Perspectives for polychlorinated trityl radicals

Ratera, Imma; Vidal-Gancedo, José; Maspoch, Daniel; Bromley, Stefan T.; Crivillers, Núria; Mas‐Torrent, Marta

doi:10.1039/d1tc02196f

Cited by 31 publications

(37 citation statements)

References 142 publications

(126 reference statements)

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“…Our characterization of Zn(II) tripyrrindione in solution, together with the fluorescence emission noted in earlier studies, indicated that the neutral zinc-bound tripyrrindione is indeed a new addition to the small cohort of stable radicals that are fluorescent at room temperature . Excitation at 599 nm elicits a bright emission at 644 nm in THF with a quantum yield of 0.23 ± 0.01 (Figure C).…”

Section: Tripyrrin-114-dionesupporting

confidence: 68%

“…Our characterization of Zn(II) tripyrrindione in solution, together with the fluorescence emission noted in earlier studies, 31 indicated that the neutral zinc-bound tripyrrindione is indeed a new addition to the small cohort of stable radicals that are fluorescent at room temperature. 48 Excitation at 599 nm elicits a bright emission at 644 nm in THF with a quantum yield of 0.23 ± 0.01 (Figure 5C). The luminescence of [Zn(TD1 • )(H 2 O)] therefore rivals that of other radical emitters, such as halogenated triarylmethyl radicals 49 and dithiadiazolyl radicals, 50 that are investigated for the development of electroluminescent devices.…”

Section: Luminescence Of the Tripyrrindione Radicalmentioning

confidence: 99%

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Biopyrrin Pigments: From Heme Metabolites to Redox-Active Ligands and Luminescent Radicals

Tomat

Curtis

2021

Acc. Chem. Res.

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Conspectus Redox-active ligands in coordination chemistry not only modulate the reactivity of the bound metal center but also serve as electron reservoirs to store redox equivalents. Among many applications in contemporary chemistry, the scope of redox-active ligands in biology is exemplified by the porphyrin radicals in the catalytic cycles of multiple heme enzymes (e.g., cytochrome P450, catalase) and the chlorophyll radicals in photosynthetic systems. This Account reviews the discovery of two redox-active ligands inspired by oligopyrrolic fragments found in biological settings as products of heme metabolism. Linear oligopyrroles, in which pyrrole heterocycles are linked by methylene or methine bridges, are ubiquitous in nature as part of the complex, multistep biosynthesis and degradation of hemes and chlorophylls. Bile pigments, such as biliverdin and bilirubin, are common and well-studied tetrapyrroles with characteristic pyrrolin-2-one rings at both terminal positions. The coordination chemistry of these open-chain pigments is less developed than that of porphyrins and other macrocyclic oligopyrroles; nevertheless, complexes of biliverdin and its synthetic analogs have been reported, along with fluorescent zinc complexes of phytobilins employed as bioanalytical tools. Notably, linear conjugated tetrapyrroles inherit from porphyrins the ability to stabilize unpaired electrons within their π system. The isolated complexes, however, present helical structures and generally limited stability. Smaller biopyrrins, which feature three or two pyrrole rings and the characteristic oxidized termini, have been known for several decades following their initial isolation as urinary pigments and heme metabolites. Although their coordination chemistry has remained largely unexplored, these compounds are structurally similar to the well-established tripyrrin and dipyrrin ligands employed in a broad variety of metal complexes. In this context, our study of the coordination chemistry of tripyrrin-1,14-dione and dipyrrin-1,9-dione was motivated by the potential to retain on these compact, versatile platforms the reversible ligand-based redox chemistry of larger tetrapyrrolic systems. The tripyrrindione ligand coordinates several divalent transition metals (i.e., Pd(II), Ni(II) Cu(II), Zn(II)) to form neutral complexes in which an unpaired electron is delocalized over the conjugated π system. These compounds, which are stable at room temperature and exposed to air, undergo reversible one-electron processes to access different redox states of the ligand system without affecting the oxidation state and coordination geometry of the metal center. We also characterized ligand-based radicals on the dipyrrindione platform in both homoleptic and heteroleptic complexes. In addition, this study documented noncovalent interactions (e.g., interligand hydrogen bonds with the pyrrolinone carbonyls, π-stacking of ligand-centered radicals) as important aspects of this coordination chemistry. Furthermore, the fluorescence of the zinc-bound ...

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Section: Tripyrrin-114-dionesupporting

confidence: 68%

Section: Luminescence Of the Tripyrrindione Radicalmentioning

confidence: 99%

Biopyrrin Pigments: From Heme Metabolites to Redox-Active Ligands and Luminescent Radicals

Tomat

Curtis

2021

Acc. Chem. Res.

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“…were the first long-lived p-radical derivatives reported almost exactly half a century ago, and despite the recent progress presented in this review, they are still the basis of the state-of-the-art p-radicals used in optics, electronics and magnetics. 39,298 TTM and PTM based D-A systems and their heteroatom derivatives have been particularly successful in optoelectronic applications delivering stable emission from the doublet excited state and facilitating record-breaking efficiencies in OLEDs, undoubtedly because of their superior steric protection and energetic stabilisation associated with kinetic and thermodynamic effects, respectively. Debate on inertness of the chlorine substituents on chlorophenylmethyl radicals regularly arises in the literature, and many of the published works correctly report variable degrees of dehalogenation during radical functionalisation (synthesis) and application (device operation).…”

Section: Discussionmentioning

confidence: 99%

Electro-optical π-radicals: design advances, applications and future perspectives

Murto

Bronstein

2022

J. Mater. Chem. C

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“…1–3 Organic π-conjugated radicals are also the subject of intense research in materials science because of their electron spin, making them innovative alternatives for the basis of next-generation optoelectronics, for instance, in organic field-effect transistors (OFETs), 4–6 organic light-emitting diodes (OLEDs), or organic magnets. 4,5,7–27 Furthermore, these molecular materials also provide fundamental insights about the nature of chemical bonds and their delocalization in open-shell systems, in addition to their other features such as narrow HOMO–LUMO energy gaps, low-lying doubly-excited states, or redox amphoterism. 4,10,12,13,15,28,29…”

Section: Introductionmentioning

confidence: 99%

Organic radicals with inversion of SOMO and HOMO energies and potential applications in optoelectronics

et al. 2022

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Perspectives for polychlorinated trityl radicals

Abstract: An organic free radical is a molecule with one or more unpaired electrons. Although most free radicals are highly reactive, chemists have developed a few families of so-called persistent organic...

Cited by 31 publications

References 142 publications

Biopyrrin Pigments: From Heme Metabolites to Redox-Active Ligands and Luminescent Radicals

Biopyrrin Pigments: From Heme Metabolites to Redox-Active Ligands and Luminescent Radicals

Electro-optical π-radicals: design advances, applications and future perspectives

Organic radicals with inversion of SOMO and HOMO energies and potential applications in optoelectronics

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