Hydride-Containing Pt-doped Cu-rich Nanoclusters: Synthesis, Structure, and Electrocatalytic Hydrogen Evolution.

A structurally precise hydride-containing Pt-doped Cu-rich nanocluster [PtH2 Cu14 {S2 P(Oi Pr)2 }6 (CCPh)6 ] (1) has been synthesized. It consists of a bicapped icosahedral Cu14 cage that encapsulates a linear PtH2 unit. Upon the addition of two equivalents of CF3 COOH to 1, two hydrido clusters are isolated. These clusters are [PtHCu11 {S2 P(Oi Pr)2 }6 (CCPh)4 ] (2), which is a vertex-missing Cu11 cuboctahedron encaging a PtH moiety, and [PtH2 Cu11 {S2 P(Oi Pr)2 }6 (CCPh)3 ] (3), a distorted 3,3,4,4,4-pentacapped trigonal prismatic Cu11 cage enclosing a PtH2 unit. The electronic structure of 2, analyzed by Density Functional Theory, is a 2e superatom. The electrocatalytic activities of 1-3 for hydrogen evolution reaction (HER) were compared. Notably, Cluster 2 exhibited an exceptionally excellent HER activity within metal nanoclusters, with an onset potential of -0.03 V (at 10 mA cm-2 ), a Tafel slope of 39 mV dec-1 , and consistent HER activity throughout 3000 cycles in 0.5 M H2 SO4 . Our study suggests that the accessible central Pt site plays a crucial role in the remarkable HER activity and may provide valuable insights for establishing correlations between catalyst structure and HER activity.

A Silver Nanocluster Assembled by a Superatomic Building Unit.

A unique assembly of a two-electron superatom, [Ag10{S2P(OiPr)2}8], as a primary building unit in the construction of a supramolecule [Ag10{S2P(OiPr)2}8]2(µ-4,4'-bpy) through a 4,4'-bipyridine (4,4'-bpy) linker is reported. This approach is facilitated by an open site in the structure that allows for effective pairing. The assembled structure demonstrates a minimal solvatochromic shift across organic solvents with variable polarities, highlighting the influence of self-assembly on the photophysical properties of silver nanoclusters.

Diselenophosphate Ligands as a Surface Engineering Tool in PdH-Doped Silver Superatomic Nanoclusters.

The first hydride-doped Pd/Ag superatoms stabilized by selenolates are reported: [PdHAg19(dsep)12] [dsep = Se2P(OiPr)2] 1 and [PdHAg20(dsep)12]+ 2. 1 was derived from the targeted transformation of [PdHAg19(dtp)12] [dtp = S2P(OiPr)2] by ligand exchange, whereas 2 was obtained from the addition of trifluoroacetic acid to 1, resulting in a symmetric redistribution of the capping silver atoms. The transformations are all achieved while retaining an 8-electron superatomic configuration. VT-NMR attests to the good stability of the NCs in solution, and single-crystal X-ray diffraction reveals the crucial role that the interstitial hydride plays in directing the position of the capping silver atoms. The total structures are reported alongside their electronic and optical properties. 1 and 2 are phosphorescent with a lifetime of 73 and 84 µs at 77 K, respectively. The first antibacterial activity data for superatomic bimetallic Pd/Ag nanoclusters are also reported.

Structural Transformation of Metastable Two-Electron Superatom Au-Doped Cu-Rich Alloy Nanocluster.

The ability to fabricate bimetallic clusters with atomic precision offers promising prospects for elucidating the correlations between their structures and properties. Nevertheless, achieving precise control at the atomic level in the production of clusters, including the quantity of dopant, characteristic of ligands, charge state of precursors, and structural transformation, have remained a challenge. Herein, we report the synthesis, purification, and characterization of a new bimetallic hydride cluster, [AuCu11(H){S2P(OiPr)2}6(C≡CPh)3] (AuCu11H). The hydride position in AuCu11H was determined using DFT calculations. AuCu11H comprises a ligand-stabilized defective fcc Au@Cu11 cuboctahedron. AuCu11H is metastable and undergoes a spontaneous transformation through ligand exchange into the isostructural [AuCu11(Cl){S2P(OiPr)2}6(C≡CPh)3] (AuCu11Cl) and into the complete cuboctahedral [AuCu12{S2P(OiPr)2}6(C≡CPh)4]+ (AuCu12) through an increase in nuclearity. These structural transformations were tracked by NMR and mass spectrometry.

