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Dalton Transactions (Cambridge, England... Sep 2023Optically active -symmetric bis(aminophenols) based on ()-2,2'-diaminobinaphthyl (BiniqH) and (,)-2,3-butanediyldianthranilate (BdanH) have been prepared by condensation...
Optically active -symmetric bis(aminophenols) based on ()-2,2'-diaminobinaphthyl (BiniqH) and (,)-2,3-butanediyldianthranilate (BdanH) have been prepared by condensation of the diamines with 3,5-di--butylcatechol. Group 10 bis(iminosemiquinone) complexes ()-(Biniq)M (M = Pd, Pt) and (,,)-(Bdan)Pd have been prepared by oxidatively metalating the corresponding ligands. In ()-(Biniq)M, the axis passes through the approximate square plane of the bis(iminosemiquinone)metal core, while in (,,)-(Bdan)Pd the axis is perpendicular to this plane. In the latter compound, the (,)-butanediyl strap binds selectively over one enantioface of the metal complex in a conformation where the methyl groups are to one another. Osmium oxo complexes with the intrinsically chiral OsO(amidophenoxide) chromophore are obtained by metalation of OsO(OCHCHO) with (,)-BdanH. Both the (,,) and (,,) diastereomers can be observed, with metalation in refluxing toluene selectively giving the latter isomer. The electronic structures of the complexes are illuminated by the circular dichroism spectra, in conjuction with the optical spectra and TDDFT calculations.
PubMed: 37668189
DOI: 10.1039/d3dt02436a -
Microscopy Research and Technique Jun 2020For nearly 50 years immunogold labeling on ultrathin sections has been successfully used for protein localization in laboratories worldwide. In theory and in practice,...
For nearly 50 years immunogold labeling on ultrathin sections has been successfully used for protein localization in laboratories worldwide. In theory and in practice, this method has undergone continual improvement over time. In this study, we carefully analyzed circulating protocols for postembedding labeling to find out if they are still valid under modern laboratory conditions, and in addition, we tested unconventional protocols. For this, we investigated immunolabeling of Epon-embedded cells, immunolabeling of cells treated with osmium, and the binding behavior of differently sized gold particles. Here we show that (in contrast to widespread belief) immunolabeling of Epon-embedded cells and of cells treated with osmium tetroxide is actually working. Furthermore, we established a "speed protocol" for immunolabeling by reducing antibody incubation times. Finally, we present our results on three-dimensional immunogold labeling.
Topics: Antibodies; Desulfurococcaceae; Epoxy Compounds; Histological Techniques; Immunohistochemistry; Microalgae; Microscopy, Immunoelectron; Microtomy; Osmium Tetroxide
PubMed: 32057162
DOI: 10.1002/jemt.23459 -
Molecules (Basel, Switzerland) Jun 2021The energy and structural parameters were obtained for all forms of the carbonyl complex of osmium Os(CO) with D and D symmetries using density functional theory (DFT)...
The energy and structural parameters were obtained for all forms of the carbonyl complex of osmium Os(CO) with D and D symmetries using density functional theory (DFT) methods. The calculations took into account various levels of relativistic effects, including those associated with nonconservation of spatial parity. It was shown that the ground state of Os(CO) corresponds to the D symmetry and thus may be characterized either as left-twisted (D) or right-twisted (D). The D↔D transitions occur through the D transition state with an activation barrier of ~10 kJ/mol. Parity violation energy difference (PVED) between D and D states equals to ~5 × 10 kJ/mol. An unusual three-center exchange interaction was found inside the {Os} fragment. It was found that the cooperative effects of the mutual influence of osmium atoms suppress the chirality of the electron system in the cluster.
PubMed: 34206080
DOI: 10.3390/molecules26113333 -
Chemistry (Weinheim An Der Bergstrasse,... Aug 2023Systematic investigations on the reactions between cis-[M(dppm) Cl ] (M=Ru/Os; dppm=1,1-bis(diphenylphosphino)methane) and pyridine/quinoline substituted homopropargylic...
Systematic investigations on the reactions between cis-[M(dppm) Cl ] (M=Ru/Os; dppm=1,1-bis(diphenylphosphino)methane) and pyridine/quinoline substituted homopropargylic alcohols uncovered the diverse Ru(II)/Os(II)-induced alkyne activation pathways. The alkynes underwent cyclization on M via a "non-vinylidene" pathway at lower temperatures, resulting in alkenyl intermediates which might further metallacyclize to give metallapyrroloindolizines. Conversely, reactions at higher temperatures induced alkyne cyclization on M via a "vinylidene" pathway, affording cyclic oxacarbene complexes. Additionally, a rare decyclization mechanism was observed during the transformation of a metallacyclization-resistant alkenyl complex into a cyclic oxacarbene complex. DFT calculations were employed to validate the experimental findings. Overall, these results not only provide insights into controlling alkyne activation pathways, but also offer new strategies for preparing metalated heterocyclic and metallacyclic complexes.
