Fluorescence microscopy observations of domain structures in Langmuir monolayers of N-stearoylserine methyl ester and N-stearoylvaline at intermediate enantiomeric compositions

Parazak, Dennis P.; Uang, J; Whitt, Sean A.; Stine, Keith J.

doi:10.1016/0009-3084(94)02416-3

Cited by 10 publications

(5 citation statements)

References 14 publications

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“…Over the past 10 years, monolayers of chiral amphiphiles with amino acid headgroups have attained great attention. − The amino acid, chain length, subphase composition, and temperature were varied, and the monolayers were studied with the help of different techniques. Recently, Mao et al carried out a lattice simulation (cellular automata calculation) of chiral discrimination effects in monolayers based on the theoretical “tripod model” introduced by Andelman. , They were able to reproduce the formation of segregated domains in racemic monolayers with homochiral interactions.…”

Section: Introductionmentioning

confidence: 99%

Appearance and Disappearance of Dendritic and Chiral Patterns in Domains of Langmuir Monolayers Observed with Brewster Angle Microscopy

2004

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Investigations on the aggregation behavior and morphology of Langmuir films of enantiomeric (L) and racemic (DL) N-acyl amino acids on pure aqueous as well as metal cation containing subphases were carried out at the mesoscale level with the help of Brewster angle microscopy (BAM). In the case of N-hexadecanoyl alanine on a pure aqueous subphase at 298 K the L-enantiomer forms crystal platelets, while the irregular fractal-like shape of the domains of the racemic mixture can be explained by a diffusion limited aggregation (DLA) growth mechanism. At 303 K the L-enantiomer shows a dendritic growth pattern, which leads to explicitly chiral domain shapes that correspond with the chirality of the film-forming molecules and for which hydrogen bridges as directed attractive forces are assumed to be responsible. The compression of the L-enantiomer on a zinc ion containing subphase is accompanied by a remarkable metamorphosis of the condensed structure. Starting from torus-like domains they were at first converted into strongly wound S-shaped domains, finally turning into a seahorse-like appearance. The origin of these chiral shapes can be explained on the basis of an electrostatic growth model. The enantiomer of N-hexadecanoyl alanine methyl ester shows three different asymmetric dendritic growth patterns. The domains of the racemic mixture are dendritic too, but in contrast they are symmetric and have a notably low branching density. On a pure aqueous subphase the L-enantiomer of N-octadecanoyl valine exhibits dendritic growth as well, but the overall outer shape of the domains is not explicitly chiral.

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Section: Introductionmentioning

confidence: 99%

Appearance and Disappearance of Dendritic and Chiral Patterns in Domains of Langmuir Monolayers Observed with Brewster Angle Microscopy

2004

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“…Chirality-dependent effects have been found in various amphiphilic monolayers. This concerns particularly the N-acyl amino acid amphiphiles, − some phospholipids, , but also aldonamides , or tailored amphiphiles …”

Section: Introductionmentioning

confidence: 99%

“…Chirality-dependent effects have been found in various amphiphilic monolayers. This concerns particularly the N-acyl amino acid amphiphiles, [5][6][7][8][9] some phospholipids, 10,11 but also aldonamides 12,13 or tailored amphiphiles. 14 Monoglycerols are interesting amphiphiles that make possible the comparison of the enantiomeric and racemic monolayers.…”

Section: Introductionmentioning

confidence: 99%

Chiral Discrimination in 1-Stearylamine-Glycerol Monolayers

Vollhardt

Gehlert

2002

J. Phys. Chem. B

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The effect of the chirality on the thermodynamic behavior, the morphological features, and the 2D crystal structures of 1-stearylamine-glycerol monolayers are studied. The results are based on measurements of the surface pressure-area (π-A) isotherms, fluorescence microscopy, and synchrotron X-ray diffraction at grazing incidence (GIXD). Although the π-A isotherms of the enantiomeric forms and the racemic mixtures agree largely to each other, the filigree domain patterns show remarkable differences, obviously driven by the chirality. The domains of the R(+) enantiomer are curved clockwise, those of the S(-) enantiomer counterclockwise, whereas those of the racemic mixtures are without a specific sense of direction. Chiral discrimination effects are also found in the lattice structure. The enantiomeric monolayers have an oblique lattice where at compression the tilt direction changes continuously from angles nearly toward NN direction to angles nearly toward NNN direction. The condensed phases of the 1:1 racemic mixtures give rise to rectangular-centered lattices indicating a phase transition accompanied by the change in the tilt direction from NN at 1 mN/m to NNN at 5 mN/m. The filigree domain patterns indicate a comparatively low ordering of the alkyl chains. Correspondingly, a short-range translational order can be concluded from the low position correlation and high tilt angles of the alkyl chains at low surface pressures.

