Tuning the stability of organic radicals: from covalent approaches to non-covalent approaches

Tang, Bohan; Zhao, Jiantao; Xu, Jiang‐Fei; Zhang, Xi

doi:10.1039/c9sc06143f

Cited by 140 publications

(124 citation statements)

References 91 publications

(115 reference statements)

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“…We started with PBI, [ 37,38 ] an industrial pigment displaying n‐type semiconductor character. [ 39 ] Due to the strong intermolecular π–π and hydrogen bond interactions, PBI derivatives usually have poor solubility in common organic solvents, thereby hindering the manufacture of solution processable organic thin film devices.…”

Section: Figurementioning

confidence: 99%

High Thermoelectric Performance in n‐Type Perylene Bisimide Induced by the Soret Effect

et al. 2020

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Low‐cost, non‐toxic, abundant organic thermoelectric materials are currently under investigation for use as potential alternatives for the production of electricity from waste heat. While organic conductors reach electrical conductivities as high as their inorganic counterparts, they suffer from an overall low thermoelectric figure of merit (ZT) due to their small Seebeck coefficient. Moreover, the lack of efficient n‐type organic materials still represents a major challenge when trying to fabricate efficient organic thermoelectric modules. Here, a novel strategy is proposed both to increase the Seebeck coefficient and achieve the highest thermoelectric efficiency for n‐type organic thermoelectrics to date. An organic mixed ion–electron n‐type conductor based on highly crystalline and reduced perylene bisimide is developed. Quasi‐frozen ionic carriers yield a large ionic Seebeck coefficient of −3021 μV K−1, while the electronic carriers dominate the electrical conductivity which is as high as 0.18 S cm−1 at 60% relative humidity. The overall power factor is remarkably high (165 μW m−1 K−2), with a ZT = 0.23 at room temperature. The resulting single leg thermoelectric generators display a high quasi‐constant power output. This work paves the way for the design and development of efficient organic thermoelectrics by the rational control of the mobility of the electronic and ionic carriers.

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Section: Figurementioning

confidence: 99%

High Thermoelectric Performance in n‐Type Perylene Bisimide Induced by the Soret Effect

et al. 2020

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“…This helps to prevent/minimize the s-dimerization, but at a cost of also reducing the access to certain kinds of radical-related reactivity. 16 Alternatively, carbon-centered radicals can be thermodynamically stabilized via spin delocalization across a highly conjugated p-system and incorporation of heteroatoms. 16 In fact, the majority of persistent carbon-centered radicals are highly delocalized, which promotes p-p interactions and spinspin communication.…”

Section: Introductionmentioning

confidence: 99%

“…16 Alternatively, carbon-centered radicals can be thermodynamically stabilized via spin delocalization across a highly conjugated p-system and incorporation of heteroatoms. 16 In fact, the majority of persistent carbon-centered radicals are highly delocalized, which promotes p-p interactions and spinspin communication. [17][18][19] On the other hand, localization of spin density can increase spin polarization [20][21][22] and foster longer excited state lifetime, 23 faster spin mixing rate, 24,25 and higher reversibility of the cation-radical redox processes under air.…”

Section: Introductionmentioning

confidence: 99%

Persistent, highly localized, and tunable [4]helicene radicals

et al. 2020

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“…In the past years, there are two main methods to stabilize organic radicals, including covalent modifications [8][9][10][11][12][13][14][15] and supramolecular approaches. [4,[16][17][18][19][20][21] For covalent modifications, functional groups are usually modified around organic radicals, served as electron-withdrawing groups or steric hindrances, for delocalizing the spin density of radicals or protecting radicals from quenching. Comparing with covalent modifications, supramolecular approaches display moderate stabilization effects on free radicals.…”

Section: Doi: 101002/marc202000080mentioning

confidence: 99%

Supramolecular Polymeric Radicals: Highly Promoted Formation and Stabilization of Naphthalenediimide Radical Anions

Yang

Guo

et al. 2020

Macromol. Rapid Commun.

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The supramolecular polymeric radicals are developed to promote the generation efficiency and stability of naphthalenediimide (NDI) radical anions. To this end, a water‐soluble bifunctional monomer bearing two naphthalene‐viologen end groups and a NDI center is designed and synthesized. The supramolecular polymeric NDI radical anions are fabricated on the basis of host–guest complexation between the NDI‐containing bifunctional monomer and cucurbit[8]uril (CB[8]) and followed by the photoinduced electron transfer process under UV light irradiation. The electrostatic effect of CB[8] and the bulky and rigid structure of supramolecular polymer are combined to stabilize the excited state of NDIs and NDI radical anions, contributing to the high enhancement of the formation of NDI radical anions with excellent stability. It is found that the highest occupied molecular orbital energy and lowest unoccupied molecular orbital energy of NDI are also lowered by the formation of supramolecular polymer. In addition, the supramolecular polymeric NDI radical anions could be utilized as a supramolecular photoreducing agent to reduce cytochrome C with a higher efficiency. It is anticipated that other radicals can also be stabilized through this strategy, and this line of research may lead to the development of novel polymeric radical materials.

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Tuning the stability of organic radicals: from covalent approaches to non-covalent approaches

Abstract: Covalent and non-covalent approaches to tune the stability of organic radicals through steric effects and the delocalization of spin density.

Cited by 140 publications

References 91 publications

High Thermoelectric Performance in n‐Type Perylene Bisimide Induced by the Soret Effect

High Thermoelectric Performance in n‐Type Perylene Bisimide Induced by the Soret Effect

Persistent, highly localized, and tunable [4]helicene radicals

Supramolecular Polymeric Radicals: Highly Promoted Formation and Stabilization of Naphthalenediimide Radical Anions

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