Thiacalix[4]arene-Protected Silver Nanoclusters Encapsulating Different Two-Electron Superatom Oligomers.

The subvalent silver kernel represents the nascent state of silver cluster formation, yet the growth mechanism has long been elusive. Herein, two silver nanoclusters (Ag30 and Ag34) coprotected by TC4A4- (H4TC4A = p-tert-butylthiacalix[4]arene) and TBPMT- (TBPMTH = 4-tert-butylbenzenemethanethiol) containing 6e and 4e silver kernels are synthesized and characterized. The trimer of the 2e superatom Ag14 kernel in Ag30 is built from a central Ag6 octahedron sandwiched by two orthogonally oriented Ag5 trigonal bipyramids through sharing vertexes, whereas a double-octahedral Ag10 kernel in Ag34 is a dimer of 2e superatoms. They manifest disparate polyhedron fusion growth patterns at the beginning of the silver cluster formation. Their excellent solution stabilities are contributed by the multisite and multidentate coordination fashion of TC4A4- and the special valence electron structures. This work demonstrates the precise control of silver kernel growth by the solvent strategy and lays a foundation for silver nanocluster application in photothermal conversion.

Monoarsine-protected icosahedral cluster [Au13(AsPh3)8Cl4]+: comparative studies on ligand effect and surface reactivity with its stibine analogue.

Ligand shells of gold nanoclusters play important roles in regulating their molecular and electronic structures. However, the similar but distinct impacts of the homologous analogues of the protecting ligands remain elusive. The C2v symmetric monoarsine-protected cluster [Au13(AsPh3)8Cl4]+ (Au13As8) was facilely prepared by direct reduction of (Ph3As)AuCl with NaBH4. This cluster is isostructural with its previously reported stibine analogue [Au13(SbPh3)8Cl4]+ (Au13Sb8), enabling a comparative study between them. Au13As8 exhibits a blue-shifted electronic absorption band, and this is probably related to the stronger π-back donation interactions between the Au13 core and AsPh3 ligands, which destabilize its superatomic 1P and 1D orbitals. In comparison to the thermodynamically less stable Au13Sb8, Au13As8 achieves a better trade-off between catalytic stability and activity, as demonstrated by its excellent catalytic performance towards the aldehyde-alkyne-amine (A3) coupling reaction. Moreover, the ligand exchange reactions between Au13As8 with phosphines, as exemplified by PPh3 and Ph2P(CH2)2PPh2, suggest that Au13As8 may be a good precursor cluster for further cluster preparation through the "cluster-to-cluster" route.

Ag22 Nanoclusters with Thermally Activated Delayed Fluorescence Protected by Ag/Cyanurate/Phosphine Metallamacrocyclic Monolayers through In-Situ Ligand Transesterification.

The composition of protection monolayer exerts great influence on the molecular and electronic structures of atomically precise monolayer protected metal nanoclusters. Four isostructural Ag/cyanurate/phosphine metallamacrocyclic monolayer protected Ag22 nanoclusters are synthesized by kinetically controlled in-situ ligand formation-driven strategy. These eight-electron superatomic silver nanoclusters feature an unprecedented interfacial bonding structure with diverse E-Ag (E=O/N/P/Ag) interactions between the Ag13 core and metallamacrocyclic monolayer, and displays thermally activated delayed fluorescence (TADF), benefiting from their distinct donor-acceptor type electronic structures. This work not only unmasks a new core-shell interface involving cyanurate ligand but also underlines the significance of high-electron-affinity N-heterocyclic ligand in synthesizing TADF metal nanoclusters. This is the first mixed valence Ag0/I nanocluster with TADF characteristic.

Nuclearity enlargement from [PW9O34@Ag51] to [(PW9O34)2@Ag72] and 2D and 3D network formation driven by bipyridines.

