Substituent-Dependent Magnetic Behavior of Discotic Benzo[<i>e</i>][1,2,4]triazinyls

Jasiński, Marcin; Szczytko, Jacek; Pociecha, Damian; Monobe, Hirosato; Kaszyński, Piotr

doi:10.1021/jacs.6b06444

Cited by 64 publications

(59 citation statements)

References 31 publications

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“…The chemistry of the benzotriazinyl radical, known as the Blatter radical, has been developed in the past decade from the viewpoints of synthetic chemistry for the basic skeleton and the transformation of functional groups, as well as a computational study on the π‐electron system . Interesting physicochemical properties, such as spin transitions accompanying a change in molecular packing, liquid‐crystalline behavior, metal coordination,,, intramolecular ferromagnetic interaction in the hetero‐biradical derivative, the formation of a high‐spin molecular assembly, and a zwitterionic singlet state accompanying fluorescence, have been observed in the benzotriazinyl radical family.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Interactions through a Nonconjugated Framework Observed in Back‐to‐Back Connected Triazinyl–Nitroxyl Biradical Derivatives

Takahashi

Matsuhashi

Miura

et al. 2018

Chemistry A European J

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Three hetero-biradical derivatives, with the structure of a back-to-back connected benzotriazinyl and tetramethyl or tetraethylisoindoline N-oxyl sharing a common benzo ring, 3-tert-butyl-1-phenyl-1,4,6,8-tetrahydro-6,6,8,8-tetramethyl-pyrrolo[4,5-g]-1,2,4-benzotriazin-4-yl-7-oxyl (1-tBu), 1,3-diphenyl-1,4,6,8-tetrahydro-6,6,8,8-tetramethyl-pyrrolo[4,5-g]-1,2,4-benzotriazin-4-yl-7-oxyl (1-Ph), and 3-tert-butyl-1-phenyl-1,4,6,8-tetrahydro-6,6,8,8-tetraethyl-pyrrolo[4,5-g]-1,2,4-benzotriazin-4-yl-7-oxyl (2-tBu), were synthesized and characterized by single-crystal X-ray analyses, variable-temperature magnetic susceptibility studies, and DFT calculations. Temperature dependences of the magnetic susceptibilities of 1-tBu, 1-Ph, and 2-tBu exhibit broad maxima at 70, 71, and 43 K, respectively. Although these radical derivatives form a columnar or chained assembly in the solid state, magnetic measurements of diluted samples in the polymer matrices and computational results imply that the magnetic properties of the polycrystalline sample can be explained by a two-spin system with an intramolecular antiferromagnetic interaction. The magnetic behavior can be reproduced by using the Bleaney-Bowers model, with 2J=-80.0 cm for 1-tBu, 2J=-77.1 cm for 1-Ph, and 2J=-48.9 cm for 2-tBu. The moderately strong intramolecular antiferromagnetic interactions can be interpreted by a through-bond interaction through the nonconjugated framework and/or through-space interactions based on molecular orbital theory. The strong distance dependency between the N-O spin site and vinylic carbon atoms indicates that the orbital interaction plays an important role in the intramolecular magnetic interaction. The reduced magnetic interaction in 2-tBu relative to those of 1-tBu and 1-Ph can be attributed to restricted rotation of the tetraethyl group.

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Section: Introductionmentioning

confidence: 99%

Magnetic Interactions through a Nonconjugated Framework Observed in Back‐to‐Back Connected Triazinyl–Nitroxyl Biradical Derivatives

Takahashi

Matsuhashi

Miura

et al. 2018

Chemistry A European J

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“…1)1 is an example of a benzotriazinyl radical with remarkable bench-top stability. Although relatively unexplored since the early report by Blatter in 1968, there has been increased recent interest in this radical and derivatives due to their suitability as building blocks for magnetic materials2345678910111213, as polymerization initiators141516 and as ligands in novel radical-metal coordination complexes1718. Related benzotriazines and N-oxide derivatives have seen application in medicinal chemistry, including as anti-cancer drugs, where benzotriazinyl radicals have been proposed as potential DNA-damaging species19202122.…”

