Mechanistic insights into the pressure-induced polymerization of aryl/perfluoroaryl co-crystals

Gerthoffer, Margaret; Xu, Bohan; Wu, Shudong; Cox, Jordan M.; Huss, Steven; Oburn, Shalisa M.; Lopez, Steven A.; Crespi, Vincent H.; Badding, John V.; Elacqua, Elizabeth

doi:10.1039/d1py01387d

Cited by 9 publications

(6 citation statements)

References 63 publications

(92 reference statements)

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“…Nanothreads were first synthesized from benzene under pressure in diamond anvil cells or Paris–Edinburgh cells, , but the high-pressure solid-state synthesis technique appears to be quite general for unsaturated hydrocarbons. To date, nanothreads have been synthesized from benzene, , pyridine, aniline, thiophene, cubane, furan, azobenzene, , pyridazine, stilbene, and arene/perfluoroarene cocrystals. − It is expected that more polymers of this kind are coming and that sample sizes of certain threads will rapidly expand as synthesis pressures continue to fall.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Studies of Furan and Thiophene Nanothreads: Structures, Cycloaddition Barriers, and Activation Volumes

2022

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This theoretical study examines the formation, structure, and stability of two of the most ordered nanothreads produced yet, those derived from furan and thiophene. The energetic consequences and activation barriers of the first two steps of oligomerization via a Diels–Alder mechanism were examined. The ca. 20 GPa difference in the synthetic pressures (lower for furan) is explainable in terms of the greater loss of aromaticity by the thiophene. The effects of pressure on the reaction profiles, operating through a volume decrease along the reaction coordinate, are illustrated. The interesting option of polymerization proceeding in one or two directions opens up the possibility of polymers with opposing, cumulative dipole moments. The computed activation volumes are consistently more negative for furan, in accordance with the lower onset pressure of furan polymerization. The energetics of three ordered polymer structures were examined. The syn polymer, with all O/S atoms on the same side, if not allowed to distort, is at a high energy relative to the other two due to the O/S lone pair repulsion, understandably greater for S than for O at the 2.8/2.6 Å separation. Set free, the syn isomers curve or arch in two- or three-dimensional (helical) ways, whose energetics are traced in detail. The syn polymer can also stabilize itself by twisting into zig-zag or helical energy minima. The release of strain in a linear thread as the pressure is relaxed to 1 atm, with consequent thread curving, is a likely mechanism for the observed loss of the crystalline order in the polymer as it is returned to ambient pressure.

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Section: Introductionmentioning

confidence: 99%

Theoretical Studies of Furan and Thiophene Nanothreads: Structures, Cycloaddition Barriers, and Activation Volumes

2022

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“…We hypothesize that pseudo-TCP occurs in a short- or medium-range-ordered amorphous solid 48 , 49 . This is distinguished from high pressure-induced TCP 50 – 60 , TCP via pressure-induced transition of solids from a photostable to a photopolymerizable crystalline phase 61 , 62 , or solid-phase polymerization that proceeds upon the injection of an external reagent 63 . The properties are compared between crystalline and amorphous polymers derived from the same monomer, which demonstrates the impact of activation methods on producing diverse polymers.…”

Section: Introductionmentioning

confidence: 99%

Mechanoactivated amorphization and photopolymerization of styryldipyryliums

Usuba,

Sun,

Nguyen

et al. 2024

Commun Mater

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Conventional topochemical photopolymerization reactions occur exclusively in precisely-engineered photoactive crystalline states, which often produces high-insoluble polymers. To mitigate this, here, we report the mechanoactivation of photostable styryldipyrylium-based monomers, which results in their amorphization-enabled solid-state photopolymerization and produces soluble and processable amorphous polymers. A combination of solid-state nuclear magnetic resonance, X-ray diffraction, and absorption/fluorescence spectroscopy reveals the crucial role of a mechanically-disordered monomer phase in yielding polymers via photo-induced [2 + 2] cycloaddition reaction. Hence, mechanoactivation and amorphization can expand the scope of topochemical polymerization conditions to open up opportunities for generating polymers that are otherwise difficult to synthesize and analyze.

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“…Mechanochemically induced polymerizations wherein pressure causes chemical reactivity can direct critical synthetic routes toward macromolecules (e.g., actin) or other polymeric architectures such as carbon-based nanothreads. − Nanothreads are synthesized through pressure-induced unidirectional polymerization of small (usually aromatic) molecules, generally at pressures ranging from 15 to 30 GPa. Elucidation of precise reaction mechanisms for nanothread production and the consequent control thereofboth to reduce reaction pressure and to access targeted reaction outcomesremain areas of active and rapid advance.…”

Section: Introductionmentioning

confidence: 99%

Photochemically Mediated Polymerization of Molecular Furan and Pyridine: Synthesis of Nanothreads at Reduced Pressures

et al. 2022

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Nanothreads are emerging one-dimensional sp3-hybridized materials with high predicted tensile strength and a tunable band gap. They can be synthesized by compressing aromatic or nonaromatic small molecules to pressures ranging from 15–30 GPa. Recently, new avenues are being sought that reduce the pressure required to afford nanothreads; the focus has been placed on the polymerization of molecules with reduced aromaticity, favorable stacking, and/or the use of higher reaction temperatures. Herein, we report the photochemically mediated polymerization of pyridine and furan aromatic precursors, which achieves nanothread formation at reduced pressures. In the case of pyridine, it was found that a combination of slow compression/decompression with broadband UV light exposure yielded a crystalline product featuring a six-fold diffraction pattern with similar interplanar spacings to previously synthesized pyridine-derived nanothreads at a reduced pressure. When furan is compressed to 8 GPa and exposed to broadband UV light, a crystalline solid is recovered that similarly demonstrates X-ray diffraction with an interplanar spacing akin to that of the high-pressure synthesized furan-derived nanothreads. Our method realizes a 1.9-fold reduction in the maximum pressure required to afford furan-derived nanothreads and a 1.4-fold reduction in pressure required for pyridine-derived nanothreads. Density functional theory and multiconfigurational wavefunction-based computations were used to understand the photochemical activation of furan and subsequent cascade thermal cycloadditions. The reduction of the onset pressure is caused by an initial [4+4] cycloaddition followed by increasingly facile thermal [4+2]-cycloadditions during polymerization.

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Mechanistic insights into the pressure-induced polymerization of aryl/perfluoroaryl co-crystals

Abstract: The pressure-induced polymerization of aryl/perfluoroaryl co-crystals offers a strategic route to obtain sequence-defined polymeric architectures, such as diamond nanothreads, that feature a stiff sp3 hybridized backbone.

Cited by 9 publications

References 63 publications

Theoretical Studies of Furan and Thiophene Nanothreads: Structures, Cycloaddition Barriers, and Activation Volumes

Theoretical Studies of Furan and Thiophene Nanothreads: Structures, Cycloaddition Barriers, and Activation Volumes

Mechanoactivated amorphization and photopolymerization of styryldipyryliums

Photochemically Mediated Polymerization of Molecular Furan and Pyridine: Synthesis of Nanothreads at Reduced Pressures

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