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A perchlorotriarylmethyl tricarboxylic acid radical 99% enriched in 13 C at the central carbon ( 13 C 1 -PTMTC) was characterized in phosphate buffered saline solution (pH = 7.2) (PBS) at ambient temperature. Samples immobilized in 1:1 PBS:glycerol or in 9:1 trehalose:sucrose were studied as a function of temperature. Isotope enrichment at C 1 creates a trityl that can be used to accurately measure microscopic viscosity. Understanding of the impact of the 13 C hyperfine interaction on electron spin relaxation is important for application of this trityl in oximetry and distance measurements. The anisotropic 13 C 1 hyperfine couplings (A x = A y = 24 ± 2 MHz, A z = 200 ± 1 MHz) are larger than for the related 13 C 1 -perdeuterated Finland trityl ( 13 C 1 -dFT) and the g anisotropy (g x = 2.0013, g y = 2.0016, g z = 2.0042) is slightly larger than for 13 C 1 -dFT. The tumbling correlation times (τ R ) for 13 C 1 -PTMTC are 0.20 ± 0.02 ns in PBS and 0.40 ± 0.05 ns in 3:1 PBS:glycerol, which are shorter than for 13 C 1 -dFT in the same solutions. T 1 for 13 C 1 -PTMTC is 3.5 ± 0.5 μs in PBS and 5.3 ± 0.4 μs in 3:1 PBS:glycerol, which are shorter than for 13 C 1 -dFT due to faster tumbling, larger anisotropy of the 13 C 1 hyperfine, and about 30% larger contribution from the local mode. In immobilized samples T 1 for 13 C 1 -PTMTC is similar to that for 13 C 1 -dFT and other trityls without chlorine or 13 C 1 substituents, indicating that the 13 C 1 and Cl substituents on the phenyl rings have little impact on T 1 . The temperature dependence of T 1 was modeled with contributions from the direct, Raman, and local mode processes. Broadening of CW linewidths of about 0.6 G in fluid solution and about 2 G in rigid lattice is attributed to unresolved 35,37 Cl hyperfine couplings.

Soluble stable radicals are used as spin probes and spin labels for in vitro and in vivo electron paramagnetic resonance (EPR) spectroscopy and imaging applications. We report the synthesis and characterization of a perchlorinated triarylmethyl radical enriched 99% at the central carbon, 13 C 1 -PTMTC . The anisotropy of the hyperfine splitting with the 13 C 1 ( A x = 26, A y = 25, A z = 199.5 MHz) and the g ( g x = 2.0015, g y = 2.0015, g z = 2.0040) are responsible for a strong effect of the radical tumbling rate on the EPR spectrum. The rotational correlation time can be determined by spectral simulation or via the line width or the apparent A z after calibration, so the spin probe 13 C 1 -PTMTC can be used to measure media microviscosity with high sensitivity.

BACKGROUND Synthetic cannabinoids have a higher affinity for the cannabinoid receptors CB1 and CB2 than natural cannabinoids. Their use can be associated with cardiovascular disease and neurological complications. A case is reported of status epilepticus and stress cardiomyopathy following the recreational use of the synthetic cannabinoid, UR-144. CASE REPORT A 19-year-old woman presented to the emergency department in status epilepticus after smoking the synthetic cannabinoid known as 'space'. Recurring seizure activity was controlled after three hours. On hospital day 3, the patient developed severe biventricular failure. Cardiac magnetic resonance imaging (MRI) confirmed the diagnosis of stress cardiomyopathy. A comprehensive urine drug screen was performed using gas chromatography-mass spectrometry (GC-MS), which was positive for UR-144, or (1-pentyl-1H-indol-3-yl)(2,2,3,3-tetramethylcyclopropyl)-methanone, and negative for all other illicit recreational drugs. The patient improved at one week following admission, with a left ventricular ejection fraction (LVEF) of 40%. She was discharged home on hospital day 10. CONCLUSIONS The use of the synthetic cannabinoid, UR-144, may be associated with prolonged status epilepticus and stress cardiomyopathy. Physicians should be aware of these potentially lethal complications associated with the recreational use of this and other illicit synthetic cannabinoids.

We report the synthesis of hydroxyethyl tetrathiatriarylmethyl radical OX063 and its deuterated analogue OX071 for biomedical EPR applications., Competing Interests: Conflicts of interest There are no conflicts to declare.