PubMed: 37198720
DOI: 10.1002/chem.202301292 -
Inorganic Chemistry Jan 2020Osmium-containing oxides are rare due to the difficulty in stabilizing complex structures with a fixed stoichiometry and metastability of the phases. Bismuth-substituted...
Osmium-containing oxides are rare due to the difficulty in stabilizing complex structures with a fixed stoichiometry and metastability of the phases. Bismuth-substituted thallium osmate pyrochlore samples, TlBiOsO, were synthesized using solid-state reactions where the solubility limit was found to be approximately = 1.4. Members of this solid solution were characterized by their structural, electronic, magnetic, and thermal properties to understand the influence of Bi substitution on the ground state. The Os-containing pyrochlores crystallize in the ideal cubic pyrochlore structure (3), and the lattice parameter was found to slightly increase as a function of Bi content. A possible interplay between structure and cation valence states was explored using both neutron powder diffraction and X-ray absorption spectroscopy, suggesting that a combination of Os/Os and Tl/Tl mixed valency throughout the solid solution allows for the stabilization of the pyrochlore structure. The system is metallic for the entire solid solution and predominantly exhibits temperature-independent paramagnetism. Specific heat measurements show an enhanced Sommerfeld coefficient, a possible flat-band signature. This system gave insight into the bonding preferences of Os, indicating a dependence on high oxidation states and mixed valence for the stability of complex structures.
PubMed: 31909983
DOI: 10.1021/acs.inorgchem.9b02939 -
Microscopy (Oxford, England) Jun 2024The two-dimensional observation of ultrathin sections from resin-embedded specimens provides an insufficient understanding of the three-dimensional (3D) morphological... (Review)
Review
The two-dimensional observation of ultrathin sections from resin-embedded specimens provides an insufficient understanding of the three-dimensional (3D) morphological information of membranous organelles. The osmium maceration method, developed by Professor Tanaka's group >40 years ago, is the only technique that allows direct observation of the 3D ultrastructure of membrane systems using scanning electron microscopy (SEM), without the need for any reconstruction process. With this method, the soluble cytoplasmic proteins are removed from the freeze-cracked surface of cells while preserving the integrity of membranous organelles, achieved by immersing tissues in a diluted osmium solution for several days. By employing the maceration method, researchers using SEM have revealed the 3D ultrastructure of organelles such as the Golgi apparatus, mitochondria and endoplasmic reticulum in various cell types. Recently, we have developed new SEM techniques based on the maceration method to explore further possibilities of this method. These include: (i) a rapid osmium maceration method that reduces the reaction duration of the procedure, (ii) a combination method that combines agarose embedding with osmium maceration to elucidate the 3D ultrastructure of organelles in free and cultured cells and (iii) a correlative immunofluorescence and SEM technique that combines cryosectioning with the osmium maceration method, enabling the correlation of the immunocytochemical localization of molecules with the 3D ultrastructure of organelles. In this paper, we review the novel osmium maceration methods described earlier and discuss their potential and future directions in the field of biology and biomedical research.
Topics: Microscopy, Electron, Scanning; Imaging, Three-Dimensional; Organelles; Animals; Osmium; Golgi Apparatus; Humans; Endoplasmic Reticulum
PubMed: 37930813
DOI: 10.1093/jmicro/dfad050 -
Metallomics : Integrated Biometal... Feb 2021The organo-osmium complex [OsII(ɳ6-p-cym)(PhAzPy-NMe2)I]+ (FY26) exhibits promising in vitro antitumour activity against mouse hepatocarcinoma Hepa1-6 and other mouse...
The organo-osmium complex [OsII(ɳ6-p-cym)(PhAzPy-NMe2)I]+ (FY26) exhibits promising in vitro antitumour activity against mouse hepatocarcinoma Hepa1-6 and other mouse or human cancer cell lines. Here, we drastically enhance water solubility of FY26 through the replacement of the PF6- counter-anion with chloride using a novel synthesis method. FY26⋅PF6 and FY26⋅Cl displayed similar in vitro cytotoxicity in two cancer cell models. We then show the moderate and late anticancer efficacy of FY26⋅PF6 and FY26⋅Cl in a subcutaneous murine hepatocarcinoma mouse model. Both efficacy and tolerability varied according to FY26 circadian dosing time in hepatocarcinoma tumour-bearing mice. Tumour and liver uptake of the drug were determined over 48 h following FY26⋅Cl administration at Zeitgeber time 6 (ZT6), when the drug is least toxic (in the middle of the light span when mice are resting). Our studies suggest the need to administer protracted low doses of FY26 at ZT6 in order to optimize its delivery schedule, for example through the use of chrono-releasing nanoparticles.
