Self‐Assembly of Two‐Component Gels: Stoichiometric Control and Component Selection

Hirst, Andrew R.; Miravet, Juan F.; Escuder, Beatriu; Noirez, Laurence; Castelletto, Valeria; Hamley, Ian W.; Smith, David K.

doi:10.1002/chem.200801475

Cited by 98 publications

(49 citation statements)

References 88 publications

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“…4,18,19 NMR peaks were observed for mobile components, whereas anything immobilized, for example within the gel fibers, would be broadened into the baseline. We used variable temperature (VT) NMR to examine the role of heat in the response of 2 in the presence of gelator 1.…”

Section: Notesmentioning

confidence: 99%

Control of Luminescence Properties in Naphthalene Diimide-Based Gel with Azodibenzoic Acid by Charge Transfer Interaction

Lee¹,

Park²,

Jung

2014

Bulletin of the Korean Chemical Society

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In recent years, the self-assembly of various organic π-systems, mediated by non-covalent bonding, have been topics of considerable interest.1 These compounds that can undergo gelation hold great promise as building blocks for materials that can be applied in the construction of optoelectronic devices.2,3 The self-sorting between aromatic compounds that can serve as electron donors and electron acceptors allows the formation of distinct p-and n-type bundles of fibers that further intermix and generate multiple junction points for efficient electron transfer and transport of the charge carriers. However, a difficulty associated with simple mixing of such compounds is the possibility of a different mode of assembly, i.e., charge-transfer interaction mediated by alternate donor-acceptor stacking. Thus, examples related to self-sorting among donor-acceptor chromophores have been limited. 4 Recently, Ghosh and colleagues has demonstrated a hydrogen-bonding mediated self-assembly, 5-9 in a mixture of bis-amide-functionalized naphthalene-diimide and dialkoxy-naphthalene, where mutual recognition between similar chromophores took place to maximize the effect of hydrogen-bonding.Naphthalene-diimide derivatives have been extensively explored as building blocks for the generation of various supramolecularly assembled systems in organic-or aqueous media, because of their n-type semiconductivity, propensity for π-stacking and electron-accepting nature.9-12 Examples of such systems include organogels, catenanes, rotaxanes, foldamers, nano-tubes, hydrogels, nanoparticles, supramolecular photosystems and synthetic ion channels. 13-16To date, the literature contains little information regarding the photoluminescence properties of hydrogels, including switching of the emission color, field emission and light emitting properties. 5,9 In view of the high photoluminescence quantum efficiencies of naphthalene diimide derivatives used as fluorescent dyes, 5,17 we expected such compounds to exhibit interesting photoluminescence properties by charge transfer interaction with guest molecules. Herein, we report the formation of a hydrogel of naphthalene-diimide (1) with 4,4'-azodibenzoic acid (2). The luminescence properties were controlled by the addition of 2. Furthermore, the life-times of hydrogels were enhanced by the charge-transfer interactions.The gel based on 1 was prepared by dissolving 1% (by weight) of 1 in water. To this solution a small volume of 2 as an additive in water was added in concentrations varying from 0.2-1.0 equivalents with respect to the gelator 1 concentration. The samples were then left to stand for a week. As shown in Fig. S1, 1 could be gelated in the presence of 0-0.6 equivalent of 2, but 1 could not gelate when the amount of added 2 exceeded 0.7 equivalent. These gels prepared from a mixture of 1 and 2 exhibited a strong emission with a variety of colors under UV irradiation, in which the emission colors were dependent on the concentration of 2.The luminescent spectra of hydrogel 1 with varying concentrat...

