Electronic Supplementary Material (ESI) for ChemComm.
This journal is © The Royal Society of Chemistry 2017
SupplementalInformationfor:
Oxygen-17DynamicNuclearPolarisationEnhanced
Solid-StateNMRSpectroscopyat18.8T
NickJ.Brownbill,1DavidGajan,2AnneLesage,2LyndonEmsley3and
FrédéricBlanc*1,4
1
DepartmentofChemistry,UniversityofLiverpool,
CrownStreet,Liverpool,L697ZD,UnitedKingdom;
2
CentredeRMNàTrèsHautsChamps,InstitutdeSciencesAnalytiques,
UniversitédeLyon(CNRS/ENSLyon/UCBLyon1),69100Villeurbanne,France;
3
InstitutdesSciencesetIngénierieChimiques,
EcolePolytechniqueFédéraledeLausanne(EPFL),1015Lausanne,Switzerland;
4
StephensonInstituteforRenewableEnergy,UniversityofLiverpool,
CrownStreet,Liverpool,L697ZD,UnitedKingdom.
*Towhomcorrespondenceshouldbeaddressed(F.B.).
E-mail:[email protected].
S1
TableofContents
S1.MaterialsandMethods
S3
S2.OverallDNPsensitivityenhancementfactorӆ
S7
S3.AdditionalFigures S9
S4.Referencesforsupplementaryinformation S12
S2
S1.MaterialsandMethods
Materials
Mg(OH)2and17OenrichedMg(OH)2(Mg(17OH)2)werepreparedbyreactionofMgOwithH2Oand
17
O-enrichedH2O,respectively,asdescribedpreviously.1
ForDNPsampleswitha1,1,2,2-tetrachloroethane(TCE)matrix,40 µlstocksolutionof16mM
TEKPol2or32mMBPDA(SigmaAldrich,complexed1:1withbenzene)radicalsinTCE(SigmaAldrich,≥98
%)wasaddedtoapre-weighedamountofpowderedsample(typically35mg)untilthepowderappeared
slightlysaturatedwithTCEsolutionandwasthenmixedhomogeneously.Thesampleswerethenpacked
directlyintothe3.2mmsapphirerotor,alongwithsomeKBr(SigmaAldrich)(~1mg)atthebottomand
closed with a poly-tetrafluoroethane (PTFE) plug and Vespel cap. When stated, samples were
“freeze/thawcycled”;thisprocessinvolvedthesamplebeinginsertedintotheprobeat115Ktofreeze
thematrix,andthenejectedtothawthesolventandwasrepeated5times.3
ForDNPsampleswithano-terphenylmatrix,OTP(SigmaAldrich,99%)andOTP-d14(Cambridge
Isotope Laboratories, 98 %, 98 %D) were mixed in predefined ratios (100:0, 50:50, 90:10 and 95:5,
respectively)andradicaladdedtocomprise1.3wt%ofthemixtureforTEKPol(correspondingto17mM)
or1.4wt%forBDPA(correspondingto34mM).AtypicalOTPmatrixcontainsamixtureofOTP/OTP-d14
(520mg)withBDPA(7.2mg),orOTP/OTP-d14(156mg)withTEKPol(2mg).Theradical/OTPmixtureswere
thendissolvedinaminimumvolumeofCDCl3(SigmaAldrich,100%,≥99.96%D)(typically300µl)togive
stockradicalsolutions.ThesamplesfortheDNPexperimentswerepreparedbytypicallyadding120µlof
stockradicalsolutionapre-weighedamountofMg(OH)2orMg(17OH)2sample(typically35mg)followed
by an additional 120 µl of CDCl3; the slurry was then thoroughly mixed before leaving the CDCl3 to
evaporate.Theresidualsolidmixturewasthenfinelygroundandpackedintoasapphirerotorwithsome
KBr at the bottom (around 1 mg), sealed with a PTFE plug and Vespel cap. When stated, samples
underwenta“freeze/meltprocess”modifiedfromtheliterature;4thepackedsamplewasmeltedat343
Kinawaterbathfor2minutes,followedbyflashfreezinginliquidnitrogenfortenseconds.Thisprocess
wasrepeatedfivetimesbeforethemeltwasrapidlyinsertedintotheNMRprobeprecooledat115K.For
S3
non-DNPexperiments,apre-weighedamountoffinelygroundsamplewaspackedintoa3.2mmzirconia
rotor(18.8T)ora4mmzirconiarotor(9.4T)andsealedwithaVespelcap.
