Pyrazol-4-yl-substituted α-nitronyl and α-imino nitroxide radicals in solution and solid states

Synthesis, Optical Properties and Magnetic Studies of 2,6‐Bis(pyrazolylmethyl)pyridine Functionalized with Two Nitronyl Nitroxide Radicals

“…The UV/Vis spectrum of B is shown in Fig-ure 2 together with those of the bis(pyrazolyl)pyridine NN biradical A and the pyrazol-4-yl nitronyl nitroxide monoradical, [16] PzNN, used as a reference. B exhibits an intense band in the visible absorption region characterized by several vibronic components (toluene, λ max = 651 nm, ε = 2420  -1 cm -1 , nǞπ*) with an intensity roughly twice that shown by the monoradical PzNN (toluene, λ max = 647 nm, ε = 1120  -1 cm -1 , nǞπ*).…”

Microwave-assisted nitroxide-mediated polymerization of alkyl acrylates

“…With the advent of newly designed nitroxide radicals (others than the TEMPO radical) [4][5][6][7][8][9], nitroxidemediated polymerizations have regained raising interest because of the growing number of monomers that nowadays can be polymerized in a controlled manner via this technique. However, the control over the polymerization often arises from equilibria that significantly decrease the reaction times.…”

High resolution NMR of free radicals: 13C magic angle spinning of two solid organic free radicals derived from 4,5-dihydro-1H-imidazol-3-oxide-1-oxyl and theoretical calculation of their NMR properties

“…8 Finally, 4,4,5,5-tetramethyl-2-(1H-pyrazol-4-yl)-2-imidazoline-1-oxyl-3-oxide 4 was prepared by Catala, Feher, Amabilino, Wurst and Veciana. 2 Solid state NMR 13 C (100.73 MHz) CPMAS NMR spectra were recorded by using a Bruker WB 400 spectrometer at 300 K with a 4 mm DVT probehead. Samples were carefully packed in a 4-mm diameter cylindrical zirconia rotors with Kel-F end-caps.…”

“…1 The α-nitronyl nitroxides derived from azoles (imidazoles, triazoles) exhibit extremely strong ferro-and antiferro-magnetic interactions, for organic radicals in which the hydrogen bonds have been involved. 2 The purpose of the present paper is twofold. On one hand to record in the solid state the 13 C CPMAS NMR spectra of two nitronylnitroxide radicals 3 and 4, and on the other, to evaluate the utility of unrestricted DFT calculations to obtain absolute shieldings of these radicals and those of 4,4,5,5-tetramethyl-2-methyl-imidazoline-1-oxyl-3-oxide 1 and of 4,4,5,5-tetramethyl-2-(4'-hydroxyphenyl)-2-imidazoline-1-oxyl-3-oxide 2.…”

“…10,11 Another important contribution to pyrazolyl-nitronylnitroxides is that of Catala, Feher, Amabilino, Wurst and Veciana who prepared compound 4. 2 Note that we published in 1995 a 13 C NMR study in solution of paramagnetic Co(II) complexes. 12 The present paper is one of the rare publications where experimental and theoretically calculated NMR chemical shifts of radicals are reported.…”