- A Photoresponsive Smart Covalent Organic Framework
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Ordered π-columnar structures found in covalent organic frameworks (COFs) render them attractive as smart materials. However, external-stimuli-responsive COFs have not been explored. Here we report the design and synthesis of a photoresponsive COF with anthracene units as the photoresponsive π-building blocks. The COF is switchable upon photoirradiation to yield a concavo-convex polygon skeleton through the interlayer [4π+4π] cycloaddition of anthracene units stacked in the π-columns. This cycloaddition reaction is thermally reversible; heating resets the anthracene layers and regenerates the COF. These external-stimuli-induced structural transformations are accompanied by profound changes in properties, including gas adsorption, π-electronic function, and luminescence. The results suggest that COFs are useful for designing smart porous materials with properties that are controllable by external stimuli.
- Huang, Ning,Ding, Xuesong,Kim, Jangbae,Ihee, Hyotcherl,Jiang, Donglin
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- Synthesis of annulated dioxins as electron-rich donors for cation radical salts
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The synthesis of a series of new alkoxylated linearly annulated dioxins is described together with their cyclic voltammetric behavior and some preliminary result on their ability to form cation radical salts. Of these dioxins, seven (8, 12, 19, 21, 27, 33, 34) are the first representatives of entirely new heterocyclic systems. Dioxins 8, 21, 22 and 27 gave good quality cation radical salts upon electrocrystallization. Graphical Abstract
- Hellberg, Jonas,Dahlstedt, Emma,Pelcman, Margit E.
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p. 8899 - 8912
(2007/10/03)
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- Synthesis, assembly, and thin film transistors of dihydrodiazapentacene: An isostructural motif for pentacene
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The study below details the synthesis, assembly, and thin film transistors from dihydrodiazapentacenes. These molecules have the same molecular shape as pentacene but are much easier to prepare and have much greater environmental stability. Thin films made from the dihydrodiazapentacene behave as field effect transistors with mobilities and on/off ratios high enough to be useful in certain applications. X-ray diffraction and AFM experiments on these films show that the molecules stack in layers with their long axis upright from the surface. Some of the derivatives synthesized for this study have unexpectedly high solubility in polar solvents such as DMF and DMSO. The crystal structure from DMF reveals self-assembled channels with each of the aniline functionalities forming a hydrogen bond with solvent. In more nonpolar solvents, the solid-state assembly switches to a herringbone motif characteristic of the linear acenes.
- Miao, Qian,Nguyen, Thuc-Quyen,Someya, Takao,Blanchet, Graciela B.,Nuckolls, Colin
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p. 10284 - 10287
(2007/10/03)
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