Polydifluoroacetylene, Polychlorofluoroacetylene, and Polydichloroacetylene

Gould, George L.; Eswara, Veena; Trifu, Roxana; Castner, David G.

doi:10.1021/ja983840a

Cited by 16 publications

(13 citation statements)

References 25 publications

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“…221 The problem with substituting the hydrogen in polyacetylene is that the larger and negatively charged fluorine substituents induce non-planarity. 221,222 Experimental work showed that perfluoropolyacetylene has increased sensitivity towards oxygen, water and light 227 other heterocyclic oligomers and polymers [232][233][234][235][236][237] were synthesized and theoretical predictions of the increased stability of the n-doped state and switching from hole to electron conductivity were confirmed. In addition, fluorination has the additional benefit of promoting the air-stability of n-channel OSCs through the formation of a kinetic barrier against oxygen and moisture.…”

Section: -223mentioning

confidence: 99%

Trends in molecular design strategies for ambient stable n-channel organic field effect transistors

2017

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aIn recent years, organic semiconducting materials have enabled technological innovation in the field of flexible electronics. Substantial optimization and development of new p-conjugated materials has resulted in the demonstration of several practical devices, particularly in displays and photoreceptors.However, applications of organic semiconductors in bipolar junction devices, e.g. rectifiers and inverters, are limited due to an imbalance in charge transport. The performance of p-channel organic semiconducting materials exceeds that of electron transport. In addition, electron transport in p-conjugated materials exhibits poorer atmospheric stability and dispersive transient photocurrents due to extrinsic carrier trapping. Thus development of air stable n-channel conjugated materials is required. New classes of materials with delocalized n-doped states are under development, aiming at improvement of the electron transport properties of organic semiconductors. In this review, we highlight the basic tenets related to the stability of n-channel organic semiconductors, primarily focusing on the thermodynamic stability of anions and summarizing the recent progress in the development of air stable electron transporting organic semiconductors. Molecular design strategies are analysed with theoretical investigations.

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Section: -223mentioning

confidence: 99%

Trends in molecular design strategies for ambient stable n-channel organic field effect transistors

2017

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“…However, synthesizing fluorinated polyacetylenes has proven difficult by the traditional means of polymerizing fluorinated acetylene. 3 Not only is difluoroacetylene an explosive and pyrophoric gas, but polymerization results in a highly irregular material that contains a mixture of −CF, −CF 2 , and −CF 3 functional groups. Burns and co-workers 4 recently achieved this elusive synthesis by leveraging the mechanochemical "unzipping" of highly strained ladderene polymers to form partially fluorinated polyacetylenes.…”

Section: ■ Introductionmentioning

confidence: 99%

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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“…10 In contrast, fluorination of polypyrrole succeeded, 11 and the expected changes in electronic structure are borne out. Polydifluoropyrrole (PDFP) shows good conductivity (∼0.1 S cm -1 ), a higher redox potential compared to that for polypyrrole (PP), and increased p-doping capacity (up to 55%).…”

Section: Introductionmentioning

confidence: 99%

Effects of Perfluorination on Thiophene and Pyrrole Oligomers

Salzner

2010

J. Phys. Chem. A

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The effect of perfluorination on thiophene and pyrrole oligomers in neutral, cationic, and anionic states was investigated with density functional theory at the (TD)B3P86-30%/6-31G* level. For the title compounds fluorination leads to planarization. For pyrroles a band gap reduction of 0.58 eV results, as unsubstituted pyrroles are nonplanar and disordered in the solid state. For thiophene the band gap is slightly increased as long thiophene oligomers are almost planar. Ionization energies and electron affinities increase upon fluorination by 0.65 and 0.60 eV for polythiophene and by 0.45 and 0.90 eV for polypyrrole. Conduction band widths increase by 0.5 for polythiophene and by 0.7 eV for polypyrrole. Spectra of charged (doped) forms are almost identical to those of the parent systems. Like parent systems, fluorinated oligomers with chain lengths of more than six rings develop a third UV absorption that increases in strength and decreases in energy upon chain length increase.

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Polydifluoroacetylene, Polychlorofluoroacetylene, and Polydichloroacetylene

Cited by 16 publications

References 25 publications

Trends in molecular design strategies for ambient stable n-channel organic field effect transistors

Trends in molecular design strategies for ambient stable n-channel organic field effect transistors

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

Effects of Perfluorination on Thiophene and Pyrrole Oligomers

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