Catalytic epoxidation of olefin over supramolecular compounds of molybdenum oxide clusters and a copper complex

Article abstract of DOI:10.1016/S1872-2067(15)60919-6

The catalytic epoxidation of olefin was investigated on two copper complex-modified molybdenum oxides with a 3D supramolecular structure, [Cu(bipy)]₄[Mo₁₅O₄₇]·2H₂O (1) and [Cu^I(bix)][(Cu^Ibix)(δ-Mo^VI₈O₂₆)_0.5] (2) (bipy = 4,4′-bipyridine, bix = 1,4-bis(imidazole-1-ylmethyl)benzene). Both compounds were catalytically active and stable for the epoxidation of cyclooctene, 1-octene, and styrene with tert-butyl hydroperoxide (t-BuOOH) as oxidant. The excellent catalytic performance was attributed to the presence of stable coordination bonds between the molybdenum oxide and copper complex, which resulted in the formation of easily accessible Mo species with high electropositivity. In addition, the copper complex also acted as an active site for the activation of t-BuOOH, thus improving these copper complex-modified polyoxometalates.

Full text of DOI:10.1016/S1872-2067(15)60919-6

ChineseꢀJournalꢀofꢀCatalysisꢀ36ꢀ(2015)ꢀ1811–1817
ꢀ
ꢀ ꢀ ꢀ
ꢀ ꢀ ꢀ ꢀ
a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m
ꢀ
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h n j c
ꢀ
ꢀ
Article
Catalyticꢀepoxidationꢀofꢀolefinꢀoverꢀsupramolecularꢀcompoundsꢀofꢀ
molybdenumꢀoxideꢀclustersꢀandꢀaꢀcopperꢀcomplexꢀ
a
b
c
b
b
b
HongchengꢀGaoꢀ ,ꢀYanꢀYanꢀ ,ꢀXiaohongꢀXuꢀ ,ꢀJiehuiꢀYuꢀ ,ꢀHuilingꢀNiuꢀ ,ꢀWenxiuꢀGaoꢀ ,ꢀ ꢀ
b
b,
WenxiangꢀZhangꢀ ,ꢀMingjunꢀJiaꢀ *
ꢀ
aꢀDepartmentꢀofꢀChemicalꢀEngineering,ꢀChengdeꢀPetroleumꢀCollege,ꢀChengdeꢀ067000,ꢀHebei,ꢀChinaꢀ
bꢀCollegeꢀofꢀChemistry,ꢀJilinꢀUniversity,ꢀChangchunꢀ130021,ꢀJilin,ꢀChinaꢀ
cꢀPharmacyꢀDepartment,ꢀDaqingꢀOilfieldꢀGeneralꢀHospital,ꢀDaqingꢀ163001,ꢀHeilongjiang,ꢀChinaꢀ
A R T I C L E ꢀ I N F O ꢀ
A B S T R A C T ꢀ
Articleꢀhistory:ꢀ
Theꢀcatalyticꢀepoxidationꢀofꢀolefinꢀwasꢀinvestigatedꢀonꢀtwoꢀcopperꢀcomplex‐modifiedꢀmolybdenumꢀ
I
I
Receivedꢀ1ꢀMayꢀ2015ꢀ
Acceptedꢀ29ꢀMayꢀ2015ꢀ
Publishedꢀ20ꢀNovemberꢀ2015ꢀ
oxidesꢀwithꢀaꢀ3Dꢀsupramolecularꢀstructure,ꢀ[Cu(bipy)]
4
[Mo15
O
47]·2H Oꢀ(1)ꢀandꢀ[Cu (bix)][(Cu bix)
2
(δ‐MoVI
O )
0.5]ꢀ(2)ꢀ(bipyꢀ=ꢀ4,4′‐bipyridine,ꢀbixꢀ=ꢀ1,4‐bis(imidazole‐1‐ylmethyl)benzene).ꢀBothꢀcom‐
8
26
poundsꢀwereꢀcatalyticallyꢀactiveꢀandꢀstableꢀforꢀtheꢀepoxidationꢀofꢀcyclooctene,ꢀ1‐octene,ꢀandꢀstyreneꢀ
withꢀtert‐butylꢀhydroperoxideꢀ(t‐BuOOH)ꢀasꢀoxidant.ꢀTheꢀexcellentꢀcatalyticꢀperformanceꢀwasꢀat‐
tributedꢀtoꢀtheꢀpresenceꢀofꢀstableꢀcoordinationꢀbondsꢀbetweenꢀtheꢀmolybdenumꢀoxideꢀandꢀcopperꢀ
complex,ꢀwhichꢀresultedꢀinꢀtheꢀformationꢀofꢀeasilyꢀaccessibleꢀMoꢀspeciesꢀwithꢀhighꢀelectropositivity.ꢀ
Inꢀaddition,ꢀtheꢀcopperꢀcomplexꢀalsoꢀactedꢀasꢀanꢀactiveꢀsiteꢀforꢀtheꢀactivationꢀofꢀt‐BuOOH,ꢀthusꢀim‐
provingꢀtheseꢀcopperꢀcomplex‐modifiedꢀpolyoxometalates.ꢀ
Keywords:ꢀ
Supramolecularꢀcompoundꢀ
Molybdenumꢀoxideꢀclusterꢀ
Copperꢀcomplexꢀ
Olefinꢀ
©ꢀ2015,ꢀDalianꢀInstituteꢀofꢀChemicalꢀPhysics,ꢀChineseꢀAcademyꢀofꢀSciences.
