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Chernyshev, E. A.; Ivanov, Pavel; Golubykh, D. N.

doi:10.1023/a:1015064326492

Cited by 17 publications

(9 citation statements)

References 8 publications

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“…Even more relevant to our own research is that the oscillatory condensation documented by these authors involves organosilanols (e.g., R 2 Si(OH) 2 or RR'Si(OH) 2 ). There are several analogies between the results presented in references20, 21 and those originating from our own laboratory, and also between the conclusions of the two research teams: In selected molecular structures of the relevant organosilanols, the molecular fragment =Si(OH) 2 appears20, 21. In our study, we postulate the presence of an intermediate enol structure with the analogous molecular fragment =C(OH) 2 (see Eqn (1b)).…”

Section: Discussionsupporting

confidence: 80%

“…In selected molecular structures of the relevant organosilanols, the molecular fragment =Si(OH) 2 appears20, 21. In our study, we postulate the presence of an intermediate enol structure with the analogous molecular fragment =C(OH) 2 (see Eqn (1b)).…”

Section: Discussionmentioning

confidence: 62%

“…In this context, it is noteworthy that oscillatory condensation has been reported in another system20, 21. Interestingly, the experimental evidence presented in those studies also originates from TLC, which emphasizes the utility of this simple analytical technique in tracing the structural lability of organic compounds.…”

Section: Discussionmentioning

confidence: 79%

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Spontaneous oscillatory in vitro chiral conversion of simple carboxylic acids and its possible mechanism

Sajewicz

Matlengiewicz

Leda

et al. 2010

J of Physical Organic Chem

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In earlier studies, we have collected experimental evidence (mostly from thin‐layer chromatography and polarimetry) on the spontaneous oscillatory in vitro chiral conversion of simple carboxylic acids dissolved in 70% aqueous ethanol. To elucidate this phenomenon, we developed a simple theoretical model of two linked Templators. Recently, we have obtained additional experimental evidence of the spontaneous condensation of chiral carboxylic acids, based on the biuret test (amino acids), high performance liquid chromatography, and 13C NMR spectroscopy (profens and hydroxy acids). We briefly describe our experimental results in the context of the existing literature and outline an improved theoretical model for these phenomena. Our system resembles in some respects the reported oscillatory condensation of organic silanols. Here, the key reaction is the formation of carboxylic acid‐derived enols. Finally, we discuss the importance of the oscillatory chiral conversion of simple carboxylic acids for biochemistry, pharmacology, and related life sciences. Copyright © 2010 John Wiley & Sons, Ltd.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 62%

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Spontaneous oscillatory in vitro chiral conversion of simple carboxylic acids and its possible mechanism

Sajewicz

Matlengiewicz

Leda

et al. 2010

J of Physical Organic Chem

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“…It is more surprising that hydro lysis occurs in the monolayer rather easily, whereas this process could not be carried out in solution even at 13 This phenomenon can be explained by the specific character of contacts of the alkoxy groups with water in the mono layer: this is almost a molecular contact, whereas these contacts are strongly hindered for the bulk reaction even in the presence of a homogenizing solvent. 19 In fact, the kinetics of this reaction can be monitored by the change in the isotherm, which was not a task of our work. How ever, the consecutive and reproducible changes in the compression isotherms in the monolayer for various ob jects confirm completely this possibility.…”

Section: (Hereinafter Hzosime 3 )mentioning

confidence: 98%

Trimethylsilyl ethers of amphiphilic carbosilane dendrimers of the third–fifths generations. Specific features of hydrolysis at the water-air interface

