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Tuning strained alkyne reactivity via organic synthesis has evolved into a burgeoning field of study largely focused on cyclooctyne, wherein physical organic chemistry helps guide rational molecular design to produce molecules with intriguing properties. Concurrent research in the field of carbon nanomaterials has produced new types of strained alkyne macrocycles, such as cycloparaphenyleneacetylenes, that possess uniquely curved aromatic π systems but hover on the edge of stability. In 2018, we introduced a strained alkyne scaffold that marries the synthetic accessibility and stability of cyclooctyne with the curved π system of carbon nanomaterials. These molecules are strained alkyne-containing cycloparaphenylenes (or [n+1]CPPs), which have been shown to possess size-dependent reactivity as well as the classic characteristics of the unfunctionalized parent CPP, such as a tunable HOMO–LUMO gap and bright fluorescence for large sizes. Herein, we elaborate further on this scaffold, introducing two modifications to the original design and fully characterizing the kinetics of the strain-promoted azide–alkyne cycloaddition (SPAAC) for each [n+1]CPP with a model azide. Additionally, we explain how electronic (the incorporation of fluorine atoms) and strain (a meta linkage which heightens local strain at the alkyne) modulations affect SPAAC reactivity via the distortion–interaction computational model. Altogether, these results indicate that through a modular synthesis and rational chemical design, we have developed a new family of tunable and inherently fluorescent strained alkyne carbon nanomaterials.
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Acenes beyond organic electronics: sensing of singlet oxygen and stimuli-responsive materials
The spectroscopic, electronic, and geometrical properties of acenes have enabled their broad applicability in organic optoelectronics. Beyond these physical characteristics of acenes, acenes also offer characteristic and predictable reaction chemistry, especially their behavior as dienes in cycloaddition reactions. Although these cycloaddition reactions, especially those with singlet oxygen ( 1 O 2 ) as the dienophile, are detrimental for organic electronics, this reactivity has led to several different applications such as sensing of 1 O 2 , the release of cytotoxic reactive oxygen species (ROS), and stimuli-responsive materials for drug delivery. The rational design of acenes in these chemically-responsive applications beyond organic optoelectronics requires an understanding of how chemical structure influences both the physical properties, such as quantum yield of emission, as well as the reactivity of acenes and their cycloadducts. Therefore, the objective of this review is to summarize how cycloaddition reactions of acenes have expanded their applications in different areas of materials chemistry, and in doing so inspire and inform the rational design of acene-based materials with applications beyond organic electronics.
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- Award ID(s):
- 1609146
- PAR ID:
- 10203387
- Date Published:
- Journal Name:
- Organic & Biomolecular Chemistry
- Volume:
- 18
- Issue:
- 45
- ISSN:
- 1477-0520
- Page Range / eLocation ID:
- 9191 to 9209
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1039/D0OB01744B
