ABSTRACT
The hydrophobic ionic liquid N-butyl-N-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)amide (BMP-TFSA IL), which contains a series of flexible ionophores of polypyridine-type small molecules or two rigid ionophores of peripherally pyridine-modified PAMAM dendrimers, was used to extract cupric ions from aqueous solutions. The polypyridine-type ionophores show good selectivity toward cupric ions at pHâ 2. The selectivity is affected by the spacing between the two amino groups. However, the pyridine-modified dendrimers showed poor selectivity, although their extraction efficiency still depended on the pH of the aqueous solution. The ionic liquids that contained small molecular ionophores and their dendrimer analogs were reused after acid washing or electrochemical reduction. During acid washing, the nitrogen atoms of the ionophores were protonated to release the cupric ions into the aqueous phase, and the copper atoms were deposited onto the electrode surface during the electrochemical reduction accompanied by the regeneration of the ionophores.
Subject(s)
Copper/chemistry , Dendrimers/chemistry , Ionic Liquids/chemistry , Hydrogen-Ion Concentration , Hydrophobic and Hydrophilic Interactions , Ions/chemistry , Pyridines/chemistryABSTRACT
A six-coordinate oxovanadium(V) thiolate complex and an eight-coordinate non-oxovanadium thiolate complex, [PPh(4)][VO(PS3'')(OCH(3))] (1) and [NEt(4)][V(PS3'')(2)] (2) (PS3'' = P(C(6)H(3)-3-Me(3)Si-2-S)(3)(3-)), respectively, have been isolated and structurally characterized. The former belongs to a limited collection of oxovanadium(V) thiolate complexes. The latter has an unusual coordination number of eight. More importantly, its consensus electronic structure derived from its spectroscopic data should be considered as the resonance forms of V(V)-thiolate and V(IV)-thiyl radical species. This implies that V(IV)-thiyl radical can maintain a stable presence in biological systems.
Subject(s)
Sulfhydryl Compounds/chemistry , Vanadates/chemistry , Vanadium Compounds/chemistry , Crystallography, X-Ray , Magnetic Resonance Spectroscopy , Models, MolecularABSTRACT
Three new phloroglucinols, garcinielliptones K (1), L (2), and M (3), and two new terpenoids, garcinielliptones N (4) and O (5), have been isolated from the seeds of Garcinia subelliptica. The structures of 1-5 including their relative configurations were elucidated by spectroscopic methods and supported by computer-generated molecular modeling. Compounds 2 and 3 showed potent inhibitory effects on the release of beta-glucuronidase, and on beta-glucuronidase and histamine, respectively, from peritoneal mast cells stimulated with p-methoxy-N-methylphenethylamine (compound 48/80) in a concentration-dependent manner. Compounds 2 and 3 showed potent effects on NO production in culture media of RAW 264.7 cells in response to lipopolysaccharide (LPS). Compound 2 also showed a potent effect on NO production in culture media of N9 cells in response to LPS/interferon-gamma (IFN-gamma).
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/isolation & purification , Garcinia/chemistry , Phloroglucinol/isolation & purification , Terpenes/isolation & purification , Triterpenes/isolation & purification , Animals , Anti-Inflammatory Agents, Non-Steroidal/chemistry , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Cells, Cultured , Interferon-gamma/metabolism , Lipopolysaccharides/metabolism , Mast Cells/drug effects , Mice , Molecular Structure , Neutrophils/drug effects , Nitric Oxide/antagonists & inhibitors , Nitric Oxide/biosynthesis , Nuclear Magnetic Resonance, Biomolecular , Phloroglucinol/chemistry , Phloroglucinol/pharmacology , Plants, Medicinal , Taiwan , Terpenes/chemistry , Terpenes/pharmacology , Triterpenes/chemistry , Triterpenes/pharmacologyABSTRACT
Two new protopine-type alkaloids, argemexicaine A (1) and argemexicaine B (2), along with thirteen known alkaloids, were isolated from MeOH extracts of Formosan Argemone mexicana L. (Papaveraceae). Physical and spectral analyses, particularly IR and thermo-modulated 1D and 2D NMR, were used to determine the transannular conformations of the isolated protopine-type alkaloids. The known benzo[ c]phenanthridine (+/-)-6-acetonyldihydrochelerythrine (5) exhibited significant anti-HIV activity in H9 lymphocytes with EC50 and TI (Therapeutic Index) values of 1.77 microg/mL and 14.6, respectively.
Subject(s)
Alkaloids/pharmacology , Anti-HIV Agents/pharmacology , Argemone , Berberine Alkaloids , HIV-1/drug effects , Phenanthrenes/pharmacology , Phytotherapy , Plant Extracts/pharmacology , Alkaloids/administration & dosage , Alkaloids/chemistry , Alkaloids/therapeutic use , Anti-HIV Agents/administration & dosage , Anti-HIV Agents/chemistry , Anti-HIV Agents/therapeutic use , Benzophenanthridines , HIV Infections/drug therapy , Humans , Inhibitory Concentration 50 , Magnetic Resonance Spectroscopy , Phenanthrenes/administration & dosage , Phenanthrenes/therapeutic use , Plant Extracts/administration & dosage , Plant Extracts/chemistry , Plant Extracts/therapeutic use , Structure-Activity RelationshipABSTRACT
High-level ab initio calculations were carried out in both gas phase and solvent (epsilon = 35.9) to estabilish that the amination of ketenimine proceeds via amine addition across the C=N bond rather than the C=C bond, followed by tautomerization to form amidine product. The HOMO of ketenimine is perpendicular to its molecular plane with the largest coefficient on C(beta), while the LUMO is in its molecular plane with the largest coefficient on C(alpha). Amination of ketenimine involves in-plane attack of amine nucleophile on C(alpha) (LUMO) of ketenimine. The labile vinylidenediamine intermediate trans-11 for the reaction of ketenimine 10 with n-butylamine was directly observed by means of low-temperature proton NMR spectra. The evidence confirms that the amination reaction is stepwise and proceeds via n-butylamine addition across the C=N bond of ketenimine 10 rather than the C=C bond, followed by a slower tautomerization of vinylidenediamine trans-11 to amidine 12. Even though the second step is much slower, the first step involving amine addition across the C=N bond is kinetic control. Surprisingly, in the reaction of 10 with n-BuNH(2), attack of n-BuNH(2) syn to the phenyl group on C(beta) of 10 is preferred, even though this produces a less stable product (trans-11); attack of n-BuNH(2) anti to phenyl group on C(beta) of 10 is lacking and results in serious nonbonding interactions between the two phenyls of the ketenimine, as they are pushed together in this transition state.