General and theoretical aspects of the COOH and COOR groups

Simonetta, M.; Carrà, Sergio

doi:10.1002/9780470771099.ch1

Cited by 12 publications

(6 citation statements)

References 128 publications

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“…These values of compound 1 in a water−ethanol system were considerably lower than those of sebacic acid in the same system. In water, compound 1 also showed two p K a values, but the order of magnitude of p K a2 was quite different from not only the p K a2 value of compound 1 measured in a water−ethanol system but also the p K a2 value of adipic acid measured in water . It already has been known that aggregated carboxylic acids have different p K a values from the corresponding unaggregated ones, due to the different manner of protonation of the carboxylate groups. , An acid−anion dimer in which one proton is shared by two adjacent carboxylate groups is formed in aggregated carboxylic acids at a certain pH range, so that p K a values of aggregated carboxylic acids are generally higher than those of unaggregated ones.…”

Section: Resultsmentioning

confidence: 96%

“…The p K a values of the triple-chain amphiphile 1 were measured at 25 °C by the conventional titration method in two solvent systems. The results are listed in Table along with the p K a values of sebacic acid, adipic acid, and acetic acid measured under the same conditions . In a water−ethanol (2/8; v/v) system (system A in Table ), compound 1 was unaggregated and soluble, in contrast to its vesicular aggregation in water (system B).…”

Section: Resultsmentioning

confidence: 99%

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New pH-Sensitive Vesicles. Release Control of Trapped Materials from the Inner Aqueous Phase of Vesicles Made from Triple-Chain Amphiphiles Bearing Two Carboxylate Groups

et al. 2001

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The pH-induced release of trapped materials from the inner aqueous phase of vesicles made from the synthetic triple-chain amphiphile 1 bearing two carboxyl groups was investigated. While a particular pH-dependence of the release of trapped materials from the inside of vesicles made from distearoylphosphatidylcholine (DSPC) was not observed, vesicles made from compound 1 showed unique pH-sensitive character toward the pH of the outer bulk phase as follows: it released less than 10% of 5(6)-carboxyfluorescein (CF) as a water-soluble marker at pH 7.5 after 1 year. But the vesicular assemblies were broken below pH 3.5−4.0, resulting in the liberation of the trapped CF into the bulk phase. The latter result is associated with a full-protonation of the carboxylate groups of compound 1. In the case of vesicles made from a mixture of DSPC and compound 1, the addition of cholesterol into the vesicle membranes was effective in providing clear pH-sensitive character for this type of vesicle. The ζ potentials of a series of vesicles containing compound 1 at various pH synchronized well with the pK a1 value of vesicles made from compound 1 and the pH-dependence of the release of trapped CF from these vesicles.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

New pH-Sensitive Vesicles. Release Control of Trapped Materials from the Inner Aqueous Phase of Vesicles Made from Triple-Chain Amphiphiles Bearing Two Carboxylate Groups

et al. 2001

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“…In the benzoic oxygen ligand configuration, the C(25)−O(1) bond distance of 1.246(4) Å is a little longer than the C(25)−O(2) distance of 1.232(4) Å. However, the COO - skeleton in 2a is less asymmetric than that of carboxylate salt analogues and the distances are smaller than the corresponding carbon−oxygen bond distances in the benzoic acid (C−OH = 1.29 Å, CO = 1.24 Å) . The Te(1), C(25), O(1), and O(2) atoms in 2a are on the same plain because the sum of the angles between these atoms is about 360°.…”

Section: Resultsmentioning

confidence: 96%

Monooxytellurane(IV) Derivatives ([10−Te−4(C3O)]). Syntheses and Molecular Structure of Triaryltelluronium Carboxylate Compounds

et al. 1998

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Bis(2,2‘-biphenylylene)tellurane (1) undergoes a ring-opening reaction on treatment with acetic and benzoic acid to afford the triaryltelluronium carboxylate derivatives [10−Te−4(C3O)] (2). (2,2‘-Biphenylylene)(2-biphenylyl)benzoyloxytellurane (λ4-tellane) (2a) and (2,2‘-biphenylylene)(2-biphenylyl)acetyloxytellurane (λ4-tellane) (2b) were subjected to X-ray crystallographic analysis, which revealed that they crystallize as monomers and dimers, respectively, and that their Te centers have a distorted trigonal-bipyramidal bonding geometry.

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“…The transition of the latter group should be at the shorter wavelength side, as carbonyl groups normally show their n-x* transition at about 210-220 nm (e =* 50 L• moTbcm*1). 23 In the CD spectra of 17a and 17b a Gaussian band centered at 235 nm is visible with Ac values of -4.0 and -0.29 L-moT^cm-1, respectively. The relatively high wavelength position of the band suggests that the chirality of the carbonyl group is not pronounced in the CD.…”

Section: Introductionmentioning

confidence: 94%

Helical configuration of poly(iminomethylenes). Synthesis and CD spectra of polymers derived from optically active isocyanides

Beijnen¹,

Nolte²,

Naaktgeboren³

et al. 1983

Macromolecules

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Each of nine chiral isocyanides, R*-N=C, in enantiomerically pure or almost pure form, is polymerized to the corresponding poly(iminomethylene), [R*-N=C<]n. The group R* either contains at least one substituent (carboxylic ester, phenyl, phosphinyl) or is unsaturated (C=C, C=C). The polymers are of the rigid-rod type with a helical main chain of carbon atoms. Because of the chirality of R*-N=C either the P or the M helix is preferentially formed. CD spectra and optical rotation at 578 nm are determined and compared with those of the model compounds R*-N=CH(i-C4H9) and the monomers. This comparison and earlier calculations on [i-C4H9-N=C<]n allowed the assignment to each polymer of the excess screw sense. The screw sense is also theoretically predicted by two approaches, a thermodynamic and a kinetic one. The latter approach gives an appreciably better fit with the experimental results.

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General and theoretical aspects of the COOH and COOR groups

Cited by 12 publications

References 128 publications

New pH-Sensitive Vesicles. Release Control of Trapped Materials from the Inner Aqueous Phase of Vesicles Made from Triple-Chain Amphiphiles Bearing Two Carboxylate Groups

New pH-Sensitive Vesicles. Release Control of Trapped Materials from the Inner Aqueous Phase of Vesicles Made from Triple-Chain Amphiphiles Bearing Two Carboxylate Groups

Monooxytellurane(IV) Derivatives ([10−Te−4(C3O)]). Syntheses and Molecular Structure of Triaryltelluronium Carboxylate Compounds

Helical configuration of poly(iminomethylenes). Synthesis and CD spectra of polymers derived from optically active isocyanides

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