Supramolecular Polymerization of C3‐Symmetric Organogelators: Cooperativity, Solvent, and Gelation Relationship. Issue 9 (23rd January 2013)

• Record Type: Journal Article
• Authors: Aparicio, Fátima; García, Fátima; Sánchez, Luis
• Is Part Of: Chemistry. Volume 19:Issue 9(2013)
• Page Start: 3239
• Page End: 3248
• Publication Date: 2013-01-23
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201202584
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>A systematic study of the influence of solvent and the size of <italic>C</italic><sub>3</sub>‐symmetric discotics on their supramolecular polymerization mechanism is presented. The cooperativity of the self‐assembly of the reported compounds is directly related to their gelation ability. The two series of <italic>C</italic><sub>3</sub>‐symmetric discotics investigated herein are based on benzene‐1, 3, 5‐tricarboxamides (BTAs) and oligo(phenylene ethynylene)‐based tricarboxamides (OPETAs) that are peripherally decorated with achiral (<bold>1 a</bold> and <bold>2 a</bold>) or chiral <italic>N</italic>‐(2‐aminoethyl)‐3, 4, 5‐trialkoxybenzamide units (<bold>1 b</bold> and <bold>2 b</bold>). The supramolecular polymerization of compounds <bold>1 a</bold>, <bold>b</bold> and <bold>2 a</bold>, <bold>b</bold> has been exhaustively investigated in a number of solvents and by using various techniques: variable‐temperature circular dichroism (VT‐CD) spectroscopy, concentration‐dependent <sup>1</sup>H NMR spectroscopy, and isothermal titration calorimetry (ITC). The supramolecular polymerization mechanism of compounds <bold>2</bold> is highly cooperative in solvents such as methylcyclohexane and toluene and is isodesmic in CHCl<sub>3</sub>. Unexpectedly, chiral compound <bold>1 b</bold> is practically CD‐silent, in contrast with previously reported BTAs. ITC measurements in CHCl<sub>3</sub> demonstrated that the supramolecular polymerization of BTA <bold>1 a</bold> is isodesmic. These results confirm the strong influence of the π‐surface of the central aromatic core of the studied discotic and the branched nature of the peripheral side chains on the supramolecular polymerization. The gelation ability of these organogelators is negated in CHCl<sub>3</sub>, in which the supramolecular polymerization mechanism is isodesmic.</p> </abstract>