[Influence of paraspinal muscle degeneration and postoperative Roussouly classification restoration on mechanical complications in female patients with degenerative scoliosis after surgery].

Objective: To investigate the impact of lumbar paraspinal muscle degeneration and postoperative failure to restore ideal Roussouly classification on the occurrence of mechanical complications (MC) following long-segment spinal correction surgery in female patients with degenerative scoliosis (DS). Methods: The clinical data of 72 female DS patients who underwent long-segment spinal correction surgery in Gulou Hospital from June 2017 to November 2021 were retrospectively analyzed. According to whether restoring the ideal Roussouly classification after surgery, the patients were divided into R group(recovery group) (n=51) and N group(non-recovery group) (n=21). According to whether mechanical complications occurred after operation within two years, the patients were divided into MC (mechanical complications)group (n=24) and NMC(non-mechanical complications) group (n=48). The RM group (n=14) experienced mechanical complications in the R group, while the RN group (n=37) did not. The NM group (n=10) experienced mechanical complications in the N group, while the NN group (n=11) did not.Radiographic assessment included Sagittal parameters of spine and pelvis, standardized cross-sectional area (SCSA) and fat infiltration rate (FI%) of paraspinal muscle at each lumbar disc level. Results: The age of DS patients in this study was (61.4±6.2) years.The incidence of MC was 33.33%(n=24)in all patients. The incidence of MC was 27.45%(n=14)in group R and 47.62%(n=10) in group N. The correction amount of pelvic tilt angle (PT) (-11.62°±10.06° vs -7.04°±8.45°, P=0.046) and T1 pelvic angle(TPA)(-12.88°±11.23° vs -7.31°±9.55°, P=0.031)during surgery were significantly higher in MC group compared to the NMC group. In group R, the FI% of paraspinal muscles in each lumbar segment of patients with postoperative MC was higher than that in patients without MC (P<0.05). In the R and N groups, there was no significant difference inthe SCSA of the lumbar paravertebral muscles between patients with postoperative MC and those without MC at each level (all P>0.05). Multivariate logistic regression analysis showed that the average FI% of lumbar PSM was correlated with the occurrence of MC after spinal fusion in DS patients.The average FI% of lumbar PSM≥22.63% was a risk factors for MC after spinal fusion (P=0.010,OR=1.088, 95%CI:1.020-1.160). Conclusions: Female DS patients with higher degree of preoperative paraspinal muscle degeneration have a higher incidence of postoperative mechanical complications. For these patients,.there is still a higher risk of mechanical complications after surgery even if the ideal Roussouly classification is restored after surgery.

[Effect of different observations on evaluation of cosmetic shoulder balance in adolescent idiopathic scoliosis patients with thoracic curve].

