EPR and Quantum Chemical Studies of the pH-sensitive Imidazoline and Imidazolidine Nitroxides with Bulky Substituents

EPR and Quantum Chemical Studies of the pH-sensitive Imidazoline and Imidazolidine Nitroxides with Bulky Substituents Full article

Journal

Applied Magnetic Resonance
ISSN: 0937-9347 , E-ISSN: 1613-7507

Output data

Year: 2010, Volume: 39, Number: 4, Pages: 437-451 Pages count : DOI: 10.1007/s00723-010-0179-z

Authors

Bobko A. A. ^1,2 , Kirilyuk I. A. ³ , Gritsan N. P. ¹ , Polovyanenko D. N. ⁴ , Grigor'ev I. A. ³ , Khramtsov V. V. ² , Bagryanskaya E. G. ⁴

Affiliations

1	(Данные Web of science) Russian Acad Sci, Inst Chem Kinet & Combust, Novosibirsk 630090, Russia
2	(Данные Web of science) Ohio State Univ, Dorothy M Davis Heart & Lung Res Inst, Columbus, OH 43210 USA
3	(Данные Web of science) Russian Acad Sci, Novosibirsk Organ Chem Inst, Novosibirsk 630090, Russia
4	(Данные Web of science) Russian Acad Sci, Int Tomog Ctr, Novosibirsk 630090, Russia

The X- and W-band electron paramagnetic resonance (EPR) spectroscopies were employed to investigate a series of imidazolidine nitroxide radicals with different number of ethyl and methyl substituents at positions 2 and 5 of a heterocycle in liquid and frozen solutions. The influence of the substituents on the line shape and width was studied experimentally and analyzed using quantum chemical calculations. Each pair of the geminal ethyl groups in the positions 2 or 5 of the imidazolidine ring was found to produce an additional hyperfine splitting (hfs) of about 0.2 mT in the EPR spectra of the nitroxides. The effect was attributed to the hfs constant of only one of four methylene hydrogen atoms of two geminal ethyl substituents not fully averaged by ethyl group rotation and ring puckering. In accordance with this assumption, the substitution of hydrogen atoms of CH2 groups in 2,2,5,5-tetraethyl-substituted imidazolidine nitroxides by deuterium leads to the substantial narrowing of EPR lines which could be useful for many biochemical and biomedical applications, including pH-monitoring. W-band EPR spectra of 2,2,5,5-tetraethyl-substituted imidazolidine nitroxide and its 2,2,5,5-tetraethyl-d(8) deuterium-substituted analog measured at low temperatures demonstrated high sensitivity of their g-factors to pH, which indicates their applicability as spin labels possessing high stability.

Bobko A.A. , Kirilyuk I.A. , Gritsan N.P. , Polovyanenko D.N. , Grigor'ev I.A. , Khramtsov V.V. , Bagryanskaya E.G.
EPR and Quantum Chemical Studies of the pH-sensitive Imidazoline and Imidazolidine Nitroxides with Bulky Substituents

Applied Magnetic Resonance. 2010. V.39. N4. P.437-451. DOI: 10.1007/s00723-010-0179-z WOS Scopus РИНЦ OpenAlex

Full text from publisher

Published online:	Oct 30, 2010
Published print:	Dec 1, 2010

Web of science:	WOS:000284154600011
Scopus:	2-s2.0-78449247077
Elibrary:	16891408
OpenAlex:	W2091778891

DB	Citing
Web of science	25
Scopus	26
Elibrary	26
OpenAlex	28