Inert carbon free radicals

Ballester, Manuel

doi:10.1351/pac196715010123

Cited by 36 publications

(37 citation statements)

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“…6 Together, these studies have been regarded as both promising and significant. 5 As a result, the synthesis of perchlorinated trityl radical has become an immense undertaking with promising implications.…”

Section: Nih-pa Author Manuscriptmentioning

confidence: 99%

“…Studies have also shown that these reactive radicals become stable and chemically inert upon perchlorination. [5][6][7][8] In light of this endeavor, highly chlorinated mono-, di-, and triarylmethanes were developed and since then they have become the most valuable chemical precursors of inert free radicals with estimated half-lives in the order of 100 years. 6 Together, these studies have been regarded as both promising and significant.…”

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confidence: 99%

“…[5][6][7][8] In light of this endeavor, highly chlorinated mono-, di-, and triarylmethanes were developed and since then they have become the most valuable chemical precursors of inert free radicals with estimated half-lives in the order of 100 years. 6 Together, these studies have been regarded as both promising and significant. 5 As a result, the synthesis of perchlorinated trityl radical has become an immense undertaking with promising implications.…”

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Synthesis and characterization of a perchlorotriphenylmethyl (trityl) triester radical: A potential sensor for superoxide and oxygen in biological systems

Dang

Wang

Feng

et al. 2007

Bioorganic & Medicinal Chemistry Letters

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Synthesis and characterization of an inert perchlorotriphenylmethyl triester radical, PTM-TE, are reported. PTM-TE was prepared by a facile 3-step synthesis using Friedal-Crafts reaction of tetrachlorobenzene with chloroform followed by ethoxycarbonylation and subsequent oxidation. PTM-TE is paramagnetic, and detected as a single sharp peak by EPR spectroscopy. In solution, the EPR linewidth of PTM-TE is highly sensitive to the dissolved oxygen content, thus enabling accurate measurement of oxygen concentration (oximetry). In addition, the radical also shows high reactivity to superoxide. The ester radical has the potential for use as a high-sensitive probe for determination of oxygen concentration and superoxide in biological systems. KeywordsPerchlorotriphenylmethyl radical; perchlorotriphenylmethyl triester; superoxide; free radicals; EPR; oximetry; spectrophotometry In 1900, Moses Gomberg reported the existence of a stable, trivalent organic free radical which challenged the prevailing belief that carbon could only have four chemical bonds. 1 As this report provided new possibilities to carbon chemistry, research aimed at understanding and developing these radicals continued to thrive and permeated through various fields of science including medicine and industrial applications. Most notably, Gomberg's work paved the way for future research on using persistent trityl radicals in clinical applications. [2][3][4] However, it is known that some radicals and diradicals are short-lived and very reactive -the half-life of triphenylmethyl radicals in aerated solution may be as low as a fraction of a second. Studies have also shown that these reactive radicals become stable and chemically inert upon perchlorination. [5][6][7][8] In light of this endeavor, highly chlorinated mono-, di-, and triarylmethanes were developed and since then they have become the most valuable chemical precursors of inert free radicals with estimated half-lives in the order of Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript 100 years. 6 Together, these studies have been regarded as both promising and significant. 5 As a result, the synthesis of perchlorinated trityl radical has become an immense undertaking with promising implications.The role of reactive oxygen species (ROS) such as superoxide, hydroxyl, and alkylperoxyl radicals has been linked to a variety of pathophysiological processes. 9 Since, oxidative stress leads to an increased production of ROS, especially superoxide, accurate determinatio...

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confidence: 99%

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Synthesis and characterization of a perchlorotriphenylmethyl (trityl) triester radical: A potential sensor for superoxide and oxygen in biological systems

Dang

Wang

Feng

et al. 2007

Bioorganic & Medicinal Chemistry Letters

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“…The so-called 'inert carbon-free radicals' belong mainly to the perchlorodiphenylmethyl (Ballester & Riera, 1954), perchlorotriphenylmethyl (Ballester, 1967;Ballester, Riera, Castafier, Badfa & Mons6, 1971) and 9-phenylfluorenyl radical (Ballester, Castafier & Pujadas, 1971) classes. They have chemical and thermal stabilities which are higher than those of the majority of normal tetrahedral carbon compounds and materials.…”

Section: Commentmentioning

confidence: 99%

Perchlorotriphenylcarbenium Hexachloroantimonate(V)

Molins¹,

Mas²,

Maniukiewicz³

et al. 1996

Acta Crystallogr C

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“…18,23 Another family of trityl radicals, the tetrachloro-TAM radicals, was first introduced in 1967 (see Figure 1B). 24 Upon substitution of the six ortho positions with chlorine atoms, the central methyl carbon was sterically shielded providing high chemical and thermal stability. 25,26 Tetrachloro-TAM radicals show broader EPR lines due to coupling with the chlorine nuclei in close vicinity, but are distinguished by better synthetic accessibility than tetrathiatrityl radicals.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Nanoencapsulation of Tetrathiatriarylmethyl and Tetrachlorotriarylmethyl (Trityl) Radical Derivatives—A Study To Advance Their Applicability as in Vivo EPR Oxygen Sensors

et al. 2015

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Tissue oxygenation plays an important role in the pathophysiology of various diseases and is often a marker of prognosis and therapeutic response. EPR (ESR) is a suitable noninvasive oximetry technique. However, to reliably deploy soluble EPR probes as oxygen sensors in complex biological systems, there is still a need to investigate and improve their specificity, sensitivity, and stability. We reproducibly synthesized various derivatives of tetrathiatriarylmethyl and tetrachlorotriarylmethyl (trityl) radicals. Hydrophilic radicals were investigated in aqueous solution mimicking physiological conditions by, e.g., variation of viscosity and ionic strength. Their specificity was satisfactory, but the oxygen sensitivity was low. To enhance the capability of trityl radicals as oxygen sensors, encapsulation into oily core nanocapsules was performed. Thus, different lipophilic triesters were prepared and characterized in oily solution employing oils typically used in drug formulations, i.e., middle-chain triglycerides and isopropyl myristate. Our screening identified the deuterated ethyl ester of D-TAM (radical 13) to be suitable. It had an extremely narrow single EPR line under anoxic conditions and excellent oxygen sensitivity. After encapsulation, it retained its oxygen responsiveness and was protected against reduction by ascorbic acid. These biocompatible and highly sensitive nanosensors offer great potential for future EPR oximetry applications in preclinical research.

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Inert carbon free radicals

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Cited by 36 publications

References 1 publication

Synthesis and characterization of a perchlorotriphenylmethyl (trityl) triester radical: A potential sensor for superoxide and oxygen in biological systems

Synthesis and characterization of a perchlorotriphenylmethyl (trityl) triester radical: A potential sensor for superoxide and oxygen in biological systems

Perchlorotriphenylcarbenium Hexachloroantimonate(V)

Synthesis, Characterization, and Nanoencapsulation of Tetrathiatriarylmethyl and Tetrachlorotriarylmethyl (Trityl) Radical Derivatives—A Study To Advance Their Applicability as in Vivo EPR Oxygen Sensors

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