The structural transformations of metal nanoclusters are typically quite complex processes involving the formation and breakage of several bonds, and thus are challenging to study. Herein, we report a case where two lacunary Keggin polyoxometallate templated silver single-pods [PW9O34@Ag51] (SD/Ag51b) fuse to a double-pod [(PW9O34)2@Ag72] by reacting with 4,4'-bipyridine (bipy) or 1,4-bis(4-pyridinylmethyl)piperazine (pi-bipy). Their crystal structures reveal the formation of a 2D 44-sql layer (SD/Ag72a) with bipy and a 3D pcu framework (SD/Ag72c) with pi-bipy. The PW9O349- retains its structure during the cluster fusion and cluster-based network formation. Although the two processes, stripping of an Ag-ligands interface followed by fusion, and polymerization, are difficult to envisage, electrospray ionization mass spectrometry provides enough evidences for such a proposal to be made. Through this example, we expect the structural transformation to become a powerful method for synthesizing silver nanoclusters and their infinite networks, and to evolve from trial-and-error to rational.

Facile high yield, excellent catalytic performance of polyoxometalate-based lanthanide phosphine oxide complexes: Syntheses, structures, photocatalysis and THz spectra.

Water pollution, which continuously threatens human health and the sustainable development of society, has become a major concern. Photocatalytic degradation is an effective strategy to remove organic dyes from wastewater. For this strategy, it is crucial to select the appropriate catalyst. Using triphenylphosphine oxide (OPPh3) as the ligand, phosphomolybdic acid as the anion template, three new lanthanide complexes [Ln(OPPh3)4(H2O)3](PMo12O40)∙4C2H5OH (1-3) (Ln = Sm, Gd, Tb) were synthesized. The raw materials for the reaction are cheap and readily available. The convenient synthesis method is environmentally friendly, with high yield (70%-80%). Complexes 1-3 are all seven-coordinated mononuclear structures centered on lanthanide ions, [PMo12O40]3- anions and solvent molecules are not coordinated with metal ions. These mononuclear structures eventually form complicated 3D supramolecular structures through hydrogen bonds, Mo-O … π or C-H … π weak interactions. Complexes 1-3 photocatalytic degradation of MB have high removal rates, as catalysts have enough stability to be reused, and can be used as excellent catalysts for the degradation of dye molecules in sewage. Among them, the removal rate of MB by photodegradation of complex 2 was highest (99.50%). In addition, the effects of different initial concentrations of MB solution and different types of organic dyes on the photocatalysis experiment were investigated. The photocatalytic reaction mechanism of complexes 1-3 was also studied. Due to the similar structures of complexes 1-3, they have almost the same THz absorption spectra with different absorption intensity, which may be attributed to the difference of the number of weak interactions. Therefore, terahertz spectroscopy can be used as a sensitive method to distinguish and determine small differences between lanthanide-organic complexes. This is the first time that this spectrum has been used to characterize lanthanide phosphine oxide complexes modified by [PMo12O40]3-.

Toward Controlled Syntheses of Diphosphine-Protected Homochiral Gold Nanoclusters through Precursor Engineering.

Controllable syntheses of Au nanoclusters (NCs) with different nuclearities are of great significance due to the kernel-dependent physicochemical properties. Herein, two pairs of enantiomeric Au NCs [Au19(R/S-BINAP)4(PhC≡C)Cl4] (SD/Au19) and [Au11(R/S-BINAP)4(PhC≡C)2]·Cl (SD/Au11), both with atropos (rigid axial chirality) diphosphine BINAP (2,2'-bis(diphenylphosphino)-1,1'-binaphthalene) as the predominant organic ligands, were controllably synthesized through precursor engineering. The former was obtained by direct reduction of HAuCl4·4H2O, while the latter was obtained by reduction of [Au(SMe2)Cl] instead. Intriguingly, the kernel of SD/Au19 contains an Au7 pentagonal bipyramid capped by two boat-like Au6 rings, which represents another type of Au19 kernel, making SD/Au19 a good candidate for comparative study with other Au19 NCs to get more insight into the distinct structural evolution of phosphine-protected Au NCs. Despite the previous chiroptical studies on some other chiral undecagold NCs, the successful attainment of the X-ray crystal structures for SD/Au11 not only provides a step forward toward better correlating the chiroptical activities with their structural details but also reveals that even the auxiliary protecting ligands also play a nontrivial role in tuning the geometrical structures of the metal NCs. The chiroptical activities of both SD/Au19 and SD/Au11 were found to originate from the chiral ligands and core distortions; the extended π-electron systems in the BINAP ligands have proved to positively contribute to the electronic absorptions and thus disturb the corresponding circular dichroism (CD) responses.

