Dynamic Supramolecular Polymers Based on Benzene‐1,3,5‐tricarboxamides: The Influence of Amide Connectivity on Aggregate Stability and Amplification of Chirality

Abstract

N‐Centred benzene‐1,3,5‐tricarboxamides (N‐BTAs) composed of chiral and achiral alkyl substituents were synthesised and their solid‐state behaviour and self‐assembly in dilute alkane solutions were investigated. A combination of differential scanning calorimetry (DSC), polarisation optical microscopy (POM) and X‐ray diffraction revealed that the chiral N‐BTA derivatives with branched 3,7‐dimethyloctanoyl chains were liquid crystalline and the mesophase was assigned as Colho. In contrast, N‐BTA derivatives with linear tetradecanoyl or octanoyl chains lacked a mesophase and were obtained as crystalline compounds. Variable‐temperature infrared spectroscopy showed the presence of threefold, intermolecular hydrogen bonding between neighbouring molecules in the mesophase of the chiral N‐BTAs. In the crystalline state at room temperature a more complicated packing between the molecules was observed. Ultraviolet and circular dichroism spectroscopy on dilute solutions of N‐BTAs revealed a cooperative self‐assembly behaviour of the N‐BTA molecules into supramolecular polymers with preferred helicity when chiral alkyl chains were present. Both the sergeants‐and‐soldiers as well as the majority‐rules principles were operative in stacks of N‐BTAs. In fact, the self‐assembly of N‐BTAs resembles closely that of their carbonyl (CO)‐centred counterparts, with the exception that aggregation is weaker and amplification of chirality is less pronounced. The differences in the self‐assembly of N‐ and CO‐BTAs were analysed by density functional theory (DFT) calculations. These reveal a substantially lower interaction energy between the monomeric units in the supramolecular polymers of N‐BTAs. The lower interaction energy is due to the higher energy penalty for rotation around the PhNH bond compared to the PhCO bond and the diminished magnitude of dipole–dipole interactions. Finally, we observed that mixed stacks are formed in dilute solution when mixing N‐BTAs and CO BTAs.

Understanding the catalytic activity of single‐chain polymeric nanoparticles in water

“…The sign and magnitude of the CD effect accord nicely with earlier observations. 31,[34][35][36][37][38] These results suggest that the controlled topology of the polymer chains allows the selfassembly motifs, that is, BTA units and Ru(II)-SDP units, to act in an orthogonal way. 27,34 Dynamic light scattering (DLS) experiments were performed to elucidate the single chain folding of the prepared copolymers.…”

Chirality induction and amplification in methylene blue H-aggregates viad- and l-phenylalanine pre-adsorbed on the tungsten oxide nanocolloid surface

“…Chiral 20 amplification in supramolecular structures has inspired a great variety of research because of its significance in understanding the origin of chirality in nature and the applications in asymmetric synthesis. [23,24] Recently, theoretical models developed by van Gestel et al [25][26][27] allow us to quantify the 25 energies that are involved in chiral amplification processes: the mismatch energy (E M ), that is, the penalty that is paid by the minority enantiomer to be present in a helix of its non-preferred sense and the helix reversal penalty (E R ), that is, the penalty that it cost for a helix to change its helical sense. Both energies are 30 derived from experimental data.…”

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

“…2 Owing to their symmetry and relatively simple structure, aggregation modes, and the vast range of possible derivatives, benzene-1,3,5-tricarboxamides (BTAs) have been a popular choice for application in supramolecular and nanomaterial chemistry. [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.…”