Objective: To investigate the correlations between cosmetic and radiographic parameters of shoulder balance, as well as the variations in cosmetic shoulder balance observed from different perspectives, among patients with adolescent idiopathic scoliosis (AIS) characterized by thoracic curves. Methods: A total of 43 patients with thoracic curves treated from July to October in 2022 in Nanjing Drum Tower Hospital were recruited in this study. There were 9 males and 34 females with a mean age of (14.3±1.5) years. All participants underwent comprehensive radiographic assessments and were photographed both from posterior and anterior views, focusing on the shoulder region as well as a higher level (maintaining a consistent vertical distance of 180 cm from the ground). Six cosmetic parameters were measured on the photographs: shoulder angle(α1), axilla angle(α2), shoulder area index 1(SAI1), shoulder area index 2 (SAI2), inner shoulder height (SHi) and outer shoulder height (SHo). Eight radiographic parameters were measured on the radiographs: radiographic shoulder height difference (RSHD), first rib angle (FRA), clavicle-rib cage intersection (CRCI), coracoid process height (CPH), T1 tilt, clavicle angle(CA), clavicle chest cage angle difference (CCAD) and Cobb angle. Differences among bilateral cosmetic indicators from different perspectives were analyzed and compared, and their correlation with bilateral radiographic indicators was studied. Results: There was no significant differences between anterior cosmetic parameters and posterior cosmetic parameters at the same level of observation(all P>0.05). However, when observing SHi, SHo, α1, and α2 at the shoulder level, it became evident that they exhibited significantly higher values compared to the corresponding higher level on the same side of the patients' bodies. This contrast was observed in both the dorsal [SHo: (0.11±1.20) cm vs (-0.44±1.39) cm, P=0.005; SHi: (0.64±0.86) cm vs (0.32±0.56) cm, P=0.003; α1:-0.47°±2.27° vs -0.77°±2.49°, P=0.014; α2:-3.06°±3.23° vs -2.21°±3.03°, P=0.034] and ventral [SHo: (0.12±1.29) cm vs (-0.48±1.35) cm, P=0.007; SHi: (0.61±0.88) cm vs (0.30±0.59) cm, P=0.006; α1:-0.46°±2.18° vs -0.69°±2.35°, P=0.018; α2:-3.26°±3.12° vs -2.05°±2.97°, P=0.029] aspects of the patients. SHi and SHo were more sensitive to this difference of height. The correlation coefficients between radiographic parameters and cosmetic aspects at the shoulder level varied from 0.374 to 0.767. Similarly, the correlation coefficients between radiographic parameters and cosmetic factors at the higher level ranged from 0.273 to 0.579 (all P<0.05). Conclusions: The cosmetic parameters had significant difference between different perspective of observation, the cosmetic parameters are needed to be observed at the shoulder level in the evaluation of patients' shoulder balance.

Hydride Doping Effects on the Structure and Properties of Eight-Electron Rh/Ag Superatoms: The [RhHx@Ag21-x{S2P(OnPr)2}12] (x = 0-2) Series.

Three hitherto unknown eight-electron rhodium/silver alloy nanoclusters, [RhAg21{S2P(OnPr)2}12] (1), [RhHAg20{S2P(OnPr)2}12] (2), and [RhH2Ag19{S2P(OnPr)2}12] (3), have been isolated and fully characterized. Cluster 1 contains a regular Rh@Ag12 icosahedral core, whereas 2 and 3 exhibit distorted RhH@Ag12 and RhH2@Ag12 icosahedral cores. The single-crystal neutron structure of 2 located the encapsulated hydride at the center of an enlarged RhAg3 tetrahedron. A similar position was found by neutron diffraction for one of the hydrides in 3, whereas the other hydride is trigonally coordinated to Rh and an elongated Ag-Ag edge. The solid-state structures of 1-3 possess C1 symmetry due to the asymmetric arrangement of the surrounding capping Ag atoms. Our investigation shows that the insertion of one hydride dopant provokes the elimination of one capping silver atom on the cluster surface, resulting in the general formula [RhHx@Ag21-x{S2P(OnPr)2}12] (x = 0-2), which maintains the same number of cluster electrons as well as neutral charge. Clusters 1-3 exhibit an intense emission band in the NIR region. Contrarily to their PdAg21 and PdHAg20 relatives, the 4d orbitals of the encapsulated heterometal are somewhat involved in the optical processes.

Controlled Shell and Kernel Modifications of Atomically Precise Pd/Ag Superatomic Nanoclusters.

The first 8-electron Pd/Ag superatomic alloys with an interstitial hydride [PdHAg19 (dtp)12 ] (dtp=S2 P(Oi Pr)2 - ) 1 and [PdHAg20 (dtp)12 ]+ 2 are reported. The targeted addition of a single Ag atom to 1 is achieved by the reaction of one equivalent of trifluoroacetic acid, resulting in the formation of 2 in 55 % yield. Further modification of the shell results in the formation of [PdAg21 (dtp)12 ]+ 3 via an internal redox reaction, with the system retaining an 8-electron superatomic configuration. The interstitial hydride in 1 and 2 contributes its 1s1 electron to the superatomic electron count and occupies a PdAg3 tetrahedron. The distributions of isomers corresponding to different dispositions of the outer capping Ag atoms are investigated by multinuclear VT NMR spectroscopy. The emissive state of 3 has a lifetime of 200 µs (λex =448; λem =842), while 1 and 2 are non-emissive. The catalytic reduction of 4-nitrophenol is demonstrated with 1-3 at room temperature.

