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Abstract The solution and mechanochemical synthesis of two cocrystals that differ in the stoichiometric ratio of the components (stoichiometric cocrystals) is reported. The components in the stoichiometric cocrystals interact through hydrogen or hydrogen/halogen bonds and differ in π‐stacking arrangements. The difference in structure and noncovalent interactions affords dramatically different thermal expansion behaviors in the two cocrystals. At certain molar ratios, the cocrystals are obtained concomitantly; however, by varying the ratios, a single stoichiometric cocrystal is achieved using mechanochemistry.
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Use of a Diels–Alder reaction to modify thermal expansion properties in charge-transfer cocrystals
A strategy for modifying thermal expansion properties in dichroic, charge-transfer cocrystals is described. A solid-state Diels–Alder reaction is used to covalently connect adjacent molecules in the cocrystal, and thermal expansion along the direction of these bonds is reduced when compared to the unreacted cocrystals.
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- Award ID(s):
- 2045506
- PAR ID:
- 10401736
- Date Published:
- Journal Name:
- CrystEngComm
- Volume:
- 24
- Issue:
- 40
- ISSN:
- 1466-8033
- Page Range / eLocation ID:
- 7024 to 7028
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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The thermal expansion behavior of a series of halogen-bonded cocrystals containing 1,4-diiodoperchlorobenzene as the donor is described. Two of the solids are polymorphs and contain 4-stilbazole as the acceptor, while the third solid contains 4-(phenylethynyl)pyridine as the acceptor, and this solid is isostructural with one of the polymorphs. All solids are sustained by I···N halogen bonds, and the least thermal expansion occurs along this direction in all solids. The polymorphs exhibit significant differences in π stacking, and we show that electronically similar face-to-face stacked rings undergo more expansion compared to electronically different stacked rings. Moreover, in the two polymorphs, the directions of moderate expansion and most expansion are reversed, demonstrating how cocrystal polymorphism can affect material properties.more » « less
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D2CE01207C
