- Ionic Highways from Covalent Assembly in Highly Conducting and Stable Anion Exchange Membrane Fuel Cells
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A major challenge in the development of anion exchange membranes for fuel cells is the design and synthesis of highly stable (chemically and mechanically) conducting membranes. Membranes that can endure highly alkaline environments while rapidly transporting hydroxides are desired. Herein, we present a design using cross-linked polymer membranes containing ionic highways along charge-delocalized pyrazolium cations and homoconjugated triptycenes. These ionic highway membranes show improved performance. Specifically, a conductivity of 111.6 mS cm-1 at 80 °C was obtained with a low 7.9% water uptake and 0.91 mmol g-1 ion exchange capacity. In contrast to existing materials, ionic highways produce higher conductivities at reduced hydration and ionic exchange capacities. The membranes retain more than 75% of their initial conductivity after 30 days of an alkaline stability test. The formation of ionic highways for ion transport is confirmed by density functional theory and Monte Carlo studies. A single cell with platinum metal catalysts at 80 °C showed a high peak density of 0.73 W cm-2 (0.45 W cm-2 from a silver-based cathode) and stable performance throughout 400 h tests.
- Kim, Yoonseob,Wang, Yanming,France-Lanord, Arthur,Wang, Yichong,Wu, You-Chi Mason,Lin, Sibo,Li, Yifan,Grossman, Jeffrey C.,Swager, Timothy M.
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supporting information
p. 18152 - 18159
(2019/11/14)
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- Ionic Highways from Covalent Assembly in Highly Conducting and Stable Anion Exchange Membrane Fuel Cells
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A major challenge in the development of anion exchange membranes for fuel cells is the design and synthesis of highly stable (chemically and mechanically) conducting membranes. Membranes that can endure highly alkaline environments while rapidly transporting hydroxides are desired. Herein, we present a design using cross-linked polymer membranes containing ionic highways along charge-delocalized pyrazolium cations and homoconjugated triptycenes. These ionic highway membranes show improved performance. Specifically, a conductivity of 111.6 mS cm-1 at 80 °C was obtained with a low 7.9% water uptake and 0.91 mmol g-1 ion exchange capacity. In contrast to existing materials, ionic highways produce higher conductivities at reduced hydration and ionic exchange capacities. The membranes retain more than 75% of their initial conductivity after 30 days of an alkaline stability test. The formation of ionic highways for ion transport is confirmed by density functional theory and Monte Carlo studies. A single cell with platinum metal catalysts at 80 °C showed a high peak density of 0.73 W cm-2 (0.45 W cm-2 from a silver-based cathode) and stable performance throughout 400 h tests.
- Kim, Yoonseob,Wang, Yanming,France-Lanord, Arthur,Wang, Yichong,Wu, You-Chi Mason,Lin, Sibo,Li, Yifan,Grossman, Jeffrey C.,Swager, Timothy M.
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supporting information
p. 18152 - 18159
(2019/11/28)
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- Facile synthesis of high specific activity 4-[1-14C]butyl-1,2-diphenylpyrazolidine-3,5-dione (phenylbutazone) using nucleophilic substitution
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Metabolism, environmental fate, and low concentration food residue studies would be facilitated by the use of radiolabeled test articles that can be readily quantified within complex matrices. However, radiochemical approaches for such studies require high specific activities to allow analytical detection of correspondingly low masses of test article. The synthesis of high specific activity (>50?μCi/μmol) [14C]-radiolabeled phenylbutazone presents a challenge using existing methodology, mainly due to the low solvent volumes required and vigorous refluxing needed to close the pyrazolidinedione ring. Herein, we report on the significant modification of an existing method that allows the synthesis of low masses of high specific activity (>50?μCi/μmol) [14C]-phenylbutazone under mild conditions with simple purification and high yield. The closure of the pyrazolidinedione ring of 1,2-diphenyl-3,5-pyrazolidinedione was accomplished as a first step with unlabeled 1,2-diphenylhydrazine and diethyl malonate in 32% yield under gram-scale conditions, which avoided the challenges of low solvent use and vigorous refluxing. Low mass of high specific activity n-[1-14C]-butyl bromide was then added via a nucleophilic substitution reaction as a final step. Yields ranged from 65% to 92% during multiple synthetic attempts with unlabeled butyl bromide and were greatly influenced by reaction stoichiometry and the selection of base.
- Singh, Anuradha,Hakk, Heldur,Lupton, Sara J.