NMRmethods
AllhighfieldDNPsolid-stateNMRexperimentswereperformedonacommercial18.8TBruker
AvanceIIIDNPsolid-stateNMRspectrometerequippedwitha527GHzgyrotronmicrowavesystem.NMR
experiments were recorded with a 3.2 mm HXY triple-resonance MAS probe, with all cross effect
experimentsbeingrecordedatν0(1H)=800.130MHzcorrespondingtothemaximumenhancement 1H
position εHforTOTAPOLat ν0(e-)=527GHz,withtheXchanneltunedto13Catν0(13C)=201.193MHzand
theYchanneltunedto 17Oatν0(17O)=108.469MHz.AllOverhausereffectexperimentswererecorded
atν0(1H)=800.215MHz,correspondingtothemaximumenhancement1HpositionεHforBDPAatν0(e-)
=527GHz,withtheXchanneltunedto 13Cat ν0(13C)=201.214MHzandtheYchanneltunedto 17Oat
ν0(17O)=108.481MHz.Allexperimentswereperformedundermagicanglespinning(MAS)atνr=12.5
kHz. All DNP experiments were conducted at ~ 131 and 115 K with (µw on) and without (µw off)
microwave,respectively.
All 1HpulsesandSPINAL-64heteronucleardecouplingwereperformedataradio-frequency(rf)
field amplitude of 100 kHz.5 All 1H-13C cross polarisation (CP) MAS experiments (Figure S1(b)) were
obtainedwitha 13Crffieldof51kHz,whilethe 1Hrffieldamplitudewasrampedtoobtainmaximum
signalata1Hrffieldofapproximately76kHz.All17Oselectivepulseswereobtainedwithanrffieldof6
kHz.All1H-17OCP-HahnechoMASexperiments(FigureS1(c))wereobtainedwitha17Orffieldof14kHz
forHartmann–Hahncontact,whilethe1Hrffieldamplitudewasrampedtoobtainmaximumsignalata
1
Hrffieldofapproximately76kHz,atacontacttimeof1ms.All1H-17OPRESTO6MASexperimentswere
obtainedwithsymmetry-basedR1817 1Hrecoupling7optimisedtoarffieldof110kHzandclosetothe
expected value of 112.5 kHz at νr = 12.5 kHz, and optimised to a recoupling duration of 80 µs,
correspondingto1rotorperiod.ThePRESTO-IIpulseprogram,consistingoftwoR1817recouplingblocks
on 1Hchannel,withaπ/2pulseduringthesetwoblocksandaπ pulsedirectlyafteronthe 17Ochannel
wasusedforallexperiments(FigureS1(d)).
S4
Standard 298 K solid state NMR measurements at 18.8 T data were conducted on the same
spectrometerasstatedabovewitha3.2mmHXYtriple-resonanceMASprobe,withallexperimentsbeing
recordedatν0(1H)=800.130MHz,withtheXchanneltunedto 13Cat ν0(13C)=201.193MHzandtheY
channeltunedto17Oatν0(17O)=108.469MHz.Allotherexperimentalparametersremainedunchanged.
StandardsolidstateNMRmeasurementsat9.4Twereperformedonacommercial9.4TBruker
Avance III HD solid-state NMR spectrometer fitted with a 4 mm HXY triple-resonance MAS probe (in
double-resonancemode),tunedtoν0(1H)=400.13MHzandXtoν0(13C)=100.03MHz.Experimentswere
performedat298KunderMASatνr=12.5kHz.All 1HpulsesandSPINAL-64heteronucleardecoupling
were performed at a radio-frequency (rf) field amplitude of 83 kHz.5 All 1H-17O CP-Hahn echo MAS
experimentswereobtainedwitha 17Orffieldof17kHz,whilethe 1Hrffieldamplitudewasrampedto
obtainmaximumsignalata 1Hrffieldofapproximately70kHzatacontacttimeof2ms. 17Oselective
pulseswereobtainedwithanrffieldof10kHz.
Recycle delays that produce optimal signal-to-noise per unit time were used (1.3 x build up).8
Chemicalshiftswereexternallyreferencedatroomtemperaturetowaterat0.0(for 17O)and4.8ppm
(for1H),andto29.45ppmfortheCHofadamantane(for13C)9.
