Assembly of Copper Alkynyl Clusters into Dimensionally Diverse Coordinated Polymers Mediated by Pyridine Ligands.

Surface ligands play crucial roles in modifying the properties of metal nanoclusters and stabilizing atomically precise structures, and also serve as vital linkers for constructing cluster-based coordination polymers. In this study, we present the results of the solvothermal synthesis of eight novel copper alkynyl clusters incorporating pyridine ligands using a one-pot method. The resulting compounds underwent characterization through elemental analysis, Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction (SCXRD). Our observations revealed that distinct pyridine ligands with varying lengths and coordination sites exert significant influence on the structure and dimensionality of the clusters. The structural diversity of these clusters led to the formation of one-dimensional (1D), two-dimensional (2D), or dimer arrangements linked by seven pyridine bridging ligands. Remarkably, these complexes exhibited unique UV-vis absorption and photoluminescence properties, which were influenced by the specific bridging ligand and structural framework. Furthermore, density functional theory (DFT) calculations demonstrated the capability of the conjugated system in the pyridine ligand to impact the band gap of clusters. This study not only unveils the inherent structural diversity in coordination polymers based on copper alkynyl clusters but also offers valuable insights into harnessing ligand engineering for structural and property modulation.

Chiral Canoe-Like Pd0 or Pt0 Alloyed Copper Alkynyl Nanoclusters Display Near-Infrared Luminescence.

Alloying nanoclusters (NCs) has emerged as a widely explored and versatile strategy for tailoring tunable properties, facilitating in-depth atomic-level investigations of structure-property correlations. In this study, we have successfully synthesized six atomically precise copper NCs alloyed with Group 10 metals (Pd or Pt). Notably, the Pd0 or Pt0 atom situated at the center of the distorted hexagonal antiprism Pd0/Pt0@Cu12 cage, coordinated with twelve Cu+ and two tBuC≡C- ligands. Moreover, ligand exchange strategies demonstrated the potential for Cl- and Br- to replace one or two alkynyl ligands positioned at the top or side of the NCs. The chirality exhibited by these racemic NCs is primarily attributed to the involvement of halogens and a chiral (Pd/Pt)@Cu18 skeleton. Furthermore, all the NCs exhibit near-infrared (NIR) luminescence, characterized by emission peaks at 705-755 nm, lifetimes ranging from 6.630 to 9.662 µs, and absolute photoluminescence quantum yields (PLQYs) of 1.75 %-2.52 % in their crystalline state. The experimental optical properties of these NCs are found to be in excellent agreement with the results of theoretical calculations. These alloy NCs not only offer valuable insights into the synthesis of Pd0/Pt0-Cu alloy NCs, but also bridge the gap in understanding the structure-luminescence relationships of Pd0/Pt0-Cu molecules.

Template-assisted synthesis of isomeric copper(i) clusters with tunable structures showing photophysical and electrochemical properties.

A comparative study of structure-property relationships in isomeric and isostructural atomically precise clusters is an ideal approach to unravel their fundamental properties. Herein, seven high-nuclearity copper(i) alkynyl clusters utilizing template-assisted strategies were synthesized. Spherical Cu36 and Cu56 clusters are formed with a [M@(V/PO4)6] (M: Cu2+, Na+, K+) skeleton motif, while peanut-shaped Cu56 clusters feature four separate PO4 templates. Experiments and theoretical calculations suggested that the photophysical properties of these clusters are dependent on both the inner templates and outer phosphonate ligands. Phenyl and 1-naphthyl phosphate-protected clusters exhibited enhanced emission features attributed to numerous well-arranged intermolecular C-H⋯π interactions between the ligands. Moreover, the electrocatalytic CO2 reduction properties suggested that internal PO4 templates and external naphthyl groups could promote an increase in C2 products (C2H4 and C2H5OH). Our research provides new insight into the design and synthesis of multifunctional copper(i) clusters, and highlights the significance of atomic-level comparative studies of structure-property relationships.