Revealing the chirality origin and homochirality crystallization of Ag14 nanocluster at the molecular level.

Although chirality is an ever-present characteristic in biology and some artificial molecules, controlling the chirality and demystifying the chirality origin of complex assemblies remain challenging. Herein, we report two homochiral Ag14 nanoclusters with inherent chirality originated from identical rotation of six square faces on a Ag8 cube driven by intra-cluster π···π stacking interaction between pntp- (Hpntp = p-nitrothiophenol) ligands. The spontaneous resolution of the racemic (SD/rac-Ag14a) to homochiral nanoclusters (SD/L-Ag14 and SD/R-Ag14) can be realized by re-crystallizing SD/rac-Ag14a in acetonitrile, which promotes the homochiral crystallization in solid state by forming C-H···O/N hydrogen bonds with nitro oxygen atoms in pntp- or aromatic hydrogen atoms in dpph (dpph = 1,6-bis(diphenylphosphino)hexane) on Ag14 nanocluster. This work not only provides strategic guidance for the syntheses of chiral silver nanoclusters in an all-achiral environment, but also deciphers the origin of chirality at molecular level by identifying the special effects of intra- and inter-cluster supramolecular interactions.

A comparative study on atomically precise Au nanoclusters as catalysts for the aldehyde-alkyne-amine (A3) coupling reaction: ligand effects on the nature of the catalysis and efficiency.

Atomically precise Au13 nanoclusters stabilized by stibines catalyze the aldehyde-alkyne-amine coupling reaction more efficiently than those stabilized by thiols or phosphines. The nature of the catalytic activity is also different, and may be attributed to the weaker coordinating ability of the stibine ligands.

[Treatment of Pauwels type III femoral neck fractures with modified percutaneous compression plate].

OBJECTIVE: To investigate the preliminary effects of modified percutaneous compression plate in treating femoral neck fractures of Pauwels type III. METHODS: From March 2012 to March 2016, 35 patients with femoral neck fracture were treated by closed reduction and internal fixation with a modified percutaneous compression plate, including 21 males and 14 females with an average age of 45 years old ranging from 23 to 62 years old. The anatomical position of fracture was divided into 8 cases of lower head type, 27 cases of head and neck. According to the Garden classification, there were 8 cases of type II, 18 of type III, and 9 of type IV fractures. All patients were closed injury. The general information, reduction quality, fracture healing time, postoperative complications were recorded and evaluated. Harris scoring was used to evaluate the hip joint function. RESULTS: All patients were followed up for 15 to 24 months with an average of 20 months. All the incisions were primary healing. The reduction quality of the femoral neck fracture was evaluated according to the Garden's alignment Index, and the quality of reduction was grade I reduction in 29 cases and grade II reduction in 6 cases. No nonunion, femoral avascular necrosis, implant failure and hip varus was observed during follow-up. Harris score was(92.70±4.60) points at final follow-up, the results of the treatment was evaluated as excellent in 26 cases, good in 8 cases, fair in 1 case. No complications such as internal fixation loosening, nail breaking, and heterotopic ossification occurred. CONCLUSIONS: Internal fixation with modified percutaneous compression plate has an advantages of decreased trauma, simple operation, rigid fixation, good function outcome, and low risk of complications.

Stibine-protected Au13 nanoclusters: syntheses, properties and facile conversion to GSH-protected Au25 nanocluster.

