Triarylmethanols with Bulky Aryl Groups and the NOESY/EXSY Experimental Observation of a Two‐Ring‐Flip Mechanism for the Helicity Reversal of Molecular Propellers

Tormyshev, Victor M.; Genaev, A. M.; Salnikov, Georgy E.; Rogozhnikova, Olga Yu.; Troitskaya, Tatiana I.; Trukhin, Dmitry V.; Mamatyuk, V. I.; Fadeev, Dmitry S.; Halpern, Howard J.

doi:10.1002/ejoc.201101243

Cited by 29 publications

(42 citation statements)

References 25 publications

(20 reference statements)

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“…If the hydrogens are all at the same distance from the unpaired electron spin, essentially a single shell, they are a factor of (36) 1/6 farther away than this r eff . This gives a distance, R(Radical) = 5.6±0.2 Å, that agrees well with the average distance calculated from the Finland trityl structure in Scheme 1 [37]. …”

Section: Discussionsupporting

confidence: 83%

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Hyperfine interactions of narrow-line trityl radical with solvent molecules

Trukhan

Yudanov

Tormyshev

et al. 2013

Journal of Magnetic Resonance

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The electron nuclear dipolar interactions responsible for some dynamic nuclear polarization (DNP) mechanisms also are responsible for the presence formally in CW EPR spectra of forbidden satellite lines in which both the electron spin and a nuclear spin flip. Such lines arising from 1H nuclei are easily resolved in CW EPR measurements of trityl radicals, a popular family of DNP reagents. The satellite lines overlap some of the hyperfine features from 13C in natural abundance in the trityl radical, but their intensity can be easily determined by simple simulations of the EPR spectra using the hyperfine parameters of the trityl radical. Isotopic substitution of 2H for 1H among the hydrogens of the trityl radical and/or the solvent allows the dipolar interactions from the 1H on the trityl radical and from the solvent to be determined. The intensity of the dipolar interactions, integrated over all the 1H in the system, is characterized by the traditional parameter called reff. For the so-called Finland trityl in methanol, the reff values indicate that collectively the 1H in the unlabeled solvent have a stronger integrated dipolar interaction with the unpaired electron spin of the Finland trityl than do the 1H in the radical and consequently will be a more important DNP route. Although reff has the dimensions of distance, it does not correspond to any simple physical dimension in the trityl radical because the details of the unpaired electron spin distribution and the hydrogen distribution are important in the case of trityls.

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Section: Discussionsupporting

confidence: 83%

“…This is not as strange as it first seems. A close examination of the solvent-accessible surface, Scheme I, shows that the surface of Finland trityl is not smooth and that small solvent molecules can come closer to the center than the trityl hydrogens [33, 37]. The spherical approximation used to derive Eqn.…”

Section: Discussionmentioning

confidence: 99%

Hyperfine interactions of narrow-line trityl radical with solvent molecules

Trukhan

Yudanov

Tormyshev

et al. 2013

Journal of Magnetic Resonance

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“…Thin layer chromatography (TLC) of radical 9 revealed the presence of two products: A green spot identified as the target radical 9 and a violet side product identified by MS to be the quinone methide (20, see Figure 2) that was recently reported. 41 In contrast to the report and according to MPLC isolation, only 3 % of compound 20 had formed.…”

Section: Synthesis Of Tetrathia-tam Radicals Their Deuterated Analogmentioning

confidence: 61%

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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“…1), one zero-ring, three one-ring, three two-ring and one three-ring flip paths [3,4,8]. For these multi-blade propeller molecules, the lowest energy (threshold) rotating mechanism can be one-ring flip [9,10], two-ring flip [5,11,12] or n-ring flip [13]. The choice of rotating mechanism should depend on the contributions of the steric effect of the attached aryl groups [14].…”

Section: Introductionmentioning

confidence: 97%