Unravelling the Pathway Complexity in Conformationally Flexible N‐Centered Triarylamine Trisamides

Abstract

Two families of C 3‐symmetrical triarylamine‐trisamides comprising a triphenylamine‐ or a tri(pyrid‐2‐yl)amine core are presented. Both families self‐assemble in apolar solvents via cooperative hydrogen‐bonding interactions into helical supramolecular polymers as evidenced by a combination of spectroscopic measurements, and corroborated by DFT calculations. The introduction of a stereocenter in the side chains biases the helical sense of the supramolecular polymers formed. Compared to other C 3‐symmetrical compounds, a much richer self‐assembly landscape is observed. Temperature‐dependent spectroscopy measurements highlight the presence of two self‐assembled states of opposite handedness. One state is formed at high temperature from a molecularly dissolved solution via a nucleation–elongation mechanism. The second state is formed below room temperature through a sharp transition from the first assembled state. The change in helicity is proposed to be related to a conformational switch of the triarylamine core due to an equilibrium between a 3:0 and a 2:1 conformation. Thus, within a limited temperature window, a small conformational twist results in an assembled state of opposite helicity.

C3‐Symmetrical π‐Scaffolds: Useful Building Blocks to Construct Helical Supramolecular Polymers

“…However, selection of a solvent in which the intermolecular interactions are weaker (decalin) induces stereomutation for this TPA and leads to CD spectra with different shapes (Figure c). Furthermore, a clear hysteresis is detected when the supramolecular polymerization mechanism is investigated by registering the corresponding heating and cooling curves (Figure b and 9d) …”

Counterintuitive consequences of competitive pathways in supramolecular polymerizations

“…Similarly, several systems that show multiple thermodynamically rather than kinetically controlled polymer morphologies at various temperatures or solvent compositions have been experimentally observed and these reports have recently gained more attention . Interestingly, these thermodynamically controlled competitive polymerizations show concentration‐independent polymer–polymer transitions that are solely determined by the relative stabilities of the aggregates, making them very responsive to changes in solvent or temperature .…”

Metal‐Bonded Redox‐Active Triarylamines and Their Interactions: Synthesis, Structure, and Redox Properties of Paddle‐Wheel Copper Complexes

“…However, for the substituted derivatives a reversible redox behavior is observed, which can be tuned by varying the substituents attached to the aromatic rings particularly at the para positions . Moreover, the molecular framework of triarylamines is also known to possess structural flexibility, which when coupled together with bulky substituents can lead to distortion or rotation within its structure …”