Superatom Pruning by Diphosphine Ligands as a Chemical Scissor.

A two-electron silver superatom, [Ag6{S2P(OiPr)2}4(dppm)2] (1), was synthesized by adding dppm (bis(diphenylphosphino)methane) into [Ag20{S2P(OiPr)2}12] (8e). It was characterized by single-crystal crystallography, multinuclear NMR spectroscopy, electrospray ionization-mass spectrometry, density functional theory (DFT), and time-dependent DFT calculations. The added dppm ligands, which carry out the nanocluster-to-nanocluster transformation, act as a chemical scissor to prune the nanocluster geometrically from an icosahedron-based Ag20 nanocluster (NC) to an octahedral Ag6 NC and electronically from eight-electron to two-electron. Eventually, dppm was involved in the protective shell to form a new heteroleptic NC. The temperature-dependent NMR spectroscopy confirms its fluxional behavior, showing the fast atomic movement at ambient temperature. Compound 1 exhibits a bright yellow emission under UV irradiation at ambient temperature with a quantum yield of 16.3%. This work demonstrates a new methodology to achieve nanocluster-to-nanocluster transformation via stepwise synthesis.

Hydride-containing 2-Electron Pd/Cu Superatoms as Catalysts for Efficient Electrochemical Hydrogen Evolution.

The first hydride-containing 2-electron palladium/copper alloys, [PdHCu11 {S2 P(Oi Pr)2 }6 (C≡CPh)4 ] (PdHCu11 ) and [PdHCu12 {S2 P(Oi Pr)2 }5 {S2 PO(Oi Pr)} (C≡CPh)4 ] (PdHCu12 ), are synthesized from the reaction of [PdH2 Cu14 {S2 P(Oi Pr)2 }6 (C≡CPh)6 ] (PdH2 Cu14 ) with trifluoroacetic acid (TFA). X-ray diffraction reveals that the PdHCu11 and PdHCu12 kernels consist of a central PdH unit encapsulated within a vertex-missing Cu11 cuboctahedron and complete Cu12 cuboctahedron, respectively. DFT calculations indicate that both PdHCu11 and PdHCu12 can be considered as axially-distorted 2-electron superatoms. PdHCu11 shows excellent HER activity, unprecedented within metal nanoclusters, with an onset potential of -0.05 V (at 10 mA cm-2 ), a Tafel slope of 40 mV dec-1 , and consistent HER activity during 1000 cycles in 0.5 M H2 SO4 . Our study suggests that the accessible central Pd site is the key to HER activity and may provide guidelines for correlating catalyst structures and HER activity.

Hydride-Containing Eight-Electron Pt/Ag Superatoms: Structure, Bonding, and Multi-NMR Studies.

Recent reports on hydride-doped noble metal nanoclusters strongly suggest that the encapsulated hydride is a part of the superatom core, but no accurate location of the hydride could be experimentally proved, so far. We report herein a hydride-doped eight-electron platinum/silver alloy nanocluster in which the position of four-coordinated hydride was determined by neutron diffraction for the first time. X-ray structures of [PtHAg19(dtp/desp)12] (dtp = S2P(OnPr)2, 1; dsep = Se2P(OiPr)2, 2) describe a central platinum hydride (PtH) unit encapsulated within a distorted Ag12 icosahedron, the resulting (PtH)@Ag12 core being stabilized by an outer sphere made up of 7 capping silver atoms and 12 dichalcogenolates. Solid-state structures of 1 and 2 differ somewhat in the spatial configuration of their outer spheres, resulting in overall different symmetries, C1 and C3, respectively. Whereas the multi-NMR spectra of 2 in solution at 173 K reveal that the structure of C3 symmetry is the predominant one, 1H and 195Pt NMR spectra of 1 at the same temperature disclose the presence of isomers of both C1 and C3 symmetry. DFT calculations found both isomers to be very close in energy, supporting the fact that they co-exist in solution. They also show that the [PtH@Ag12]5+ kernel can be viewed as a closed-shell superatomic core, the µ4-hydride electron contributing to its eight-electron count. On the other hand, the 1s(H) orbital contributes only moderately to the superatomic orbitals, being mainly involved in the building of a Pt-H bonding electron pair with the 5dz2(Pt) orbital.

