Halogen effects on the solid-state packing of phenylalanine derivatives and the resultant gelation properties

Ramalhete, Susana M.; Foster, Jamie S.; Green, Hayley R.; Nartowski, Karol P.; Heinrich, Margaux; Martin, Peter C; Khimyak, Yaroslav Z.; Lloyd, Gareth O.

doi:10.1039/c7fd00108h

Cited by 10 publications

(11 citation statements)

References 49 publications

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“…On the other hand, the gelation ability is also highly influenced by properties such as solubility and polarity [ 16 , 17 , 18 ]. Slight variations on the polarity of the gelator may either improve or reduce its gelling ability depending on the solvent used for the process [ 14 , 19 , 20 ]. Several works reported the influence of fluorine on the physical properties and self-assembly ability of different types of compounds [ 21 , 22 , 23 , 24 ].…”

Section: Introductionmentioning

confidence: 99%

Fluorine Effect in the Gelation Ability of Low Molecular Weight Gelators

Ravarino

Domenico

Barbalinardo

et al. 2022

Gels

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The three gelators presented in this work (Boc-D-Phe-L-Oxd-OH F0, Boc-D-F1Phe-L-Oxd-OH F1 and Boc-D-F2Phe-L-Oxd-OH F2) share the same scaffold and differ in the number of fluorine atoms linked to the aromatic ring of phenylalanine. They have been applied to the preparation of gels in 0.5% or 1.0% w/v concentration, using three methodologies: solvent switch, pH change and calcium ions addition. The general trend is an increased tendency to form structured materials from F0 to F1 and F2. This property ends up in the formation of stronger materials when fluorine atoms are present. Some samples, generally formed by F1 or F2 in 0.5% w/v concentration, show high transparency but low mechanical properties. Two gels, both containing fluorine atoms, show increased stiffness coupled with high transparency. The biocompatibility of the gelators was assessed exposing them to fibroblast cells and demonstrated that F1 and F2 are not toxic to cells even in high concentration, while F0 is not toxic to cells only in a low concentration. In conclusion, the presence of even only one fluorine atom improves all the gelators properties: the gelation ability of the compound, the rheological properties and the transparency of the final materials and the gelator biocompatibility.

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Section: Introductionmentioning

confidence: 99%

Fluorine Effect in the Gelation Ability of Low Molecular Weight Gelators

Ravarino

Domenico

Barbalinardo

et al. 2022

Gels

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“…It has been reported that a mixture of MA and ADPE can be applied as a low molecular weight gelator for less polar solvents, such as 1,2-dichloroethane . The electron-withdrawing halogen atom may further enhance the gelation ability. − Higher selectivity for the ( S )-salt was observed when crystallized from dioxane or acetone and the efficiency increased to 0.83 (entries 6–7). On the other hand, the ( R )-salt was preferentially obtained via crystallization from water (entry 1) although the efficiency was not high.…”

Section: Resultsmentioning

confidence: 99%

Solvent-Induced Chirality Switching in the Enantioseparation of Halogen-Substituted Mandelic Acids: Structural Effects on Molecular Packing

Kawasaki

Meng

Tsukamoto

et al. 2019

Crystal Growth & Design

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The solvent effect on the enantioseparation of halogen-substituted mandelic acid derivatives via diastereomeric salt formation has been investigated. The diastereomeric salts of para-halogen-substituted mandelic acid derivatives (p-X-MA) were obtained with high efficiency. In addition, both diastereomeric salts of p-F-MA were successfully obtained by controlling the concentration of the acetone solution. Efficient solvent-induced chirality switching was generally observed for meta-halogen-substituted mandelic acid derivatives (m-X-MA). Water, aprotic solvents, and short-chain alcohols such as i-PrOH gave the (S)-salt, whereas the (R)-salt is preferentially formed from long-chain alcohols such as n-BuOH and s-BuOH. Crystallographic analysis of the salts showed that the inclusion of the alcohol solvent in the diastereomeric salts changed the hydrogen-bonding network and molecular packing. The molecular packing was dependent on the size of the halogen substituents and the solvent used. Finally, this technique has been successfully applied to the preparation of both pure enantiomers of m-Cl-MA.

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“…The latter was expected to bring a supplementary possibility of π–π stacking interactions 46 . In order to evaluate the existence, the extent and the influence of potential π–π stacking interactions, two lysine derivatives were synthesized which differed by the presence of one chlorine atom substituting the ortho position of the aromatic ring (in compound 7 ) 47–50 . The carboxylic acid group was left unmodified so as to contribute to the ability to establish hydrogen bonds and keep water solubility high enough.…”

Section: Resultsmentioning

confidence: 99%

Rheological investigation of supramolecular physical gels in water/dimethylsulfoxide mixtures by lysine derivatives

Euzcateguy

Parajua‐Sejil

Marchal

et al. 2021

Polymer International

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Two derivatives of lysine were synthesized by acylating the Nα with dodecanoic acid starting from commercial precursors in which the Nε was already acylated by the benzoyloxycarbonyl or o‐chloro‐benzoyloxycarbonyl group. Both derivatives self‐assembled in dimethylsulfoxide/water mixtures (above 40% v/v water) leading to solid‐like formulations. The rheological properties were studied as a function of gelator concentration and solvent composition. From stress sweep experiments it was assumed that the gels consisted of jammed suspensions of mesoscopic clusters formed by self‐assembly processes similar to those at the origin of crystallization. The temporal variation of storage and loss moduli was monitored immediately after mixing over times between 20 and 120 min using isothermal oscillatory rheological experiments. Experimental curves were satisfactorily depicted using previously reported semi‐empirical equations. Both transient evolution and stationary values were consistent with the representation of gels as resulting from the formation, one‐dimensional growth and dynamic arrest of fractal clusters (with fractal dimension between 1.6 and 2.0). The presence of a chlorine atom within the aromatic ring of one of the lysine derivatives induced a significant increase of the gelation time scale and a decrease of rheological moduli. © 2021 Society of Chemical Industry

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Halogen effects on the solid-state packing of phenylalanine derivatives and the resultant gelation properties

Cited by 10 publications

References 49 publications

Fluorine Effect in the Gelation Ability of Low Molecular Weight Gelators

Fluorine Effect in the Gelation Ability of Low Molecular Weight Gelators

Solvent-Induced Chirality Switching in the Enantioseparation of Halogen-Substituted Mandelic Acids: Structural Effects on Molecular Packing

Rheological investigation of supramolecular physical gels in water/dimethylsulfoxide mixtures by lysine derivatives

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