Chiral Amplification of the Structure and Viscoelasticity of a Supramolecular Polymeric System Consisting of N,N‘,N‘‘-Tris(3,7-Dimethyloctyl)Benzene-1,3,5-Tricarboxamide and n-Decane

Abstract

The influence of a chiral gelator molecule, N,N ‘,N ‘ ‘-tris-(S)-(3,7-dimethyloctyl)benzene-1,3,5-tricarboxamide ((S)DO3B), on the structure in the formation of supramolecular polymers and viscoelasticity was examined in an organogel system consisting of a racemic mixture of the gelator molecule, N,N ‘,N ‘ ‘-tris(3,7-dimethyloctyl)benzene-1,3,5-tricarboxamide (DO3B), and n-decane. In the absence of the chiral gelator, equal amounts were observed of the right- and left-handed helicities of the formed columnar supramolecular polymers. Addition of (S)DO3B markedly induced one helicity in excess, due to the Majority Rule effect. Although there are two possibilities, (1) left- and right-handled helices within single supramolecular polymers and (2) mixtures of homochiral supramolecular helical polymers, the viscoelasticity of the system supports the former. Without (S)DO3B, 60% of the amide groups of the gelators formed hydrogen bonding in the system; upon increasing the relative (S)DO3B composition (relative to the total gelator concentration), the amount of amide groups that formed hydrogen bonding increased up to 90%. The viscoelasticity of the organogel system was described using the Maxwell model, with only one set of relaxation time and strength irrespective of the relative composition of (S)DO3B. Relaxation strength was proportional to the square of the total gelator concentration as observed in entangled flexible polymer solutions, and was barely dependent on the relative composition of (S)DO3B. Relaxation time was less dependent on the total concentration of gelators; slightly longer relaxation times were observed with increasing relative compositions of (S)DO3B. Changes of the structure of the formed supramolecular polymers induced by the addition of (S)DO3B did not influence the molecular weight between the entanglement points whatsoever, whereas the relaxation time (corresponding to the lifetime of entanglement points) was affected.

Asymmetrically Substituted Benzene‐1,3,5‐tricarboxamides: Self‐Assembly and Odd–Even Effects in the Solid State and in Dilute Solution

“…Vibrations for the NH stretch at ≈3240 cm −1 , the CO stretch at ≈1640 cm −1 and the amide II at ≈1560 cm −1 have typically been attributed to the presence of threefold, α‐helical‐type intermolecular hydrogen bonding between neighbouring molecules 7a. 2a, g We can now confirm, by measuring the IR spectrum of sBTA‐methoxyethyl, which has a known crystal structure, that indeed these values are representative for well‐defined intermolecular hydrogen bonds between neighbouring molecules within the same column (Table 1, entry 1; Figure S2A in the Supporting Information). In contrast, sBTA‐CH 3 shows a completely deviating IR spectrum: two sharp NH stretching vibrations are observed at 3333 and 3259 cm −1 , whereas the amide II band is found at the low value of 1539 cm −1 (Table 1, entry 2; Figure S2B in the Supporting Information).…”

“…As Hanabusa et al. recently showed, the solution behaviour of rac ‐3,7‐dimethyloctyl‐substituted BTAs differs significantly from the optically enriched derivatives 2g. In addition, the solubility of symmetrically α‐ and β‐methyl‐substituted derivatives is poor in alkane solvents 8…”

Amplification of Chirality in Dynamic Supramolecular Aggregates

“…Interestingly, the addition of the chiral S enantiomer 9 b increased the amount of hydrogen‐bonded amide groups, as evidenced by IR spectroscopy, and an increase in the relaxation time of the system was observed from rheology measurements. Moreover, the formation of an excess of one helicity as a result of the majority‐rule effect was found when more 9 b was added to the racemate 9 d (comprised of 9 b and 9 c ) 58…”

Synthesis and self-assembly of novel hydrazide derivatives containing multi-alkoxy chains with different lengths

“…Most of the organogelators reported in the literatures [5][6][7][8][9][10], can form a three-dimensional network by self-organization through non-covalent interactions such as hydrogen bonding, van der Waals interactions, p-stacking, and coordination. In our previous papers, we reported the gelatinization behavior of a series of wedge-shaped [11], twin-tapered [12] and side-on [13] hydrazide derivatives with different alkoxy chains.…”