Interstitial Hydrides in Nanoclusters can Reduce M(I) (M=Cu, Ag, Au) to M(0) and Form Stable Superatoms.

High-nuclearity clusters resemble the closest model between the determination of atomically precise chemical species and the bulk metallic version thereof, and both impacts on a variety of applications, including catalysis, optics, sensors, and new energy sources. Our interest lies with the nanoclusters of the Group 11 (Cu, Ag, Au) metals stabilized by dichalcogenido and hydrido ligands. Herein, we describe superatoms formed by the clusters and their relationship with precursor hydrido clusters. Specifically, our concept seeks to demonstrate a possible correlation that exist between hydrido clusters (and nanoalloys) and the formation of superatoms, with the loss of hydrides and typically with release of H2 gas. These reactions appear to be internal self-redox reactions and require no additional reducing agent, but does seem to require a similar core structure. Knowledge of such processes could provide insight into how clusters grow and an understanding in bridging the atomically precise cluster - metal nanoparticle mechanism.

Oxocarbon Anions Templated in Silver Clusters.

Three types of oxocarbon anions as templates were used to synthesize high-nuclear silver clusters, [Ag16(C2O4){S2P(OEt)2}12]2(PF6)4 (1), [Ag16(C4O4){S2P(OEt)2}12]2(PF6)4 (2), and [Ag32(S)2(C5O5)2{S2P(OEt)2}22](PF6)2 (3), and characterized by multi-NMR spectroscopy and X-ray crystallography. As the template size increases, the shape and size of the clusters change accordingly. The template effect in high-nuclear silver clusters has been investigated in this work.

Homoleptic Silver-Rich Trimetallic M20 Nanocluster.

Two silver-rich M20 alloy nanoclusters (NCs), [Cu3.5Ag16.5{S2P(OnPr)2}12] (1) and [Cu2.5AuAg16.5{S2P(OnPr)2}12] (2), were synthesized and fully characterized by electrospray ionization mass spectrometry, NMR spectroscopy, and X-ray crystallography. Cluster 2, the first structurally characterized trimetallic M20 NC, was produced by doping one Au atom into a bimetallic M20 NC. Structural analyses showed the preferred positions of Group 11 metals in the yielded M20 NCs. Their antioxidation ability has been investigated, and the time-dependent UV-vis spectrum shows that the presence of CuI atoms in structures 1 and 2 can improve the antioxidant ability.

Reactivities of Interstitial Hydrides in a Cu11 Template: En Route to Bimetallic Clusters.

In sharp contrast to surface hydrides, reactivities of interstitial hydrides are difficult to explore. When treated with a metal ion (Cu+ , Ag+ , and Au+ ), the stable CuI dihydride template [Cu11 H2 {S2 P(Oi Pr)2 }6 (C≡CPh)3 ] (H2 Cu11 ) generates surprisingly three very different compounds, namely [CuH2 Cu11 {S2 P(Oi Pr)2 }6 (C≡CPh)3 ]+ (1), [AgH2 Cu14 {S2 P(Oi Pr)2 }6 ((C≡CPh)6 ]+ (2), and [AuCu11 {S2 P(Oi Pr)2 }6 (C≡CPh)3 Cl] (3). Compounds 1 and 2 are both MI species and maintain the same number of hydride ligands as their H2 Cu11 precursor. Neutron diffraction revealed the first time a trigonal-pyramidal hydride coordination mode in the AgCu3 environment of 2. 3 has no hydride and exhibits a mixed-valent [AuCu11 ]10+ metal core, making it a two-electron superatom.

