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Dynamics of Meso–Chiral Interconversion in a Butterfly‐Shape Overcrowded Alkene Rotor Tunable by Solvent Properties
Author(s) -
Kartha Kalathil K.,
Takai Atsuro,
Futera Zdeněk,
Labuta Jan,
Takeuchi Masayuki
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202102719
Subject(s) - chemistry , solvophobic , diastereomer , alkene , molecular dynamics , solvent , solvent effects , polarizability , computational chemistry , photochemistry , stereochemistry , organic chemistry , molecule , catalysis
Elucidation of dynamics of molecular rotational motion is an essential part and challenging area of research. We demonstrate reversible diastereomeric interconversion of a molecular rotor composed of overcrowded butterfly‐shape alkene ( FDF ). Its inherent dual rotatory motion (two rotors, one stator) with interconversion between two diastereomers, chiral trans‐ FDF and meso cis‐ FDF forms, has been examined in detail upon varying temperatures and solvents. The free energy profile of 180° revolution of one rotor part has a bimodal shape with unevenly positioned maxima (transition states). FDF in aromatic solvents adopts preferentially meso cis‐conformation, while in non‐aromatic solvents a chiral trans‐conformation is more abundant owing to the solvent interactions with peripheral hexyl chains (solvophobic effect). Moderate correlations between the trans‐ FDF /cis‐ FDF ratio and solvent parameters, such as refractive index, polarizability, and viscosity were found.