanocluster is directly obtained by pulling out two units of “Au-SeR” from the [Au₂₅(SePh)₁₈]⁻ nanocluster, which is similar to the “small molecular” reaction. In order to further understand this novel conversion, DFT calculations were performed, in which, with addition of two H^– in the [Au₂₅(SeH)₁₈]⁻ model, two Au atoms will depart from the structure of the [Au₂₅(SeH)₁₈]⁻, which is consistent with the experimental results. Furthermore, the as-prepared [Au₂₃(SePh)₁₆]⁻ nanoclusters can be converted into [Au₂₅(PET)₁₈]⁻ nanocluster (PET = SCH₂CH₂Ph) with excess PET under the reductive condition, which is quite remarkable due to a stronger bond of Au–Se in comparison to Au–S of the final product. Interestingly, the number of the PET ligands on the surface of the 25-atoms nanocluster can be controlled by the addition of the reductant. Based on these results, a circularly progressive mechanism of ligand exchange is proposed. This may offer a new approach to synthesis of new gold nanoclusters and also have significant contribution for understanding and further exploration of the mechanism of ligand exchange

Crystal Structure of Selenolate-Protected Au₂₄(SeR)₂₀ Nanocluster

We report the X-ray structure of a selenolate-capped Au₂₄(SeR)₂₀ nanocluster (R = C₆H₅). It exhibits a prolate Au₈ kernel, which can be viewed as two tetrahedral Au₄ units cross-joined together without sharing any Au atoms. The kernel is protected by two trimeric Au₃(SeR)₄ staple-like motifs as well as two pentameric Au₅(SeR)₆ staple motifs. Compared to the reported gold–thiolate nanocluster structures, the features of the Au₈ kernel and pentameric Au₅(SeR)₆ staple motif are unprecedented and provide a structural basis for understanding the gold–selenolate nanoclusters

Isomerism in Au–Ag Alloy Nanoclusters: Structure Determination and Enantioseparation of [Au₉Ag₁₂(SR)₄(dppm)₆X₆]³⁺

Revealing structural isomerism in a nanocluster remains significant but challenging. Herein, we have obtained a pair of structural isomers, [Au₉­Ag₁₂­(SR)₄­(dppm)₆­X₆]³⁺-C and [Au₉­Ag₁₂­(SR)₄­(dppm)₆­X₆]³⁺-Ac [dppm = bis­(diphenyphosphino)­methane; HSR = 1-adamantanethiol/<i>tert</i>-butylmercaptan; X = Br/Cl; C stands for one of the structural isomers being chiral; Ac stands for another being achiral], that show different structures as well as different chiralities. These structures are determined by single-crystal X-ray diffraction and further confirmed by high-resolution electrospray ionization mass spectrometry. On the basis of the isomeric structures, the most important finding is the different arrangements of the Au₅Ag₈@Au₄ metal core, leading to changes in the overall shape of the cluster, which is responsible for structural isomerism. Meanwhile, the two enantiomers of [Au₉­Ag₁₂­(SR)₄­(dppm)₆­X₆]³⁺-C are separated by high-performance liquid chromatography. Our work will contribute to a deeper understanding of the structural isomerism in noble-metal nanoclusters and enrich the chiral nanocluster

Effects of Single Platinum Atom Doping on Stability and Nonlinear Optical Properties of Ag₂₉ Nanoclusters

The properties of atomically precise noble metal nanoclusters can be modified by the addition of other metals, which may offer augmented characteristics, making them more suitable for real-life applications. In this work, we report the effects of single platinum atom doping of a class of atomically precise silver nanoclusters protected by dithiolated ligands on their optical properties both in linear and nonlinear optical (NLO) regimes and on their stability over time. Pt doping of Ag29 preserves their NLO properties (in particular two-photon excited photoluminescence)