PublishedꢀbyꢀElsevierꢀB.V.ꢀAllꢀrightsꢀreserved.
Epoxidation
1
.ꢀ ꢀ Introductionꢀ
stableꢀheterogeneousꢀPOM‐basedꢀcatalystsꢀforꢀtheꢀepoxidationꢀ
ofꢀolefins,ꢀwhichꢀareꢀimportantꢀprocessesꢀforꢀtheꢀproductionꢀofꢀ
fineꢀchemicalsꢀ[15].ꢀRecently,ꢀAli’sꢀgroupꢀ[16]ꢀsynthesizedꢀtwoꢀ
novelꢀ copperꢀ complex‐modifiedꢀ Andersonꢀ typeꢀ POMs,ꢀ
Theꢀdesignꢀandꢀsynthesisꢀofꢀinorganic‐organicꢀhybridꢀmate‐
rialsꢀbasedꢀonꢀpolyoxometalatesꢀ(POMs)ꢀhaveꢀbecomeꢀaꢀsignif‐
icantꢀresearchꢀareaꢀdueꢀtoꢀtheirꢀinterestingꢀstructuresꢀandꢀnu‐
merousꢀ potentialꢀ applicationsꢀ inꢀ materialꢀ science,ꢀ medicine,ꢀ
magnetism,ꢀ electrochemistry,ꢀ andꢀ catalysisꢀ [1–6].ꢀ Recently,ꢀ aꢀ
newꢀclassꢀofꢀsupramolecularꢀcompoundꢀcomposedꢀofꢀaꢀtransi‐
tionꢀmetalꢀ(e.g.,ꢀCu,ꢀNi,ꢀandꢀAg)ꢀcomplexꢀ(TMC)ꢀandꢀPOMꢀunitsꢀ
haveꢀdrawnꢀconsiderableꢀattentionꢀbecauseꢀtheꢀcombinationꢀofꢀ
aꢀtransitionꢀmetalꢀcomplexꢀwithꢀPOMsꢀcanꢀhelpꢀconstructꢀver‐
satileꢀ intriguingꢀ supramolecularꢀ structures,ꢀ andꢀ haveꢀ novelꢀ
physicochemicalꢀpropertiesꢀforꢀvariousꢀapplicationsꢀ[7–14].ꢀ ꢀ
InꢀtheꢀcatalyticꢀapplicationꢀofꢀPOM‐basedꢀcompounds,ꢀmoreꢀ
recentꢀ studiesꢀ haveꢀ focusedꢀ onꢀ developingꢀ highlyꢀ activeꢀ andꢀ
[(Na
[(Cu(en)
foundꢀthatꢀtheseꢀcompoundsꢀshowedꢀmoderateꢀcatalyticꢀactivi‐
4 2 2 6
(H O)14)(Cu(gly)) ][TeMo O24]ꢀ (glyꢀ =ꢀ glycine)ꢀ andꢀ
2 3
)
(TeW 24)]·6H
6
O
2
Oꢀ (enꢀ =ꢀ ethylene‐diamine),ꢀ andꢀ
tyꢀ forꢀ theꢀ epoxidationꢀ ofꢀ styreneꢀ andꢀ cyclohexeneꢀ withꢀ tert‐
butylhydroperoxideꢀ(t‐BuOOH).ꢀInꢀaꢀworkꢀreportedꢀbyꢀCuiꢀandꢀ
co‐authorsꢀ [17],ꢀ itꢀ wasꢀ foundꢀ thatꢀ aꢀ fewꢀ hybridꢀ compoundsꢀ
ꢀ
2+
2+
2+
composedꢀofꢀPOMs,ꢀtransitionꢀmetalꢀionsꢀ(Ni ,ꢀCu ,ꢀandꢀCd ),ꢀ