Monostibine-protected ionic Au13 nanoclusters, namely, [Au13(L)8(Cl)4][Cl] (L= SbPh3, 2a·Cl; Sb(p-tolyl)3, 2b·Cl) were prepared by the direct reduction of Au(L)Cl with NaBH4 in dichloromethane. Anion exchange with 2a·Cl afforded [Au13(SbPh3)8(Cl)4][X] (X = PF6, 2a·PF6; BPh4, 2a·BPh4). All these have been characterized by multinuclear NMR, ESI-MS and UV-Vis spectroscopy. Crystallographic analysis of 2a·BPh4 reveals that the cation possesses C 2v symmetry and the tridecagold core adopts a closed icosahedron configuration. The weaker coordinating ability of the stibine ligands leads to the ready reaction of 2b·Cl with PPh3 or glutathione (GSH) to form the smaller phosphine-protected cluster [Au11(PPh3)8Cl2][Cl] or larger thiolate-protected cluster Au25(SG)18, respectively. In the latter reaction, the addition of a small amount (0.5 to 3.5 equivalents) of a suitable oxidant such as K3(Fe(CN)6 accelerates the conversion rate significantly.

[Study on discourse right construction of China's medical aid to Africa].

OBJECTIVE: To analyze the discourse right construction of China's medical aid to Africa, so as to provide evidences for improving the effect and sustainable development of China's medical aid to Africa. METHODS: The documents of the discourse right that China constructed in the medical aid to Africa were selected at different periods as discourse samples. The achievement and deficiency were analyzed from four aspects, namely confident, charismatic, influential, and dominant. RESULTS: China's medical team made much in the discourse right construction in their aid to Africa, but some China's medical team members were still too cautious and too low-key. China's medical team gained the trust of the people of Africa, but the language communication difficulties still hampered in China's medical aid to Africa. Chinese medical team were widely praised by the African society, but in the west, some African media, even China's media still neglected to report China's doctors. China's international discourse right were greatly improved, but western countries still dominated the public opinion. CONCLUSIONS: China should refer to the actual situation of medical aid to Africa to strengthen the construction of discourse right.

[Design of the reduction fixator and its clinical application in treating fracture of lesser trochanter of femur].

OBJECTIVE: To discuss the clinical significance of the reduction and fixation for femoral lesser trochanteric fragment in treating the femoral comminuted intertrochanteric fractures. METHODS: From January 2012 to December 2013,32 patients with intertrochanteric fractures were treated by surgery, and self-designed reduction fixators were used in the patients for the fixation of lesser trochanter of femur. There were 11 males and 21 females, ranging in age from 45 to 81 years old with an average of 64 years old. According to the Evans typing, 12 cases were type II, 13 cases were type III and 7 cases were type IV. Simple lag screw fixed in 19 cases and steel wire fixed in 13 cases. Hip joint function was evaluated according Harris score and the complications such as coxa adducta,cutting of femoral head and neck,implants breakage were observed. RESULTS: Thirty-two patients were followed up from 9 to 24 months with an average of 13 months. Coxa adducta occurred in 1 case,no cutting of femoral head and neck occurred and implants breakage were found. The mean Harris score was 91.80 ± 3.05 in 32 patients. CONCLUSION: The reconstruction and fixation for the posterior medial bone cortex continuity is a key factor on affect the stability of femoral intertrochanteric fracture. Self-designed reduction fixators can effective reduce and fix the lesser trochanter of femur, it has advantage of fast reduction and fixation, and simple operation.

[Operative treatment for proximal humeral fracture with rotator cuff tear in elderly patients].

OBJECTIVE: To explore operative clinical outcomes of proximal humeral fracture with rotator cuff tear in elderly patients. METHODS: From March 2010 to August 2014,54 elderly patients with proximal humeral fractures with rotator cuff tear were performed operation, including 30 males and 24 females aged from 68 to 83 years old with an average of 71.5 years old. Thirty patients were caused by falling down, 24 cases were caused by traffic accident. According to Neer classification, 3 cases were part I, 11 cases were part II, 21 cases were part III and 19 cases were part IV. All patients were operated with open reduction and plate internal fixation, 46 cases suffered from rotator cuff tear and carried out repair of rotator cuff; 8 cases were not suffered from rotator cuff tear. Postoperative Neer evaluation of shoulder's function were used to assess clinical results. RESULTS: Forty-six patients with rotator cuff tear were followed up from 8 to 21 months with an average of 11 months. All fractures were obtained bone union. No incision infection, axillary nerve injury,loosening screw, plate breakage, shoulder joint dislocation and humeral head osteonecrosis were occurred. According to Neer evaluation of shoulder's function, total score was 88.60 ± 5.12, and 30 cases got excellent results, 7 cases good, 7 cases moderate and 2 cases poor. CONCLUSION: For osteoporotic proximal humeral fractures with rotator cuff tear in elderly patients' plate with rivet repair at stage I is an effective stable method, and provide advantages for earlier exercise of shoulder joint, then receive good clinical effects in further.