et al. 2007

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Carbosilane dendrimers from the third to fifth generation with hydroxy groups in the surface layer of the dendrimer were synthesized, as well as their analogs with latent hydroxy groups. The dendrimers differ by the density of the carbosilane core and hydrophilic shell. The amphiphilic nature of the synthesized compounds was manifested already for more hydro phobic trimethylsilyl derivatives of dendrimers. This allowed one to observe the hydrolysis of these objects during compression of their monolayers at the water surface in the Langmuir bath. The parameters of the molecular structure of the dendrimers exert a determining effect on the rate and completeness of the hydrolysis.Amphiphilic dendrimers are stable monomolecular mi celles, unlike multimolecular micelles, which are formed by linear amphiphilic systems. 1-3 This specific feature of molecular organization assumes a basically different be havior of amphiphilic dendrimers at the water-air inter face. Common micelle forming surfactants form classical lamellar monolayers with distinct orientation of each surfactant molecule in the monolayer, 4 whereas for dendrimers this rearrangement is joined with conforma tional strains. 5-12 From this point of view, investiga tion of the compression of monolayers of amphiphilic dendrimers with different molecular parameters can pro vide very important information on the relationship be tween the molecular structure of the dendrimers and con formational flexibility of their molecules upon a change in the external conditions. To obtain information of this kind, one need representative series of studied objects in which these or other structural factors are varied gradually in order to reveal certain tendencies and monitor their development.We have earlier 13 synthesized a series of amphiphilic dendrimers of the fifth generation with different densities of the molecular structure of the hydrophobic core of the dendrimer and hydrophilic shell. The purpose of the present work is to synthesize representative series of amphiphilic carbosilane dendrimers of the third-fifth generations with different ratios of the hydrophobic and hydrophilic parts of the molecular structure as the tri methylsiloxy derivatives and to study the hydrolysis pro cess in the monomolecular layers at the water-air in terface. Results and DiscussionSynthesis. Polyallyl carbosilane dendrimers with dif ferent densities of the molecular structure were used as A (hereinafter )

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“…In the literature [30,31], certain reports were found on the spontaneous condensation of chiral siliceous compounds that have proved oscillatory in nature. Chemical structures of these chiral siliceous compounds roughly resemble those of the chiral low-molecular-weight carboxylic acids, which were in the focus of our own interest.…”

Section: Scheme 2 Parallel Chiral Conversion and Condensation Of Promentioning

confidence: 99%

On ups and downs by analysis of profen drugs. A mini review

Sajewicz

Kowalska

2012

Acta Chromatographica

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Summary. Drug analysis is among the most sensitive areas of chemical analysis, simply because of its relevance to human health. Profens make the most important group of nonsteroidal anti-inflammatory drugs (NSAIDs), and in many countries some of them are freely sold over the counter. The in vitro liquid chromatographic analysis of profen drugs faces certain not commonly recognized yet acute and often impassable problems, due to the specific physicochemical properties of these compounds. In this mini review, we share our experience on the practical failures with the enantioseparation of profen drugs both by means of chiral planar and column chromatography. By use of such analytical techniques as polarimetry, 1 H and 13 C NMR spectroscopy, and mass spectrometry, we point out objectively the reasons that make liquid chromatographic enantioseparation of profens an almost impossible task. These compounds have an inherent ability (both in aqueous and nonaqueous solutions) to undergo oscillatory chiral conversion and oscillatory condensation, combined with a highly pronounced gelating ability. In our view, the oscillatory chiral conversion of profens questions the credibility of widespread claims on the superiority of the curative potential with the (+)-profens over that of the respective (-)-antimers (although the rightfulness of such claims cannot be dismissed, as the in vivo and in vitro behavior of many drugs are known to sometimes fundamentally differ). Moreover, it seems highly probable that, due to their highly pronounced gelating property, profen drugs can easily clog the blood vessels and thereby jeopardize living organisms.

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Cited by 17 publications

References 8 publications

Spontaneous oscillatory in vitro chiral conversion of simple carboxylic acids and its possible mechanism

Spontaneous oscillatory in vitro chiral conversion of simple carboxylic acids and its possible mechanism

Trimethylsilyl ethers of amphiphilic carbosilane dendrimers of the third–fifths generations. Specific features of hydrolysis at the water-air interface

On ups and downs by analysis of profen drugs. A mini review

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