Ag6 Cu8 (C=CAr)14 (DPPB)2 : A Rigid Ligand Co-Protected Bimetallic Silver(I)-Copper(I) Cluster with Room-Temperature Luminescence.

Metal clusters have become increasingly important in various applications, with ligands playing a crucial role in their construction. In this study, we synthesized a bimetallic cluster, Ag6 Cu8 (C=CAr)14 (DPPB)2 (Ag6 Cu8 ), using a rigid acetylene ligand, 3,5-bis(trifluoromethyl)phenylacetylide. Through single-crystal structure characterization, we discovered that the butterfly-shaped Ag2 Cu2 motifs were subject to distortion due to steric hindrance imposed by the rigid ligand. These motifs assembled together through shared vertices and edges. Mass spectrometry analysis revealed that the primary fragments detected during electrospray ionization (ESI) testing corresponded to the Ag2 Cu2 motifs. Furthermore, we conducted a comprehensive investigation of the cluster's solution properties employing 31 P NMR, UV-vis absorption, and photoluminescent measurements. In contrast to previously reported Ag/Cu bimetallic clusters protected by flexible ligands, Ag6 Cu8 protected by rigid ligands exhibited intriguing room temperature fluorescence properties alongside excellent thermal stability. DFT calculations on Ag6 Cu8 and Ag6 Cu8 with the rigid aromatic ring removed revealed that the presence of the rigid aromatic ring can lower the electronic energy levels of the cluster, and reduce the energy gap from 4.05 eV to 3.45 eV. Moreover, the rigid ligand further suppressed the non-radiative transition process, leading to room temperature fluorescence emission.

Anion-templated silver thiolated clusters affected by carboxylate ligands.

Under the guidance of anion templates V10O286- and SO42-, the novelty of cluster assembly can be increased by using different carboxylate ligands. Herein, the synthesis, crystal structure and electrochemical properties of three anion-templated silver thiolated clusters are reported, namely V10O28@Ag46(iPrS)28(CF3CO2)12(DMF)2 (1), V10O28@Ag46(iPrS)30(CF3CO2)8(PhCO2)2(DMF)4 (2), and [SO4@Ag20(iPrS)10(PTA)3(HPTA)2]n (3, H2PTA = phthalic acid). Single-crystal X-ray diffraction analysis showed that 1 and 2 are discrete clusters V10O28@Ag46. The addition of PhCO2H in the second step of 1 leads to obtaining 2 with different organic shells. If the addition of H2PTA is made, 3 with a three-dimensional (3D) structure containing the SO42- template can be obtained. Both V10O286- and SO42- templates were generated in situ under solvothermal conditions. This work is the first where heterogeneous silver clusters containing the V10O286- anion template protected by an isopropyl thiolate ligand and a Ag20 cluster with a 3D structure are obtained. The assembly process influenced by carboxylic acid deserves to be continuously explored in the future.

Copper(I) Alkynyl Clusters with Crystallization-Induced Emission Enhancement.

Four copper(I) alkynyl complexes incorporating phosphate ligands, namely, [Cu16(tBuC≡C)12(PhOPO3)2]n (1; PhOPO3 = phenyl phosphate), [Cu16(tBuC≡C)12(1-NaphOPO3)2]n (2; 1-NaphOPO3 = 1-naphthyl phosphate), [VO4@Cu25(tBuC≡C)19(1-NaphOPO3)](PF6)0.5(F)0.5 (3), and [PO4@Cu25(tBuC≡C)19(1-NaphOPO3)](PF6)0.5(F)0.5 (4), were solvothermally synthesized and well-characterized by IR spectroscopy, powder X-ray diffraction, and single-crystal X-ray diffraction. Single-crystal X-ray analysis revealed that the Cu16 cluster-based coordination chain polymers 1 and 2 are formed by assembly during crystallization, while 3 and 4 contain high-nuclearity copper(I) composite clusters enclosing orthovanadate and phosphate template ions, respectively, that are supported by ROPO32- ligands. Complexes 1-4 exhibit crystallization-induced emission enhancement. Their crystalline state shows strong luminescence, in striking contrast to the weak emission of the amorphous state and solution phase. A detailed investigation of the crystal structure suggests that well-arranged C-H···π and π···π interactions between the ligands are the major factors for this enhanced emission. Clusters 3 and 4 also exhibit photocurrent responses upon visible-light illumination.

