Pyridyl-Substituted Nitronyl Nitroxides: Comprehensive Magnetochemical and Quantum Chemical Study.

A series of pyridyl-substituted nitronyl nitroxides was synthesized and structurally characterized. A comprehensive magnetochemical and quantum chemical study of extended raw of the nitroxides with different substituents R in the pyridine fragment was performed. It was shown, that temperature-dependent magnetic properties are determined by the short contacts between nitroxide groups of adjacent molecules as well as between nitroxide group and methyl substituents in the pseudo axial positions of imidazoline fragments.

Ferrocenyl-substituted nitronyl nitroxide in the design of one-dimensional magnets.

By the reaction of M(hfac) (M = Mn(II), Co(II), Cu(II), and Zn(II); hfac is the hexafluoroacetylacetonate anion) and ferrocenyl-substituted nitronyl nitroxide (L), we succeeded in the synthesis of stable heterospin complexes: mononuclear [Zn(hfac)L], trinuclear {[Cu(hfac)]L} and chain polymer [Mn(hfac)L] and [Co(hfac)L]. The specific steric bulkiness of the ferrocenyl substituent leads to the formation of -type coordination polyhedra in the [Mn(hfac)L] and [Co(hfac)L] chains. The introduction of the ferrocene substituent leads to an effective weakening of intermolecular or interchain magnetic exchange coupling.

Novel pyridyl-substituted nitronyl nitroxides as potential antiarrhythmic and hypotensive agents with low toxicity and enhanced stability in aqueous solutions.

This study explores the antiarrhythmic and hypotensive potential of pyridyl-substituted nitronyl nitroxides derivatives, uncovering the crucial role of a single carbon moiety of the pyridine cycle alongside radical and charged oxygen centers of the imidazoline fragment. Notably, the introduction of fluorine atoms diminished the antiarrhythmic effect, while the most potent derivatives featured the nitronyl nitroxide pattern positioned at the third site of the pyridine cycle. Gender-dependent responses were observed in lead compounds L and L, with L inducing temporary bradycardia and hypotension specifically in female rats, and L causing significant blood pressure reduction followed by rebound in females compared to milder effects in males.

High-field EPR of copper(II)-nitroxide compound exhibiting three-step phase transition: structural insights from the field-induced sample orientation.

Copper(II)-nitroxide based Cu(hfac)L compounds exhibit unusual magnetic behavior that can be induced by various stimuli. In many aspects, the magnetic phenomena observed in Cu(hfac)L are similar to classical spin-crossover behavior. However, these phenomena originate from polynuclear exchange-coupled spin clusters Cu-O˙-N< or >N-˙O-Cu-O˙-N<.

2-Imidazoline Nitroxide Derivatives of Cymantrene.

The 2-imidazoline nitroxide derivatives of cymantrene-2-(-cyclopentadienyl)tricarbonylmanganese(I)-4,4,5,5-tetramethyl-4,5-dihydro-1-imidazole-3-oxide-1-oxyl (NNMn) and 2-(-cyclopentadienyl)tricarbonylmanganese(I)-4,4,5,5-tetramethyl-4,5-dihydro-1-imidazole-1-oxyl (INMn) were synthesized. It was shown that NNMn and INMn exhibit a sufficiently high kinetic stability both in solids and in solutions under normal conditions. Their structural characteristics, magnetic properties and electrochemical behavior are close to Re(I) analogs.