BTFA
BPFB
BTFP
3-BTFMA
TFET
BTFMA
A
0.374
0.520
0.588
0.680
0.539
0.705
X0
1.588
1.583
1.606
1.637
1.604
1.618
1
w
0.0437
0.0601
0.0483
0.0546
0.0456
0.0525
Supplementary Table 1. Fitting parameters (A, xo and w) used to interpret the dependence of
chemical shift change  of CF3 tags to solvent polarity, using the formula  = A/(1+exp(-(Pyx0)/w)).
Methanol:H2O 4:1
3:1
2:1
1:1
1:2
1:3
1:4
Difference
BTFA
-85.239 -85.214 -85.139 -85.003 -84.911 -84.873 -84.860 0.379
BPFB
-79.465 -79.348 -79.248 -79.148 -79.025 -78.976 -78.959 0.506
BTFP
-78.320 -78.296 -78.192 -78.000 -77.837 -77.768 -77.729 0.591
TFET
-66.518 -66.497 -66.406 -66.220 -66.063 -66.007 -65.974 0.544
3-BTFMA
-63.217 -63.194 -63.124 -62.933 -62.724 -62.631 -62.575 0.642
BTFMA
-62.595 -62.561 -62.461 -62.248 -62.046 -61.952 -61.907 0.688
Supplementary Table 2. 19F NMR spectra of each of the probes in different solvent systems
composed of methanol and water. Note that the difference in the rightmost column in the above
table designates the difference between the chemical shift in the highest water sample from that of
the highest methanol sample.
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Supplementary Figures
Figure S1. 19F NMR spectra of each of the probes shown in Figure 1, for both water to MeOH ratios
of 0.25 (black) to 4.0 (red). Note that TFET labeling of the peptide proved to be incomplete and in
water the peptide-bound and peptide-free signals appear downfield and upfield, respectively. The
expected triplet in TFET spectra arises from the 3-bond scalar coupling to the methylene 1H nuclei.
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Figure S2. 19F NMR chemical shifts (normalized to 19F shifts in H2O) as a function of
solvent polarity. This plot uses a relative solvent polarity scale where H2O is
arbitrarily assigned a polarity = 1. This relative polarity scale is defined by
chromophore absorbance in various solvents. See Christian Reichardt, Solvents and
Solvent Effects in Organic Chemistry, Wiley-VCH Publishers, 3rd ed.).
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