Matrix isolation and DFT calculations of the TMM radical cation generated via the single electron oxidation of a methylenecyclopropane

Ikeda, Hiroshi; Namai, Hayato; Kato, Nobuyuki; Ikeda, Teruyo

doi:10.1016/j.tetlet.2005.12.063

Cited by 14 publications

(14 citation statements)

References 26 publications

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“…Emission in this case was assigned to triplet‐triplet fluorescence (T−T FL) arising from the excited triplet state of the ring opened trimethylenemethane (TMM) biradical 3 2 a .. * . These observations demonstrated that triplet biradicals 3 2 .. * are produced by a 3 step pathway (Scheme , route A) involving (1) irradiation promoted charge separation of 1 generating 1 .+ and 1 .− , (2) ring‐opening reaction of 1 .+ forming TMM‐type radical cations 2 .+ , and (3) CR of 2 .+ and 1 .− …”

Section: Methodsmentioning

confidence: 91%

“…Emission in this case was assigned to triplet-triplet fluorescence (TÀ T FL) arising from the excited triplet state of the ring opened trimethylenemethane (TMM) biradical 3 2 a ** *. [13,14] These observations demonstrated that triplet biradicals 3 2 ** * are produced by a 3 step pathway (Scheme 1, route A) involving (1) irradiation promoted charge separation of 1 generating 1 * + and 1 * À , (2) ring-opening reaction of 1 * + forming TMM-type radical cations 2 * + , [11,15] and (3) CR of 2 * + and 1 * À . [16,17] It is interesting to point out that the general mechanistic route responsible for γ- [10,11] or X-ray [12] induced TL is similar to that operating in organic light-emitting diodes (OLEDs), where emission takes place from excited species generated by CR between radical cations and radical anions.…”

Section: Rates Of Ring Opening Of Radical Cation Intermediates Governmentioning

confidence: 89%

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Rates of Ring Opening of Radical Cation Intermediates Govern Differences in Thermoluminescence between 1‐ and 2‐Naphthyl‐Substituted Methylenecyclopropanes

et al. 2019

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In this study, we observed that methylenecyclopropane 1 c, possessing geminal phenyl and 1‐naphthyl groups at C‐2 of the three membered ring, emits green thermoluminescence (TL) in a low temperature matrix, associated with two sets of bands in the 480–600 and 600–700 nm regions. The bands are assigned to phosphorescence from 31 c* and triplet‐triplet (T−T) fluorescence (FL) from the corresponding trimethylenemethane biradical 32 c..*, respectively. In contrast, as previously reported, the analogous 2‐naphthyl derivative 1 b emits red TL associated with two bands in the 350–450 and 600–700 nm regions, which are assigned to FL from 11 b* and T−T FL from 32 b..*. The results of spectroscopic studies and density functional theory calculations show that the observed dissimilarity in the TL properties of 1 b and 1 c is a consequence of differences in the rate of methylenecyclopropane ring opening of 1 b.+ and 1 c.+ associated with stereoelectronic effects of the naphthyl groups.

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Section: Methodsmentioning

confidence: 91%

Section: Rates Of Ring Opening Of Radical Cation Intermediates Governmentioning

confidence: 89%

Rates of Ring Opening of Radical Cation Intermediates Govern Differences in Thermoluminescence between 1‐ and 2‐Naphthyl‐Substituted Methylenecyclopropanes

et al. 2019

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“…DFT calculations often give more satisfactory results. Indeed our experience has shown that charge and spin densities ( q and ρ , respectively) calculated by using the B3LYP method are of sufficiently high quality to explain the reactivity of 2,2′,3,3′‐tetraphenylbicyclopropenyl radical cations [restricted B3LYP/6‐31G(p)], the molecular geometries and electronic structure of the geminally diphenyl‐substituted trimethylenemethane radical cation and 1,4‐diphenylcyclohexane‐1,4‐diyl radical cation ( 5 •+ ) (UB3LYP/cc‐pVDZ), and the classical and nonclassical radical ions derived from 7‐benzhydrylidenenorbornene analogs, in addition to other reactive intermediates of this type …”

Section: Methodsmentioning

confidence: 99%

Density functional theory study of silole‐fused tetramethyleneethane biradicals with orbital interactions

Kano

Mizuno

Ikeda

2011

J of Physical Organic Chem

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The geometries, energy gap between singlet and triplet states (S–T gap), electronic transitions, and molecular orbitals of the diphenyl derivative of the silole‐fused tetramethyleneethane (TME) (3,4‐dimethylenesilole) biradical 7•• were determined by using the density functional theory method at the unrestricted Becke, three‐parameter, Lee–Yang–Parr/cc‐pVDZ level. In a manner similar to that of the parent TME biradical, the S–T gap of 7•• is small. The wavelengths of electronic transitions of 37•• (λET = 450 nm) are calculated to be different from that of 17•• (λET = 673 nm). These differences are attributed to interactions between orbitals of the two allyl radical moieties, especially, the existence of double σ*–π* conjugation, that is, π*–σ*–π* conjugation, that takes place in the silole subunit. Copyright © 2011 John Wiley & Sons, Ltd.