NMR data were processed with TopSpin 3.2 and MatLab. The signal enhancement factor was
determinedbycomparingtheintensityofthespectrawithmicrowaveirradiationturnedonandturned
off(unlessexplicitlystatedtohavebeenacomparisonoftotalsignalintegrals).
S5
PulseProgramSchemes
(a)
(b)
mw on/off
eπ/2
1
π/2
π/2
τVD
H
mw on/off
e-
1
H
N
(c)
mw on/off
π/2
O
CP
τ
SPINAL64
CP
CP
τr
μw on/off
e-
π/2
N
17
C
(d)
e-
H
CP SPINAL64
N
13
1
π/2
τ
1
H
π
τR1
τR2
(R1817)0
(R1817)90
π
π/2
τr
17
O
SPINAL64
Τ
Τ
FigureS1:DNPpulseprogramdepictionsof(a)1Hsaturationrecoveryexperiment,whereτvdisavariable
delay,tocalculateT1,RTwithµwoff,or τDNPwith µwonwhereτDNPistheDNPbuilduptimeandT1,RTis
the1Hrelaxationtimeatroomtemperature.(b)Pre-saturatedCPpulseprogramused,whereτ =1.3xT1,
RT with µwoff,or1.3x τDNP with µwon.(c)Pre-saturatedCPHahnEchopulseprogramused,whereτ=
1.3 x T1, RT with µw off, or 1.3 x τDNP with µw on, and τr = one rotor period. (d) PRESTO-II using R1817
recouplingsequences,whereτR1, τR2 andΤareallequaltoanintegerofrotorperiods.Inallexperiments
N=100,witha1µsdelaybetweenpulses.
S6
S2.OverallDNPsensitivityenhancementfactor Σ†
TheoverallDNPsensitivityenhancementfactorΣ†10–14isameasureoftheenhancementofDNP,
takingintoconsiderationthedifferingconditionsfromstandardsolidstateNMRatroomtemperature,
andtimedifferencesbetweenthetwoexperiments. Σ† wasdeterminedusingthefollowingexperiments:
(a) DNPNMRat131K,at18.8Twith µwatν0(e-)=527GHz,
(b) DNPNMRat131K,at18.8Twithout µw,
(c) RoomtemperatureNMRdata,ateither18.8Tor9.4T,
(d) NMRdataat131K,at18.8Tinthesamematrixas(a)withoutradicaladded,
andcalculatedusingthefollowingequation:
Σ"=
ΛRT
ΛDNP
TRT
TDNP
SDNP mRT
SRT mDNP NSRT T%,'(
θ
NSDNP τDNP
Eq.S1
where Λ,S,mandNSarethefullwidthofthelineshapeathalfmaximum(FWHM),thesignaltonoise
ratios,themassofsampleusedandthenumberofscansrecorded,respectively.SubscriptDNPandRT
indicate data taken from experiments (a) and (c), respectively. T1,RT is the 1H relaxation time at room
temperature(spectrum(c))andτDNPistheDNPbuilduptime(spectrum(a))andare determinedthrough
asaturationrecoveryexperiment(FigureS1a).Atlowtemperature,bothvaluesareoftensimilarbutnot
alwaysasthesignalbuildupduringµwirradiationisdrivenpredominantlybyDNPpolarisationtransfer
ratherthan1Hlongitudinalrelaxation.θisthebleachingfactordeterminedas:
θ=
1 SDNP mLT
ε SLT mDNP NSLT
NSDNP
Eq.S2
whereεistheDNPsignalenhancementbetween(a)and(b),respectively,andSLT,mLT andNSLTarethe
signaltonoiseratio,themassandthenumberofscansrecordedin(d),respectively.
Inthispaper,two Σ†valueswerecalculated:18.8TDNPvs18.8Troomtemperaturedatausing
3.2 mm rotors, and 18.8 T DNP vs 9.4 T room temperature data using 4 mm rotors (the latter being
perhapsthemostcommonlyusedsolidstateNMRhardware).