Isolation and Structural Elucidation of 15-Nuclear Copper Dihydride Clusters: An Intermediate in the Formation of a Two-Electron Copper Superatom.

Highly reactive copper-dihydride clusters, [Cu15 (H)2 (S2 CNR2 )6 (C2 Ph)6 ](PF6 ) {R = n Bu (1H ), n Pr (2H ), i Bu (3H )}, are isolated during the reaction of [Cu28 H15 {S2 CNn Bu2 }12 ](PF6 ) with ten equivalents of phenylacetylene. They are found to be intermediates in the formation of the earlier reported two-electron superatom [Cu13 (S2 CNR2 )6 (C2 Ph)4 ]+ . Better yields are obtained by reacting dithiocarbamate sodium salts, [Cu(CH3 CN)4 ](PF6 ), BH4- and phenylacetylene. The presence of two hydrides in the isolated clusters is confirmed by the synthesis and characterization of its deuteride analogue [Cu15 (D)2 (S2 CNR2 )6 (C2 Ph)6 ]+ , and a single-crystal neutron structure of 2H . Structural characterization of 1H reveals a new bicapped icosahedral copper(I) cage encapsulating a linear copper dihydride (CuH2 )- unit. Reaction of 3H with Au(I) salts yields a highly luminescent [AuCu12 (S2 CNi Bu2 )6 (C2 Ph)4 ]+ cluster.

[Cu{SC(O)OiPr}]96: A Giant Self-Assembled Copper(I) Supramolecular Wheel Exhibiting Photoluminescence Tuning and Correlations with Dynamic Solvation and Solventless Synthesis.

The hierarchical self-organization of structurally complex high-nuclearity metal clusters with metallosupramolecular wheel architectures that are obtained from the self-assembly of smaller solvated cluster units is rare and unique. Here, we use the potentially heteroditopic monothiocarbonate ligand and demonstrate for the first time the synthesis and structure of a solvated non-cyclic hexadecanuclear cluster [Cu{SC(O)OiPr}]16·2THF (1) that can simultaneously desolvate and self-assemble in solution and subsequently form a giant metallaring, [Cu{SC(O)OiPr}]96 (2). We also demonstrate a luminescent precursor to cluster (2) can be achieved through a solventless and rapid mechanochemical synthesis. Cluster (2) is the highest nuclearity copper(I) wheel and the largest metal cluster containing a heterodichalcogen (O, S) ligand reported to date. Cluster (2) also exhibits solid-state luminescence with relatively long emission lifetimes at 4.1, 13.9 (µs). The synthetic strategy described here opens new research avenues by replacing solvent molecules in stable {Cu16} clusters with designed building units that can form new hybrid and multifunctional finite supramolecular materials. This finding may lead to the development of novel high-nuclearity materials self-assembled in a facile manner with tunable optical properties.

Synthesis and Luminescence Properties of Two-Electron Bimetallic Cu-Ag and Cu-Au Nanoclusters via Copper Hydride Precursors.

The synthesis, structural characteristics, and photophysical properties of luminescent Cu-rich bimetallic superatomic clusters [Au@Cu12(S2CNnPr2)6(C≡CPh)4]+ (1a+), [Au@Cu12{S2P(OR)2}6(C≡CPh)4]+ (2+), (2a+ = iPr; 2b+ = nPr), [Au@Cu12{S2P(C2H4Ph)2}6(C≡CPh)4]+ (2c+), and [Ag@Cu12{S2P(OnPr)2}6(C≡CPh)4]+ (3+) were studied. Compositionally uniform clusters 1+-3+ were isolated from the reaction of dithiolato-stabilized, polyhydrido copper clusters with phenylacetylene in the presence of heterometal salts. By using X-ray diffraction, the structures of 1a+, 2a+, 2b+, and 3+ were able to be determined. ESI-mass spectrometry and elemental analysis confirmed their compositions and purity. The structural characteristics of these clusters are similar with respect to displaying gold (or silver)-centered Cu12 cuboctahedra surrounded by six dithiocarbamate/dithiophosph(in)ate and four alkynyl ligands. The doping of Au and Ag atoms into the polyhydrido copper nanoclusters significantly enhances their PL quantum yields from Ag@Cu12 (0.58%) to Au@Cu12 (55%) at ambient temperature in solution. In addition, the electrochemical properties of the new alloys were investigated by cyclic voltammetry.

