Inert carbon free radicals. 3. Monofunctionalized radicals from perchlorotriphenylcarbenium hexachloroantimonate

Ballester, Manuel; Riera, J.; Castañer, J.; Rodríguez, Antonio García; Rovira, C.; Veciana, Jaume

doi:10.1021/jo00144a019

Cited by 44 publications

(34 citation statements)

References 3 publications

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“…To overcome these difficulties, compound 4 was first converted into the hexaester 5 with diazomethane 32. Afterwards, treatment of 5 with tetrabutylammonium hydroxide yielded the intermediate carbanion, which presented the absorption band characteristic of an anionic PTM species at 520 nm 33. This intermediate was then oxidized to the corresponding radical 6 by addition of an excess of para ‐chloranil.…”

Section: Resultsmentioning

confidence: 99%

Three‐Dimensional Six‐Connecting Organic Building Blocks Based on Polychlorotriphenylmethyl Units—Synthesis, Self‐Assembly, and Magnetic Properties

Roques

Maspoch

Wurst

et al. 2006

Chemistry A European J

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The synthesis of a three-dimensional, six-connecting, organic building block based on a robust, rigid, and open-shell polychlorotriphenylmethyl (PTM) unit (radical 1) is reported, and its self-assembly properties are described in detail. The tendencies of this highly polar molecule and its hydrogenated precursor, compound 4, to form hydrogen bonds with oxygenated solvents ([1THF(6)] and [4THF(6)]) were reduced by replacing THF with diethyl ether in the crystallization process to yield two-dimensional (2D) hydrogen-bonded structures ([1(Et(2)O)(3)] and [4(Et(2)O)(3)]). The presence of direct hydrogen bonds between the radicals in the latter phase of 1 gives rise to very weak ferromagnetic intermolecular interactions at low temperatures, whereas when the radicals are isolated by THF molecules these interactions are antiferromagnetic and very weak. The role played by the carboxylic groups not only in the self-assembly properties but also in the transmission of the magnetic interactions has been illustrated by determination of the crystal structure and measurement of the magnetic properties of the corresponding hexaester radical 6, in which the close packing of molecular units gives rise to weak antiferromagnetic intermolecular interactions. Attempts to avoid solvation of the molecules in the solid state and to increase the structural and magnetic dimensionality were pursued by recrystallization of both compounds 1 and 4 from concentrated nitric acid, affording two three-dimensional (3D) robust hydrogen-bonded structures. While the structure obtained with compound 4 is characterized by the presence of polar channels and boxes containing water guest molecules along the c axis, radical 1 was oxidized to the corresponding fuchsone 10, which presented a completely different close-packed, guest-free structure.

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Section: Resultsmentioning

confidence: 99%

Three‐Dimensional Six‐Connecting Organic Building Blocks Based on Polychlorotriphenylmethyl Units—Synthesis, Self‐Assembly, and Magnetic Properties

Roques

Maspoch

Wurst

et al. 2006

Chemistry A European J

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“…Spectra of aH-PTM derivatives show bands in the 220 and 290-330 nm regions: these are assigned to the benzenoid character of the molecule. [51] Upon excitation at 340 nm, the PTM radical shows an intense emission centered at 690 nm, whereas this emission is not observed for the aH-precursor. [53,54] To understand the solid-state photoluminescence (PL) properties of Ln-based coordination polymers 1-5 and 1'-5', the solid-state properties of both carboxylic and carboxylate forms of the aH-and radical PTM ligands were first investigated.…”

Section: Wwwchemeurjorgmentioning

confidence: 98%

“…[51,52] Typically, the UV-visible absorption spectrum of a PTM radical is characterized by several absorptions at around 220, 290-330, 370-395, and 500-575 nm. Radical character transitions correspond to the last two absorptions; the one between 500 and 575 nm is responsible for the intense red color.…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

Three‐Dimensional Open‐Frameworks Based on Ln^IIIIons and Open‐/Closed‐Shell PTM Ligands: Synthesis, Structure, Luminescence, and Magnetic Properties

Datcu

Roques

Jubera

et al. 2011

Chemistry A European J

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A series of isostructural open-framework coordination polymers formulated as [Ln(dmf)(3)(ptmtc)] (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5); PTMTC = polychlorotriphenylmethyl tricarboxylate) and [Ln(dmf)(2)H(2)O(αH-ptmtc)] (Ln = Sm (1'), Eu (2'), Gd (3'), Tb (4'), Dy (5')) have been obtained by treating Ln(III) ions with PTMTC ligands with a radical (PTMTC(3-)) or a closed-shell character (αH-PTMTC(3-)). X-ray diffraction analyses reveal that these coordination polymers possess 3D architectures that combine large channels and fairly rare lattice complex T connectivity. In addition, these compounds show selective framework dynamic sorption properties. For both classes of ligands, the ability to act as an antenna in Ln sensitization processes has been investigated. No luminescence was observed for compounds 1-5, and 3' because of the PTMTC(3-) ligand and/or Gd(III) ion characteristics. Conversely, photoluminescence measurements show that 1', 2', 4', and 5' emit dark orange, red, green, and dark cyan metal-centered luminescence. The magnetic properties of all of these compounds have been investigated. The nature of the {Ln-radical} exchange interaction in these compounds has been assessed by comparing the behavior of the radical-based coordination polymers 1-5 with those of the compounds with the diamagnetic ligand set. While antiferromagnetic {Sm-radical} interactions are found in 1, ferromagnetic {Ln-radical} interactions propagate in the 3D architectures of 3, 4, and 5 (Ln = Gd, Tb, and Dy, respectively). This procedure also provided access to information on the {Ln-Ln} exchange existing in these magnetic systems.

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“…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. 3. Monofunctionalized radicals from perchlorotriphenylcarbenium hexachloroantimonate

Cited by 44 publications

References 3 publications

Three‐Dimensional Six‐Connecting Organic Building Blocks Based on Polychlorotriphenylmethyl Units—Synthesis, Self‐Assembly, and Magnetic Properties

Three‐Dimensional Six‐Connecting Organic Building Blocks Based on Polychlorotriphenylmethyl Units—Synthesis, Self‐Assembly, and Magnetic Properties

Three‐Dimensional Open‐Frameworks Based on Ln^IIIIons and Open‐/Closed‐Shell PTM Ligands: Synthesis, Structure, Luminescence, and Magnetic Properties

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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Inert carbon free radicals. 3. Monofunctionalized radicals from perchlorotriphenylcarbenium hexachloroantimonate

Cited by 44 publications

References 3 publications

Three‐Dimensional Six‐Connecting Organic Building Blocks Based on Polychlorotriphenylmethyl Units—Synthesis, Self‐Assembly, and Magnetic Properties

Three‐Dimensional Six‐Connecting Organic Building Blocks Based on Polychlorotriphenylmethyl Units—Synthesis, Self‐Assembly, and Magnetic Properties

Three‐Dimensional Open‐Frameworks Based on LnIIIIons and Open‐/Closed‐Shell PTM Ligands: Synthesis, Structure, Luminescence, and Magnetic Properties

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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Three‐Dimensional Open‐Frameworks Based on Ln^IIIIons and Open‐/Closed‐Shell PTM Ligands: Synthesis, Structure, Luminescence, and Magnetic Properties