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Section: Notesmentioning

confidence: 99%

Control of Luminescence Properties in Naphthalene Diimide-Based Gel with Azodibenzoic Acid by Charge Transfer Interaction

Lee¹,

Park²,

Jung

2014

Bulletin of the Korean Chemical Society

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“…However, the structures observed: ribbons, tubes, and sheets along with other shapes, are formed by noncovalent interactions between the molecules of the various components, which is very similar to a natural motif. [8][9][10][11][12][13][14][15][16][17] Two component systems in particular have been used in the past because of the ease of having different charged ends, geometries, and amphiphilic properties that can interact to form a shape. Using smaller biobased molecules is a rather interesting motif because of a potentially easier synthesis and less complicated assembly.…”

Section: Introductionmentioning

confidence: 99%

Self-Assembling Functionalized Amino Acids into Unusual Shapes

2011

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Multi-component small molecule systems that are amphiphilic or that can hydrogen bond end-toend or side-to-side have been shown to self-assemble into a variety of shapes including fibers, rods, sheets, plates, spheres, and tubes. Recently, we have identified a simple route to selfassemble the same shapes from one-component systems. The structures form by attaching ethyl vinyl sulfone (EVS) to amino acids in water at room temperature. Choice of amino acid, amount of EVS substitution, and solvent conditions determine the final shape. Functionalized amino acids spontaneously form structures like fibers, spheres, tubes, and donuts when dried from solution. Here we focus on fibers and tubes.

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“…Both LG2-Lys and DG2-Lys were prepared by following the synthetic methodology previously reported for these aminoacid derivatives. 7,20 Preparation of the gels. Stock solutions of the G2-Lys dendron and the corresponding amine were prepared.…”

Section: Methodsmentioning

confidence: 99%

“…6 More relevant is the component selection exhibited by multicomponent gels that allows the incorporation and immobilization of certain substances ignoring others that remain in solution. 7 LMWGs are being utilized as crystallization media for different substances. Importantly, the interest of pharmaceutical industry in new and effective ways of drug formulation is currently prompting the use of both conventional or supramolecular gels as media for controlling the crystal growth of different polymorphs of drugs.…”

Section: Introductionmentioning

confidence: 99%

Multi-component supramolecular gels for the controlled crystallization of drugs: synergistic and antagonistic effects

et al. 2015

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The applicability of multi-component gels, based on the combination of Lys-based dendrons and alkyl amines, for the crystallization of common drugs is presented. The results presented herein demonstrate that active pharmaceutical ingredients (APIs) with no carboxylic acid in their structure readily crystallize inside the organogels formed by a second generation lysine-based dendron (G2-Lys) and aliphatic amines. The thermodynamic parameters (Hdiss, Sdiss and Gdiss) of the corresponding three-component mixture (API+G2-Lys dendron + amine) have been calculated by using VT 1 H NMR. Interestingly, the presence of carbamazepine (CBZ) in the mixture of G2-Lys and decylamine allows efficient gelation at room temperature in contrast with the behaviour observed for an unmodified G2-Lys dendron and decylamine mixture that only forms toluene gels at -20ºC a synergistic effect in which the API enhances gelation. On the other hand, aspirin (ASP) or indomethicin (IND), that possess a carboxylic acid in their structure, do not crystallize inside the organogel formed by G2-Lys dendron and the amine indeed they prevent formation of the gel. The Ka values of the complexes G2-Lys···decylamine and IND···decylamine have been calculated by 1 H NMR titrations in toluene-d8. The higher Ka value for the complex IND···decylamine justifies that this pair is thermodynamically favoured thus preventing the formation of the complex between the Lys-based dendron and the amine, which underpins gel fibre assembly, and also preventing effective crystallization of the API an antagonistic effect. Overall, these results demonstrate the active roles played by all components when multi-component gels are used for API crystallisation.

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Self‐Assembly of Two‐Component Gels: Stoichiometric Control and Component Selection

Cited by 98 publications

References 88 publications

Control of Luminescence Properties in Naphthalene Diimide-Based Gel with Azodibenzoic Acid by Charge Transfer Interaction

Control of Luminescence Properties in Naphthalene Diimide-Based Gel with Azodibenzoic Acid by Charge Transfer Interaction

Self-Assembling Functionalized Amino Acids into Unusual Shapes

Multi-component supramolecular gels for the controlled crystallization of drugs: synergistic and antagonistic effects

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