S7
TableS1. Σ†OCPCalculationParametersComparedto18.8Taand9.4TbRoomTemperatureSpectraFor
Mg(17OH)2
Effect
CrossEffect
OverhauserEffect
Radical
1.3wt%TEKPol
1.4wt%BDPA
Matrix
TCE
OTP
OTP/
OTP-d14
(50:50)
OTP/
OTP-d14
(90:10)
OTP/
OTP-d14
(95:5)
TCE
OTP
OTP/
OTP-d14
(90:10)
OTP/
OTP-d14
(95:5)
ε
14
6
12
11
12
5
2
17
3
3700
3600
3600
3600
3600
3700
3600
3550
3700
860
182
120
337
534
291
48
173
30
0.016
0.019
0.011
0.019
0.021
0.018
0.003
0.006
0.004
NSDNP
16
8
8
8
8
16
8
8
8
θ
0.8
0.8c
0.8c
0.8c
0.8c
0.8
0.8c
0.8
0.8c
τDNP(s)
11.2
2.6
7.9
8.3
9.8
30
19.2
31.2
27
Σ o
(18.8T)
72
38
54
71
53
13
24
34
9
Σ †o
(9.4T)
400
211
300
399
294
74
132
189
51
ΛDNP
(Hz)
SDNP
(a.u.)
mDNP
(mg)
†
ΛRT=3500Hz,SRT=34a.u.,mRT=20mg,NSRT=128, τ2=3s,T1,RT=0.7s,TDNP=131K(calculatedthrough
T1of 79BrinKBraddedtorotor15),TRT=298K. b ΛRT=7100Hz,SRT=56a.u.,mRT=70mg,NSRT=80,τ2=
8.5 s, T1,RT, = 6.5 s, TDNP = 131 K. TRT = 298 K.c Value assumed from the other calculated data that are
constantatθ=0.8.
a
S8
S3.AdditionalFigures
OE 18.8 T
CE 9.4 T
OE 9.4 T
80
450
70
400
60
350
300
50
250
40
200
30
150
20
100
10
50
0
0
Σ†O CP at 9.4T
Σ†O CP at 18.8 T
CE 18.8 T
0
10 20 30 40 50 60 70 80 90 100
% OTP-d14
FigureS2.Σ†OCPmeasuredontheMg(17OH)2sampleandOTPmatrixattheCEposition(square)with1.3
wt%TEKPolasthepolarisingagentandtheOEposition(triangle)with1.4wt%BDPAasthepolarising
agent with positions as a function of the OTP-d14 component of the OTP matrix compared with room
temperatureNMRspectraat(a)18.8Tand(b)9.4T.
S9
FigureS3.Comparisonof17ONMRlineshapesofMg(17OH)2impregnatedwith16mMTEKPolinTCEand
obtainedwith(a)aCPHahnechoand(b)aPRESTO6Hahnechosequence,plottedinabsoluteintensity,
showing difference in line shape and intensity between CP and PRESTO polarisation transfer steps.
Asterisks(*)denotespinningsidebands.SeeFigure1forallotherinformation.
Figure S4. Comparison of 17O CP Hahn Echo (a, b) and 1H one pulse (c, d) NMR spectra of
Mg(17OH)2with16mMTEKPolinTCEandrecordedatν0(1H)=800.130MHzwithµwatν0(e-)=
527 GHz (green) at T = 131 K and without µw (red) at T = 115 K. (b, d) are freshly prepared
materialafter5freeze-thawcyclesand(a,c)arethesamesampleafter20hat253Kand5
freeze-thawcycles.Asterisks(*)denotespinningsidebands.
S10
FigureS5.Comparisonof17OCPHahnEcho(a)and1Honepulse(b)NMRspectraofMg(17OH)2
with32mMBDPAinTCErecordedat ν0(1H)=800.215MHzwithµwatν0(e-)=527GHz(green)
atT=131Kandwithoutµw(red)atT=115Kafter5freeze-thawcycles.Asterisks(*)denote
spinningsidebands.
FigureS6.Comparisonof13CCP(a,b)and1Honepulse(c,d)NMRspectraofMg(17OH)2with1.4
wt%.BDPAinOTP/OTP-d14(90:10)andrecordedatν0(1H)=800.215MHzwithµwatν0(e-)=527
GHz(green)atT=131Kandwithoutµw(red)atT=115K.(b,d)arematerialspackedandrun
withnofreeze/meltcycling(a,c)arethesamesampleafter5freeze-meltcycles.Asterisks(*)
denotespinningsidebands.
S11
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S12