andꢀaꢀ4,4′‐bipyridineꢀorganicꢀligandꢀwereꢀactiveꢀforꢀtheꢀepoxi‐
dationꢀofꢀstyrene.ꢀCurrently,ꢀitꢀisꢀstillꢀaꢀveryꢀattractiveꢀsubjectꢀtoꢀ
developꢀmoreꢀefficientꢀandꢀstableꢀTMC‐modifiedꢀPOMsꢀasꢀcata‐
lystsꢀforꢀolefinꢀepoxidation.ꢀ
*ꢀCorrespondingꢀauthor.ꢀTel:ꢀ+86‐431‐85155390;ꢀFax:ꢀ+86‐431‐85168420;ꢀE‐mail:ꢀjiamj@jlu.edu.cnꢀ
ThisꢀworkꢀwasꢀsupportedꢀbyꢀtheꢀNationalꢀNaturalꢀScienceꢀFoundationꢀofꢀChinaꢀ(21173100ꢀandꢀ21320102001).ꢀ
DOI:ꢀ10.1016/S1872‐2067(15)60919‐6ꢀ|ꢀhttp://www.sciencedirect.com/science/journal/18722067ꢀ|ꢀChin.ꢀJ.ꢀCatal.,ꢀVol.ꢀ36,ꢀNo.ꢀ11,ꢀNovemberꢀ2015 ꢀ

1812ꢀ
HongchengꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ36ꢀ(2015)ꢀ1811–1817ꢀ
Previously,ꢀ weꢀ reportedꢀ thatꢀ someꢀ N‐heterocyclicꢀ ligands‐
ꢀ
2.2.ꢀ ꢀ Characterizationꢀofꢀtheꢀcatalystsꢀ
modifiedꢀ octamolybdate‐basedꢀ supramolecularꢀ compoundsꢀ
wereꢀactiveꢀheterogeneousꢀcatalystꢀforꢀtheꢀepoxidationꢀofꢀcy‐
cloocteneꢀandꢀ1‐octeneꢀwithꢀt‐BuOOH.ꢀTheꢀformationꢀofꢀaꢀmul‐
tidimensionalꢀ supramolecularꢀ structureꢀ usingꢀ multipleꢀ weakꢀ
interactions,ꢀ suchꢀ asꢀ hydrogenꢀ bondsꢀ andꢀ π‐πꢀ interactions,ꢀ
playsꢀ aꢀ keyꢀ roleꢀ inꢀ fabricatingꢀ activeꢀ andꢀ stableꢀ POM‐basedꢀ
catalysts.ꢀTheꢀcatalyticꢀpropertiesꢀvariedꢀconsiderablyꢀwithꢀtheꢀ
organicꢀ ligandꢀ andꢀ theꢀ multidimensionalꢀ supramolecularꢀ
structureꢀ[18].ꢀAsꢀaꢀcontinuationꢀofꢀtheꢀwork,ꢀweꢀinvestigatedꢀ
theꢀ catalyticꢀ epoxidationꢀ propertiesꢀ ofꢀ twoꢀ copperꢀ complexesꢀ
Crystallographicꢀ dataꢀ forꢀ allꢀ compoundsꢀ wereꢀ collectedꢀ atꢀ
ꢀ
120°CꢀonꢀaꢀSiemensꢀSMARTꢀCCDꢀusingꢀgraphite‐
ꢀ
monochroma‐
ꢀ radiationꢀ(λꢀ =ꢀ 0.071073ꢀ nm).ꢀ Absorptionꢀ correc‐
tionsꢀ wereꢀ carriedꢀ outꢀ withꢀ theꢀ SADABSꢀ program.ꢀ Theꢀ struc‐
