Double-bond fixation and aromatic stability in cyclic difulvalene systems

Toyota, Azumao; Nakajima, Takeshi; Koseki, Shirou

doi:10.1039/p29840000085

Cited by 8 publications

(4 citation statements)

References 4 publications

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“…Synthesis was achieved from a double ejection of dinitrogen from bis-pyrazole and the X-ray results showed an almost planar molecule with significant bond length variations in the fused benzene rings in analogy with the 1,5-diyne analogue. Compound 276 and a range of other cyclopropa-fused cyclooctatetraenes were addressed in MINDO/3 and PPP SCF-MO studies and the adventitious use of cyclopropa fusion for planarizing nine- and ten-membered rings was pointed out . Much more recently Schleyer has predicted that the unknown dicyclopropa[ a,f ]cyclodecapentaene (1,6-dicyclopropa[10]annulene) ( 277 ) will be planar with D 2 h symmetry and exhibit properties consistent with aromaticity.…”

Section: Heteroatom and Related Ring Systemsmentioning

confidence: 99%

Cycloproparenes

Halton

2003

Chem. Rev.

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Section: Heteroatom and Related Ring Systemsmentioning

confidence: 99%

Cycloproparenes

Halton

2003

Chem. Rev.

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“…22 Several research groups have studied benzocyclobutene (BCB)23-27 theoretically. Some of these papers discuss the Mills-Nixon effect, but no paper has appeared so far which examines the electronic structures of the nitrogen analogue, benzoazacyclobutene.…”

Section: Resultsmentioning

confidence: 99%

FORS MCSCF Study on Nitrenophenylmethylene (C6H4CHN)

Koseki¹,

Tomioka²,

Toyota³

1994

J. Phys. Chem.

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Electronic structure calculations for the ortho, meta, and para isomers of nitrenophenylmethylene (c6H4-CHN) are carried out by using the full-optimized-reaction-space (FORS) multiconfiguration self-consistentfield (MCSCF) method with the STO-3G basis set. The ortho isomer is predicted to possess a singlet ground state with a bond-alternated structure. However, since the energy barrier for the isomerization reaction of the ortho structure to a bicyclic one (benzoazacyclobutene or benz[b]azete) is less than 10 kcaymol, the ortho isomer is considered to have a relatively short lifetime and hence to exist in the stable bicyclic form. The para isomer also has a singlet ground state with a bond-alternated structure, but it may easily react with molecular oxygen, as suggested experimentally, because the lowest triplet state is very close in energy to the singlet ground state. In marked contrast, the meta isomer has a quintet ground state, and this aspect is well reflected in the bonding, which shows no appreciable n conjugation between a benzene nucleus and two radical substituents.

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“…Very few, i.e. on the order of 10, organic INVEST molecules were predicted on the basis of computations alone 2,13,14 with little to no experimental evidence, 15,16 and, as far as we know, no inorganic INVEST molecule is known to date. Besides inherently inverted molecules, it has been shown in recent years that the influence of the environment can also make the gap negative, 17 for instance in exciplexes, 18 through strong light-matter coupling in microcavities, 19 and polarizable environments.…”

Section: Introductionmentioning

confidence: 99%

Organic Molecules with Inverted Gaps between First Excited Singlet and Triplet States and Appreciable Fluorescence Rates

Pollice

Friederich²,

Lavigne³

et al. 2020

Preprint

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One of the recent proposals for the design of state-of-the-art emissive materials for organic light emitting diodes (OLEDs) is the principle of thermally activated delayed fluorescence (TADF). The underlying idea is to enable facile thermal upconversion of excited state triplets, which are generated upon electron-hole recombination, to excited state singlets by minimizing the corresponding energy difference resulting in devices with up to 100% internal quantum efficiencies (IQEs). Ideal emissive materials potentially surpassing TADF emitters should have both negative singlet-triplet gaps and appreciable fluorescence rates to maximize reverse intersystem crossing (rISC) rates from excited triplets to singlets while minimizing ISC rates and triplet state occupation leading to long-term operational stability. However, molecules with negative singlet-triplet gaps are extremely rare and, to the best of our knowledge, not emissive. In this work, based on computational studies, we describe the first molecules with negative singlet-triplet gaps and considerable fluorescence rates and show that they are more common than hypothesized previously.

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Double-bond fixation and aromatic stability in cyclic difulvalene systems

Cited by 8 publications

References 4 publications

Cycloproparenes

Cycloproparenes

FORS MCSCF Study on Nitrenophenylmethylene (C6H4CHN)

Organic Molecules with Inverted Gaps between First Excited Singlet and Triplet States and Appreciable Fluorescence Rates

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