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Molecules (Basel, Switzerland) Jan 2021A number of mono- and dioligosilanylated silocanes were prepared. Compounds included silocanes with 1-methyl-1-tris(trimethylsilyl)silyl,...
A number of mono- and dioligosilanylated silocanes were prepared. Compounds included silocanes with 1-methyl-1-tris(trimethylsilyl)silyl, 1,1-bis[tris(trimethylsilyl)silyl], and 1,1-bis[tris(trimethylsilyl)germyl] substitution pattern as well as two examples where the silocane silicon atom is part of a cyclosilane or oxacyclosilane ring. The mono-tris(trimethylsilyl)silylated compound could be converted to the respective silocanylbis(trimethylsilyl)silanides by reaction with KOBu and in similar reactions the cyclosilanes were transformed to oligosilane-1,3-diides. However, the reaction of the 1,1-bis[tris(trimethylsilyl)silylated] silocane with two equivalents of KOBu leads to the replacement of one tris(trimethylsilyl)silyl unit with a -butoxy substituent followed by silanide formation via KOBu attack at one of the SiMe units of remaining tris(trimethylsilyl)silyl group. For none of the silylated silocanes, signs of hypercoordinative interaction between the nitrogen and silicon silocane atoms were detected either in the solid state. by single crystal XRD analysis, nor in solution by Si-NMR spectroscopy. This was further confirmed by cyclic voltammetry and a DFT study, which demonstrated that the N-Si distance in silocanes is not only dependent on the energy of a potential N-Si interaction, but also on steric factors and through-space interactions of the neighboring groups at Si and N, imposing the orientation of the p(N) orbital relative to the N-Si-X axis.
Topics: Organosilicon Compounds; Silanes; Silicon
PubMed: 33466467
DOI: 10.3390/molecules26010244 -
Toxicology and Industrial Health Mar 20191,1,1,3,3,3-Hexamethyldisilazane (HMDZ) is used industrially to treat the surface of silica, as an intermediate adhesion promoter or silylating agent in the...
1,1,1,3,3,3-Hexamethyldisilazane (HMDZ) is used industrially to treat the surface of silica, as an intermediate adhesion promoter or silylating agent in the semiconductor industry, as a chemical modifier of inorganic fillers, and as a water scavenger silicone sealant. In animal studies, HMDZ is considered to be slightly to at most moderately toxic following acute administration via oral, dermal, and inhalation routes of exposure. HMDZ is neither an eye irritant nor was it dermally irritating under semiocclusive conditions; however, it caused dermal necrosis in two studies under occlusive conditions. HDMZ is not genotoxic or mutagenic in in vitro assays and was not reproductively or developmentally toxic in an inhalation screening study in rats. Short-term and subacute, high-dose inhalation exposure to HMDZ produced respiratory tract irritation, reduced feed consumption, changes in clinical chemistry parameters, and reversible central nervous system depression in rats. In a 90-day inhalation exposure study in rats, HMDZ exposure-related effects were observed in the kidneys of male rats but were determined to be alpha-2µ-nephropathy, thus, not relevant to humans. Based on the results of the 90-day (subchronic) inhalation study, 75 ppm was determined to be the no-observed adverse effect level (NOAEL) and was selected as the point of departure for the derivation of the 8-h time-weighted average (TWA), health-based workplace environmental exposure level (WEEL) value. This subchronic inhalation NOAEL was adjusted to account for duration of exposure, interindividual variability, and intraindividual variability. The resulting 8-h TWA WEEL value of 10 ppm is fully expected to provide a significant margin of safety against any potential adverse health effects in workers following long-term inhalation exposure to HMDZ vapor. A 15-min short-term exposure limit of 50 ppm was also established to protect workers from reversible effects produced by acute, high-dose inhalation of HMDZ vapor. A skin notation (Skin) is warranted because of the potential for the dermal route to significantly contribute to the overall exposure to HMDZ.
Topics: Animals; Female; Humans; Male; No-Observed-Adverse-Effect Level; Occupational Exposure; Organosilicon Compounds; Rats; Toxicity Tests
PubMed: 30760128
DOI: 10.1177/0748233719825531 -
Molecules (Basel, Switzerland) Apr 2017The purification of endohedral metallofullerenes by high performance liquid chromatography is very time-consuming and expensive. A number of rapid and inexpensive... (Review)
Review
The purification of endohedral metallofullerenes by high performance liquid chromatography is very time-consuming and expensive. A number of rapid and inexpensive non-chromatographic methods have thus been developed for large-scale purification of metallofullerenes. In this review, we summarize recent advances in non-chromatographic purification methods of metallofullerenes. Lewis acid-based complexation is one of the most efficient and powerful methods for separation of metallofullerenes from empty fullerenes. The first oxidation potential of metallofullerenes is a critical factor that affects the separation efficiency of the Lewis acid-based method. Supramolecular methods are effective for separation of fullerenes and metallofullerenes that are different in size and shape. Chemical/electrochemical reduction and exohedral functionalization are also utilized to separate and purify metallofullerenes on a large scale.
