The comparative spreading behavior of enantiomeric and racemic tyrosine amphiphiles

Marr-Leisy, D.; Neumann, R.; Ringsdorf, Helmut

doi:10.1007/bf01412955

Cited by 13 publications

(10 citation statements)

References 11 publications

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“…Π-A curves of the films over aqueous subphases were consistent with the literature data. [35][36][37] All of the films became more expanded over saturated dl-aspartic acid and d,l-asparagine monohydrate solutions, although this expansion effect was more marked for the l-tyrosine films. The expansion of the Π-A curves occurred up to surface pressures of approximately 20-25 mN m -1 ; above these surface pressures the films became condensed and attained the same limiting areas per molecule as found for the films over aqueous solutions (see Figure 2).…”

Section: Resultsmentioning

confidence: 99%

Role of Interfacial Tension in Nucleation beneath Monolayer Films

1997

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Monolayer films at high surface pressures are well-ordered, and due to their 2D crystallinity they can act as sites of preferential nucleation. Recently it has been demonstrated that films at lower surface pressures can also be preferential nucleators, despite their decreased ordering. In this study we show that identifying the factors which can reduce the interfacial tension is vital to understanding the varied mechanisms through which nucleation beneath monolayer films can occur. In particular, the preferential nucleation that is observed at low to medium surface pressures is explained by the compressible film rearranging so as to minimize the lattice mismatch with the nucleating crystal face, thereby reducing the interfacial tension of the system. We introduce a more quantitative approach in this paper to gain a greater insight into this phenomenon. The nucleating species must be adsorbed upon the film as a prerequisite for nucleation. We demonstrate that the extent of this adsorption may be modeled using the appropriate Π−A curves and an equation derived from the Gibbs and Langmuir adsorption isotherms. This approach also allows values for the adsorption energy and interfacial tension for 100% adsorption to be estimated.

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Section: Resultsmentioning

confidence: 99%

Role of Interfacial Tension in Nucleation beneath Monolayer Films

1997

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“… and had melting points of 197−198 °C and 163−164 °C, respectively. The NMR, infrared, and mass spectrometry data obtained from the film materials agreed with published data. − …”

Section: Methodsmentioning

confidence: 99%

“…Materials. Film compounds were synthesized from the purest available starting materials: L-alanine octadecyl ester hydrochloride was synthesized following the procedure of Penney et al 30 and had a melting point of 112-114 °C; L-aspartic acid tetradecyl ester hydrochloride was synthesized following the procedure of Koch 31 and had a melting point of 109-111 °C; L-tyrosine O-octadecylcarbamoyl hydrochloride and its methyl ester were synthesized following the procedure of Marr-Leisy et al 32 and had melting points of 197-198 °C and 163-164 °C, respectively. The NMR, infrared, and mass spectrometry data obtained from the film materials agreed with published data.…”

Section: Methodsmentioning

confidence: 99%

“…The NMR, infrared, and mass spectrometry data obtained from the film materials agreed with published data. [30][31][32] The purity of the other materials used were as follows: L-and DLaspartic acid (99%, BDH), D-, L-, and D,L-asparagine (99%, BDH), Milli-Q water (conductivity 0.05 µS/cm), chloroform (99.9%, Aldrich), and trifluoroacetic acid (99%, Aldrich).…”

Section: Methodsmentioning

confidence: 99%

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A New Mechanism for Nucleation beneath Monolayer Films?

1998

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The nucleation of the amino acids, aspartic acid and asparagine monohydrate, beneath monolayer films has been investigated as a function of film material and surface pressure. For the first time, nucleation has been shown to occur preferentially beneath films at low to medium surface pressures and not at high surface pressures as previously found. At high surface pressures, where the film was close-packed, the nucleation rate was low. In contrast, the nucleation rate was optimum under films at low to medium surface pressures. Since the close-packed films were unable to induce significant nucleation promotion, it is highly unlikely that this optimum nucleation at lower surface pressures occurs beneath close-packed film islands, but rather it is induced by the inherent nature of the films at lower surface pressures. We believe these novel results arise from both the substantial adsorption of the amino acid zwitterions between the film molecules and the exploitation of the greater compressional freedom of films at lower surface pressures, which enables greater lattice mismatches between the film and nucleating crystal face to be accommodated. Based on these findings, a new mechanism for nucleation beneath monolayer films is proposed. By using molecular modeling it was possible to demonstrate the existence of an electrostatic and geometric correlation between the film and nucleating crystal face in all cases. Therefore nucleation beneath the monolayers was governed by both strong adsorption upon the film and a correspondence between the structure and geometry of the film and nucleating crystal face, the latter correspondence being facilitated by the greater compressibility of the lower surface pressure films.

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“…Daruber hinaus wird durch die Einfuhrung synthetischer Amphiphile die Moglichkeit geschaffen, Aggregate mit bestimmten Funktionen zu generieren 'I. Einen besonders interessanten Aspekt stellt in Anlehnung an native Phospholipide die Synthese chiraler Amphiphile dar. Bis heute ist nur wenig daruber bekannt, welchen Ein-flu0 ihre Chiralitat auf das Aggregationsverhalten und auf die Eigenschaften der gebildeten Aggregate ausiibt 6,7).…”

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Synthese chiraler Liposomenbausteine mit s‐Triazin als verknüpfende Partialstruktur

Staatz¹,

Roth²

1989

Liebigs Ann. Chem.

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Um ein variables System ein‐ und zweikettiger chiraler Amphiphile zu synthetisieren, die sich als Liposomenbausteine eignen, wurde s‐Triazin als Verknüpfungseinheit zwischen lipophilem und hydrophilem Molekülteil ausgewählt. Der lipophile Teil besteht aus langkettigen Alkoholen oder Alkylaminen, während der hydrophile Teil der Moleküle durch die trifunktionellen Aminosäuren L‐Cystein, L‐Serin oder L‐Lysin gebildet wird. Diese sind über ihre ω‐Funktion mit dem s‐Triazin verbunden. Aufgrund der Aminosäurestruktur der neuen Lipide ist eine dünnschichtchromatographische Kontrolle ihrer optischen Reinheit möglich. Bei der Untersuchung der neuen Verbindungen auf ihre Eignung als Vesikelbausteine erweisen sich nur die zweikettigen Cystein‐Amphiphile als Liposomenbildner.

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The comparative spreading behavior of enantiomeric and racemic tyrosine amphiphiles

Cited by 13 publications

References 11 publications

Role of Interfacial Tension in Nucleation beneath Monolayer Films

Role of Interfacial Tension in Nucleation beneath Monolayer Films

A New Mechanism for Nucleation beneath Monolayer Films?

Synthese chiraler Liposomenbausteine mit s‐Triazin als verknüpfende Partialstruktur

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