Pyrene‐Based Fluorescent Supramolecular Hydrogel: Scaffold for Energy Transfer

Abstract

The self-assembled gelation of an amino-acid-based low molecular weight gelator having a pyrene moiety at the N terminus and a bis-ethyleneoxy unit linked with succinic acid at the C terminus is reported. This amphiphile is capable of gelating binary mixtures (1/3 v/v) of CH3CN/water, DMSO/water, and DMF/water, and the minimum gelation concentration (MGC) varied from 0.2 to 0.3% w/v. The sodium salt of the amphiphile efficiently gelates water with an MGC of 1.5% w/v. The participation of different noncovalent interactions in supramolecular gelation by formation of fibrillar networks was investigated by spectroscopic and microscopic methods. High mechanical strength of the supramolecular gels is indicated by storage moduli on the order of 10(3) Pa. The hydrogel was utilized for energy transfer, whereby inclusion of only 0.00075% w/v of acridine orange resulted in about 50% quenching of the fluorescence intensity of the gel through fluorescence resonance energy transfer.

Hydrogelation Induced by Change in Hydrophobicity of Amino Acid Side Chain in Fmoc‐Functionalised Amino Acid: Significance of Sulfur on Hydrogelation

“…Despite the decrease in pH, neither Boc‐M nor Cbz‐M formed a gel under similar conditions, indicating the significance of the Fmoc‐moiety in Fmoc‐M gelation. Although the Fmoc‐moiety is required, based on various reports on LMW amino acid and dipeptide based gelators, it is proposed that other large aromatic moieties such as pyrene and naphthalene may induce hydrogelation when they are functionalised with methionine.…”

“…In recent years, numerous LMW gelators, especially based on functionalised amino acids and smaller peptides, have been designed or identified as potential hydrogelators to construct soft materials with promising properties. In general, the amino terminal of amino acids and the N‐terminus of smaller peptides have been functionalised with different aromatic moieties, including fluorenylmethoxycarbonyl (Fmoc‐), naphthalene, perylenes, azobenzene, and pyrene . Among these functionalities, Fmoc‐ has been used broadly to construct hydrogels because of its common use in peptide synthesis and because of the ease with which it can be attached to amino acids and peptides.…”

Internal Probing of the Supramolecular Organization of Pyrene‐Based Organogelators

“…With regard to pyrene, only few examples have been reported in the recent literature. [12][13][14] We describe herein the synthesis and un-results show that despite its relatively high meltingp oint (229-231 8C) and poor solubility,a nd hence strong intermolecular interactions, compound 1 forms gels in chlorinateds olvents whatever their boiling points. Scanning electron microscopy (SEM) also confirmed the tendency of compound 1 to form self-assembled nanofibers, as illustrated in Figure S1 in the Supporting Information, where networks of intertwined fibers can be observed after evaporation of the solvent.…”

Supramolecular hydrogels: synthesis, properties and their biomedical applications

“…[67][68][69][70] Most striking is the fact that the light-emitting properties (e.g., wavelength, intensity) of these supramolecular hydrogels can be readily tuned by either applying a suitable external stimulus or altering the internal composition. [67][68][69][70] Most striking is the fact that the light-emitting properties (e.g., wavelength, intensity) of these supramolecular hydrogels can be readily tuned by either applying a suitable external stimulus or altering the internal composition.…”