Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics.
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Supportinginformationfor:
SizableDynamicsinSmallPores:CO2LocationandMotionintheα-MgFormateMetalOrganicFramework
[a]
YuanjunLu, BryanE.G.Lucier,[a]YueZhang,[a]PengjuRen,[b,c]
AnminZheng,[d]YiningHuang[a,*]
[a]
DepartmentofChemistry,TheUniversityofWesternOntario,1151RichmondStreet,
London,Ontario,Canada,N6A5B7
[b]
StateKeyLaboratoryofCoalConversion,InstituteofCoalChemistry,Chinese
AcademyofSciences,Taiyuan,030001,P.R.China
[c]
NationalEnergyCenterforCoaltoCleanFuels,SynfuelsChinaCo.,Ltd,Huairou
District,Beijing,101400,P.R.China
[d]
StateKeyLaboratoryofMagneticResonanceandAtomicandMolecularPhysics,
WuhanCenterforMagneticResonance,WuhanInstituteofPhysicsandMathematics,
theChineseAcademyofSciences,Wuhan430071,P.R.China
TableofContents
Item Page
TableS1.TheextractedwobblingandhoppinganglesofCO2inα-Mgformate 2
FigureS1.ExperimentalandsimulatedpowderX-raydiffractionpatterns 3
FigureS2.ThedistributionofcarbonatomsofCO2inα-Mgformate
atvarioustemperatures,ascalculatedbyMDsimulations 4
FigureS3.ThecalculatedmeansquareddisplacementofCO2inα-Mgformate 5
FigureS4.Crystallatticeofα-Mgformate,crystallographicallyunique
hydrogenpositions,andCO2adsorptionsites
6
13
FigureS5.Experimentalandmotionally-simulated CSSNMRspectra
7
FigureS6.ThedynamicmotionsofCO2moleculesinα-Mgformate
8
FigureS7.CO2location,position,andmotioninα-Mgformate 9
1
TableS1.TheextractedwobblingaandhoppingbanglesofCO2inα-Mgformate,as
derivedfrom13CSSNMRspectrausingEXPRESS.1Bothmotionalratesareinthefast
motionregime(i.e.,≥107Hz)throughouttheexperimentaltemperaturerange.
Temperature(°K)
393
373
353
333
313
293
273
253
233
213
193
173
a
Wobbling(α,°)
47.5
47.5
47.5
48
48
49
49
49
48.5
48
47
45
Hopping(β,°)
41
42
44
45
45
42
39
36
32
27
23
23
Theuncertaintyofeachwobblingangleis±0.1°.bTheuncertaintyofeachhopping
angleis0.2°.
1
R.L.VoldandG.L.Hoatson,J.Magn.Reson.,2009,198,57-72.
2
FigureS1.PowderXRD(pXRD)resultsoftheactivatedandas-madeα-MgformateMOF,
alongwiththecalculatedpXRDpatterns.
3
FigureS2.ThexyplaneprojectionofthedistributionofcarbonatomsofCO2inα-Mgformateatvarioustemperatures,ascalculated
byMDsimulations.Thedecreaseinlocalizedintensityathighertemperatures,andincreaseinintensitybetweenthemaxima,isdue
toincreasedCO2mobilitywithinthechannelsofα-Mgformate.
4
FigureS3.Thecalculatedmeansquareddisplacement(MSD)ofthecenterofmass(COM)ofCO2inα-Mgformateatatemperature
of253K.
5
Figure S4. The extended crystal lattice of α-Mg formate, as viewed down the crystallographic b axis, is shown. There are six
crystallographicallyuniquehydrogenpositionsinthisMOF,butonlythethreehydrogenatomswhichprotrudeintotheporeinterior
areshownhere,highlightedbypurple,yellow,andgreencircles.Forclarity,thethreetypesofhydrogenatomsarelabeledwithin
separateadjacentchannels,althoughtheyallexistwithinthesamechannel.TheredcirclesdenotetheCO2adsorptionsites,andare
onlyshowninthreechannels,butarepresentinallchannels.
6
(a) Experimental
(b) Wobblingand
hopping
(c) Wobblingonly
(d) Hoppingonly
393K
373K
353K
333K
313K
293K
273K
253K
233K
213K
193K
173K
200 150 100 50 ppm 200 150 100 50 ppm 200 150 100 50 ppm 300 200 100
13
0 ppm FigureS5.Theexperimental CVTSSNMRspectraofCO2-loadedα-Mgformateareshownin(a),alongwithsimulationsin(b),(c),
and(d).In(b),motionalsimulationsincorporatinglocalizedwobblingandnon-localizedtwofoldhoppingaredepicted;thesematch
wellwiththeexperimentalspectrain(a).Incontrast,thesimulatedspectrashownin(c)thatonlyconsiderlocalizedwobblingof
CO2,aswellasspectrain(d)thatonlyincorporatethenon-localizedtwofoldhopping(d)ofCO2,arebothpoormatchestothe
experimentalspectra.Notethedifferenceinx-axisscalein(d).
7
β
C6wobblingaxis
α
α
C2hoppingaxis
FigureS6.ThedynamicmotionsofCO2moleculesintheα-MgformateMOFareillustrated.CO2participatesinalocalizedwobbling
throughanangleofα,modeledbyaC6sixfoldrotation,alongwithanon-localizedtwofold(C2)hoppingthroughanequivalentangle
β.
8
(a)
C6wobbling
axis
(b)
α
120°
β
β
C2hoppingaxis
FigureS7.In(a),thelocalizedC6wobblingofCO2throughanangleofαaboutanindividualhydrogen-basedadsorptionsitewithin
theporesofα-Mgformateisshown.TheH(formate)…O-C(CO2)angleis120°andH(formate)…O(CO2)distanceisca.3.2Angstroms,
accordingtoMDsimulations(seemaintext).Theillustrationin(b)isadepictionofthenon-localizedC2hoppingofCO2throughan
angleofβbetweenhydrogen-basedadsorptionsitesalongthebaxisofα-Mgformate.
9