The nature of stability and adsorption interactions of binary Au-Li clusters with bridge adsorption structures.

Earlier findings have confirmed that CO molecules have propensities to adsorb on low-coordinated gold atoms (top sites) of Au-based clusters, which can be treated by the Blyholder model wherein the σ donation and π-back donation take place. Here, the structural features and stability of (AuLi)n (n = 1-9) clusters were first analyzed using the GA-DFT method. The new adsorption modes, vibration frequencies and electronic interactions for Au-Li clusters with CO were investigated in detail. More excitingly, we found that CO prefers to adsorb on the bridge sites of the Au-Li clusters rather than on the top sites, which are much lower in energies than the top adsorptions, and the C-O stretching frequencies are also red-shifted. AIMD simulations show that the adsorption structures still have good thermal stability at 500 K. The density of states reveals that the electronic structures of Au-Li clusters have excellent stability for the bridge adsorptions of CO molecules. The ETS-NOCV analysis and NPA charges show that the direction of charge flow is from Au-Li clusters → CO. Our study provides an idea to elucidate the new adsorption mechanism on Au-Li clusters and the connection between the geometries and reaction properties.

Planar σ-Aromaticity in Ga-Doped Au Clusters.

Recently, the first example of Au-Ga clusters is synthesized and characterized, which can be described by the jellium model as a superatom with 8 valence electrons that come from the joint contribution of Au and Ga atoms, opening a whole new field for further research. Here, the structure features and stability of one Ga-doped Au cluster with magic number electrons (6 and 8) are analyzed in detail. Moreover, the valence electron fillings and chemical bonding of them are also further explored. It is found that Au3Ga and Au5Ga clusters present planar configurations, and they have higher stability than that of neighbor clusters. The AIMD simulations show that these two clusters still have a good thermal stability at 500 K. The molecular orbital analyses show that the Au3Ga and Au5Ga have three and one typical delocalization orbital throughout the whole planar spaces, respectively, following the planar σ-aromaticity rule. The ELF and LOL analyses are further performed, and the results are consistent with the molecular orbital analyses. The NICSzz-scan curves confirm that the Au3Ga is more aromatic than the Au5Ga, and the reason is that the former has more delocalized electrons than the latter. Our work opens up aromaticity studies in the Au-Ga clusters.

New Insights into Adsorption Properties of the Tubular Au26 from AIMD Simulations and Electronic Interactions.

Recently, we revealed the electronic nature of the tubular Au26 based on spherical aromaticity. The peculiar structure of the Au26 could be an ideal catalyst model for studying the adsorptions of the Au nanotubes. However, through Google Scholar, we found that no one has reported connections between the structure and reactivity properties of Au26. Here, three kinds of molecules are selected to study the fundamental adsorption behaviors that occur on the surface of Au26. When one CO molecule is adsorbed on the Au26, the σ-hole adsorption structure is quickly identified as belonging to a ground state energy, and it still maintains integrity at a temperature of 500 K, where σ donations and π-back donations take place; however, two CO molecules make the structure of Au26 appear with distortions or collapse. When one H2 is adsorbed on the Au26, the H-H bond length is slightly elongated due to charge transfers to the anti-bonding σ* orbital of H2. The Au26-H2 can maintain integrity within 100 fs at 300 K and the H2 molecule starts moving away from the Au26 after 200 fs. Moreover, the Au26 can act as a Lewis base to stabilize the electron-deficient BH3 molecule, and frontier molecular orbitals overlap between the Au26 and BH3.

Synthesis of Ag3PO4/Ag/g-C3N4 Composite for Enhanced Photocatalytic Degradation of Methyl Orange.