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p. 386 - 390
(2018/03/21)
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- A novel prodrug strategy for β-dicarbonyl carbon acids: Syntheses and evaluation of the physicochemical characteristics of C-phosphoryloxymethyl (POM) and phosphoryloxymethyloxymethyl (POMOM) prodrug derivatives
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The C-phosphoryloxymethyl (POM) and phosphoryloxymethyloxymethyl (POMOM) prodrugs resulting from derivatization at the reactive α-carbon of β-dicarbonyl carbon acid drugs represent a unique approach for improving their chemical stability and aqueous solubility. This work evaluates the physicochemical and in vitro enzymatic bioconversion lability of selected prodrugs of phenylbutazone and phenindione. The POM and POMOM prodrug derivatives of phenylbutazone are highly water soluble (≥250 mg/mL), chemically stable with projected shelf-lives of 4.5 years (pH 3.5, 258C) and 1.1 years (pH 6.0, 25°C), respectively. Interestingly, both prodrug derivatives do not display a pH-dependency typical of many phosphate monoesters, although the similarities of their apparent thermodynamic activation parameters indicate a hydrolysis mechanism similar to other phosphates. These prodrugs undergo alkaline phosphatases catalyzed bioconversion to their respective carbon acids with an expected faster rate exhibited by the POMOM derivatives. Additionally, in marked contrast to the oxidative instability of phenindione, its POM prodrug is stable. The results from these studies reaffirm the rationale of transiently "masking" the reactive a-carbon/proton bond by covalently incorporating a POM or POMOM promoiety. This prodrug strategy presents a twofold advantage, enhancement of aqueous solubility and prevention of oxidative instability, two intrinsic formulation limitations found for β-dicarbonyl carbon acid drugs.
- Dhareshwar, Sundeep S.,Stella, Valentino J.
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p. 2711 - 2723
(2011/04/15)
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- Mucosal adhesive device for long-acting delivery of pharmaceutical combinations in oral cavity
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Mucosal adhesive devices are provided for use in the oral cavity for therapy against infections. The devices are dosage units which comprise a combination of antimicrobial agents such as antifungal agents and anti-inflammatory agents, optionally also a local anesthetic. The dosage units yield a gradual and relatively constant release of the pharmaceuticals over at least a 12-hour period.
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- Water dispersion containing ultrafine particles of organic compounds
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A water-dispersible condensate of water-insoluble ultrafine particles of medicine or hormones having a particle size of at largest 4 μm prepared by the steps of heating the medicine or hormone in a vacuum vessel at a temperature of 30° C. higher than the boiling point and at a pressure between 0.01 Torr and 10 Torr to evaporate the medicine or hormone and condensing the medicine or hormone on a recovery plate to obtain the condensate.
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- Method for preventing renal papillary necrosis with prostaglandins
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The present invention provides a method for the prevention of renal papillary necrosis induced by non-steroidal anti-inflammatory compounds (NOSAC) comprising the administration of certain prostaglandins.
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- Contraceptive method
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Contraceptive method comprises maintaining in the genital tract of a female mammal a pyrazolone derivative in a concentration effective to inhibit the fertilization of ova. In addition to effectively inhibiting the enzymes or other sperm components necessary for conception, the compounds used in the method of the invention are advantageous in having low toxic, caustic or irritating properties, so that the contraceptive compositions are suitable for long-term use without adverse side-effects.
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- Benzo-as-triazine derivatives
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The invention relates to new benzo-as-triazine derivatives of the formulae (I) and (Ia) and pharmaceutically acceptable acid addition salts thereof, STR1 wherein R1 and R2 each represent hydrogen, a C1-20 alkylcarbonyl group, a phenylcarbonyl or phenyl-(C1-4 alkyl)-carbonyl group having optionally one or more halogen, hydroxy or C1-3 alkoxy substituents which may be the same or different, furthermore a pyridylcarbonyl, a pyrazinylcarbonyl, a furylcarbonyl, a chloroacetyl or a C1-4 alkoxycarbonyl group, or R1 and R2 may form, together with the adjacent nitrogen atoms, a pyrazole ring having optionally a C1-6 alkyl substituent in position 4, with the proviso that one of R1 and R2 is always different from hydrogen, R3 stands for hydrogen, mercapto group, a C1-4 alkylmercapto group, amino group, a C1-4 alkylamino group, a piperazino group having optionally an N-alkyl or 2-pyridyl substituent, a morpholino group or a piperidino group, and R4 stands for hydrogen, halogen, C1-4 alkyl or C1-4 alkoxy group. The compounds of the formulae (I) and (Ia) are prepared by acylating the respective 2,4,5-unsubstituted 4,5-dihydro-benzo-as-triazine derivatives. The new compounds of the formulae (I) and (Ia) possess analgesic, antiphlogistic and narcosis-potentiating effects.
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- Topical pharmaceutical formulations, carrier compositions therefor, and preparation thereof
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A carrier composition for cutaneously absorbable topical pharmaceutical formulations of pharmacologically active agents is disclosed which comprises at least one partial glyceride of a fatty acid of medium chain length. This vehicle enhances the permeation of the topical formulation through the skin. A topical formulation which comprises this permeation enhancing vehicle is suitable for cutaneously applying pharmacologically active agents which are locally and/or systematically effective in the body.
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