tureꢀwasꢀsolvedꢀbyꢀdirectꢀmethodsꢀandꢀrefinedꢀonꢀF ꢀbyꢀtheꢀfullꢀ
tizedꢀ Moꢀ K
α
2
matrixꢀ leastꢀ squaresꢀ techniqueꢀ withꢀ theꢀ SHELXL‐97ꢀ programꢀ
softwareꢀ[19].ꢀGeometricꢀcalculationsꢀwereꢀusedꢀtoꢀlocateꢀtheꢀ
positionsꢀ ofꢀ theꢀ hydrogenꢀ atoms.ꢀ Fourierꢀ transformꢀ infraredꢀ
(FT‐IR)ꢀspectraꢀ(KBrꢀpellets)ꢀwereꢀrecordedꢀwithꢀaꢀNicoletꢀIm‐
pactꢀ 410ꢀ spectrometer.ꢀ Powderꢀ X‐rayꢀ diffractionꢀ (XRD)ꢀ pat‐
ternsꢀwereꢀobtainedꢀonꢀaꢀShimadzuꢀXRD‐6000ꢀdiffractometerꢀ
usedꢀ toꢀ modifyꢀ molybdenumꢀ oxides,ꢀ [Cu(bipy)]
4
[Mo15
O
47]·
ꢀ
I
I
2H
2
Oꢀ (1)ꢀ (bipyꢀ =ꢀ 4,4′‐bipyridine)ꢀ andꢀ [Cu (bix)][(Cu bix)
ꢀ
(δ‐
ꢀ
MoVI
O
)
0.5]ꢀ(2)ꢀ(bixꢀ=ꢀ1,4‐bis(imidazole‐1‐ylmethyl)
ꢀ
benzene).ꢀ
withꢀ Cuꢀ K ꢀ radiationꢀ rangeꢀ fromꢀ 5°ꢀ toꢀ 70°ꢀ atꢀ aꢀ scanꢀ rateꢀ ofꢀ
8
26
α
Theꢀ structuresꢀ andꢀ electrochemicalꢀ propertiesꢀ ofꢀ theseꢀ twoꢀ
compoundsꢀhaveꢀrecentlyꢀbeenꢀstudiedꢀbyꢀtwoꢀresearchꢀgroupsꢀ
6°/min.ꢀ X‐rayꢀ photoelectronꢀ spectroscopyꢀ (XPS)ꢀ analysisꢀ wasꢀ
carriedꢀoutꢀonꢀaꢀThermoꢀESCALABꢀ250ꢀspectrometerꢀwithꢀanꢀ
MgꢀKꢀ(1253.6ꢀeV)ꢀachromaticꢀX‐rayꢀsource.ꢀ
[13,14].ꢀInꢀtheꢀpresentꢀwork,ꢀitꢀwasꢀfoundꢀthatꢀbothꢀcompoundsꢀ
1ꢀ andꢀ 2ꢀ exhibitedꢀ excellentꢀ catalyticꢀ activityꢀ andꢀ stabilityꢀ forꢀ
theꢀ epoxidationꢀ ofꢀ olefins.ꢀ Theꢀ roleꢀ ofꢀ theꢀ copperꢀ complexesꢀ
wasꢀdiscussedꢀonꢀtheꢀbasisꢀofꢀtheꢀstructuralꢀcharacteristicsꢀandꢀ
catalyticꢀpropertiesꢀofꢀtheseꢀtransitionꢀmetalꢀcomplex‐modifiedꢀ
POMsꢀcatalysts.ꢀ ꢀ
2.3.ꢀ ꢀ Catalyticꢀtestꢀ
Theꢀactivityꢀandꢀselectivityꢀofꢀallꢀtheꢀcatalystsꢀwereꢀstudiedꢀ
usingꢀtheꢀepoxidationꢀofꢀvariousꢀolefinsꢀwithꢀt‐BuOOHꢀasꢀoxi‐
dantꢀ andꢀ chloroformꢀ orꢀ acetonitrileꢀ asꢀ theꢀ solvent.ꢀ Typically,ꢀ
2.ꢀ ꢀ Experimentalꢀ