In this study, we have successfully constructed Ag3PO4/Ag/g-C3N4 heterojunctions via the hydrothermal method, which displays a wide photo-absorption range. The higher photocurrent intensity of Ag3PO4/Ag/g-C3N4 indicates that the separation efficiency of the photogenerated electron-hole pairs is higher than that of both Ag3PO4 and Ag/g-C3N4 pure substances. It is confirmed that the efficient separation of photogenerated electron-hole pairs is attributed to the heterojunction of the material. Under visible light irradiation, Ag3PO4/Ag/g-C3N4-1.6 can remove MO (~90%) at a higher rate than Ag3PO4 or Ag/g-C3N4. Its degradation rate is 0.04126 min-1, which is 4.23 and 6.53 times that of Ag/g-C3N4 and Ag3PO4, respectively. After five cycles of testing, the Ag3PO4/Ag/g-C3N4 photocatalyst still maintained high photocatalytic activity. The excellent photocatalysis of Ag3PO4/Ag/g-C3N4-1.6 under ultraviolet-visible light is due to the efficient separation of photogenerated carriers brought about by the construction of the Ag3PO4/Ag/g-C3N4 heterostructure. Additionally, Ag3PO4/Ag/g-C3N4 specimens can be easily recycled with high stability. The effects of hydroxyl and superoxide radicals on the degradation process of organic compounds were studied using electron paramagnetic resonance spectroscopy and radical quenching experiments. Therefore, the Ag3PO4/Ag/g-C3N4 composite can be used as an efficient and recyclable UV-vis spectrum-driven photocatalyst for the purification of organic pollutants.

Adsorption properties of pyramidal superatomic molecules based on the structural framework of the Au20 cluster.

The pyramidal Au20 cluster is a highly inert and stable superatomic molecule, but it is not suitable as a potential catalyst for covalent bond activations, e.g., CO oxidation reaction. Herein, the adsorption and electronic properties of CO molecules on various pyramidal clusters based on the structural framework of Au20 are investigated using density functional theory. According to the SVB model, we constructed isoelectronic superatomic molecules with different pyramid configurations by replacing the vertex atoms of the Au20 using metal M atoms (M = Li, Be, Ni, Cu, and Zn group atoms). After the CO molecules are adsorbed on the vertex atoms of these metal clusters, we analyzed the CO adsorption energies, C-O bond stretching frequencies, and electronic properties of the adsorption structures. It was found that the adsorption of CO molecules results in minimal changes in the parent geometries of the pyramidal clusters, and most adsorption structures are consistent with the geometry of CO adsorption at the vertex site of the Au20 cluster. There are significant red shifts when CO molecules are adsorbed on the Ni/Pd/Pt atoms of the clusters, and their CO adsorption energies were also greater. The molecular orbitals and density of states reveal that there are overlaps between the frontier orbitals of the clusters and CO, and the electronic structure of NiAu19- is not sensitive to CO. The ETS-NOCV analysis shows that the increase in the density of the bonding area caused by the orbital interactions between the fragments is higher than the decrease in the density of the bonding area caused by Pauli repulsion, presenting that the direction of charge flow in the deformation density is from CO → clusters. From energy decomposition analysis (EDA) and NPA charge, we find a predominant covalent nature of the contributions in CO⋯M interactions (σ-donation). Our study indicates that the SVB model provides a new direction to expand the superatomic catalysts from the superatom clusters, which also provides inference for the extension of the single atom catalysis.

Superatomic and adsorption properties of Ni atom doped Au clusters.

Due to their strong relativistic effects, Au clusters exhibit many unusual geometric structures. Among them, Au7-, Au8 and Au9+ have 18 valence electrons satisfying the magic numbers in the jellium model, respectively, but these three non-spherical clusters are not superatoms. In general, a single dopant atom can drastically change the structural and electronic properties of Au clusters. Here, we searched structures of NiAu7-, NiAu8 and NiAu9+ clusters using the genetic algorithm program (GA) combined with density functional theory (DFT). It was found that the alloy clusters are all 3D spherical structures. The molecular orbitals and density of states analysis indicate that they have completely filled superatomic shells (1S21P6), in which the electronic structure of the Ni atom is d10. Then, the electrostatic potential surfaces of the alloy clusters are analyzed, and the calculated results show that the NiAu8 superatom has remarkable σ-holes with positive potential regions. Moreover, these electron-deficient regions can be considered as interaction sites with some electron donors. After a Lewis base CO gas molecule is adsorbed on the Au-based superatom, we found that the C-O bond distance becomes slightly elongated and its stretching frequency presents a significant red-shift. This is due to the fact that 5d electrons of the Au atom of the NiAu8 transfer towards the anti-bond π orbitals of the CO molecule. Hence, this is an effective strategy for finding new types of superatoms and potential catalysts for covalent bond activation.

