Probing the Limits of the Majority-Rules Principle in a Dynamic Supramolecular Polymer

Abstract

By systematic variation of the chemical structure of benzene-1,3,5-tricarboxamide (BTA) derivatives, the effect of chemical structure on the amplification of chirality was studied and quantified. In combination with temperature-dependent amplification experiments, the limits of the majority-rules principle were also investigated. For all BTA derivatives a high, constant helix reversal penalty was determined, which is related to the intermolecular hydrogen bonds that are present in all studied derivatives. For asymmetrically substituted BTA derivatives an odd-even effect was found in the degree of chiral amplification when changing the position of the stereogenic center with respect to the amide functionality. It was found that the mismatch penalty could be directly related to the number of stereocenters present in the molecules. Increasing this number from one to three resulted in an increase in this energy penalty while leaving the helix reversal penalty unaffected. For the majority-rules principle this implies that a single stereocenter present in the molecule contains sufficient chiral information at the molecular level to result in a chirally amplified state at the supramolecular level. Further evidence that the mismatch penalty is directly related to the number of stereocenters was obtained from mixed majority-rules experiments where two BTA derivatives with different numbers of stereocenters with opposite stereoconfiguration were studied in a majority-rules experiment. Finally, the ultimate limits of chiral amplification for the majority-rules principle were investigated, revealing that, given a certain helix reversal penalty, there is an optimum to which the mismatch penalty can be reduced while also enhancing the degree of chiral amplification. Temperature-dependent majority-rules experiments could indeed confirm these simulations. These findings show the relevance of both energy penalties when trying to enhance the degree of chiral amplification for the majority-rules principle in a one-dimensional helical supramolecular polymer.

Supramolecular Chirality in Self-Assembled Systems

“…224 To quantify the majority-rules and sergeants-and-soldiers data, Meijer et al proposed two free energy penalties, i.e., HRP and MMP, in the chiral amplification in supramolecular assemblies. Herein, the HRP (helix reversal penalty) describes the energy penalty of a helix reversal in the aggregate.…”

Sterically demanding benzene-1,3,5-tricarboxamides: tuning the mechanisms of supramolecular polymerization and chiral amplification

“…24,25 This effect is known as the ''majority rules'' effect. 24,25 This effect is known as the ''majority rules'' effect.…”

“…6 Moreover, both C 3 -symmetric BTAs and desymmetrized BTAs with at least two different peripheral substituents are synthetically well accessible via amide coupling reactions of activated carboxylic acids with amine nucleophiles, giving access to a wide variety of structurally diverse supramolecular building blocks. [8][9][10] Mechanistically, two types of supramolecular polymerization processes can be distinguished for the self-assembly of these supramolecular motifs. [8][9][10] Mechanistically, two types of supramolecular polymerization processes can be distinguished for the self-assembly of these supramolecular motifs.…”

Benzene-1,3,5-tricarboxamide n-alkyl ester and carboxylic acid derivatives: tuneable structural, morphological and thermal properties

“…[3][4][5][6][7][8][9] Numerous studies into the self-assembly properties of BTAderived structures and their supramolecular polymerization have been carried out, especially by Palmans, Meijer and coworkers. 8,9,10,11 We have recently focused our efforts on the use of BTA-based ligands in the generation of functional soft materials such as lanthanide and transition metal ion based metallogels. 12 We have also employed the BTA unit in the generation of tripodal anion receptors 13 and N-methyl BTA derived platforms for the formation of anion-directed selfassembled cages and self-sorting assemblies.…”