Recent advances in stable main group element radicals: preparation and characterization

Abstract

This review presents the recent advances in the synthesis, characterization, reactivity and physical properties of isolable main group elements radicals.

Construction of stable luminescent donor–acceptor neutral radicals: a theoretical study

“…Generally, the kinetic stability is related to the lifetime ( t 1/2 ) of radicals that can reflect the photostability to some extent. 24 For example, the % V Bur value of TTM is 46.1 and that of PTM is 52.7, which is well in line with the experimental t 1/2 of TTM (3.3 × 10 1 s) and PTM (1.0 × 10 2 s), since PTM has the greatly enhanced photostability with much longer t 1/2 . 37 However, although the steric of PTM is larger than that of BCz , its lifetime is shorter than that of BCz ( t 1/2 = 8 × 10 3 s), 25 which we speculate is related to the higher reactivity of the central carbon radical in PTM .…”

“…23 Despite the great success of luminescent radicals in OLEDs and other devices, the available material systems are much less than the closed-shell luminescent molecules, because of their rarity and low stability under ambient conditions or in photoexcited states. 24 The electron-accepting tris (2,4,6-trichlorophenyl)methyl radical (TTM), perchlorotriphenylmethyl radical (PTM) and bis (2,4, 6-trichlorophenyl)-methyl radical (BTM) are three typical examples of stable radicals that show efficient photoluminescence under ambient conditions. 25 The central carbon atom of TTM/PTM/BTM derivatives is sp 2 hybridized to allow for spin delocalization and is sterically shielded by six chlorine atoms, affording their high chemical stabilities; the ease of their synthesis offers versatile derivatization of triarylmethyl skeletons to tune the luminescence properties of the TTM/PTM/BTM radicals.…”

Synthesis and Single‐Electron Oxidation of Bulky Bis(m‐terphenyl)chalcogenides: The Quest for Kinetically Stabilized Radical Cations

“…Main group element centered radicals have received tremendous interest ever since Gomberg's seminal discovery of the trityl radical. [1,2] Amongst those, sulfur-based radicals play a pivotal role. [3][4][5][6] Diorgano sulfide radical cations, [R 2 S] * + (R = alkyl, aryl), generated from their neutral parents, R 2 S, by chemical one-electron oxidation, photolysis in the presence of a sensitizer or gamma radiolysis are only short-lived.…”

“…Main group element centered radicals have received tremendous interest ever since Gomberg's seminal discovery of the trityl radical [1,2] . Amongst those, sulfur‐based radicals play a pivotal role [3–6] .…”

Non-aromatic 1,3-Disilapyrroles: a class of stable organosilicon-based triplet diradicals

“…4,5 However, owing to their extremely high reactivity, the isolation of these diradicals remains challenging. 4,[6][7][8][9][10] By taking advantage of thermodynamic and kinetic stabilization, Niecke and co-workers isolated the rst carbon-based C 2 P 2 four-membered singlet diradical species in 1995. 11 Since then several cyclic four-membered heteronuclear X 2 Y 2 -ring species including two silicon-based Si 2 N 2 and Si 2 C 2 containing singlet diradicals were isolated and characterized.…”