Prediction of the Au4S crystal via a superatom network model: from clusters to solids.

Owing to their unique properties, thiolate-protected gold clusters (denoted as Aun(SR)m) have attracted intense research interest both experimentally and theoretically. The superatom complex (SAC) and superatom network (SAN) models are significantly well-known concepts to explain the electronic stability of Aun(SR)m. Based on the structural characters of Aun(SR)m, the tetrahedral Au4 unit was found to be an elementary building block and used to design a series of tetrahedron-network clusters. In this work, we first build a Au22(µ4-S)(SH)12 cluster consisting of a network of four non-conjugated tetrahedral Au4 units and confirm that it is a local minimum on the potential energy surface by density functional theory calculations. Chemical bonding analysis by the AdNDP method reveals that the electronic structure of Au22(µ4-S)(SH)12 follows the SAN (4 × 2e) model. Based on the structural character of the Au22(µ4-S)(SH)12 cluster, we utilize the diamond lattice as a template to construct a stable Au4S crystal in which each S atom binds to four Au4 superatoms. The computational results demonstrate that the structure has rather good dynamic and thermal stabilities, and it is an indirect semiconductor with a band gap of 2.68 eV at the HSE06 level. Chemical bonding analysis performed by the SSAdNDP method reveals that the Au4S can be seen as a SAN crystal. These bonding patterns and properties of the solid provide references for further investigation of cluster-assembled materials.

Sex Differences in the Antidepressant and Neurocognitive Effects of Nonconvulsive Electrotherapy in Patients with Treatment-Refractory Depression.

Objective: The objective of this study was to examine sex differences in the antidepressant and neurocognitive effects of adjunctive nonconvulsive electrotherapy (NET) in patients with treatment-refractory depression (TRD), which has not yet been thoroughly investigated. Methods: The study enrolled 20 patients with TRD, comprising 11 males and 9 females, who underwent a series of 6 NET sessions. The 17-item Hamilton Depression Rating Scale (HAMD-17) was used to assess depressive symptoms, response, and remission at baseline and after the first, third, and sixth NET sessions. The Wisconsin Card Sorting Test (WCST) was used to assess neurocognitive function at baseline and after the sixth NET session. Results: After completing 6 NET sessions, female patients experiencing TRD exhibited a higher inclination toward achieving an antidepressant response (77.8% vs. 45.5%, P = .197) and antidepressant remission (22.2% vs. 0%, P = .189) when compared to their male counterparts. No significant differences were observed in changes in the HAMD-17 and WCST subscale scores (all P > .05), including completing classification number, total error number, persistent error number, and random error number between males and females. Additionally, no significant correlations were observed between baseline WCST subscale scores and changes in HAMD-17 scores or endpoint scores, irrespective of sex (all P > .05). Conclusion: These pilot findings suggest that female patients with TRD exhibited increased rates of achieving antidepressant response and remission after undergoing NET. However, further studies should be conducted to confirm these findings.

Stanford neuromodulation therapy for treatment-resistant depression: a systematic review.

Objective: This systematic review of randomized controlled studies (RCTs) and observational studies evaluated the efficacy and safety of stanford neuromodulation therapy (SNT) for patients with treatment-resistant depression (TRD). Methods: A systematic search (up to 25 September, 2023) of RCTs and single-arm prospective studies was conducted. Results: One RCT (n = 29) and three single-arm prospective studies (n = 34) met the study entry criteria. In the RCT, compared to sham, active SNT was significantly associated with higher rates of antidepressant response (71.4% versus 13.3%) and remission (57.1% versus 0%). Two out of the three single-arm prospective studies reported the percentage of antidepressant response after completing SNT, ranging from 83.3% (5/6) to 90.5% (19/21). In the three single-arm prospective studies, the antidepressant remission rates ranged from 66.7% (4/6) to 90.5% (19/21). No severe adverse events occurred in all the four studies. Conclusion: This systematic review found SNT significantly improved depressive symptoms in patients with TRD within 5 days, without severe adverse events.