Topics: Chromatography, High Pressure Liquid; Fullerenes; Lewis Acids; Organosilicon Compounds; Oxidation-Reduction; Photochemical Processes
PubMed: 28468241
DOI: 10.3390/molecules22050718 -
Environmental Science & Technology Nov 2022Volatile methyl siloxanes (VMS) are ubiquitous in indoor environments due to their use in personal care products. This paper builds on previous work identifying sources...
Volatile methyl siloxanes (VMS) are ubiquitous in indoor environments due to their use in personal care products. This paper builds on previous work identifying sources of VMS by synthesizing time-resolved proton-transfer reaction time-of-flight mass spectrometer VMS concentration measurements from four multiweek indoor air campaigns to elucidate emission sources and removal processes. Temporal patterns of VMS emissions display both continuous and episodic behavior, with the relative importance varying among species. We find that the cyclic siloxane D5 is consistently the most abundant VMS species, mainly attributable to personal care product use. Two other cyclic siloxanes, D3 and D4, are emitted from oven and personal care product use, with continuous sources also apparent. Two linear siloxanes, L4 and L5, are also emitted from personal care product use, with apparent additional continuous sources. We report measurements for three other organosilicon compounds found in personal care products. The primary air removal pathway of the species examined in this paper is ventilation to the outdoors, which has implications for atmospheric chemistry. The net removal rate is slower for linear siloxanes, which persist for days indoors after episodic release events. This work highlights the diversity in sources of organosilicon species and their persistence indoors.
Topics: Siloxanes; Environmental Monitoring; Organosilicon Compounds; Ventilation
PubMed: 36327170
DOI: 10.1021/acs.est.2c05438 -
Molecules (Basel, Switzerland) Mar 2021In this study, new biodegradable and biocompatible amphiphilic polymers were obtained by modifying the peripheral hydroxyl groups of branched polyethers and polyesters...
In this study, new biodegradable and biocompatible amphiphilic polymers were obtained by modifying the peripheral hydroxyl groups of branched polyethers and polyesters with organosilicon substituents. The structures of the synthesized polymers were confirmed by NMR and GPC. Organosilicon moieties of the polymers were formed by silatranes and trimethylsilyl blocks and displayed hydrophilic and hydrophobic properties, respectively. The effect of the ratio of hydrophilic to hydrophobic organosilicon structures on the surface activity and biological activity of macromolecules was studied, together with the effect on these activities of the macromolecules' molecular weight and chemical structure. In particular, the critical micelle concentrations were determined, the effect of the structure of the polymers on their wetting with aqueous solutions on glass and parafilm was described, and the aggregation stability of emulsions was studied. Finally, the effect of the polymer structures on their antifungal activity and seed germination stimulation was examined.
Topics: Antifungal Agents; Ascomycota; Biocompatible Materials; Bridged Bicyclo Compounds, Heterocyclic; Micelles; Molecular Structure; Organosilicon Compounds; Polyesters
PubMed: 33810558
DOI: 10.3390/molecules26071893 -
Immunotherapy Dec 2021Near infrared photoimmunotherapy (NIR-PIT) is a molecularly targeted treatment for cancers achieved by injecting a conjugate of IRDye700DX (IR700), a water-soluble... (Review)
Review
Near infrared photoimmunotherapy (NIR-PIT) is a molecularly targeted treatment for cancers achieved by injecting a conjugate of IRDye700DX (IR700), a water-soluble silicon phthalocyanine derivative in the near infrared, and a monoclonal antibody that targets cancer cell antigens. NIR-PIT is a highly specific treatment with few side effects that results in rapid immunogenic cell death. Despite it being a very effective and innovative therapy, there are a few challenges preventing full implementation in clinical practice. These include the limits of near infrared light penetration, selection of targets, concerns about tumor lysis syndrome and drug costs. However, NIR-PIT has been approved by the regulatory authorities in Japan, allowing for exploration of how to mitigate challenges while maximizing the benefits of this treatment modality.
