Mono‐ and Dinuclear Phosphorescent Rhenium(I) Complexes: Impact of Subcellular Localization on Anticancer Mechanisms

Elucidation of relationship among chemical structure, cellular uptake, localization, and biological activity of anticancer metal complexes is important for the understanding of their mechanisms of action. Organometallic rhenium(I) tricarbonyl compounds have emerged as potential multifunctional anticancer drug candidates that can integrate therapeutic and imaging capabilities in a single molecule. Herein, two mononuclear phosphorescent rhenium(I) complexes ( Re1 and Re2 ), along with their corresponding dinuclear complexes ( Re3 and Re4 ), were designed and synthesized as potent anticancer agents. The subcellular accumulation of Re1–Re4 was conveniently analyzed by confocal microscopy in situ in live cells by utilizing their intrinsic phosphorescence. We found that increased lipophilicity of the bidentate ligands could enhance their cellular uptake, leading to improved anticancer efficacy. The dinuclear complexes were more potent than the mononuclear counterparts. The molecular anticancer mechanisms of action evoked by Re3 and Re4 were explored in detail. Re3 with a lower lipophilicity localizes to lysosomes and induces caspase‐independent apoptosis, whereas Re4 with higher lipophilicity specially accumulates in mitochondria and induces caspase‐independent paraptosis in cancer cells. Our study demonstrates that subcellular localization is crucial for the anticancer mechanisms of these phosphorescent rhenium(I) complexes.     

Optimization of STEM-HAADF Electron Tomography Reconstructions by Parameter Selection in Compressed Sensing Total Variation Minimization-Based Algorithms

A novel procedure to optimize the 3D morphological characterization of nanomaterials by means of high angle annular dark field scanning-transmission electron tomography is reported and is successfully applied to the analysis of a metal- and halogen-free ordered mesoporous carbon material. The new method is based on a selection of the two parameters (μ and β) which are key in the reconstruction of tomographic series by means of total variation minimization (TVM). The parameter-selected TVM reconstructions obtained using this approach clearly reveal the porous structure of the carbon-based material as consisting of a network of parallel, straight channels of ≈6 nm diameter ordered in a honeycomb-type arrangement. Such an unusual structure cannot be retrieved from a TVM 3D reconstruction using default reconstruction values. Moreover, segmentation and further quantification of the optimized 3D tomographic reconstruction provide values for different textural parameters, such as pore size distribution and specific pore volume that match very closely with those determined by macroscopic physisorption techniques. The approach developed can be extended to other reconstruction models in which the final result is influenced by parameter choice.     

[Nb@Ge13/14]3−: New Family Members of Ge-Based Intermetalloid Clusters

During the past two decades, single-atom-centered medium-sized germanium clusters [M@Ge_n] (M=transition metals, n>12) have been extensively explored, both from theoretical perspectives and experimental gas-phase syntheses. However, the actual structural arrangements of the Ge₁₃ and Ge₁₄ endohedral cages are still ambiguous and have long remained an unresolved problem for experimental implementation. In this work, we successfully synthesize 13-/14-vertex Ge clusters [Nb@Ge₁₃]³⁻ ( 1 ) and [Nb@Ge₁₄]³⁻ ( 2 ), which are structurally characterized and exhibit unprecedented topologies, neither classical deltahedra nor 3-connected polyhedral structures. Theoretical analysis indicates that the major stabilization of the Ge backbones arises due to the substantial interaction of Ge 4p-AOs with the endohedral Nb 4d-AOs through three/four-center two-electron bonds with an enhanced electron density accumulated over the shortest Nb−Ge13 contact in 1 . Low occupancies of the direct two-center two-electron (2c–2e) Nb−Ge and Ge−Ge σ bonds point to a considerable degree of electron delocalization over the Ge cages revealing their electron deficiency.     

