Donor−Acceptor-Promoted Gelation of Polyaromatic Compounds

Abstract

Low molecular mass organogels are nonconventional polymeric structures in which a minute amount of low molecular weight compound can reversibly gelify the whole solution without forming covalent bonds between the monomers. In this article, we demonstrate that certain electron acceptors (taking dinitrobenzoates as model compounds) that are incapable of gelifying the solvent on their own can assemble as much as a 15-16-fold larger amount of polyaromatic hydrocarbons (PAHs) and form two-component donor-acceptor organogels in different solvents. At the core of the long-range order stand donor-acceptor pairs. We assess our claims by detailed 1H NMR, spectrophotometry, fluorescence, and time-resolved fluorescence methods. The thermodynamics of the gelation process is described on the basis of temperature dependent 1H NMR studies. We believe that, in this case, 1H NMR provides direct quantification of the dissolved concentrations of the different species and therefore provides a direct way to measure the enthalpy, entropy, and free energy associated with gel formation.

Charge-transfer interaction mediated organogels from 18β-glycyrrhetinic acid appended pyrene

“…Based on the T gel values at different concentrations, the thermodynamic parameters, i.e. Δ H °, Δ S °, and Δ G ° at 298 K in different solvents were calculated and are summarized in Table 2 (for the calculated details see Supporting Information File 1) [51]. The order of Δ G ° values in different solvents was in accordance with that of their T gel , and the CT complex of 3 and 4 had the stronger gelation ability in ethylene glycol than in the other solvents.…”

Supramolecular Assemblies by Charge‐Transfer Interactions between Donor and Acceptor Chromophores

“…Subsequently more reports have appeared on the gelation of different D-A pairs and describe the relationship between gelation properties and the molecular structure of the building blocks, nature of the solvent, and the D/A stoichiometry. [71][72][73][74] While these examples deal with gelation by only CT interactions, there is a significant interest in additionally using other supramolecular forces, such as hydrogen bonding, for formation of fibrillar two-component assemblies. TTF and its derivatives [75][76][77] are well-known donors with electroactive properties.…”

Evolution of Vesicular Self‐Assemblies of the Salts of a Natural Triterpenoid Arjunolic Acid into Superstructured Ambidextrous Gels and Study of Their Entrapment Properties

“…The free energy changes during gel to sol transition of compound 1 in water and n‐ octanol were also identical (Table S1). The positive free energy changes ( ΔG o values) obtained in all the cases studied during gel to sol transition indicated the stability of the gels …”

“…The positive free energy changes (DG o values) obtained in all the cases studied during gel to sol transition indicated the stability of the gels. [34] Morphological characterisation of the self-assemblies…”