Topics: Animals; Antineoplastic Agents, Immunological; Humans; Immunoconjugates; Immunotherapy; Indoles; Infrared Rays; Neoplasms; Organosilicon Compounds; Phototherapy
PubMed: 34693721
DOI: 10.2217/imt-2021-0241 -
Journal of Controlled Release :... Dec 2015Nanoparticle anticancer drug delivery enhances therapeutic efficacies and reduces side effects by improving pharmacokinetics and biodistributions of the drug payloads in... (Review)
Review
Nanoparticle anticancer drug delivery enhances therapeutic efficacies and reduces side effects by improving pharmacokinetics and biodistributions of the drug payloads in animal models. Despite promising preclinical efficacy results, monotherapy nanomedicines have failed to produce enhanced response rates over conventional chemotherapy in human clinical trials. The discrepancy between preclinical data and clinical outcomes is believed to result from the less pronounced enhanced permeability and retention (EPR) effect in and the heterogeneity of human tumors as well as the intrinsic/acquired drug resistance to monotherapy over the treatment course. To address these issues, recent efforts have been devoted to developing nanocarriers that can efficiently deliver multiple therapeutics with controlled release properties and increased tumor deposition. In ideal scenarios, the drug or therapeutic modality combinations have different mechanisms of action to afford synergistic effects. In this review, we summarize recent progress in designing hybrid nanoparticles for the co-delivery of combination therapies, including multiple chemotherapeutics, chemotherapeutics and biologics, chemotherapeutics and photodynamic therapy, and chemotherapeutics and radiotherapy. The in vitro and in vivo anticancer effects are also discussed.
Topics: Animals; Antineoplastic Agents; Drug Combinations; Drug Delivery Systems; Ferric Compounds; Gold; Humans; Nanoparticles; Neoplasms; Organometallic Compounds; Organosilicon Compounds; Polymers
PubMed: 26387745
DOI: 10.1016/j.jconrel.2015.09.029 -
Chemical Record (New York, N.Y.) Aug 2016Aggregation-induced emission (AIE) luminogens show abnormal fluorescent behavior; they are non-emissive in solution, but they become strongly emissive after aggregation.... (Review)
Review
Aggregation-induced emission (AIE) luminogens show abnormal fluorescent behavior; they are non-emissive in solution, but they become strongly emissive after aggregation. Sensing and imaging are the major applications of AIE luminogens. By properly manipulating the aggregation and deaggregation of AIE molecules, various bio-/chemosensors have been developed. Moreover, AIE molecules with targeting groups have been devised for imaging of organelles and cancer cells. In this account, we report our recent work on the application of AIE luminogens for the construction of bio-/chemosensors and imaging.
Topics: Animals; Biosensing Techniques; DNA, Single-Stranded; Fluorescent Dyes; G-Quadruplexes; Humans; Indoles; Luminescence; Metals; Molecular Imaging; Neoplasms; Organelles; Organosilicon Compounds; Proteins; Stilbenes
PubMed: 27427427
DOI: 10.1002/tcr.201600045 -
International Journal of Toxicology 2017Dimethiconol and its esters and reaction products are used in cosmetics as either skin-conditioning agents or hair-conditioning agents. The Cosmetic Ingredient Review... (Review)
Review
Dimethiconol and its esters and reaction products are used in cosmetics as either skin-conditioning agents or hair-conditioning agents. The Cosmetic Ingredient Review (CIR) Expert Panel reviewed relevant data and concluded that these ingredients are safe in the present practices of use and concentration described in this safety assessment. While there is an absence of data on reproductive and developmental toxicity and limited tumorigenicity and toxicokinetics data, the Panel reasoned that these ingredients would not be absorbed through the skin, obviating concern over potential reproductive and developmental toxicity or carcinogenicity.
Topics: Animals; Consumer Product Safety; Cosmetics; Esters; Humans; Lethal Dose 50; Molecular Structure; Organosilicon Compounds; Toxicity Tests
PubMed: 29243542
DOI: 10.1177/1091581817739429 -
Angewandte Chemie (International Ed. in... Jan 2021A nickel-catalyzed asymmetric reductive hydroarylation of vinyl amides to produce enantioenriched α-arylbenzamides is reported. The use of a chiral bisimidazoline (BIm)...
A nickel-catalyzed asymmetric reductive hydroarylation of vinyl amides to produce enantioenriched α-arylbenzamides is reported. The use of a chiral bisimidazoline (BIm) ligand, in combination with diethoxymethylsilane and aryl halides, enables the regioselective introduction of aryl groups to the internal position of the olefin, forging a new stereogenic center α to the N atom. The use of neutral reagents and mild reaction conditions provides simple access to pharmacologically relevant motifs present in anticancer, SARS-CoV PLpro inhibitors, and KCNQ channel openers.
Topics: Alkenes; Benzamides; Catalysis; Imidazolines; Molecular Conformation; Nickel; Organosilicon Compounds; Stereoisomerism; Thermodynamics
PubMed: 33015909
DOI: 10.1002/anie.202011342