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Quaternary Ammonium (quaternary + ammonium)
Terms modified by Quaternary Ammonium Selected AbstractsComparison of Physicochemical Properties of New Ionic Liquids Based on Imidazolium, Quaternary Ammonium, and Guanidinium CationsCHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2007Prashant Abstract More than 50 ionic liquids were prepared by using imidazolium, quaternary ammonium, and guanidinium cations and various anions. In these series, different cationic structures such as 1-benzyl-3-methylimidazolium [Bzmim]+, 1,3-dibenzylimidazolium [BzmiBz]+, 1-octyl-3-methylimidazolium [C8mim]+, 1-decyl-3-methylimidazolium [C10mim]+, tricapryl-methylammonium [Aliquat]+, benzyltriethylammonium [BzTEA]+, phenyltrimethylammonium [PhTMA]+, and dimethyldihexylguanidinium [DMG]+ were combined with anions, p -toluenesulfonate [TSA],, dicyanoamide [DCA],, saccharine (2-sulfobenzoic acid imide sodium salt) [SAC],, trifluoroacetate [TFA],, bis(trifluoromethanesulfonyl)imide [Tf2N],, trifluoromethanesulfonate [TfO],, and thiocyanate [SCN],. Important physical data for these ionic liquids are collated, namely solubility in common solvents, viscosity, density, melting point and water content. Apart from the viscosity, the Newtonian and non-Newtonian behavior of these ionic liquids is also disclosed. Stability of these ionic liquids under thermal, basic, acidic, nucleophilic, and oxidative conditions was also studied. The features of the solid,liquid phase transition were analyzed, namely the glass transition temperature and the heat capacity jump associated with the transition from the non-equilibrium glass to the metastable supercooled liquid. A degradation temperature of each ionic liquid was also determined. Comparisons of the properties of various ionic liquids were made. [source] Synthesis of Zwitterionic Water-Soluble Oligofluorenes with Good Light-Harvesting AbilityADVANCED FUNCTIONAL MATERIALS, Issue 13 2010Chengfen Xing Abstract A new water-soluble zwitterionic oligofluorene bearing carboxylic acid and quaternary ammonium as pendant groups (OF-1) is synthesized and characterized. It forms aggregates by intermolecular electrostatic interactions and exhibits similar light-harvesting ability as that of conjugated polymers. Efficient fluorescence resonance energy transfer (FRET) occurs from OF-1 to double-stranded DNA tagged with fluorescein (dsDNA-F1). A photoresponsive oligofluorene (OF-3) is also synthesized by protecting OF-1 with 1-(2-nitrophenyl)ethanol. Photolysis of OF-3 can produce OF-1 to result in a fluorescence "turn-on" response, thus the FRET from OF-3 to dsDNA-Fl can be turned on by light irradiation. OF-3 offers the potential for remote DNA sensing. [source] Antibacterial effects of MDPB against anaerobes associated with endodontic infectionsINTERNATIONAL ENDODONTIC JOURNAL, Issue 8 2010N. Izutani Izutani N, Imazato S, Noiri Y, Ebisu S. Antibacterial effects of MDPB against anaerobes associated with endodontic infections. International Endodontic Journal. Abstract Aim, To investigate the antibacterial effects of 12-methacryloyloxydodecylpyridinium bromide (MDPB), an antibacterial monomer synthesized by combining quaternary ammonium with a methacryloyl group, against three anaerobes associated with endodontic infections using planktonic and biofilm cells. Methodology, The antibacterial activity of unpolymerized MDPB against Enterococcus faecalis, Fusobacterium nucleatum and Prevotella nigrescens was examined by agar-disc diffusion tests and determination of the minimum inhibitory/bactericidal concentrations (MIC/MBC). Rapid killing effects of MDPB against three bacteria in planktonic form were examined by a cell number counting method, and those against biofilm cells were assessed by a viability staining method. Results, MDPB demonstrated inhibition against all of the bacteria tested by agar-disc diffusion tests. The MIC/MBC values of MDPB for the three anaerobes were much smaller than those of other resin monomers, although greater compared with those of cetylpyridinium chloride or chlorhexidine diacetate for E. faecalis and F. nucleatum. Significant reduction in viable planktonic cells was obtained by contact with 250 ,g mL,1 of MDPB for 20 s (P < 0.05, Fisher's PLSD tests), and 40 s contact with 500 ,g mL,1 or 20 s contact with 1000 ,g mL,1 of MDPB resulted in more than 90% killing. Biofilm cells of all species were completely killed by application of 1000 ,g mL,1 of MDPB for 60 s. Conclusion, MDPB was found to have strong antibacterial effects against E. faecalis, F. nucleatum and P. nigrescens, and such effects were rapidly exhibited even against biofilm cells, suggesting the usefulness of application of MDPB to resin-based materials for root canal filling. [source] Comparison of Physicochemical Properties of New Ionic Liquids Based on Imidazolium, Quaternary Ammonium, and Guanidinium CationsCHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2007Prashant Abstract More than 50 ionic liquids were prepared by using imidazolium, quaternary ammonium, and guanidinium cations and various anions. In these series, different cationic structures such as 1-benzyl-3-methylimidazolium [Bzmim]+, 1,3-dibenzylimidazolium [BzmiBz]+, 1-octyl-3-methylimidazolium [C8mim]+, 1-decyl-3-methylimidazolium [C10mim]+, tricapryl-methylammonium [Aliquat]+, benzyltriethylammonium [BzTEA]+, phenyltrimethylammonium [PhTMA]+, and dimethyldihexylguanidinium [DMG]+ were combined with anions, p -toluenesulfonate [TSA],, dicyanoamide [DCA],, saccharine (2-sulfobenzoic acid imide sodium salt) [SAC],, trifluoroacetate [TFA],, bis(trifluoromethanesulfonyl)imide [Tf2N],, trifluoromethanesulfonate [TfO],, and thiocyanate [SCN],. Important physical data for these ionic liquids are collated, namely solubility in common solvents, viscosity, density, melting point and water content. Apart from the viscosity, the Newtonian and non-Newtonian behavior of these ionic liquids is also disclosed. Stability of these ionic liquids under thermal, basic, acidic, nucleophilic, and oxidative conditions was also studied. The features of the solid,liquid phase transition were analyzed, namely the glass transition temperature and the heat capacity jump associated with the transition from the non-equilibrium glass to the metastable supercooled liquid. A degradation temperature of each ionic liquid was also determined. Comparisons of the properties of various ionic liquids were made. [source] Purification,chemical structure,electrical property relationship in gold nanoparticle liquids,APPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2010Robert I. MacCuspie Abstract Macroscopic assemblies of nanoparticles with fluid like characteristics, i.e. nanoparticle liquids (NPLs), are a new class of materials that exhibit unique properties compared with dispersions of nanoparticles in a molecularly distinct matrix phase. By focusing on reaction ratios, techniques to maximize concentration of reactants and quantification of chemical content during washing steps, a high degree of control over the purity of NPLs was maintained while allowing for easy scalability in batch sizes and synthesis throughput. A range of tertiary amines and quaternary ammoniums were used to successfully synthesize Au NPLs from a range of Au nanoparticles with nominal diameters from 6 to 20 nm and initially stabilized with either citrate or dodecanethiol. Stable Au NPLs after purification exhibited a sub-equivalence ratio of canopy to ligand molecules within the corona. This small canopy density most likely arose from the incommensurate areal density of anionic charge within the ligand shell relative to the larger size of the cationic canopy molecule, resulting in a population of cation,anion pairs too weakly bound to be retained in the initial assembly of the canopy post-purification. Finally, increasing either the volume fraction or molecular weight of the canopy was found to increase exponentially the electrical resistance of the bulk NPLs. Removal of excess canopy molecules created a conductive Au NPL that improved hot-current switching durability by at least two orders of magnitude beyond prior reports. Published in 2010 by John Wiley & Sons, Ltd. [source] Decreased biliary excretion of tributylmethyl ammonium in cholestyramine pretreated rats due to reduced formation of ion-pair complexes with hepatic bile saltsBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 9 2007M. K. Choi Abstract The hypothesis that higher molecular weight (MW) quaternary ammoniums (QAs) form lipophilic ion-pair complexes with bile salts in the liver, and are subsequently excreted into bile via a canalicular transporter, P-gp, was re-examined in the present study for its validity. The biliary excretion of tributylmethyl ammonium (TBuMA), a QA with a MW of 200, in bile salt-depleted rats was determined. Depletion was induced by a daily oral administration of a resin, cholestyramine, at a dose of 0.5,g/kg for 2 consecutive weeks, which decreased the concentration of total bile salts in the liver by 38%. When TBuMA was administered intravenously (12,µmol/kg) to these rats, the plasma level, area under the plasma concentration-time curve (AUC), systemic clearance (CL) and volume of distribution (Vss) of the compound remained unchanged, whereas bile flow (23.03 vs 16.94,µl/min, p<0.05) and biliary clearance (CLbile, 12.75 vs 5.34,ml/min/kg, p<0.01) were decreased significantly. These results implied the biliary clearance of TBuMA in rats with bile salt depletion was significantly decreased as a result of decreased ion-pair complexation of TBuMA. The above results are consistent with our hypothesis and the existence of a MW threshold (i.e. 200±50 for rats) for the biliary excretion of QAs. Copyright © 2007 John Wiley & Sons, Ltd. [source] | |||||||||||||