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“…[30][31][32][33] This behavior was investigated on films of different chiral amino acids. Some of the examined amphiphiles show homochiral discrimination [34][35][36][37][38][39] and heterochiral discrimination, 35 respectively. Films of 2-hydroxyhexadecanoic acid show homochiral discrimination in the case of Zn 2+ cations in the subphase and heterochiral discrimination in the case of Ca 2+ and Pb 2+ cations in the subphase.…”

Section: Introductionmentioning

confidence: 99%

“…Heterochiral discrimination means the preferred interaction between the two antipodal enantiomers in the racemic film in contrast to the interaction between the enantiomers with the same configuration. − This behavior was investigated on films of different chiral amino acids. Some of the examined amphiphiles show homochiral discrimination − and heterochiral discrimination, respectively. Films of 2-hydroxyhexadecanoic acid show homochiral discrimination in the case of Zn 2+ cations in the subphase and heterochiral discrimination in the case of Ca 2+ and Pb 2+ cations in the subphase. , In addition to these chiral effects observed in monolayers at the air−water interface, bilayer systems also show chiral discrimination …”

Section: Introductionmentioning

confidence: 99%

Hydrogen-Bond-Induced Chiral Discrimination in Monolayers of Bipolar Methyl Dihydroxyoctadecanoates^,^,

et al. 2000

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The insertion and systematical displacement of two vicinal hydroxyl groups along the hydrophobic alkyl chain of methyl octadecanoates generates bipolar amphiphiles. These molecules offer the possibility to investigate the influence of the position and the stereochemistry of the hydroxyl groups on monolayer properties and intermolecular interactions. Monolayers of enantioenriched and racemic vicinally dihydroxylated methyl octadecanoates (DHOs) were investigated using fluorescence microscopy, fluorescence spectroscopy, and grazing incidence X-ray diffraction (GIXD). The monolayers of racemic threo-2,3-DHO, erythro-9,10-DHO, and 17,18-DHO show heterochiral discrimination in fluorescence microscopy investigations due to a preferential interaction between the enantiomers with the opposite configuration. GIXD measurements exhibit rectangular unit cells for the racemic films, while the enantiomers form oblique and therefore chiral structures. Erythro-9,10-DHO exhibits an extraordinarily large lattice spacing due to the disturbing effect of the hydroxyl groups. The formation of rectangular lattices by racemic films strongly suggests that chiral phases such as in the case of the enantiomers are prevented by the dimerization due to stereospecific hydrogen bonds between the two antipodal enantiomers. Accordingly, the individual enantioenriched amphiphiles are able to distinguish between the same and antipodal enantiomers, and thus they are able to recognize chemical structures at a molecular level. Fluorescence spectroscopy at the air−water interface revealed whether the hydroxyl groups or the methyl ester of the α,ω-bipolar amphiphile 17,18-DHO is directed to the water surface in the condensed state at subphase temperatures of 278 and 293 K, respectively.

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Fluorescence microscopy observations of domain structures in Langmuir monolayers of N-stearoylserine methyl ester and N-stearoylvaline at intermediate enantiomeric compositions

Cited by 10 publications

References 14 publications

Appearance and Disappearance of Dendritic and Chiral Patterns in Domains of Langmuir Monolayers Observed with Brewster Angle Microscopy

Appearance and Disappearance of Dendritic and Chiral Patterns in Domains of Langmuir Monolayers Observed with Brewster Angle Microscopy

Chiral Discrimination in 1-Stearylamine-Glycerol Monolayers

Hydrogen-Bond-Induced Chiral Discrimination in Monolayers of Bipolar Methyl Dihydroxyoctadecanoates^,^,

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Fluorescence microscopy observations of domain structures in Langmuir monolayers of N-stearoylserine methyl ester and N-stearoylvaline at intermediate enantiomeric compositions

Cited by 10 publications

References 14 publications

Appearance and Disappearance of Dendritic and Chiral Patterns in Domains of Langmuir Monolayers Observed with Brewster Angle Microscopy

Appearance and Disappearance of Dendritic and Chiral Patterns in Domains of Langmuir Monolayers Observed with Brewster Angle Microscopy

Chiral Discrimination in 1-Stearylamine-Glycerol Monolayers

Hydrogen-Bond-Induced Chiral Discrimination in Monolayers of Bipolar Methyl Dihydroxyoctadecanoates,,

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Hydrogen-Bond-Induced Chiral Discrimination in Monolayers of Bipolar Methyl Dihydroxyoctadecanoates^,^,