Exploring molecular recognition pathways within a family of gelators with different hydrogen bonding motifs

Hardy, John G.; Hirst, Andrew R.; Ashworth, Ian W.; Brennan, Colin; Smith, David K.

doi:10.1016/j.tet.2007.03.120

Cited by 56 publications

(38 citation statements)

References 61 publications

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“…The smaller fibres associated with C6R will constitute a network with a larger number of contact points and greater degree of entanglement, supportive of the higher T gel value. 18 Crucially, the different morphologies, must result from differing amine chirality leading to diastereomeric complexes with differing assembly modes.…”

Section: Gelation With Different Enantiomersmentioning

confidence: 99%

Enantioselective Component Selection in Multicomponent Supramolecular Gels

2014

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ABSTRACT:We investigate a two-component acid-amine gelation system in which chirality plays a vital role. A carboxylic acid based on a second generation L-lysine dendron interacts with chiral amines and subsequently assembles into supramolecular gel fibers. The chirality of the amine controls the assembly of the resulting diastereomeric complexes, even if this chirality is relatively 'poor quality'. Importantly, the selective incorporation of one enantiomer of an amine over the other into the gel network has been demonstrated, with the R amine that forms complexes which assemble into the most stable gel being primarily selected for incorporation. Thermodynamic control has been proven by forming a gel exclusively with an S amine, then allowing the R enantiomer to diffuse through the gel network, displacing it from the solid-like fibers, demonstrating these gels adapt and evolve in response to chemical stimuli to which they are exposed. Excess amine, which remains unincorporated within the 'solid-like' gel fiber network, can diffuse out and be reacted with an isocyanate, allowing us to quantify the enantioselectivity of component selection, but also demonstrating how gels can act as selective reservoirs of potential reagents, releasing them on demand to undergo further reactions -hence component-selective gel assembly can be coupled with controlled reactivity.

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Section: Gelation With Different Enantiomersmentioning

confidence: 99%

Enantioselective Component Selection in Multicomponent Supramolecular Gels

2014

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“…In contrast, gels with 1 , 2 , or 3 as gelators, having been stored for 2 months in sealed bottles, at room temperature, resulted in phase separation. This is not a surprising result considering that 1, 2, or 3 must have reacted with the base (the solvent), and resulted in the formation of new gelators [47][48][49], being dicholesterol-based gelators, in which two cholesteryl moieties are connected by the organic diamines (cf. Scheme 2).…”

Section: Gelation Behaviors Of the Compoundsmentioning

confidence: 99%

Supramolecular gels based on organic diacid monoamides of cholesteryl glycinate

Liu

Yan

Peng

et al. 2008

Journal of Colloid and Interface Science

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“…We designed a polymerizable L-lysine-based gelator 1 (Figure 1) in order to obtain thermally stable LC gels through covalently cross-linking after the formation of the fibrous networks. Two acrylate groups are introduced into the extremity of the alkyl chains of L-lysine-based bisurea gelator 3 [19][20] (Figure 1). Photopolymerization of selfassembled fibers is an effective method to produce stable gels.…”

Section: Resultsmentioning

confidence: 99%

“…We focused on the lysine scaffold to design hydrogen-bonded gelators. [17][18][19][20] In our previous study, it was found that the lysinebased gelators can be used for light-scattering electrooptical materials exhibiting high contrast, low driving voltage and fast response times. 6 Therefore, the introduction of polymerizable groups into the lysinebased gelators is expected to produce efficient and stable lightscattering nematic LC gels.…”

Section: Introductionmentioning

confidence: 99%

Liquid-crystalline gels exhibiting electrooptical light scattering properties: fibrous polymerized network of a lysine-based gelator having acrylate moieties

Eimura

Yoshio

Shoji

et al. 2012

Polym J

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New liquid-crystalline (LC) gels composed of a lysine-based bisurea derivative having terminal acrylate moieties and a nematic liquid crystal, 4-cyano-4 0 -pentylbiphenyl, have been prepared to develop light-scattering electrooptical materials. Randomly dispersed networks of the polymerizable fibers are obtained by self-assembly of the lysine derivative through the formation of hydrogen bonds in the isotropic phase of the nematic LC molecule. After the isotropic-nematic transition of the LC molecule occurs at 35 1C on cooling, light-scattering nematic LC gels are formed because of the formation of microphase-separated structures of fibrous solids and the liquid crystal. The fibrous structures are fixed by photopolymerization, leading to the enhancement of thermal stability. The polymerized LC gels exhibit electrooptical switching between light-scattering and transparent states with lower driving voltages than the non-polymerized LC gels. The threshold voltages of the LC gels based on the polymerizable lysine gelator are also lower than those of the LC gels containing a non-polymerizable lysine gelator. Polymer Journal (2012) 44, 594-599; doi:10.1038/pj.2012.21; published online 21 March 2012Keywords: electrooptical properties; gel; gelator; hydrogen bond; liquid crystal; photopolymerization; self-assembly INTRODUCTION Liquid crystals have been widely used as electrooptical materials because their molecular alignment can be controlled by external electric fields. 1 Their electrooptical switching properties can be tuned by the incorporation of self-assembled fibers, 2-10 organic and inorganic particles, 11,12 and dendrimers 13 into liquid crystals as well as the encapsulation or phase separation of liquid crystals in polymer matrices. 14-16 Liquid-crystalline (LC) physical gels are formed by fibrous self-assembly of small amounts of gelators (0.2-5.0 wt%) in liquid crystals. [2][3][4][5][6][7][8][9][10] In these materials, the liquid crystals and the fibrous aggregates of the gelators form microphase-separated structures. The efficient electrooptical switching and the induction of light-scattering electrooptical effects of nematic liquid crystals were achieved by the formation of finely dispersed fibers of gelators in liquid crystals. [5][6][7][8][9] The electrooptical properties of the LC physical gels were examined for twisted nematic 5,6 and light-scattering modes. 7 To enhance thermal stability of the anisotropic gels, a new type of light-scattering LC gel has been developed by self-assembly of an L-valine-based gelator having methacryloyl moieties and a room temperature nematic liquid crystal. 10 The gelator formed randomly aligned fibrous aggregates through the formation of intermolecular hydrogen bonds in the isotropic phase of LC molecules. Photopolymerization of the gelator forming the self-assembled

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Exploring molecular recognition pathways within a family of gelators with different hydrogen bonding motifs

Cited by 56 publications

References 61 publications

Enantioselective Component Selection in Multicomponent Supramolecular Gels

Enantioselective Component Selection in Multicomponent Supramolecular Gels

Supramolecular gels based on organic diacid monoamides of cholesteryl glycinate

Liquid-crystalline gels exhibiting electrooptical light scattering properties: fibrous polymerized network of a lysine-based gelator having acrylate moieties

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