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ChemComm
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Journal Name
COMMUNICATION
DOI: 10.1039/D0CC00916D
Advanced Light Source (ALS), Lawrence Berkeley National
Laboratory, both being supported by the Office of Science,
Office of Basic Energy Sciences, of the U.S. Department of
Energy under Contract No. DE-AC02-05CH11231. We
gratefully acknowledge Liana Klivansky and Teresa Chen for
their assistance and training and Dr. Matthew Kolaczkowski for
helpful discussions. The authors also thank the `Centro de
Servicios de Informática y Redes de Comunicaciones´ (CSIRC)
(Universidad de Granada, Spain) and `Servicio de
Supercomputación de la Universidad de Castilla-La Mancha´ for
providing computing time.
HOMO
LUMO
Fig. 3 Frontier molecular orbital density diagrams of 5 calculated
at the B3LYP//6-311++G** level, showing intraannular electron
density.
S1 and S3). The long transannular C-C bond distances observed
in the single-crystal X-ray structure are reproduced
computationally, with the geometry-optimized structure of 5
displaying two even transannular C-C bond distances of 1.60 Å.
The frontier molecular orbital (FMO) density diagrams of
compounds 5, 6, and 7 provide more insight about the electronic
effects of the pyrazinophane geometry (Figure 3 and S1). The
FMO density diagrams of 5 show electron density primarily
residing on the dithienylpyrazine chromophores. However, in
both of the FMO density diagrams of 5, significant electron
density between the pyrazine rings can be seen, indicating a
through-space interaction. The intraannular interaction that this
would imply was proposed early on in the study of cyclophanes
in order to explain the reduced optical band-gaps of cyclophanes
as compared to their monomeric analogs as well as their behavior
when reduced or oxidized.6, 7, 9
Conflicts of interest
There are no conflicts to declare.
Notes and references
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TD-DFT calculations using the TD-PBE0 functional at the 6-
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This work was performed at the Molecular Foundry as a user
This journal is © The Royal Society of Chemistry 20xx
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