Construction of Silver Clusters Capped by Zwitterionic Ethynide Ligands.

A zwitterionic ligand 3-(triethylammonio)propyne (TAP) has been employed to construct nine silver ethynide compounds for the first time. Single-crystal X-ray analyses reveal that compounds 1 and 2 are silver ethynide assemblies based on the Ag3 subunits and clusters 3-8 are small discrete clusters of Ag3, Ag6, Ag8, and Ag12, respectively, ligated by the bulky TAP ligand with different auxiliary ligands. In addition, upon acquiring the tripod-like tBuPO32-, a unprecedented 80 nuclei silver ethynide cluster was isolated and determined to be [(CF3CO2)5@Ag80(TAP)14(tBuPO3)16(CF3CO2)24]19+ by crystallography and thermogravimetric analysis. The C1 symmetry of Ag80 was deconstructed to be two [Ag40(TAP)7(tBuPO3)8(CF3CO2)12]12+ secondary building subunits arranged in a cross way, with five CF3CO2- trapped in the center. These results highlight that the elaborate selection of ethynide ligands is of great importance in the synthesis of novel silver ethynide clusters.

[MRI diagnosis of osteochondral lesions in the talus and the dynamic follow up analysis after osteochondral transplantation].

OBJECTIVE: To investigate MRI findings of osteochondral lesions in the talus;to evaluate the value of MRI in diagnosing and determining the stage of osteochondral lesions;to analyze the follow up clinical value of MRI in osteochondral transplantation of autologous bone. METHODS: A total of 79 patients from February 2013 to March 2015 had been retrospectively analyzed. All the patients were treated in our hospital. The ankle arthroscopy results were used as the reference standard, and the accuracy of MRI in diagnosis and Hepple staging had been investigated. Fifteen patients with cartilage transplantation of autologous bone were followed up with MRI examination and evaluation of cartilage repair score(MOCART) after one year. The values of MRI in the postoperative follow up were analyzed. RESULTS: Hepple staging of 79 patients was shown as follows:7 cases of stage I, 12 cases of stage II, 24 cases of stage III, 16 cases of stage IV, and 20 cases of stage V. Ankle arthroscopy grading of 59 patients in this group(in addition of 20 cases of stage V):2 cases of grade A, 2 cases of grade B, 4 cases of grade C, 14 cases of grade D, 22 cases of grade E, and 15 cases of grade F. The accuracy rate of MRI in determining Hepple V was set at 100%, and Hepple stage I corresponds to the arthroscopic A, B, C stage, stage II corresponds to D stage, stage III corresponds to E stage, stage IV corresponds to F stage. The accuracy rate of MRI in determining Hepple stage I to IV was 87.5%, 85.7%, 95.4% and 93.3% respectively. After cartilage transplantation of autologous bone, MRI of 15 patients showed cartilage surface in transplanted area was smooth, bone healed well, and the surrounding edema disappeared. The MOCART was 30 to 80 scores with an average score 59.0±15.6;9 cases of these 15 patients were(9/15, 60%) higher than 60 score. CONCLUSIONS: MRI plays a significant role in clinical diagnosis and staging of the talus osteochondral injury. As a method of long term follow up after cartilage transplantation, MRI can well evaluate the rapair of the postoperative osteochondral injury.

[Research advances of fat embolism syndrome in forensic medicine].

Fat embolism syndrome (FES) is a common and life-threatening clinical syndrome, which is a difficult problem frequently encountered in medical science, especially in forensic medicine and orthopaedics. FES would be easily mistaken or missed by forensic examiner due to the lack of the specific symptoms and signs. This article reviews the etiology, pathogenesis, pathology, the mechanism of death, as well as the advances of the forensic medicine diagnosis of FES with current literatures update.