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Unravelling the Pathway Complexity in Conformationally Flexible N ‐Centered Triarylamine Trisamides
Author(s) -
Adelizzi Beatrice,
Filot Ivo A. W.,
Palmans Anja R. A.,
Meijer E. W.
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201603938
Subject(s) - triphenylamine , stereocenter , chemistry , supramolecular chemistry , hydrogen bond , crystallography , chemical physics , stereochemistry , photochemistry , crystal structure , molecule , enantioselective synthesis , organic chemistry , catalysis
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.