[Transpedicular porking and grafting for the treatment of thoracolumbar spinal fracture].

OBJECTIVE: To investigate the application of transpedicular porking repositor, thread device and transpedical interbody bone grafting apparatus in the treatment of thoracolumbar spinal fracture. METHODS: From March 2008 to March 2011, 17 males and 15 females with thoracolumbar spinal fracture were treated by using self-designed transpedicular porking reposito, thread device and transpedical interbody bone grafting apparatus. The average age was 39.4 years (ranged from 25 to 65 years). All the cases were checked by X-ray and CT before and one week, one year after operation, removal of internal fixation. The angle of injured vertebral sagittal, cobbs angle and injured vertebral height were measured. RESULTS: All patients were followed up, and the duration ranged for 14 to 21 months (averaged 16 months). The content of following up included loss of ithycyphos and height of spinal, fracture healing and implant fixation. Nerve vascular complication caused by implantation didn't occurred; interverbral body fusion was good. The results preoperative, 1 week and year postoperative and 3 months after taking out the internal fixation showed injured spinal height maintained well, loss and collapse of height and angle did not occurred. CONCLUSION: Treating thoracolumbar spinal fracture can obtained satisfactory effects by using transpedicular porking repositor, thread device and transpedical interbody bone grafting apparatus. It has advantages of minimal invasive, and can promote fracture healing earlier, recover spinal height, rebuild stability of spinal, prevent loss and collapse of vertebral body height to avoid anterior lumbar surgery on the late stage.

Direct arylation of unactivated aromatic C-H bonds catalyzed by a stable organic radical.

A stable zwitterionic radical can catalyze direct arylation of unactivated aromatic C-H bonds via a chain homolytic aromatic substitution mechanism in the presence of potassium tert-butoxide.

New metal-anion radical framework materials: Co(II) compounds showing ferromagnetic to antiferromagnetic phase transition at about 344 K, and Zn(II) compounds exhibiting terminal anion ligand induced direct white-light-emission.

The preparation, X-ray crystallography, EPR, magnetic and luminescent investigation of new metal-anion radical framework materials based on a new anion radical ligand generated by in situ deprotonation of a stable zwitterionic radical are described herein. N,O,N-tripodal anion radical ligand (bipo(-)˙) links metal cations, giving rise to four isostructural one-dimensional metal-organic frameworks, [M(bipo(-)˙)(L)](n) [M = Zn, L = HCOO(-) (1), SCN(-) (1a), N(3)(-) (1b); M = Co, L = Br(-) (3)]. The tripodal bipo(-)˙ ligand and one co-ligand, 1,4-benzenedicarboxylate, coordinate to metals leading to two isostructural two-dimensional metal-organic frameworks, [M(bipo(-)˙)(BDC)(0.5)](n) [M = Zn (2) and Co (4)]. The two Co(II) compounds are the first examples that exhibit unusual ferromagnetic to antiferromagnetic phase transition with transition temperature over room temperature, which can be demonstrated by the cooling and warming measurements of susceptibility. Compound 4 also exhibits long-range magnetic ordering with the critical temperature at about 44 K proved by ac susceptibility measurements. The metal-radical frameworks exhibit distinctly different fluorescence emissions. Especially, the isomorphous one-dimensional Zn(II) compounds show interesting terminal anion ligand-induced photoluminescent color changes, including direct and invariable white-light-emission with terminal SCN(-) ligand.

New zwitterionic radical salts: dimers in solution and unusual magnetic and luminescent properties in the solid state.

A new and stable zwitterionic (neutral) radical and its perchlorate salts exist as diamagnetic pi-dimers in solution, and pi-stacking 1D chains with interesting magnetic and luminescent properties in solid state.