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Lanthanide (Ln) elements are generally found in the oxidation state +II or +III, and a few examples of +IV and +V compounds have also been reported. In contrast, monovalent Ln(+I) complexes remain scarce. Here we combine photoelectron spectroscopy and theoretical calculations to study Ln-doped octa-boron clusters (LnB8-, Ln = La, Pr, Tb, Tm, Yb) with the rare +I oxidation state. The global minimum of the LnB8- species changes from Cs to C7v symmetry accompanied by an oxidation-state change from +III to +I from the early to late lanthanides. All the C7v-LnB8- clusters can be viewed as a monovalent Ln(I) coordinated by a η8-B82- doubly aromatic ligand. The B73-, B82-, and B9- series of aromatic boron clusters are analogous to the classical aromatic hydrocarbon molecules, C5H5-, C6H6, and C7H7+, respectively, with similar trends of size and charge state and they are named collectively as "borozenes". Lanthanides with variable oxidation states and magnetic properties may be formed with different borozenes.

The discovery of borospherenes unveiled the capacity of boron to form fullerene-like cage structures. While fullerenes are known to entrap metal atoms to form endohedral metallofullerenes, few metal atoms have been observed to be part of the fullerene cages. Here we report the observation of a class of remarkable metallo-borospherenes, where metal atoms are integral parts of the cage surface. We have produced La3B18- and Tb3B18- and probed their structures and bonding using photoelectron spectroscopy and theoretical calculations. Global minimum searches revealed that the most stable structures of Ln3B18- are hollow cages with D3h symmetry. The B18-framework in the Ln3B18- cages can be viewed as consisting of two triangular B6 motifs connected by three B2 units, forming three shared B10 rings which are coordinated to the three Ln atoms on the cage surface. These metallo-borospherenes represent a new class of unusual geometry that has not been observed in chemistry heretofore.

We report a study on the electronic structure and chemical bonding of the BiB molecule using high-resolution photoelectron imaging of cryogenically cooled BiB− anion. By eliminating all the vibrational hot bands, we can resolve the complicated detachment transitions due to the open-shell nature of BiB and the strong spin–orbit coupling. The electron affinity of BiB is measured to be 2.010(1) eV. The ground state of BiB− is determined to be 2Π(3/2) with a σ2π3 valence electron configuration, while the ground state of BiB is found to be 3Σ−(0+) with a σ2π2 electron configuration. Eight low-lying spin–orbit excited states [3Σ−(1), 1Δ(2), 1Σ+(0+), 3Π(2), 3Π(1), 1Π(1)], including two forbidden transitions, [3Π(0−) and 3Π(0+)], are observed for BiB as a result of electron detachment from the σ and π orbitals of BiB−. The angular distribution information from the photoelectron imaging is found to be critical to distinguish detachment transitions from the σ or π orbital for the spectral assignment. This study provides a wealth of information about the low-lying electronic states and spin–orbit coupling of BiB, demonstrating the importance of cryogenic cooling for obtaining well-resolved photoelectron spectra for size-selected clusters produced from a laser vaporization cluster source. [ABSTRACT FROM AUTHOR]

Boron has been found to be able to form multiple bonds with lead. To probe Pb–B bonding, here we report an investigation of three Pb-doped boron clusters, PbB2−, PbB3O−, and PbB4O2−, which are produced by a laser ablation cluster source and characterized by photoelectron spectroscopy and ab initio calculations. The most stable structures of PbB2−, PbB3O−, and PbB4O2− are found to follow the formula, [PbB2(BO)n]− (n = 0–2), with zero, one, and two boronyl ligands coordinated to a triangular and aromatic PbB2 core, respectively. The PbB2− cluster contains a B＝B double bond and two Pb–B single bonds. The coordination of BO is observed to weaken Pb–B bonding but strengthen the B＝B bond in [PbB2(BO)n]− (n = 1, 2). The anionic [PbB2(BO)2]− and its corresponding neutral closed-shell [PbB2(BO)2] contain a B≡B triple bond. A low-lying Y-shaped isomer is also observed for PbB4O2−, consisting of a central sp2 hybridized B atom bonded to two boronyl ligands and a PbB unit. [ABSTRACT FROM AUTHOR]