Efficacy and safety of intermittent theta burst stimulation versus high-frequency repetitive transcranial magnetic stimulation for patients with treatment-resistant depression: a systematic review.

Objective: Intermittent theta-burst stimulation (iTBS), which is a form of repetitive transcranial magnetic stimulation (rTMS), can produce 600 pulses to the left dorsolateral prefrontal cortex (DLPFC) in a stimulation time of just over 3 min. The objective of this systematic review was to compare the safety and efficacy of iTBS and high-frequency (≥ 5 Hz) rTMS (HF-rTMS) for patients with treatment-resistant depression (TRD). Methods: Randomized controlled trials (RCTs) comparing the efficacy and safety of iTBS and HF-rTMS were identified by searching English and Chinese databases. The primary outcomes were study-defined response and remission. Results: Two RCTs (n = 474) investigating the efficacy and safety of adjunctive iTBS (n = 239) versus HF-rTMS (n = 235) for adult patients with TRD met the inclusion criteria. Among the two included studies (Jadad score = 5), all were classified as high quality. No group differences were found regarding the overall rates of response (iTBS group: 48.0% versus HF-rTMS group: 45.5%) and remission (iTBS group: 30.0% versus HF-rTMS group: 25.2%; all Ps > 0.05). The rates of discontinuation and adverse events such as headache were similar between the two groups (all Ps > 0.05). Conclusion: The antidepressant effects and safety of iTBS and HF-rTMS appeared to be similar for patients with TRD, although additional RCTs with rigorous methodology are needed.

Accelerated intermittent theta burst stimulation for major depressive disorder or bipolar depression: A systematic review and meta-analysis.

We aimed to systematically evaluate the clinical efficacy and safety of accelerated intermittent theta burst stimulation (aiTBS) for patients with major depressive disorder (MDD) or bipolar depression (BD). A random-effects model was adopted to analyze the primary and secondary outcomes using the Review Manager, Version 5.3 software. This meta-analysis (MA) identified five double-blind randomized controlled trials (RCTs) comprising 239 MDD or BD patients with a major depressive episode. Active aiTBS overperformed sham stimulation in the study-defined response. This MA found preliminary evidence that active aiTBS resulted in a greater response in treating major depressive episodes in MDD or BD patients than sham stimulation.

Electronic shells of a tubular Au26 cluster: a cage-cage superatomic molecule based on spherical aromaticity.

Gold clusters, which display a variety of unusual geometric structures due to their strong relativistic effects, have attracted much attention. Among them, Au26 has a high-symmetry tubular structure (D6d) with a large HOMO-LUMO energy gap, but its electronic stability still remains unclear. In this paper, the electronic nature of the Au26 cluster is investigated using the density functional theory method. Depending on the super valence bond model, the tubular Au26 cluster with 26 valence electrons could be viewed as a superatomic molecule composed of two open cages based on spherical aromaticity, and its molecule-like electronic shell closure is achieved via a super triple bond (σ, 2π) between the two cages. Based on this new cage-cage superatomic structural model, a series of similar tubular clusters are predicted from the Au26 skeleton. The two capped Au atoms are replaced by Cu, Ag and In atoms, respectively, to form tubular D6d Au24Cu2 and Au24Ag2 (26e) and Au24In2 (30e) clusters, where the super triple bonds also exist. Moreover, tubular D5d Au20In2 (26e) is obtained by replacing hexatomic Au6 rings in the bulk of Au24In2 with pentagonal Au5 rings. Chemical bonding analysis reveals that there is a super quintuple bond (σ, 2π, 2δ) between two open (Au10In) cages, in accordance with the 26e Li20Mg3 superatomic molecule composed of two icosahedral superatoms. Our study proposes the new cage-cage structural model of superatomic molecules based on spherical aromaticity, which extends the range of the super valence bonding pattern and gives inferences for further study of superatomic clusters.