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“…Matrix isolation of 2 · + + generated by g-irradiation of alow temperature matrixof1 g-Irradiation of as ubstrate in an n-butylchloride (nBuCl) matrix at 77 Ki sastandard methodology to isolate and observe radical cations established by Shida and co-workers. [25,26] g-Irradiation of degassed nBuCl matricesc ontaining 1b and 1d (5 mm) at 77 Kg ave rise to sharp absorption bands at l AB = 578 and 660 nm, respectively (Figure 8). These bands were similar to transient absorption bands seen in the LFP experiments ( Figure 4c,d).…”

Section: Dft and Td-dft Calculationsf Or Transient Intermediatesmentioning

confidence: 99%

Electron‐Transfer Reactions Triggered by Uncharged or Cationic Photosensitizer: Methodology for Generation of o‐Quinodimethane and Analysis of Back Electron‐Transfer Process

et al. 2017

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Photoinduced electron transfer (PET) followed by back electron transfer (BET) reactions of 1,2-bis(a-styryl)benzenes 1,g enerates o-quinodimethane derivative 2 via the corresponding radical cation 2 · + .T his process serves as af acile methodt of orm o-quinodimethane intermediates. The intermediacy of 2 · + and 2 werec onfirmed by using various spectroscopicm ethods and trapping reactions with 3 O 2 and dienophiles. Kinetic analysisu sing nanosecond time-re-solved absorption showed that 2 · + was transformed to 2 via aB ET process, in which the decay of 2 · + and rise of 2 have almostt he same rate constants of k DECAY = 5.6 10 5 s À1 and k RISE = 5.9 10 5 s À1 ,r espectively.T he net BET rate constant evaluated by using Marcus theory is much faster than these experimental values, owing to the reduction based on diffusion.[a] Prof.form (M · + + +A · )a nd thes econdE Ti n( D + +M · + )f orms (D · + + +M). Ther esulting long distance betweenD · + andA · effectivelyp reventsf ormationo f[ D · + //A · ], thereforet he lifetime of D · + is substantially extended.I nt erms of analyzingt he BETp rocess, the most importanti nt hise fforti sB ET between( D · + + +A · ), whichi s formed in theP ET reactionss hown in Scheme 1b and1 c. As showni nS cheme1d, ther atec onstant (k BET )i sd efined fort he BETreactioni nt he encounterc omplex [D · + //A · ] EC that relatest o theassociation anddissociationof(D · + + A · ).Uncharged organic sensitizers, such as 9,10-dicyanoanthracene (DCA, Figure 1) and 1,4-dicyanonaphthalene (DCN), are conventional. Typical cationic sensitizers such as N-methylquinoliniumt etrafluoroborate (NMQ + BF 4 À ), [6] 2,4,6-triphenylpyrylium tetrafluoroborate( TPP + BF 4 À ), and N-methyl-9-mesitylacridinium perchlorate (Mes-Acr + ClO 4 À ,F ukuzumip hotocatalyst 7 ) can promote reactions of free D · + .R ecently,o rganometallic complexes,s uch as Ru(bpy) 3 2 + (Cl À ) 2 and fac-Ir(ppy) 3 ,h ave also been used in organic synthesis. [8] Upon excitation by visible light, these complexes undergo intersystem crossing to form long-lived triplet excited states.T he long lifetime induces ah igh possibility of collision with D, while the triplet state at alow energy level results in relatively low oxidation ability. g-Irradiationi naspecific solvent can also induce ET without any sensitizer and is often used forspectroscopic measurements.Kinetic analysiss uch as Stern-Volmer analysis is ap owerful tool to examine the synthetics tudy on aP ET reaction. When using an on-fluorescents ensitizer,l aser flash photolysis (LFP) provides informationa bout the formation and decay of D · + (Figure 2a). However, information on the recovery of Db yB ET,

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Matrix isolation and DFT calculations of the TMM radical cation generated via the single electron oxidation of a methylenecyclopropane

Cited by 14 publications

References 26 publications

Rates of Ring Opening of Radical Cation Intermediates Govern Differences in Thermoluminescence between 1‐ and 2‐Naphthyl‐Substituted Methylenecyclopropanes

Rates of Ring Opening of Radical Cation Intermediates Govern Differences in Thermoluminescence between 1‐ and 2‐Naphthyl‐Substituted Methylenecyclopropanes

Density functional theory study of silole‐fused tetramethyleneethane biradicals with orbital interactions

Electron‐Transfer Reactions Triggered by Uncharged or Cationic Photosensitizer: Methodology for Generation of o‐Quinodimethane and Analysis of Back Electron‐Transfer Process

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