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A Crystalline π‐Stack Containing Five Stereoisomers: Insights into Conformational Isomorphism, Chirality Inversion, and Disorder
Author(s) -
NowakKról Agnieszka,
Röhr Merle I. S.,
Schmidt David,
Würthner Frank
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201705445
Subject(s) - crystallography , chirality (physics) , molecule , crystal structure , point reflection , chemistry , crystal (programming language) , chemical physics , materials science , chiral symmetry , physics , condensed matter physics , organic chemistry , quantum mechanics , nambu–jona lasinio model , computer science , programming language , quark
Abstract An unprecedented crystal‐packing arrangement of a tetramethoxy‐bay‐substituted perylene bisimide (PBI) consists of three crystallographically independent molecules, that is, an achiral ( AC ) PBI of saddle‐shaped geometry along with two pairs of propeller‐like twisted ( P )‐ and ( M )‐enantiomeric PBI frameworks. All these five conformations are observed within a single π‐stack revealing an intriguing packing sequence with an inversion of chirality from P to M via AC . Nudged elastic band calculations for the isolated molecule show that AC is a local minimum of the P to M interconversion path. In addition, two minor conformations were observed in the crystal, one of which resembles a transition‐state molecule. Theoretical studies of dimeric and trimeric stacks reveal that the coexistence of all these structures in the crystal lattice is aided by the strong dispersion interactions between PBI cores and perfectly interdigitated dodecyl chains which stabilize energetically higher conformations.