Nitroxides with two pK values--useful spin probes for pH monitoring within a broad range.

@article{Kirilyuk2005NitroxidesWT,
  title={Nitroxides with two pK values--useful spin probes for pH monitoring within a broad range.},
  author={Igor A Kirilyuk and Andrey A. Bobko and Valery V Khramtsov and Igor A Grigor'ev},
  journal={Organic & biomolecular chemistry},
  year={2005},
  volume={3 7},
  pages={1269-74}
}
A series of 4-dialkylamino-2,5-dihydroimidazole nitroxides with pyridine-4-yl, 4-dimethylaminophenyl or 4-hydroxyphenyl groups in position 2 of the imidazole ring were prepared using the reaction of RMgBr with corresponding 5-dialkylamino-4,4-dimethyl-4H-imidazole 3-oxides. The EPR spectra of the nitroxides were shown to be pH-sensitive due to consecutive protonation of the amidino moiety and the basic group(s) at position 2 of the imidazole ring. The 5,5-dimethyl-4-(dimethylamino)-2-ethyl-2… CONTINUE READING