Supramolecular gel chemistry: developments over the last decade

Steed, Jonathan W.

doi:10.1039/c0cc03293j

Cited by 590 publications

(337 citation statements)

References 68 publications

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“…[1][2][3] These gels adopt a number of nanoscopic morphologies including fibrous, helical, ribbon-like, tubular, lamellar and vesicular structures. [4][5][6] As well as finding applications in their own right 3,7,8 such frameworks have been used as scaffolds to template the formation of rigid, nanostructured 25 materials.…”

Section: Introductionmentioning

confidence: 99%

Using gel morphology to control pore shape

et al. 2014

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'Using gel morphology to control pore shape.', New journal of chemistry., 38 (3). pp. 927-932. Further information on publisher's website:http://dx.doi.org/10.1039/c3nj01295fPublisher's copyright statement: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. concentrations are compared. Small changes in the molecular structure of the gelator can therefore be used to produce polymeric materials with very different pore shapes, sizes and adsorption characteristics.

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Section: Introductionmentioning

confidence: 99%

Using gel morphology to control pore shape

et al. 2014

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“…[1][2][3][4][5] These gels are formed by noncovalent interactions to assemble supramolecular networks that trap solvent. 6 Among the various types of supramolecular gels, those crosslinked by metal coordination are particular interesting.…”

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Self-healing metal-coordinated hydrogels using nucleotide ligands

et al. 2015

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A supramolecular gel formed by Zn 2+ coordination with adenosine monophosphate (AMP) is reported. The adenine base, the monophosphate, and Zn 2+ are all important for gel formation. Mechanically disrupted gels can re-form upon centrifugation; applications of this gel for guest molecule entrapment are explored.Supramolecular gels have received considerable attention in recent years both as intriguing examples of self-assembly and as a means of creating smart materials.1-5 These gels are formed by noncovalent interactions to assemble supramolecular networks that trap solvent. 6Among the various types of supramolecular gels, those crosslinked by metal coordination are particular interesting. A few types of ligands have been developed for this purpose. For example, Craig and coworkers reported organopalladium−pyridine coordination. 16,17 Self-healing is a very interesting and useful feature of metal-coordinated gels; broken gel pieces can seal together with a mild mechanical force.Most of previously reported gels have to use specially designed ligands (e.g. incorporating a segment of PEG chain in addition to the metal ligand) to facilitate solvent trapping and gelation. Few reports are based on pure small molecule ligands. We reason that small molecule ligands will allow a higher metal density and thus may display different properties.Adenine, a purine nucleobase, is an important ligand in supramolecular chemistry. Adenine and its derivatives can form many complexes by coordination (with metal ions) and hydrogen bonding (with organic molecules). [18][19][20] With metal ions, it may form metalorganic frameworks, 21 and nanoparticles. [22][23][24][25] Recently, the gelation of adenine with tricarboxylic acid compounds was reported based on hydrogen bonding and π-π stacking. 26,27 We are interested in exploring whether it is possible to achieve gelation by metal coordination with adenine derivatives. Guanine and its derivatives have been mixed with monovalent metal ions to form gels based on quadruplex formation. 28-31 However, little has been done on adenine derivatives. Nanoparticles are the most common products. [22][23][24][25] Compared to nanoparticles, hydrogels are more attractive materials for making stimuli-responsible materials. [32][33][34][35][36][37][38][39] In this work, we communicate such an example, its property in guest molecule encapsulation, and healing.Since most previous work focused on adenine nucleobase and nucleoside as ligands, we started with nucleotide coordination in this work. Zn 2+ was chosen as the metal because it is a good Lewis acid that can be coordinated by a diverse range of ligands. In addition, it is a relatively biocompatible metal with low toxicity. We first studied the reaction between Zn 2+ and three kinds of nucleotides (AMP, GMP and CMP). TMP was not included since thymine has very weak coordination ability at neutral pH. Zn 2+ was respectively titrated into the solutions of AMP, GMP and CMP, and the UV-vis extinction at 550 nm was recorded. Since none of the products are c...

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“…A long wavelength negative to short wavelength positive component indicates a left-handed and vice versa for right-handed assemblies. 1 The indication of the close association of naphthalene groups into chiral assemblies is further indicated by the hypochromic shifting of the naphthalene absorbance maxima. Absorbance maxima may be derived from HT[V] data collected by CD measurements as shown in Figure S3.…”

Section: Supplementary Informationmentioning

confidence: 99%

Structural determinants in a library of low molecular weight gelators

et al. 2015

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ARTICLELow molecular weight hydrogels are formed by molecules that form a matrix that immobilises water to form a self-supporting gel. Such gels have uses as biomaterials such as molecular scaffolds and structures for tissue engineering. One class of low molecular weight gelators (LMWG), naphthalene-conjugated dipeptides, has been shown to form hydrogels via selfassembly following a controlled drop in pH. A library of naphthalene-dipeptides has been generated previously although the relationship between the precursor sequence and the resulting self-assembled structures remained unclear. Here, we have investigated the structural details of a set of dipeptide sequences containing alanine (A) and valine (V) conjugated to naphthalene groups substituted with a Br, CN or H at the 6-position. Electron microscopy, circular dichroism and X-ray fibre diffraction shows that these LMWG may be structurally classified by their composition: the molecular packing is determined by the class of conjugate, whilst the chirality of the self-assemblies can be attributed to the dipeptide sequence. This provides insights into the relationship between the precursor sequence and the macromolecular and molecular structures of the fibres that make up the resulting hydrogels. IntroductionThe formation of hydrogels from low molecular weight gelators (LMWG) is a useful route to the production of materials for a wide range of applications. 1, 2 A recent expansion in the number of LMWG systems reported has led to a rapid growth in reports of characterisation and applications of a particular class of this type of molecule, namely aromatic conjugated dipeptide LMWG. 3-8 These systems typically consist of a hydrophobic, often aromatic, dipeptide sequences conjugated to Fmoc (9-fluorenylmethoxycarbonyl) 9, 10 or naphthalene 3, 4 ; further conjugations have also been reported. 11,12 Through the use of an environmental cue, 13 such as an enzymatic trigger, 14 temperature, 15,16 or light 12 some of these conjugates selfassemble into anisotropic fibrils that can eventually cause hydrogelation through the immobilisation of water by the fibrillar network. There are now a large number of systems reported in the literature. 17 It is apparent from previous work that two LMWG molecules that differ only by a single amino acid can give rise to hydrogels with dramatically different rheological and phase properties. 3,4,10,18 However, the structural basis for these differences in material properties is not understood.The short-range molecular architecture of some LMWG systems has been studied. For example, the chirality of assembled naphthalene conjugated dipeptides has been reported to correlate to the D-or L-enantiomer of the incorporated amino acids with left-and right-handed assemblies being formed respectively. 3 Other reports have indicated that proteinaceous additives induce changes to the chiral organisation of the self-assembled hydrogelating molecules. 19 In addition to the plethora of molecular hydrogels with varying material properties available, the...

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Supramolecular gel chemistry: developments over the last decade

Cited by 590 publications

References 68 publications

Using gel morphology to control pore shape

Using gel morphology to control pore shape

Self-healing metal-coordinated hydrogels using nucleotide ligands

Structural determinants in a library of low molecular weight gelators

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