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A new water‐soluble and lipid‐insoluble spin probe: application to the study of aqueous sucrose solutions
Author(s) -
Belton Peter S.,
Sutcliffe Leslie H.,
Gillies Duncan G.,
Wu Xiaoping,
Smirnov Alex I.
Publication year - 1999
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199901)37:1<36::aid-mrc405>3.0.co;2-8
Subject(s) - chemistry , microviscosity , aqueous solution , spin probe , rotational correlation time , nitroxide mediated radical polymerization , relaxation (psychology) , nitroxyl , rotational diffusion , solubility , oxygen , analytical chemistry (journal) , organic chemistry , molecule , polymer , psychology , social psychology , biochemistry , radical polymerization , membrane , copolymer
A new ESR spin probe, sodium1,1,3,3‐tetrakis(trideuteromethyl)isoindolin‐2‐yloxyl‐4‐sulphonate, which is related to the extensively studiedgeneric free radical 1,1,3,3‐tetramethylisoindolin‐2‐yloxyl(TMIO), was synthesized. The latter has greater chemical and biochemicalstability than any other nitroxyl radical and in low‐viscosity media it exhibitsnear isotropic tumbling motion. It is therefore a very useful spin probe for ESR investigationsof (i) microviscosity, (ii) measurements of oxygen concentrations andrates of oxygen diffusion and (iii) ESR imaging experiments. Substituents can beintroduced into the basic TMIO radical: here the synthesis of the sulphonated form is described;it has a very high solubility in water, which is important for in vivo biologicalapplications where a low‐volume, high‐concentration spin probe may need to beinjected. In this paper, its use is demonstrated in a study of the microviscosities of aqueoussucrose solutions at concentrations up to 65% and over a range of temperatures. Generalassumptions were tested concerning the effect of inhomogeneous broadening from unresolved protonhyperfine coupling constants on the calculations of rotational correlation times. For this purpose,the well known spin probes Fremy' salt (peroxylamine disulphonate) anddi‐ tert ‐butyl nitroxide were used. The ESR results are compared with those fromprevious NMR relaxation studies of aqueous sucrose solutions. © 1999 John Wiley & Sons, Ltd.