1217367-86-6Relevant academic research and scientific papers
Dynamic supramolecular polymers based on benzene-1, 3, 5-tricarboxamides: The influence of amide connectivity on aggregate stability and amplification of chirality
Stals, Patrick J.M.,Everts, Jeffrey C.,De Bruijn, Robin,Filot, Ivo A.W.,Smulders, Maarten M.J.,Martin-Rapun, Rafael,Pidko, Evgeny A.,De Greef, Tom F.A.,Palmans, Anja R.A.,Meijer
, p. 810 - 821 (2010)
N-Centred benzene-1, 3, 5-tri- carboxamides (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-dimethyl- octanoyl 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 spectrosco- py showed the presence of threefold, intermolecular hydrogen bonding be-tween 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 spec- troscopy 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.