M2B7-(M=Mg,Zn)团簇的双重芳香性促进Mg-Mg和Zn-Zn单键的形成

本文使用密度泛函理论设计了两个无需配体的具有Mg-Mg和Zn-Zn单键的团簇Mg₂B₇^-和Zn₂B₇^-. 这两种团簇的全局能量最低构型均以M₂²⁺(B₇^3-)的形式存在，其中M-M单键处于准平面六边形形状的B₇部分的上方. 化学键分析证实了这些团簇中Mg-Mg和Zn-Zn单键的存在，这些单键是在异常稳定的B₇^3-的驱动下生成的. 该B₇^3-部分同时具有σ和π双重芳香性. 计算得到Mg₂B₇^-和Zn₂B₇^-的垂直跃迁能分别为2.79 eV和2.94 eV.     

Synthesis,characterization, and some electrocatalytic properties of heteromultinuclear FeI/RuII Clusters

A series of new heteromultinuclear Fe^I/Ru^II clusters are described. The complexes (η⁶-arene)RuFe₂S₂(CO)₆ (arene = p-cymene 1 , C₆Me₆ 2 ) and Fe₂[μ-S (Cp*Ru)(CO)₂]₂(CO)₆ (Cp* = η⁵-C₅Me₅) ( 3 ) were prepared by the reduction reactions of (μ-S)₂Fe₂(CO)₆ with 2 equiv of LiHBEt₃, followed by treatment (μ-SLi)₂Fe₂(CO)₆ with ruthenium-arene complexes Ru₂(μ-Cl)₂Cl₂(η⁶-arene)₂ or Cp*Ru (CO)₂Cl in 22–33% yields. Further reactions of 1 and 2 with 1 equiv of triphenylphosphine in the presence of the decarbonylating agent Me₃NO·2H₂O, afforded the corresponding monophosphine-substituted Fe^I/Ru^II complexes (η⁶-arene)RuFe₂S₂(CO)₅(Ph₃P) (arene = p-cymene 4 , C₆Me₆ 5 ) in 75% and 78% yields. While treatment of parent complex 1 or 2 with 1 equiv of diphosphine Ph₂PCH₂PPh₂ (dppm) in xylene at reflux temperature resulted in the formation of the diphosphine-bridged RuFe₂S₂(CO)₉ derivate RuFe₂S₂(CO)₇(dppm) ( 6 ). The possible pathway for the formation was proposed. Two isomers of novel macrocyclic complexes involve the (η⁶-arene) Ru-bridged quadruple-butterfly Fe/S clusters [{μ-S (CH₂)₃S-μ}{(μ-CS₂)Fe₂(CO)₆}₂]₂[(η⁶-arene)Ru]₂ (arene = p-cymene 7a and 7b , C₆Me₆ 8a and 8b ) were isolated by reactions of two μ-CS₂-containing dianion [{μ-S (CH₂)₃S-μ}{(μ-S=CS)Fe₂(CO)₆}₂]²⁻ with [Ru₂(μ-Cl)₂Cl₂(η⁶-arene)₂], in which the propylene groups are attached to two S atoms by ee and ea types of bonds respectively. All the new complexes 1 – 8 have been characterized by elemental analysis, spectroscopy, and particularly for 1 – 6 , 7b and 8a by X-ray crystallography. In addition, the electrochemical properties of representative complexes 1 – 4 and 6 have been investigated.     

Polypyridine-Based Helical Amide Foldamer Channels: Rapid Transport of Water and Protons with High Ion Rejection

Synthetic strategies that enable rapid construction of covalent organic nanotubes with an angstrom-scale tubular pore remain scarcely reported. Reported here is a remarkably simple and mild one-pot polymerization protocol, employing POCl₃ as the polymerization agent. This protocol efficiently generates polypyridine amide foldamer-based covalent organic nanotubes with a 2.8 nm length at a yield of 50 %. Trapping single-file water chains in the 2.8 Å tubular cavity, rich in hydrogen-bond donors and acceptors, these tubular polypyridine ensembles rapidly and selectively transport water at a rate of 1.6×10⁹ H₂O⋅S⁻¹⋅channel⁻¹ and protons at a speed as fast as gramicidin A, with a high rejection of ions.     

Performance guarantees of local search for minsum scheduling problems

Mathematical Programming - We study the worst-case performance guarantee of locally optimal solutions for the problem of minimizing the total weighted and unweighted completion time on parallel...