Supplementary material
Fig.1 shows 1H spin-lattice relaxation data for decalin solution of 4-oxo-TEMPO-d16-15N in
the frequency range covered by FC experiments – this is a counterpart of Fig.2 of the paper, in
which analogous data for 4-oxo-TEMPO-d16-14N solution are shown.
22
15
4-oxo-TEMPO-d16- N in decalin
20
R1Ipar [s-1]
18
16
14
12
10
308K
298K
283K
273K
262K
254K
250K
247K
244K
8
6
4
2
0
1000
2000
(I)
0.5
3000
[Hz]
4000
0.5
Fig.1
1
H spin-lattice relaxation rates, R1par
I  I  , versus
 I in decalin solution of 4-oxo-TEMPO-
d16-14N in the frequency range covered by FC experiments (shown in Ref.25); solid black
lines – fits in regime II (the intermediate frequency range); dashed green line indicates the
limit S  A / 2 ; dashed-dotted black line indicates the frequency  I above which the effects
of the hyperfine coupling becomes negligible, i.e. the high frequency expression (Eq.12) can
be used.
1
In Fig.2 one sees that the relaxation dispersion in regime II is well pronounced even if the
translational dynamics is already very fast -
the diffusion coefficient approaches
D12  1.5 *10 9 m 2 / s .
8
4-oxo-TEMPO-d16 in decalin
R1Ipar [s-1]
7
14
N
6
308K
298K
283K
15
N
5
4
3
200
400
600
(I)
800
0.5
[Hz]
1000
1200
1400
0.5
Fig.2
1
H spin-lattice relaxation rates, R1par
I  I  , versus
 I in decalin solutions of 4-oxo-TEMPO-
d16-14N (solid symbols) and 4-oxo-TEMPO-d16-15N (open symbols) at 308K, 298K and 283K;
solid black lines – fits in regime II; dashed green line indicates the limit S  A / 2 .
2
Fig.3 is
15
N -counterpart of Fig.5 of the paper - it shows 1H spin-lattice relaxation rates,
versus square root of frequency for glycerol solution of 4-oxo-TEMPO-d16-15N in the
frequency range covered by FC experiments.
300
15
4-oxo-TEMPO-d16- N in glycerol
250
Rpar
[s-1]
1I
200
363K
353K
343K
338K
333K
328K
323K
150
100
50
0
1000
2000
(I)
0.5
3000
[Hz]
4000
0.5
Fig.3
1
H spin-lattice relaxation rates, R1par
 I in glycerol solution of 4-oxo-TEMPOI  I  , versus
d16-15N in the frequency range covered by FC experiments (shown in Ref.25); solid red lines –
fits in regime III (the high frequency range); dashed green line marks the limit S  A / 2 ;
dashed-dotted black line indicates the frequency  I above which the effects of the hyperfine
coupling becomes negligible, i.e. Eq.12 holds.
3
Fig.4 illustrates the fast diffusion limit for regime I using the data for glycerol solutions of 4oxo-TEMPO at 363K and 353K .
105
4-oxo-TEMPO-d16in glycerol
100
14
N
363 K
353 K
15
N
95
R1Ipar [s-1]
90
85
80
75
70
65
60
100
200
300
400
(I)
0.5
[Hz]
500
600
0.5
Fig.4
1
H spin-lattice relaxation rates, R1par
 I in glycerol solutions of 4-oxo-TEMPOI  I  , versus
d16-14N (solid symbols) and 4-oxo-TEMPO-d16-15N (open symbols); solid blue lines – fit in
regime I (low frequency) for 4-oxo-TEMPO-d16-14N; dashed light blue lines – fits in regime
I for 4-oxo-TEMPO-d16-15N; dashed green line indicates the limit S  A / 2 .
Fig.5 contains 1H spin-lattice relaxation data (glycerol solutions at 318K and 313K) which are
at low frequencies (regime I) affected by electron spin relaxation. The values of the diffusion
coefficient obtained from regime I and regime III considerably deviate. At 313K the
difference between the slopes for
14
N and
15
N radicals is lost due to the electron spin
relaxation.
4
450
4-oxo-TEMPO-d16 in glycerol
14
N
400
318K
313K
15
N
R1Ipar [s-1]
350
300
250
200
150
a)
100
0
1000
2000
(I)
0.5
3000
[Hz]
4-oxo-TEMPO-d16 in glycerol
14
N
400
4000
0.5
318K
313K
15
N
R1Ipar [s-1]
350
300
250
b)
200
100
200
300
(I)
0.5
400
[Hz]
500
600
0.5
Fig.5. a) 1H spin-lattice relaxation rates, R1par
 I in glycerol solutions of 4-oxoI  I  , versus
TEMPO-d16-14N (solid symbols) and 4-oxo-TEMPO-d16-15N (open symbols) in the frequency
range covered by FC relaxometry (the data for 313K have been shown in Ref.25); solid red
lines – fits in regime III (high frequency); b) the same data up to  I  500kHz ; solid blue line
5
– fits in regime I (low frequency) for 4-oxo-TEMPO-d16-14N; dashed light blue line – fit in
regime I for 4-oxo-TEMPO-d16-15N; dashed green line indicates the limit S  A / 2 .
Fig.6 explicitly shows that there is no contribution to the relaxation scenario from methyl
group protons.
14
4-oxo-TEMPO- N in glycerol
h16
250
353K
343K
333K
323K
d16
R1Ipar [s-1]
200
150
100
50
1000
2000
3000
0.5
0.5
(I) [Hz]
4000
Fig.6
1
H spin-lattice relaxation rates, R1par
 I in glycerol solutions of 4-oxo-TEMPOI  I  , versus
d16-14N (solid squares ) and 4-oxo-TEMPO-h16-15N (open triangles).
6
In Fig. 7 relaxation dispersion data for glycerol solutions of CTPO(3-carbamoyl - 2,2,5,5Tetramethyl-3-pyrrolin-1-oxyl), 4-hydroxy-TEMPO (4-hydroxy-2,2,6,6-tetramethylpiperidine
1-oxyl) and CProxyl (3-carbamoyl-2,2,5,5-tetramethylpyrrolidin-1-oxyl) plotted versus
I
are shown for the entire frequency range of FC NMR relaxometry.
220
353K
343K
333K
323K
200
180
160
CProxyl
-1
120
par
R1I [s ]
140
100
4-hydroxyTEMPO
CTPO
80
60
40
20
b)
0
1000
2000
(I)
0.5
3000
[Hz]
4000
0.5
Fig.7
1
H spin-lattice relaxation rates, R1par
I  I  , versus
 I in glycerol solutions of selected non-
deuterated nitroxide radicals (14N); corresponding fits in regime III (high frequency) – solid
red lines.
7