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. 2015 Jul 29;6(11):6482–6495. doi: 10.1039/c5sc02499d

Table 6. LLIT 13C DNP enhancements polarized at 0.33 T for substrate/TEMPO systems and acid dissociation constants (pKa)101,102 at 25 °C of 13C–H protons.

System (solute/solvent/TEMPO conc.) Nucleus Absolute enhancement pKa Type of carbon hybridization
Phenylacetylene/NA/0.01 M (ref. 45) 13C-β +1400 ± 210 21 sp
Phenylacetylene/NA/0.14 M (ref. 45) 13C-α +290 ± 44 —
Benzaldehyde/cyclohexane/0.1 M (ref. 67) 13CHO– +373 ± 56 14.9 sp2
13C-ortho +131 ± 20 —
Nitrobenzene/cyclohexane/0.1 M (ref. 66) 13C-ortho +587 ± 88 —
13C-meta +198 ± 30 —
13C-para +366 ± 55 —
Chloroform/0.0052 M (ref. 44) 13CHCl3 +2200 ± 330 15.5 sp3
Nitromethane/benzene/0.1 M (ref. 66) 13CH3NO2 +996 ± 149 10
Carbon tetracholoride/1-chlorobutane/0.08M (ref. 44) 13CCl4 +770 ± 115 —
Acetonitrile/carbon tetrachloride/0.1 M (ref. 103) 13CH3CN +520 ± 100 25
1-Chlorobutane/carbon tetrachloride/0.08 M (ref. 44) Cl13CH2CH2CH2CH3 +460 ± 70 —
Ethyl acetoacetate/benzene/cyclohexane/0.1 M (ref. 66) CH3CO13CH2COOCH2CH3 +440 ± 66 11
Diethyl malonate/benzene/cyclohexane/0.1 M (ref. 66) (CH3CH2OOC)213CH2 +401 ± 60 13
Triphenylmethane/cyclohexane/0.1 M (ref. 66) 13CH(Ph)3 +129 ± 19 31.4
Diphenylmethane/cyclohexane/0.1 M (ref. 66) 13CH2(Ph)2 +67 ± 10 33.4
Benzene/0.1 M (ref. 66) 13C6H6 –200 ± 30 43 sp2
C60/C6D6/0.1 M (ref. 65) 13C60 –250 ± 20 —
Benzonitrile/cyclohexane/0.1 M (ref. 67) 13C-ipso –281 ± 42 —
Phenylamine/cyclohexane/0.1 M (ref. 67) 13C-ipso –318 ± 48 —
Toluene/cyclohexane/0.1 M (ref. 66) 13C-ipso –423 ± 63
Benzaldehyde/cyclohexane/0.1 M (ref. 67) 13C-ipso –456 ± 20 —
Anisole/cyclohexane/0.1 M (ref. 67) 13C-ipso –457 ± 69 —
Nitrobenzene/cyclohexane/0.1 M (ref. 66) 13C-ipso –572 ± 86 —
Diethyl malonate/benzene/cyclohexane/0.1 M (ref. 66) (CH3CH2OO13C)2CH2 –642 ± 96 —
Ethyl acetoacetate/benzene/cyclohexane/0.1 M (ref. 66) CH3COCH213COOCH2CH3 –711 ± 107 —
CH313COCH2COOCH2CH3 –720 ± 108 —
Acetone/carbon tetrachloride/cyclohexane/0.1 M (ref. 66) (CH3)213CO –744 ± 112 —
Toluene/cyclohexane/0.1 M (ref. 66) 13CH3Ph –209 ± 31 41.2 sp3
Adamantane/benzene/0.1 M (ref. 66) –13CH2– –209 ± 13 —
–13CH– –254 ± 14 —
Cyclohexane/NA/0.1 M (ref. 45) 13C6H12 –270 ± 40 45
1-Chlorobutane/carbon tetrachloride/0.08 M (ref. 44) ClCH213CH2CH2CH3 –200 ± 30 —
ClCH2CH213CH2CH3 –400 ± 60 —
ClCH2CH2CH213CH3 –290 ± 44 —