Table 1.

Common paramagnetic probes

Probe name[a]	Paramagnetic group	Molecular structures[b]	T1e [s]	Reference
oxygen	.O2−		≈10−12	[11–13, 14b]
manganese chloride	manganese(II)		10−8–10−9	[15, 17b,c]
nickel acetylacetonate	nickel(II)		≈10−12	[17a]
nickel 1,7-dicarboxymethyl-1,4,7,10-tetraazacyclododecane (Ni2+-DO2A)	nickel(II)		≈10−12	[30]
di-tert-butylaminoxyl (DTNB)	R2NO.		≈10−7	[18a]
3-oxyl-2,2,4,4-tetramethyloxazolidine	R2NO.		≈10−7	[18b]
4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPOL)	R2NO.		≈10−7	[4a, 20, 22, 23, 31]
4-amino-2,2,6,6-tetramethylpiperidin-1-oxyl	R2NO.		≈10−7	[24, 26a]
4-carboxy 2,2,6,6-tetramethylpiperidin-1-oxyl	R2NO.		≈10−7	[26a]
3-carboxy 2,2,5,5-tetramethylpyrrolidine-1-oxyl	R2NO.		≈10−7	[24]
16-doxyl stearic acid (16-DSA)	R2NO.		≈10−7	[17b,c, 27]
5-doxyl stearic acid (5-DSA)	R2NO.		≈10−7	[17b,c, 27]
gadolinium ethylenediaminetetraacetic acid [Gd(EDTA)−]	gadolinium(III)		≈10−8	[32]
gadolinium diethylenetriaminepentaacetic acid [Gd(DTPA)2−]	gadolinium(III)		≈10−8	[29, 31]
gadolinium tetraazacyclododecanetetraacetic acid [Gd(DOTA)−]	gadolinium(III)		≈10−8	[27, 33]
Gd(DTPA-BMA)	gadolinium(III)		≈10−8	[4a, 34]
gadolinium 4,7,10,23,26,29-hexakis(carboxylmethyl)-2,12,21,31-tetraoxo-1,4,7,10,13,-20,23,26,29,32-decaazatricyclo[14,20]-p-xylene [Gd2(L7)]	gadolinium(III)		≈10−8	[20g, 35]

^[a]Commonly used abbreviations are given in parentheses.

^[b]Molecular structures were generated by using ChemDraw.