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Updated: Jan 7, 2026

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
Preference for Heterochiral Dimers of Propylene Oxide Induced by Noncovalent Interactions with Pyrrole as an Achiral
Kento Sakurai1, Yoshiteru Matsumoto2
1Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Ohya 836, Suruga, Shizuoka 422-8529, Japan.
Abstract:
Chirality preference is the quantitative outcome of chirality recognition. Propylene oxide (PO) may exhibit a chirality preference in its dimer (PO2). However, the homo- and heterochiral PO2 show almost the same intermolecular binding energies. Herein, we investigate how noncovalent interactions with pyrrole (Py) induce chirality preference in PO2. The NH stretching bands of jet-cooled Py1-PO2 were measured by using IR cavity ringdown spectroscopy. The observed band intensities indicated that heterochiral Py1-PO2 was 1.3-fold more abundant than the homochiral one. Quantum chemical calculations demonstrated that the three most stable species are all heterochiral Py1-PO2 among the 18 diastereomers, reproducing the experimental heterochiral preference. The heterochiral preference derives from three-point interactions, C-H···O, C-H···π, and O···H-N, between Py1-(R)-PO1 and (R)- or (S)-PO. The non-covalent interaction (NCI) analysis showed that more heterochiral Py1-PO2 satisfied three-point interactions. Consequently, the achiral-tag Py served as a unique mediator of PO2's chirality preference.
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