Impact of Molecular Size and Shape on the Supramolecular Co‐Assembly of Chiral Tricarboxamides: A Comparative Study

Abstract

Ac omparative investigationo ft he chiral amplification features of as eries of three families of C 3-symmetric tricarboxamides, 1,3,5-triphenylbenzenetricarboxamides (TPBAs), benzenetricarboxamides(BTAs) and oligo(phenylene ethynylene) tricarboxamides (OPE-TAs), is here reported. As previously observed for BTAs and OPE-TAs, as imilard ichroic response is obtained for TPBAsd ecorated with one, two or three chiral side chains bearing stereogenic centers, thus confirming the efficient transfer of point chirality to the supramolecular helical aggregates.U nlike BTAs andO PE-TAs, the chiral amplificationa bility of TPBAs in majority rules experiments shows an egligible dependence on the number of chiralc entersp er monomeric unit, and stands the largest amongt he series of tricarboxamides. Detailed experimental and theoretical studies demonstrate that the rotationa ngle betweent he TPBA units in the helical stack is intermediate to that observed for BTAs and OPE-TAs. This feature strongly conditions the steric interactions between vicinal molecules in the stack and the final chiral amplificationo utcome. Furthermore, theoreticalc alculations show that achiral side chainsf avor the interdigitation of the helical aggregates and thereby the formationof bundle superstructures.

Distance Matters: Biasing Mechanism, Transfer of Asymmetry, and Stereomutation in N-Annulated Perylene Bisimide Supramolecular Polymers

“…We also evaluated the ability of chiral N-annulated PBIs 1 to undergo amplification of asymmetry by developing majority rules (MR) and sergeants-and-soldiers (SaS) experiments. 11a , 12 In the MR experiments, unequal amounts of the two enantiomers ( S )-1 and ( R )-1 , with the total concentration kept constant, are mixed together. In this case, the ECD spectra registered at different ( S )-1 / ( R )-1 ratios show the same weak and noisy profile as that registered for pristine enantiomers ( Figure 6 a).…”

“… 11 Amplification of asymmetry, by using sergeants-and-soldiers (SaS) or majority rules (MR) experiments, is an efficient strategy to attain helical homopolymers from the coassembly of different entities. 12 Importantly, a cooperative mechanism is behind most of the examples of transfer and amplification of asymmetry in supramolecular polymers, with very few examples being reported for helical supramolecular polymers formed by following isodesmic or weakly cooperative processes. 13 …”

“…Supramolecular chirality is usually obtained by the efficient transfer of asymmetry from the molecular to the supramolecular level, starting from self-assembling units bearing elements of asymmetry (point or/and axial chirality) . Amplification of asymmetry, by using sergeants-and-soldiers (SaS) or majority rules (MR) experiments, is an efficient strategy to attain helical homopolymers from the coassembly of different entities . Importantly, a cooperative mechanism is behind most of the examples of transfer and amplification of asymmetry in supramolecular polymers, with very few examples being reported for helical supramolecular polymers formed by following isodesmic or weakly cooperative processes …”

Efficient calculation of protein–ligand binding free energy using GFN methods: the power of the cluster model

“…5,6 Compared with other traditional semi-empirical quantum mechanical (SQM) methods, the GFNn-xTB methods (n = 0,1,2) are more efficient and accurate in calculation, and their parameterized elements cover most of the periodic table up to Z = 86. [1][2][3][4][7][8][9][10][11][12] The GFNn-xTB methods can be used to calculate the vibrational frequencies, [13][14][15] structure optimization [16][17][18] and non-covalent interactions 11,14,15,19 for large systems containing more than 1000 atoms. [1][2][3][4] In order to describe bio-macromolecular systems quickly and easily, Grimme et al recently developed a completely automated and partially polarized generic field GFN-FF 20 based on the GFNn-xTB methods.…”

“…5,6 Compared with other traditional semi-empirical quantum mechanical (SQM) methods, the GFN n -xTB methods ( n = 0,1,2) are more efficient and accurate in calculation, and their parameterized elements cover most of the periodic table up to Z = 86. 1–4,7–12 The GFN n -xTB methods can be used to calculate the vibrational frequencies, 13–15 structure optimization 16–18 and non-covalent interactions 11,14,15,19 for large systems containing more than 1000 atoms. 1–4…”