The Synthesis and Characterization of Stable Radicals Containing the Thiazyl (SN) Fragment and Their Use as Building Blocks for Advanced Functional Materials

Hicks, Robin G.

doi:10.1002/9780470666975.ch9

Cited by 24 publications

(7 citation statements)

References 256 publications

(295 reference statements)

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“…354−367 The relative stability of these diyls, most of which have a singlet ground state, arises from a combination of electronic, steric, and strain effects preventing a barrier-less ring closure. 363 Another important class of stable, localized main group diradicals are the (bis)aminoxyls, hydrazyls, thiazyls, and verdazyls, 368,369 etc. (cf.…”

Section: Chemical Reviewsmentioning

confidence: 99%

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Do Diradicals Behave Like Radicals?

et al. 2019

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This review sets out to understand the reactivity of diradicals and how that may differ from monoradicals. In the first part of the review, we delineate the electronic structure of a diradical with its two degenerate or nearly degenerate molecular orbitals, occupied by two electrons. A classification of diradicals based on whether or not the two SOMOs can be located on different sites of the molecule is useful in determining the ground state spin. Important is a delocalized to localized orbital transformation that interchanges “closed-shell” to “open-shell” descriptions. The resulting duality is useful in understanding the dual reactivity of singlet diradicals. In the second part of the review, we examine, with a consistent level of theory, activation energies of prototypical radical reactions (dimerization, hydrogen abstraction, and addition to ethylene) for representative organic diradicals and diradicaloids in their two lowest spin states. Differences and similarities in reactivity of diradicals vs monoradicals, based on either a localized or delocalized view, whichever is suitable, are then discussed. The last part of this review begins with an extensive, comparative, and critical survey of available measures of diradical character and ends with an analysis of the consequences of diradical character for selected diradicaloids.

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Section: Chemical Reviewsmentioning

confidence: 99%

“…Another important class of stable, localized main group diradicals are the (bis)aminoxyls, hydrazyls, thiazyls, and verdazyls, , etc. (cf.…”

Section: Some Typical Diradicals and Diradicaloidsmentioning

confidence: 99%

Do Diradicals Behave Like Radicals?

et al. 2019

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“…However, most single component neutral π-radicals are insulators or poorly conductive semiconductors (σ RT < 10 -10 S cm -1 ) due to the conduction barrier originating from the on-site Coulomb repulsion (U, Mott insulator) 7,8 and the steric hindrance needed to impart kinetic stability inhibiting intermolecular interactions 9,10 . High conductivities in single component neutral radicals with σ RT > 10 -6 S cm -1 have been reported in several systems, such as bisdithiazolyl and related radicals [11][12][13][14][15][16][17] (σ RT = 4 × 10 -2 S cm -1 at most 17 , measured for single crystals), and betainic TCNQ 18 and N,N'-dicyanoquinodiiminide 19 radicals (σ RT = 3.2 × 10 -5 and 1.6 × 10 -5 S cm -1 and at most, measured for compressed pellets, respectively), betainic TTF radicals 20 (σ RT = 1.0 × 10 -1 S cm -1 at most, measured for compressed pellets), where the heteroatom effects and strong polarizability contribute to the reduction of U. It should be noted that carrier doping into neutral radical crystals generates the MV state and dramatically increases conductivity 21,22 .…”

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confidence: 98%

Mixed valence salts based on carbon-centered neutral radical crystals

2018

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Organic neutral radicals have been predicted to exhibit various electronic functions such as electrical conduction. However, most organic neutral radicals are insulators, because they cannot form sufficient intermolecular interactions due to the bulky substituent groups required for stabilization. Here we report that one-dimensional assemblies of carbon-centered neutral π-radicals, namely 4,8,12,trioxotriangulene derivatives, possess effective conducting pathways as a result of strong intermolecular interactions based on twoelectron-multicenter bonding. The columns of trioxotriangulene derivatives with weak π-dimerization and uniform π-stacking exhibit semiconducting behaviors, with high conductivities of~10 −3 S cm −1 as a single component purely organic molecular system. We exploit this general tendency to form one-dimensional assemblies, and the large 25 π-electronic system with a robust condensed polycyclic structure, to obtain mixed-valence salts consisting of neutral radicals and the corresponding anionic species with a higher roomtemperature conductivity of 1-125 S cm −1 .

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“…Since the first synthesis by Markovski and co-workers, a number of cyclic thiazyl radical compounds have been synthesized and crystallized. − These compounds are remarkable owing to their stability (low reactivity of the unpaired electron), their electron donor character, and their ability to form covalent-like intermolecular interactions, which make them candidates as organic molecular conductors. , In fact, Oakley and co-workers reported that a single crystal of an N -methyl bisdithiazolyl radical exhibits high conductivity reaching nearly 10 –3 S/cm at room temperature, which is comparable to nickel bisdithiolato-complex [Ni(dmit) 2 ](NBu 4 ) 0.29 , a typical high-conductive molecular crystal …”

Section: Introductionmentioning

confidence: 99%

Theoretical Study on Third-Order Nonlinear Optical Property of One-Dimensional Cyclic Thiazyl Radical Aggregates: Intermolecular Distance, Open-Shell Nature, and Spin State Dependences

et al. 2018

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Using the spin-unrestricted density functional theory method, we investigate the relationship between structure, spin state, and second hyperpolarizability (γ) of the finite and infinite one-dimensional open-shell aggregates composed of cyclic thiazyl radicals, that is, 1,2,3,5-dithiadiazolyl (DTDA) radicals. The DTDA aggregates with antiferromagnetic spin-alignment exhibit much greater enhancement of γ than the aggregates with ferromagnetic spinalignment and the closed-shell benzene aggregates due to the intermediate open-shell singlet nature of the antiferromagnetic DTDA aggregate. It is found that this enhancement shows strong intermolecular distance dependences: the intermolecular distance giving the largest enhancement of γ decreases with increasing the number of molecules, and intermolecular distance alternation reduces the γ. For the infinite antiferromagnetic DTDA aggregate with a realistic intermolecular distance d = 3.1 Å, the γ per monomer reaches 1.9 × 10 6 au, which is comparable to that of the infinite open-shell singlet aggregate of phenalenyl radicals, and exhibits ∼2400 times enhancement as compared to that of the closed-shell benzene aggregate. This feature indicates the high-potential application of open-shell singlet cyclic thiazyl radical aggregates to outstanding third-order NLO materials.

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The Synthesis and Characterization of Stable Radicals Containing the Thiazyl (SN) Fragment and Their Use as Building Blocks for Advanced Functional Materials

Cited by 24 publications

References 256 publications

Do Diradicals Behave Like Radicals?

Do Diradicals Behave Like Radicals?

Mixed valence salts based on carbon-centered neutral radical crystals

Theoretical Study on Third-Order Nonlinear Optical Property of One-Dimensional Cyclic Thiazyl Radical Aggregates: Intermolecular Distance, Open-Shell Nature, and Spin State Dependences

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