We present an investigation on the structures and chemical bonding of two Bi-doped boron clusters BiBn− (n = 4, 5) using photoelectron spectroscopy and theoretical calculations. The electron affinities of BiB4 and BiB5 are measured to be 2.22(2) eV and 2.61(2) eV, respectively. Well-resolved photoelectron spectra are obtained and used to compare with theoretical calculations to verify the structures of BiB4− and BiB5−. Both clusters adopt planar structures with the Bi atom bonded to the periphery of the planar Bn moiety. Chemical bonding analyses reveal that the Bn moiety maintains σ and π double-aromaticity. The Bi atom is found to induce relatively small structural changes to the Bn moiety, very different from transition metal-doped boron clusters. [ABSTRACT FROM AUTHOR]

Split liver transplantation is an essential means which expand the donor pool currently and the two livers obtained after splitting are marginal donor livers. The adoption of Static Cold Storage during allocation and preservation leads to a higher cold ischemia time, thus increasing the occurrence of related postoperative complications, which limits the further development of split-liver transplantation. Mechanical perfusion as a complement to split liver transplantation can minimize the damage to the marginal donor liver during preservation and reduce the occurrence of ischemia-reperfusion. At present, mechanical perfusion has achieved better efficacy in other types of marginal donor liver transplantation such as DCD, elderly donor liver, fatty liver, and so on. In recent years, mechanical perfusion has also shown great potential for application in split-liver transplantation, and limited clinical studies have shown outstanding therapeutic effects. Therefore, this paper will summarize the research progress and mechanisms related to the application of mechanical perfusion in split liver transplantation in order to promote the application of mechanical perfusion in split liver transplantation and reduce the damage of the organ during preservation. [ABSTRACT FROM AUTHOR]

Objective: To explore the mechanism of Nauclea Officinalis of anti-liver cancer effect based on network pharmacology, and to preliminarily verify anti-liver cancer activity of Nauclea Officinalis through cell screening. Methods: Network pharmacology was used to screen for common targets of Nauclea Officinalis and liver cancer, protein-protein interaction (PPI) network was constructed, and enrichment analysis and mechanism prediction were conductd. Molecular docking of main active ingredients of Nauclea Officinalis with core targets was made. Preliminary verification was performed by in vitro cell experiments such as CCK8, cell apoptosis, and PCR. Results: After the screening, 14 active ingredients of Nauclea Officinalis were obtained, with 587 related targets. After mapping with liver cancer targets, there were 288 common targets, mainly including TP53, SRC, STAT3, and other core targets. Among them, compounds such as strictosamide, pumiloside and vincosamide may be potential active ingredients of Nauclea Officinalis of anti-liver cancer effect. They may participate in protein phosphorylation and negative regulation of the apoptosis process by mediating cancer pathways, PI3K/Akt and EGFR tyrosine kinase inhibitors resistance signaling pathways to play an anti-liver cancer role; molecular docking results showd that active ingredients of Nauclea Officinalis had a stable binding with liver cancer core targets; in vitro cell experiments showd that main ingredient strictosamide of Nauclea Officinalis had cytotoxicity against liver cancer cells, inhibited liver cancer cell proliferation (P<0.001), down-regulated gene expression of liver cancer HepG2 cells SRC, STAT3, MAPK3 (P<0.05), and induced liver cancer cell apoptosis (P<0.001). Conclusion: This study preliminarily explores the potential mechanism of active ingredients of Nauclea Officinalis against liver cancer and its preliminary pharmacological effects, providing a theoretical basis for the study of Nauclea Officinalis of anti-liver cancer mechanism. [ABSTRACT FROM AUTHOR]

Borophenes are atom-thin boron layers that can be grown on coinage metal substrates and have become an important class of synthetic 2D nanomaterials. The interactions between boron and substrates are critical to understand the growth mechanisms of borophenes. Here, we report an investigation of copper-boron interactions in the Cu2B8− bimetallic cluster using photoelectron spectroscopy and quantum chemical calculations. Well-resolved photoelectron spectra are obtained at several photon energies and are combined with theoretical calculations to elucidate the structures and bonding of Cu2B8−. Global minimum searches reveal that Cu2B8− consists of a Cu2 dimer atop a B8 molecular wheel with a long Cu–Cu bond length close to that in Cu2+. Chemical bonding analyses indicate that there is clear charge transfer from Cu2 to B8, and the Cu2B8− cluster can be viewed as a [Cu2+]-borozene complex, [Cu2+][B82–]. In the neutral cluster, no Cu–Cu bond exists and Cu2B8 consists of two Cu+ centers interacting with doubly aromatic B82− borozene. The charge transfer interactions between Cu and boron in the Cu2B8− cluster are analogous to charge transfer from the copper substrate to the first borophene layer recently reported to be critical in the growth of bilayer borophenes on a Cu(111) substrate. [ABSTRACT FROM AUTHOR]