Topics: Animals; Antineoplastic Agents; Carcinoma, Hepatocellular; Cell Line, Tumor; Coordination Complexes; Dose-Response Relationship, Drug; Liver Neoplasms; Male; Mice; Mice, Inbred C57BL; Mice, Nude; Tissue Distribution
PubMed: 33595653
DOI: 10.1093/mtomcs/mfaa003 -
Dalton Transactions (Cambridge, England... Jun 20202-(Arylamino)-4,6-di-tert-butylphenols containing 4-substituted phenyl groups (RapH2) react with oxobis(ethylene glycolato)osmium(vi) in acetone to give square pyramidal...
2-(Arylamino)-4,6-di-tert-butylphenols containing 4-substituted phenyl groups (RapH2) react with oxobis(ethylene glycolato)osmium(vi) in acetone to give square pyramidal bis(amidophenoxide)oxoosmium(vi) complexes. A mono-amidophenoxide complex is observed as an intermediate in these reactions. Reactions in dichloromethane yield the diolate (Hap)2Os(OCH2CH2O). Both the glycolate and oxo complex are converted to the corresponding cis-dichloride complex on treatment with chlorotrimethylsilane. The novel bis(aminophenol) ligand EganH4, containing an ethylene glycol dianthranilate bridge, forms the chelated bis(amidophenoxide) complex (Egan)OsO, where the two nitrogen atoms of the tetradentate ligand bind in the trans positions of the square pyramid. Structural and spectroscopic features of the complexes are described well by an osmium(vi)-amidophenoxide formulation, with the amount of π donation from ligand to metal increasing markedly as the co-ligands change from oxo to diolate to dichloride. In the oxo-bis(amidophenoxides), the symmetry of the ligand π orbitals results in only one effective π donor interaction, splitting the energy of the two osmium-oxo π* orbitals and rendering the osmium-oxo bonding appreciably anisotropic.
PubMed: 32525176
DOI: 10.1039/d0dt01735c -
Journal of Anatomy Jan 2022Brachial plexus injury (BPI) occurs when the brachial plexus is compressed, stretched, or avulsed. Although rodents are commonly used to study BPI, these models poorly...
Brachial plexus injury (BPI) occurs when the brachial plexus is compressed, stretched, or avulsed. Although rodents are commonly used to study BPI, these models poorly mimic human BPI due to the discrepancy in size. The objective of this study was to compare the brachial plexus between human and Wisconsin Miniature Swine (WMS ), which are approximately the weight of an average human (68-91 kg), to determine if swine would be a suitable model for studying BPI mechanisms and treatments. To analyze the gross anatomy, WMS brachial plexuses were dissected both anteriorly and posteriorly. For histological analysis, sections from various nerves of human and WMS brachial plexuses were fixed in 2.5% glutaraldehyde, and postfixed with 2% osmium tetroxide. Subsequently paraffin sections were counter-stained with Masson's Trichrome. Gross anatomy revealed that the separation into three trunks and three cords is significantly less developed in the swine than in human. In swine, it takes the form of upper, middle, and lower systems with ventral and dorsal components. Histological evaluation of selected nerves revealed differences in nerve trunk diameters and the number of myelinated axons in the two species. The WMS had significantly fewer myelinated axons than humans in median (p = 0.0049), ulnar (p = 0.0002), and musculocutaneous nerves (p = 0.0454). The higher number of myelinated axons in these nerves for humans is expected because there is a high demand of fine motor and sensory functions in the human hand. Due to the stronger shoulder girdle muscles in WMS, the WMS suprascapular and axillary nerves were larger than in human. Overall, the WMS brachial plexus is similar in size and origin to human making them a very good model to study BPI. Future studies analyzing the effects of BPI in WMS should be conducted.
Topics: Animals; Brachial Plexus; Hand; Humans; Shoulder; Swine; Swine, Miniature; Upper Extremity
PubMed: 34355792
DOI: 10.1111/joa.13525 -
Nature Communications Apr 2022The limited therapeutic effect on hypoxic and refractory solid tumors has hindered the practical application of photodynamic therapy. Herein, we report our investigation...
The limited therapeutic effect on hypoxic and refractory solid tumors has hindered the practical application of photodynamic therapy. Herein, we report our investigation of an osmium-peroxo complex (Os2), which is inactive in the dark, but can release a peroxo ligand O upon light irradiation even in the absence of oxygen, and is transformed into a cytotoxic osmium complex (Os1). Os1 is cytotoxic in the presence or absence of irradiation in hypoxic tumors, behaving as a chemotherapeutic drug. At the same time, the light-activated Os2 induces photocatalytic oxidation of endogenous 1,4-dihydronicotinamide adenine dinucleotide in living cancer cells, leading to ferroptosis, which is mediated by glutathione degradation, lipid peroxide accumulation and down-regulation of glutathione peroxidase 4. In vivo studies have confirmed that the Os2 can effectively inhibit the growth of solid hypoxic tumors in mice. A promising strategy is proposed for the treatment of hypoxic tumors with metal-based drugs.
Topics: Animals; Antineoplastic Agents; Hypoxia; Mice; Neoplasms; Osmium; Oxygen; Photochemotherapy
PubMed: 35473926
DOI: 10.1038/s41467-022-29969-z