An asparagine/tryptophan organogel showing a selective response towards fluoride anions

Lozano, Virginia; Hernández, Rebeca; Ardá, Ana; Jiménez‐Barbero, Jesús; Mijangos, Carmen; Pérez‐Pérez, María‐Jesús

doi:10.1039/c1jm10505a

Cited by 29 publications

(11 citation statements)

References 49 publications

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“…48,49 In our systems, the presence of the magnetic field during gelation does not significantly affect the surface chemical or mechanical properties of the final hydrogels (ESI, † Section 1.3). STD spectroscopy can be used to study ligand binding to a number of substrates including proteins, 50 gels 29,51 and solid reaction supports. 52 The very broad 1 H resonances of the gel fibres are saturated by a train of selective RF pulses.…”

Section: Classificationmentioning

confidence: 99%

Probing the surface chemistry of self-assembled peptide hydrogels using solution-state NMR spectroscopy

2017

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The surface chemistry of self-assembled hydrogel fibres - their charge, hydrophobicity and ion-binding dynamics - is recognised to play an important role in determining how the gels develop as well as their suitability for different applications. However, to date there are no established methodologies for the study of this surface chemistry. Here, we demonstrate how solution-state NMR spectroscopy can be employed to measure the surface chemical properties of the fibres in a range of hydrogels formed from N-functionalised dipeptides, an effective and versatile class of gelator that has attracted much attention. By studying the interactions with the gel fibres of a diverse range of probe molecules and ions, we can simultaneously study a number of surface chemical properties of the NMR invisible fibres in an essentially non-invasive manner. Our results yield fresh insights into the materials. Most notably, gel fibres assembled using different tiggering methods bear differing amounts of negative charge as a result of a partial deprotonation of the carboxylic acid groups of the gelators. We also demonstrate how chemical shift imaging (CSI) techniques can be applied to follow the formation of hydrogels along chemical gradients. We apply CSI to study the binding of Ca and subsequent gelation of peptide assemblies at alkaline pH. Using metal ion-binding molecules as probes, we are able to detect the presence of bound Ca ions on the surface of the gel fibres. We briefly explore how knowledge of the surface chemical properties of hydrogels could be used to inform their practical application in fields such as drug delivery and environmental remediation.

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Section: Classificationmentioning

confidence: 99%

Probing the surface chemistry of self-assembled peptide hydrogels using solution-state NMR spectroscopy

2017

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“…This approach has been used to characterise a gelation system by irradiating at 100 ppm (''off-resonance'') and -1 ppm (''on-resonance'') in the 1 H NMR spectrum. 90 However, STD signals were seen for all gelator resonances, and also the solvent molecules (in this case, acetonitrile and water), suggesting that the whole structure was involved in gelation, as was the solvent, playing an explicit role in mediating assembly. This approach may, in the future, prove useful for probing molecular recognition processes within complex gel mixtures in more detail.…”

Section: Techniques For the Characterisation Of Molecular Gelsmentioning

confidence: 95%

Techniques for the Characterisation of Molecular Gels

Nebot

Smith

2013

Functional Molecular Gels

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Molecular gels represent a case of hierarchical self-assembly of low molecular weight compounds into well ordered fibrillar architectures through non-covalent interactions. The resulting nanomaterials have found applications in multiple fields. In order to facilitate these applications, detailed study of their self-assembly mechanisms and properties at different length scales is required. The hierarchical nature of these materials means that a wide and multidisciplinary set of techniques have been developed and applied for the fundamental study of molecular gels. Different techniques are optimal for characterising aspects of the gel on each length scale – molecular, nano, microscopic and macroscopic. The present chapter uses selected examples to describe the different techniques that have been applied so far for a complete characterization of these systems. In particular, we focus on spectroscopy for probing molecular assembly, microscopy & diffraction/scattering to probe the nanoscale structuring, and calorimetric & rheological studies to provide insight into macroscopic performance. This chapter also focuses on aspects of gel characterisation such as chirality, kinetics and solvent effects.

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“…Prasad and co‐workers described a nice example of visual‐size fluoride anion detection by using gel obtained from compound 10 based on poly(arylether) dendrons with an anthracene chromophore linked through an acylhydrazone as a spacer unit ( Scheme ) 27b. A robust “instant gel” is readily obtained by stirring the mixture of the poly(arylether) dendrimer derivatives and anthraldehyde (1:1 ratio) in chloroform/methanol mixture for a short time at room temperature.…”

Section: Visual‐size Molecular Recognition Based On Molecular Gelsmentioning

confidence: 99%

“…); after: c) 1 min; d) 3 min; e) 5 min; f) 7 min; g) 9 min; h) 10 min; and, i) after subsequent addition of 0.2 mL of water. Reproduced with permission 27b. Copyright 2011 American Chemical Society.…”

Section: Visual‐size Molecular Recognition Based On Molecular Gelsmentioning

confidence: 99%

Visual‐Size Molecular Recognition Based on Gels

2013

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Since their discovery, stimuli-responsive organogels have garnered considerable and increasing attention from a broad range of research fields. In consideration of an one-dimensional ordered relay in anisotropic phase, the assembled gel networks can amplify various properties of the functional moieties possessed by the gelator molecules. Recently, substantial efforts have been focused on the development of facile, straightforward, and low-cost molecular recognition approaches by using nanostructured gel matrices as visual sensing platforms. In this research news, the recent progresses in macroscopic or visual-size molecular recognition for a number of homologues, isomers, and anions, as well as extremely challenging chiral enantiomers, using polymer and molecular gels are reviewed. Several strategies--including guest molecular competition, hydrogen-bonding blocking, and metal-coordination--for visual discrimination are included. Finally, the future trends and potential application in facile visual-size molecular recognition based on organogel matrices are highlighted.

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An asparagine/tryptophan organogel showing a selective response towards fluoride anions

Cited by 29 publications

References 49 publications

Probing the surface chemistry of self-assembled peptide hydrogels using solution-state NMR spectroscopy

Probing the surface chemistry of self-assembled peptide hydrogels using solution-state NMR spectroscopy

Techniques for the Characterisation of Molecular Gels

Visual‐Size Molecular Recognition Based on Gels

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