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confidence: 99%

New Blatter-type radicals from a bench-stable carbene

et al. 2017

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Stable benzotriazinyl radicals (Blatter's radicals) recently attracted considerable interest as building blocks for functional materials. The existing strategies to derivatize Blatter's radicals are limited, however, and synthetic routes are complex. Here, we report that an inexpensive, commercially available, analytical reagent Nitron undergoes a previously unrecognized transformation in wet acetonitrile in the presence of air to yield a new Blatter-type radical with an amide group replacing a phenyl at the C(3)-position. This one-pot reaction of Nitron provides access to a range of previously inaccessible triazinyl radicals with excellent benchtop stabilities. Mechanistic investigation suggests that the reaction starts with a hydrolytic cleavage of the triazole ring followed by oxidative cyclization. Several derivatives of Nitron were prepared and converted into Blatter-type radicals to test the synthetic value of the new reaction. These results significantly expand the scope of using functionalized benzotriazinyls as stable radical building blocks.

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“…Radicals in series 1[n] were obtained in typical yields of 70-90 % using our recently reported protocol [7,9] involving addition of ArLi to benzo[e] [1,2,4]triazine 2 followed by aerial oxidation of the intermediate anion (Scheme 1). The ArLi reagents were generated from the corresponding ArBr 3[n] and t-BuLi.…”

Section: Synthesismentioning

confidence: 99%

“…Recently, we reported [7] discotic materials derived from the exceptionally stable benzo[e] [1,2,4]triazin-4-yl [8] in which the electron spin is delocalized in the π-system of the rigid core. Preliminary experiments indicated that the contact of the π faces and hence the type of spin-spin interactions is controlled by the peripheral substituents.…”

Section: Introductionmentioning

confidence: 99%

Tuning the Magnetic Properties of Columnar Benzo[e][1,2,4]triazin‐4‐yls with the Molecular Shape

et al. 2019

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A homologous series of disc-like 1,3,6-trisubstituted benzo [e] [1,2,4]triazin-4-yls 1[n] was synthesized and their structural, thermal, optical, magnetic, and electric properties were investigated. The results demonstrate that all members of the series display a Col h phase with clearing temperatures depending on the length of the alkoxy chains at the N(1) position, hence the shape of the disc. Powder XRD and magnetic data indicate a gradual change in the column diameter and magnetic behavior in the series in transition from half-disc in 1[0] (antiferromagnetic interactions) to full-disc geometry in the 1[12] homologue (ferromagnetic interactions with J/k B = + 7.5 K). Studies of binary systems revealed that a 1 : 1 mixture of 1[0] and 1[12] exhibits modest stabilization of the Col h phase with an expanded range, and magnetic behavior typical for 1[0] in the rigid phase obtained from the melt. Electric measurements demonstrated hole mobility of~10 À 3 cm 2 V À 1 s À 1 and dark conductivity of~10 À 11 Scm À 1 in the mixture and individual compounds. The latter is enhanced up to 4 times by simultaneous illumination with UV light.[a] Dr.

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Substituent-Dependent Magnetic Behavior of Discotic Benzo[e][1,2,4]triazinyls

Cited by 64 publications

References 31 publications

Magnetic Interactions through a Nonconjugated Framework Observed in Back‐to‐Back Connected Triazinyl–Nitroxyl Biradical Derivatives

Magnetic Interactions through a Nonconjugated Framework Observed in Back‐to‐Back Connected Triazinyl–Nitroxyl Biradical Derivatives

New Blatter-type radicals from a bench-stable carbene

Tuning the Magnetic Properties of Columnar Benzo[e][1,2,4]triazin‐4‐yls with the Molecular Shape

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