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cyclization_18e_CHEMRXIV.pdf (1.57 MB)
Transformation Between 2D and 3D Covalent Organic Frameworks via Reversible [2+2] Cycloaddition
Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
submitted on 21.02.2020 and posted on 24.02.2020by Thaksen Jadhav, Yuan Fang, Cheng-Hao Liu, Afshin Dadvand, Ehsan Hamzehpoor, William Patterson, Antranik Jonderian, Robin Stein, Dmitrii F. Perepichka
We report the first transformation between crystalline
vinylene-linked two-dimensional (2D) polymers and crystalline
cyclobutane-linked three-dimensional (3D) polymers. Specifically, absorption-edge
irradiation of the 2D poly(arylenevinylene) covalent organic frameworks (COFs)
results in topological [2+2] cycloaddition cross-linking the π-stacked layers in
3D COFs. The reaction is reversible and heating to 200°C leads to a cycloreversion while retaining the COF
crystallinity. The resulting difference in connectivity is manifested in the
change of mechanical and electronic properties, including exfoliation,
blue-shifted UV-Vis absorption, altered luminescence, modified band structure and different acid-doping
behavior. The Li-impregnated 2D and 3D COFs show a significant
ion conductivity of 1.8×10−4 S/cm and 3.5×10−5 S/cm,
respectively. Even higher room temperature proton conductivity of 1.7×10-2
S/cm and 2.2×10-3 S/cm was found for H2SO4-treated
2D and 3D COFs, respectively.