theꢀ epoxidationꢀ ofꢀ olefinsꢀ wasꢀ performedꢀ inꢀ aꢀ 10ꢀ mLꢀ round‐
ꢀ
bottomedꢀflaskꢀequippedꢀwithꢀaꢀrefluxꢀcondenserꢀatꢀaꢀtemper‐
atureꢀofꢀ35,ꢀ45,ꢀorꢀ61ꢀ°C.ꢀTheꢀcatalystꢀ(0.005ꢀmmol),ꢀsubstrateꢀ
2
2
.1.ꢀ ꢀ Synthesisꢀofꢀtheꢀcatalystsꢀ
(1.0ꢀ mmol),ꢀt‐BuOOHꢀ(1.0ꢀmmol),ꢀandꢀsolventꢀ(chloroformꢀorꢀ
.1.1.ꢀ ꢀ [Cu(bipy)]
Bipyꢀ(0.5ꢀmmol,ꢀ0.0961ꢀg),ꢀCu(OAc)
g),ꢀ(NH Mo Oꢀ(0.2ꢀmmol,ꢀ0.248ꢀg),ꢀandꢀtriethylamineꢀ
0.02ꢀ mL)ꢀ wereꢀ addedꢀ intoꢀ 15ꢀ mLꢀ ofꢀ distilledꢀ waterꢀ atꢀ roomꢀ
4
[Mo15O47]·2H
2
Oꢀ(1)ꢀ ꢀ
acetonitrile,ꢀ 2ꢀ mL)ꢀ wereꢀ addedꢀ intoꢀ theꢀ flask.ꢀ Samplesꢀ wereꢀ
withdrawnꢀ atꢀ regularꢀ intervalsꢀ andꢀ filteredꢀ beforeꢀ measure‐
mentꢀ byꢀ aꢀ gasꢀ chromatographꢀ (Shimadzuꢀ GC‐14Cꢀ FID).ꢀ Theꢀ
catalyticꢀperformanceꢀofꢀcatalystꢀwasꢀevaluatedꢀbyꢀtheꢀconver‐
sionꢀofꢀolefinꢀandꢀselectivityꢀtoꢀitsꢀepoxideꢀusingꢀtolueneꢀasꢀtheꢀ
internalꢀstandard.ꢀ
2
·H Oꢀ(0.5ꢀmmol,ꢀ0.099ꢀ
2
)
4 6
7
O24·4H
2
(
temperature.ꢀTheꢀpHꢀofꢀtheꢀmixtureꢀwasꢀadjustedꢀtoꢀ3.0ꢀwithꢀ
HClꢀsolutionꢀ(1ꢀmol/L).ꢀAfterꢀstirringꢀforꢀ1ꢀhꢀatꢀroomꢀtempera‐
ture,ꢀtheꢀmixtureꢀwasꢀtransferredꢀtoꢀaꢀsealedꢀTeflon‐linedꢀauto‐
claveꢀ(25ꢀmL)ꢀandꢀheatedꢀatꢀ170ꢀ°Cꢀforꢀ5ꢀd.ꢀWhenꢀtheꢀmixtureꢀ
wasꢀslowlyꢀcooledꢀ(10ꢀ°C/h)ꢀtoꢀroomꢀtemperature,ꢀbrownꢀblockꢀ
crystalsꢀofꢀ1ꢀwereꢀobtainedꢀafterꢀwashingꢀwithꢀdistilledꢀwater.ꢀ
Theꢀcrystalsꢀwereꢀdriedꢀatꢀroomꢀtemperatureꢀandꢀgaveꢀaꢀyieldꢀ
ofꢀ40%ꢀbasedꢀonꢀMo.ꢀ ꢀ
3.ꢀ ꢀ Resultsꢀandꢀdiscussionꢀ
3.1.ꢀ ꢀ Synthesisꢀandꢀstructureꢀofꢀtheꢀcatalystsꢀ
Theꢀ proceduresꢀ forꢀ theꢀ synthesisꢀ ofꢀ compoundsꢀ 1ꢀ andꢀ 2ꢀ
wereꢀsimilarꢀtoꢀthoseꢀinꢀtheꢀliteratureꢀ[13,14].ꢀMinorꢀmodifica‐
tionꢀsuchꢀasꢀusingꢀdifferentꢀreagentsꢀandꢀsynthesisꢀconditionsꢀ
