Homochiral oligopeptides generated via an asymmetric induction in racemic 2D crystallites at the air–water interface; the system ethyl/thio-ethyl esters of long-chain amphiphilic α-amino acids

Rubinstein, Irina; Kjær, Kristian; Weissbuch, Isabelle; Lahav, Meir

doi:10.1039/b507457f

Cited by 13 publications

(9 citation statements)

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“…A regular and ordered insoluble monolayer can be utilized as a template to induce water-soluble solutes to form threedimensional crystals at the air/liquid interface (Birman et al, 2010;Weissbuch et al, 2003Weissbuch et al, , 2009Plaut et al, 2003;Rubinstein et al, 2005;Stripe et al, 2012;Frey et al, 1996). However, these insoluble amphiphiles may introduce complications owing to their influence on the interfacial crystallization (Stripe et al, 2012), unfavorable for understanding the relationship between the molecular structure of the crystallizing material and the resulting crystal morphology and properties.…”

Section: Introductionmentioning

confidence: 99%

Monolayer effect of a gemini surfactant with a rigid biphenyl spacer on its self-crystallization at the air/liquid interface

Chen

Yao

et al. 2015

J Appl Cryst

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A gemini surfactant with a biphenyl spacer can spontaneously generate crystals at the air/solution interface. X-ray crystallography reveals that surfactant molecules exhibit an almost fully extended conformation with interdigitating alkyl chains, together with an approximate co-planarity of two C-C-C planes in two alkyl chains of one gemini molecule, and a prominent dihedral angle between the benzene rings and C-C-C planes of the alkyl chains. Infrared reflection-absorption spectroscopy shows that the gemini surfactant was stretched at the air/water interface, with the hydrocarbon chains oriented at a tilt angle of $75 with respect to the surface normal. In particular, the biphenyl group is more or less perpendicular to the water surface, and the C-C-C plane of the alkyl chain tends to be parallel to the water surface. Both results point out a remarkable similarity in the molecular conformation between the crystal and the monolayer. Meanwhile, dynamic light scattering and transmission electron microscopy results indicate that the crystallization of such gemini surfactants at the interface is contrary to the crystallization behavior in the bulk phase, meaning that the surfactant solution can only form a supersaturated solution as it is cooled, though the crystallization temperature of 296 K is lower than the Krafft temperature ($303 K). Therefore, our findings indicate that the Gibbs monolayer of the gemini surfactant plays a critical role in its interfacial crystallization. Additionally, multiple weak intermolecular interactions, involving van der Waals interaction,stacking and cationic-interactions, as well as the hydrophobic effect during the aggregation of the gemini molecule in solution, are responsible for the formation of the interfacial crystal.

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Section: Introductionmentioning

confidence: 99%

Monolayer effect of a gemini surfactant with a rigid biphenyl spacer on its self-crystallization at the air/liquid interface

Chen

Yao

et al. 2015

J Appl Cryst

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“…Subsequently, when the reaction was initiated with Ag + ions, or mixtures of I 2 /KI were inserted into the aqueous solution, it occurred preferentially between molecules of the same handedness along the translation a-axis (Figure 8.2d,e), to yield isotactic diastereoisomers. The racemic composition of the isotactic peptides could be desymmetrized by addition of the corresponding enantiopure ethyl esters, as these esters form 2-D quasi-racemates with the thioesters by being incorporated within the rows of thioesters of the same handedness [31]. The results of these studies showed that the esters operate not only as efficient initiators but also as chain terminators of the peptides of opposite absolute configuration.…”

Section: Isotactic Oligomers Generated Within Monolayers At the Air-wmentioning

confidence: 65%

“…The results of these studies showed that the esters operate not only as efficient initiators but also as chain terminators of the peptides of opposite absolute configuration. This yields shorter chains with a different composition, in contrast to the isotactic chains, which grow unperturbed [31].…”

Section: Isotactic Oligomers Generated Within Monolayers At the Air-wmentioning

confidence: 99%

“Absolute” Asymmetric Polymerization within Crystalline Architectures: Relevance to the Origin of Homochirality

Weissbuch

Lahav

2012

Materials Science and Technology

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The emergence of the homochiral proteins and nucleic acids, composed from residues of L-amino acids and D-sugars respectively, from the achiral prebiotic world still provides an unsolved conundrum in the field of the origin of life. This mist results from the fundamental symmetry rules as defined, at the end of the nineteenth century, by the Curie principle [1], which states that, '' . . . a physical event cannot have a symmetry lower than that of the event that caused it.''There are two classes of asymmetric transformation, which are in keeping with this symmetry rule. In the first class, chiral reactants are converted, via chemical reactions, into chiral products; in the second class, ''mirror-symmetry'' can be broken spontaneously in either a single or a small number of chemical reactions. In a large number of related independent events, however, the system will preserve its initial nonchiral symmetry. Such class of stochastic asymmetric transformations might have been relevant to chiro-biogenesis, provided the scenario can be accepted that life started in a small number of locations, and that the handedness generated by chance has been amplified and propagated during a competition with heterochiral architectures, such that one of the homochiral architectures has tripped and the other has won the rivalry [2][3][4][5].In this chapter, the second class of stochastic asymmetric synthesis of polymers -referred to as ''absolute'' asymmetric synthesis -and which has been materialized in laboratory experiments, is described. Several successful systems of ''mirror-symmetry breaking'' have been shown to comprise the following steps: spontaneous self-assembly of molecules into crystalline-like supramolecular architectures that create a local homochiral molecular environment exerting asymmetric induction in the ensuing propagation of the polymerization reaction. Farina [6] coined the term ''through-space'' asymmetric transformations in order to distinguish them from the common ''through-bond'' reactions.Here, attention is confined especially to the asymmetric transformations of achiral monomers within crystalline or quasi-crystalline architectures. In particular, the early studies of asymmetric polymerizations performed within enantiomorphous

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“…Advanced analyses of surface monolayers with high sensitivity techniques such as polarized infrared reflection-adsorption spectroscopy [50] and Brewster angle microscopy combined with GIXD technique [51] will assist the progress of this research field especially if combined with theoretical approaches based on computational modeling and energy calculations [52,53]. Several possible outcomes other than the often proposed sensor uses must be given serious consideration, while purposes related to nonlinear optics [54] and surface reactions [55,56] have already been reported for chiral monolayers. However, an important goal for subsequent research is chiral recognition involving the unique characteristics of the air-water interface.…”

Section: Resultsmentioning

confidence: 99%

Chiral recognition at the air–water interface

Ariga

Michinobu

Nakanishi

et al. 2008

Current Opinion in Colloid & Interface Science

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Homochiral oligopeptides generated via an asymmetric induction in racemic 2D crystallites at the air–water interface; the system ethyl/thio-ethyl esters of long-chain amphiphilic α-amino acids

Cited by 13 publications

References 13 publications

Monolayer effect of a gemini surfactant with a rigid biphenyl spacer on its self-crystallization at the air/liquid interface

Monolayer effect of a gemini surfactant with a rigid biphenyl spacer on its self-crystallization at the air/liquid interface

“Absolute” Asymmetric Polymerization within Crystalline Architectures: Relevance to the Origin of Homochirality

Chiral recognition at the air–water interface

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