Doping effect on the structure and properties of eight-electron silver nanoclusters.

The bimetallic M20 and M21 compounds, {[Cu3Ag17{S2P(OiPr)2}12]0.5 [Cu4Ag16{S2P(OiPr)2}12]0.5} ({[1a]0.5[1b]0.5}) and [Cu4Ag17{S2P(OiPr)2}12](PF6) (2), have been structurally characterized, in which the Cu(I) ions are randomly distributed on the eight outer positions capping the eight-electron [Ag13]5+ core. DFT calculations show that the statistical disorder results from the nearly neutral preference of copper to occupy any of the eight outer positions. Surprisingly, the UV-Vis absorption spectra of the M20 and M21 bimetallic nanoclusters display an almost identical absorption profile as that of their homometallic [Ag20{S2P(OiPr)2}12] and [Ag21{S2P(OiPr)2}12]+ relatives. This is rationalized by TD-DFT calculations, which show that the frontier orbitals of such eight-electron alloys are largely independent from the nature of the capping metal ions. A blue-shifted absorption is observed upon replacing by Au the central Ag atom in 2, forming the trimetallic compound [Cu4AuAg16{S2P(OiPr)2}12](PF6) (3).

Efficacy of erector spinae plane block for analgesia in breast surgery: a systematic review and meta-analysis.

The erector spinae plane block is a new regional anaesthesia technique that provides truncal anaesthesia for breast surgery. This systematic review and meta-analysis was undertaken to determine if the erector spinae plane block is effective at reducing pain scores and opioid consumption after breast surgery. This study also evaluated the outcomes of erector spinae plane blocks compared with other regional blocks. PubMed, Embase, Scopus, the Cochrane Central Register of Controlled Trials and ClinicalTrials.gov were searched. We included randomised controlled trials reporting the use of the erector spinae plane block in adult breast surgery. Risk of bias was assessed with the revised Cochrane risk-of-bias tool. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework was used to assess trial quality. Thirteen randomised controlled trials (861 patients; 418 erector spinae plane block, 215 no blocks, 228 other blocks) were included. Erector spinae plane block reduced postoperative pain compared with no block: at 0-2 hours (mean difference (95% CI) -1.63 (-2.97 to -0.29), 6 studies, 329 patients, high-quality evidence, I2  = 98%, p = 0.02); at 6 hours (mean difference (95% CI) -0.90 (-1.49 to -0.30), 5 studies, 250 patients, high-quality evidence, I2  = 91%, p = 0.003); at 12 hours (mean difference (95% CI) -0.46 (-0.67 to -0.25), 5 studies, 250 patients, high-quality evidence, I2  = 58%, p < 0.0001); and at 24 hours (mean difference (95% CI) -0.50 (-0.70 to -0.30), 6 studies, 329 patients, high-quality evidence, I2  = 76%, p < 0.00001). Compared with no block, erector spinae plane block also showed significantly lower postoperative oral morphine equivalent requirements (mean difference (95% CI) -21.55mg (-32.57 to -10.52), 7 studies, 429 patients, high-quality evidence, I2  = 99%, p = 0.0001). Separate analysis of studies comparing erector spinae plane block with pectoralis nerve block and paravertebral block showed that its analgesic efficacy was inferior to pectoralis nerve block and similar to paravertebral block. The incidence of pneumothorax was 2.6% in the paravertebral block group; there were no reports of complications of the other blocks. This review has shown that the erector spinae plane block is more effective at reducing postoperative opioid consumption and pain scores up to 24 hours compared with general anaesthesia alone. However, it was inferior to the pectoralis nerve block and its efficacy was similar to paravertebral block. Further evidence, preferably from properly blinded trials, is required to confirm these findings.