Free tetraradicals

Rozantsev, É. G.; Golubev, Vasiliy A.

doi:10.1007/bf00846732

Cited by 7 publications

(4 citation statements)

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“…The same uncertainty applies to organic oligomeric radicals in the water phase. There are some indications 13,16) that FS reacts with these species. It is, however, not known whether these reactions actually occur under emulsion polymerization conditions.…”

Section: Eq (4)mentioning

confidence: 99%

Particle growth in butadiene emulsion polymerization, 1. The use of Fremy salt as aqueous radical scavenger

Verdurmen

Geurts

German

1994

Macro Chemistry & Physics

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The kinetics of the seeded emulsion polymerization of butadiene in combination with variable Fremy salt (potassium nitrosodisulfonate) concentrations was investigated in order to monitor non‐steady state kinetics necessary for obtaining information on entry and exit of radicals from latex particles. Fremy salt is used because it is an entirely water‐soluble stable radical that in principle can scavenge water‐soluble radicals produced by a water‐soluble initiator like peroxodisulfate, but allegedly will not interfere with radicals within latex particles. Adequate buffering of the pH is a prerequisite for stable Fremy salt concentrations in time. Emulsion polymerizations in the presence of Fremy salt showed that not all radicals in the aqueous phase of a swollen polybutadiene latex are scavenged. The use of Fremy salt to monitor non‐steady state kinetics in the seeded emulsion polymerization of butadiene in the presence of tertiary dodecyl mercaptan yields no satisfying results. The use of Fremy salt seems to be restricted to systems where the rate of polymerization is strongly influenced by variation in initiator concentration, i.e. the styrene system or the butadiene system in the absence of tertiary dodecyl mercaptan.

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Section: Eq (4)mentioning

confidence: 99%

Particle growth in butadiene emulsion polymerization, 1. The use of Fremy salt as aqueous radical scavenger

Verdurmen

Geurts

German

1994

Macro Chemistry & Physics

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“…Another strategy for the stabilization of unpaired electrons is through delocalization via π-conjugation in planar molecular structures. ,,− This approach is effective to design systems with any number of unpaired electrons and can lead to singlet or doublet ground states with thermally accessible high-spin states (polyradicals) or singlet or doublet ground states with a little higher-lying high-spin states (polyradicaloids). The most widely studied polyradical(oid)s are diradical(oid)s with potential applications in organic electronics and spintronics, n-channel or ambipolar field effect transistors (FETs), organic magnetic materials, molecular switches, singlet fission with solar energy conversion capability, batteries, nonlinear optics, functional dyes, and photodynamic therapy. ,,− The history of higher-order polyradicals starts in 1964 with the first synthesized triradical and tetraradical, after which many experimental and theoretical studies followed. − ,− …”

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confidence: 99%

“…The most widely studied polyradical(oid)s are diradical(oid)s with potential applications in organic electronics and spintronics, n-channel or ambipolar field effect transistors (FETs), organic magnetic materials, molecular switches, singlet fission with solar energy conversion capability, batteries, nonlinear optics, functional dyes, and photodynamic therapy. 1 , 6 , 23 − 37 The history of higher-order polyradicals starts in 1964 with the first synthesized triradical 38 and tetraradical, 39 after which many experimental and theoretical studies followed. 11 − 21 , 40 − 55 …”

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confidence: 99%

Pathway to Polyradicals: A Planar and Fully π-Conjugated Organic Tetraradical(oid)

Betkhoshvili,

Moreira,

Poater

et al. 2024

J. Phys. Chem. Lett.

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In this work, we provide a general strategy to stabilize the ground state of polyradical(oid)s and make higher spin states thermally accessible. As a proof of concept, we propose to merge two planar fully π-conjugated diradical(oid)s to obtain a planar and cross-conjugated tetraradical(oid). Using multireference quantum chemistry methods, we show that the designed tetraradical(oid) is stabilized by aromaticity and delozalization in the π-system and has six thermally accessible spin states within 1.72 kcal/mol. Analysis of the electronic structure of these six states of the tetraradical(oid) shows that its frontier π-system consists of two weakly interacting subsystems: aromatic cycles and four unpaired electrons. Conjugation between unpaired electrons, which favors closed-shell structures, is mitigated by delocalization and the aromaticity of the bridging groups, leading to the synergistic cross-coupling between two diradical(oid) subunits to stabilize the tetraradical(oid) electronic structure.

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“…The procedure for NAD(P) regeneration generally considered best is that using flavin mononucleotide (FMN) with dioxygen as the ultimate oxidizing agent. 5,6 This procedure is convenient, the reaction is energetically favorable and, FMN is innocuous to enzymes. However, this noncatalytic regeneration system is not efficient enough for routine use in large-scale synthesis because large quantities of FMN and NAD(P) are required to achieve useful rates, and separation of products from the cofactors is inconvenient.…”

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confidence: 99%