- Synthesis, Surface and Antimicrobial Activity of Piperidine-Based Sulfobetaines
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A new method for the preparation of new heterocyclic amine surfactants based on sulfobetaines is proposed. Interfacial activities of the surfactants obtained in aqueous solution were studied by surface tension measurements. The critical micelle concentration, surface excess concentration, minimum area per surfactant molecule, and standard Gibbs energy of adsorption were determined. The adsorption properties of these compounds depend significantly on the alkyl chain length. Alkyl chain length also affects biological properties of the new surfactants, determining the minimum inhibitory concentration and size of inhibited growth zone. The compounds have high antimicrobial activity.
- Wieczorek, Daria,Dobrowolski, Adam,Staszak, Katarzyna,Kwa?niewska, Dobrawa,Dubyk, Patrycja
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- New ester based gemini surfactants: the effect of different cationic headgroups on micellization properties and viscosity of aqueous micellar solution
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A new series of ester functionalized cationic gemini surfactants having different cationic headgroups (i.e. piperidinium, pyrrolidinium, morpholinium and quaternary ammonium) have been synthesized and characterized using NMR and Mass spectroscopy. These new gemini surfactants were investigated for their micellization and viscosity properties using surface tension, conductivity, fluorescence and rheology thechniques. The physicochemical properties of the aqueous surfactant system were influenced by polarity, size and the nature of cationic headgroups as the surface, thermodynamic and viscosity properties of these gemini surfactants were found to be dependent on the type of cationic headgroup. The current research finding establishes the structure-property relationship of the surfactant molecule specifically taking into account the dominant role displayed by the nature of the cationic headgroup.
- Bhadani, Avinash,Tani, Misako,Endo, Takeshi,Sakai, Kenichi,Abe, Masahiko,Sakai, Hideki
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p. 19474 - 19483
(2015/07/27)
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- Micelles for the self-assembly of "off-on-off" fluorescent sensors for pH windows
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A micellar approach is proposed to build a series of systems featuring an "off-on-off" fluorescent window response with changes in pH. The solubilizing properties of micelles are used to self-assemble, in water, plain pyrene with lipophilized pyridine and tertiary amine moieties. Since these components are contained in the small volume of the same micelle, pyrene fluorescence is influenced by the basic moieties: protonated pyridines and free tertiary amines behave as quenchers. Accordingly, fluorescence transitions from the "off" to the "on" state, and viceversa, take place when the pH crosses the pKa values of the amine and pyridine fragments. To obtain an "off-on-off" fluorescent response in this investigation we use either a set of dibasic lipophilic molecules (containing covalently linked pyridine and tertiary amine groups) or combinations of separate, lipophilic pyridines and tertiary amines. The use of combinations of dibasic and mono-basic lipophilic molecules also gives a window-shaped fluorescence response with changes in pH: it is the highest pyridine pKa and the lowest tertiary amine pKa that determine the window limits. The pKa values of all the examined lipophilic molecules were determined in micelles, and compared with the values found for the same molecules in solvent mixtures in which they are molecularly dispersed. The effect of micellization is to significantly lower the observed protonation constants of the lipophilized species. Moreover, the more lipophilic a molecule is, the lower the observed logK value is. Accordingly, changing the substituents on the basic moieties or modifying their structure, tuning the lipophilicity of the mono- or dibases, and choosing among a large set of possible combination of lipophilized mono- and dibases have allowed us to tune, almost at will, both the width and the position along the pH axis of the obtained fluorescent window.
- Diaz-Fernandez, Yuri,Foti, Francesco,Mangano, Carlo,Pallavicini, Piersandro,Patroni, Stefano,Perez-Gramatges, Aurora,Rodriguez-Calvo, Simon
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p. 921 - 930
(2007/10/03)
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- Nematocidal activity of long alkyl chain amides, amines and their derivatives on dog roundworm larvae
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The nematocidal activity of amides and amines having a long alkyl chain against the second-stage larva of dog roundworm, Toxocara canis, was examined. Long chain acyl amides with smaller substituents on the nitrogen showed stronger activity and the activity of cyclic amine amides was stronger than that of acyclic ones. In a series of homologous amides, the activity was dependent on the alkyl chain length: it reached a maximum at an optimal chain length and decreased in both shorter and longer homologues. The relationship between the activity and hydrophobicity of the homologues was analysed by the use of the bilinear model. The hydrophobicity of a compound, which gives a maximal activity, was similar for all neutral amides, but amides which have an additional amine group in the molecule had different values. Tertiary amines and their salts having a long alkyl chain also showed nematocidal activities comparable to those of the corresponding amides. The salts killed the larva at concentrations lower than their critical micell concentration, suggesting that they behave as a single molecule for the nematocidal action.
- Kiuchi,Nishizawa,Kawanishi,Kinoshita,Ohsima,Uchitani,Sekino,Ishida,Kondo,Tsuda
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p. 3234 - 3244
(2007/10/02)
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- Ruthenium Complex Catalyzed N-Heterocyclization. Syntheses of N-Substituted Piperidines, Morpholines, and Piperazines from Amines and 1,5-Diols
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1,5-Pentanediol reacts with aliphatic and aromatic primary amines in the presence of a ruthenium catalyst modified with phosphonic ligands to give N-substituted piperidines in fair to goods yields.The reactions were carried out at 150-180 deg C for 5 h in dioxane.The nature of the phosphorus ligands has a remarkable effect on the catalytic activity, For the reaction of aromatic amines, triphenylphosphine is effective, while for aliphatic amine more basic tributyl- or triethylphosphine is preferable.Amines also react with diethylene glycol and N-substituted diethanolamines in the presence of the ruthenium catalyst to give N-substituted morpholines and piperazines in good yields, respectively.
- Tsuji, Yasushi,Huh, Keun-Tae,Ohsugi, Yukihiro,Watanabe, Yoshihisa
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p. 1365 - 1370
(2007/10/02)
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