Mechanochemical synthesis of an elusive fluorinated polyacetylene

Boswell, Benjamin R.; Mansson, Carl M. F.; Cox, Jordan M.; Jin, Zexin; Romaniuk, Joseph A. H.; Lindquist, Kurt P.; Cegelski, Lynette; Xia, Yan; Lopez, Steven A.; Burns, Noah Z.

doi:10.1038/s41557-020-00608-8

Cited by 75 publications

(82 citation statements)

References 30 publications

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“…The computed bands and their oscillator strengths are summarized in Table S3. These oscillator strengths are ~10 4 stronger than the excited state absorption bands. If correct, they must belie a correspondingly lower concentration of charge transfer contact pairs to yield optical densities on the same order as the S1 excited state absorption.…”

Section: Transient Absorption Spectroscopymentioning

confidence: 93%

“…In the demonstration of this reaction by Burns et al, the ratio of photons to molecular reagents was 168:1 and achieved a 41% synthetic yield. 4 Interpreting this through the lens of these results shows that although most absorption events result in the reformation of the D6h HFB, provided there is a small but exclusive pathway leading to Dewar-HFB, constant upcycling of the HFB by using a high molar excess of photons still yields an effective reaction.…”

Section: Simulated Photochemical Dynamicsmentioning

confidence: 94%

“…5 (B) Photochemical cascade reaction of Burns and co-workers. 4 The 4π electrocyclic ring-closing reaction is known for many highly fluorinated cyclic polyenes, many of which result from cycloadditions with HFB. [6][7][8][9] HFB itself undergoes the same ringclosing reaction, 10 photochemically isomerizing to hexafluoro-Dewar-benzene (Dewar-HFB) chemoselectively.…”

Section: Figure 1 (A)mentioning

confidence: 99%

“…This wavelength was selected to match the 255 nm lamps employed in gram scale reactors for these syntheses. 4 The transient absorption spectrum is rendered at a series of pump-probe delays denoted by colorcoordinated legend. The stick spectrum represents the computed excited state absorption spectra at the S1 minimum energy geometry.…”

Section: Transient Absorption Spectroscopymentioning

confidence: 99%

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Role of the Perfluoro Effect in the Selective Photochemical Isomerization of Hexafluorobenzene

et al. 2021

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Hexafluorobenzene and many of its derivatives exhibit a chemoselective photochemical isomerization, resulting in highly-strained, Dewar-type bicyclohexenes. While the changes in absorption and emission associated with benzene hexafluorination have been attributed to the socalled "perfluoro effect," the resulting electronic structure and photochemical reactivity of hexafluorobenzene are still unclear. We now use a combination of ultrafast time-resolved spectroscopy, multiconfigurational computations, and non-adiabatic dynamics simulations to develop a holistic description of the absorption, emission, and photochemical dynamics of the 4πelectrocyclic ring-closing of hexafluorobenzene and the fluorination effect along the reaction coordinate. Our calculations suggest that the electron-withdrawing fluorine substituents induce a vibronic coupling between the lowest-energy 1B2u (ππ*) and 1E1g (πσ*) excited states by selectively stabilizing the σ-type states. The vibronic coupling occurs along vibrational modes of e2u symmetry which distorts the excited-state minimum geometry resulting in the experimentally broad, featureless absorption bands, and a ~100 nm Stokes shift in fluorescence-in stark contrast to benzene. Finally, the vibronic coupling is shown to simultaneously destabilize the reaction pathway towards hexafluoro-benzvalene and promote molecular vibrations along the 4π ring-closing pathway, resulting in the chemoselectivity for hexafluoro-Dewar-benzene. File list (2)download file view on ChemRxiv HFB_SI_JACS-final.docx (3.46 MiB) download file view on ChemRxiv HFB_JACS-final.pdf (1.38 MiB)

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Section: Transient Absorption Spectroscopymentioning

confidence: 93%

Section: Simulated Photochemical Dynamicsmentioning

confidence: 94%

Section: Figure 1 (A)mentioning

confidence: 99%

Section: Transient Absorption Spectroscopymentioning

confidence: 99%

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Role of the Perfluoro Effect in the Selective Photochemical Isomerization of Hexafluorobenzene

et al. 2021

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“…3 Mechanical force is both ubiquitous and straightforward to apply using a range of different methods that provide temporal and spatial control, [4][5][6][7][8][9] making it an appealing stimulus for responsive materials. A wide variety of mechanophores have been developed that produce functional changes in polymers subjected to mechanical force including catalyst activation, 10,11 conductivity switching, [12][13][14] small molecule release, [15][16][17] fluorescence changes, [18][19][20][21] and chemiluminescence, 22 among others. Mechanophores that generate a change in color are particularly useful due to their ability to act as molecular force beacons, providing straightforward visual identification of the locations of stress and/or strain in polymeric materials.…”

Section: Introductionmentioning

confidence: 99%

A modular approach to mechanically gated photoswitching with color-tunable molecular force probes

Barber

Robb

2021

Chem. Sci.

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Fluorinated Polymers: Synthesis and Applications

Schwarz

Diesendruck

2022

PATAI'S Chemistry of Functional Groups

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Fluorinated polymers are unique in their properties AND, as a consequence, have found a variety of particular applications ranging from the pharmaceutical industry to paints, energy‐storage devices, microelectronics, and even optical devices and, as such, became ubiquitous in our everyday life. This polymer family presents high stability toward acids, bases, and organic solvents and typically maintains their properties even at very high temperatures. In addition, they are resistant to oxidation, are electric insulators, possess low surface tension, and can present excellent optical transmitting properties. As with other fluorinated molecules, fluorinated polymers are synthetic, and therefore, a rich chemistry was developed in order to create a large variety of materials, both to understand their properties AND to address specific needs in different applications. In this chapter, the chemistry behind monomer synthesis, polymerization, and polymers are described, looking at the intended and accidental discoveries, all of which were key to advance modern‐life technologies.

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Mechanochemical synthesis of an elusive fluorinated polyacetylene

Cited by 75 publications

References 30 publications

Role of the Perfluoro Effect in the Selective Photochemical Isomerization of Hexafluorobenzene

Role of the Perfluoro Effect in the Selective Photochemical Isomerization of Hexafluorobenzene

A modular approach to mechanically gated photoswitching with color-tunable molecular force probes

Fluorinated Polymers: Synthesis and Applications

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