(pHꢀ values,ꢀ heatingꢀ temperatures)ꢀ wereꢀ usedꢀ inꢀ orderꢀ toꢀ getꢀ
crystallineꢀproductsꢀwithꢀhighꢀqualityꢀandꢀyield.ꢀForꢀinstance,ꢀ
I
I
VI
8
2
.1.2.ꢀ ꢀ [Cu (bix)][(Cu bix)(δ‐Mo
CuCl ·2H Oꢀ (0.5ꢀ mmol,ꢀ 0.085ꢀ g),ꢀ bixꢀ (0.5ꢀ mmol,ꢀ 0.119ꢀ g),ꢀ
NH Mo Oꢀ (0.1ꢀ mmol,ꢀ 0.124ꢀ g),ꢀ andꢀ triethylamineꢀ
0.02ꢀmL)ꢀwereꢀaddedꢀintoꢀ15ꢀmLꢀofꢀdistilledꢀwater.ꢀTheꢀpHꢀofꢀ
26
O )0.5]ꢀ(2)ꢀ
2
2
(
(
)
4 6
7
O24·4H
2
theꢀreagentꢀNH
4
VO ꢀwasꢀusedꢀforꢀtheꢀsynthesisꢀofꢀcompoundꢀ1ꢀ
3
theꢀmixtureꢀwasꢀadjustedꢀtoꢀ5.0ꢀwithꢀHClꢀorꢀNaOHꢀsolutionꢀ(1ꢀ
mol/L).ꢀAfterꢀstirringꢀforꢀ1ꢀhꢀatꢀroomꢀtemperature,ꢀtheꢀmixtureꢀ
wasꢀ transferredꢀ intoꢀ aꢀ sealedꢀ Teflon‐linedꢀ autoclaveꢀ (25ꢀ mL)ꢀ
andꢀheatedꢀatꢀ170ꢀ°Cꢀforꢀ5ꢀd.ꢀRedꢀblockꢀcrystalsꢀofꢀ2ꢀwereꢀcol‐
lectedꢀafterꢀtheꢀmixtureꢀwasꢀslowlyꢀcooledꢀ(10ꢀ°C/h)ꢀtoꢀroomꢀ
temperature.ꢀ Theꢀ crystalsꢀ wereꢀ washedꢀ withꢀ distilledꢀ waterꢀ
andꢀdriedꢀatꢀroomꢀtemperatureꢀtoꢀgiveꢀaꢀyieldꢀofꢀ45%ꢀbasedꢀonꢀ
Mo.ꢀ ꢀ
inꢀtheꢀliteratureꢀ[13],ꢀbutꢀourꢀpresentꢀworkꢀconfirmedꢀthatꢀtheꢀ
introductionꢀ ofꢀ thisꢀ V‐containingꢀ reagentꢀ wasꢀ notꢀ necessaryꢀ
andꢀ aꢀ relativelyꢀ highꢀ yieldꢀ ofꢀ 1ꢀ canꢀ beꢀ achievedꢀ byꢀ theꢀ opti‐
mizedꢀsynthesisꢀconditionsꢀdescribedꢀinꢀtheꢀexperimentalꢀsec‐
tion.ꢀ ꢀ
SingleꢀcrystalꢀXRDꢀanalysisꢀrevealedꢀthatꢀcompoundꢀ1ꢀhasꢀ
anꢀopenꢀmultitrackꢀCu–Nꢀcoordinationꢀpolymericꢀchain‐
fiedꢀ molybdenumꢀ oxideꢀ 3Dꢀ supramolecularꢀ structureꢀ (Fig.ꢀ
(a)),ꢀwhichꢀisꢀconsistentꢀwithꢀtheꢀpreviouslyꢀreportedꢀstruc‐
tureꢀ inꢀ theꢀ literatureꢀ [13].ꢀ Theꢀ molecularꢀ structureꢀ unitꢀ ofꢀ 1ꢀ
ꢀ
modi‐
1
.
2
.1.3.ꢀ ꢀ Referenceꢀsampleꢀ(H
2
bix)[(Hbix)
2
(γ‐Mo
8
O
26)]2H
2
Oꢀ(3)ꢀ ꢀ
4
–
Theꢀsynthesisꢀofꢀ3ꢀwasꢀsimilarꢀtoꢀthatꢀofꢀ2,ꢀbutꢀwithoutꢀtheꢀ
additionꢀ ofꢀ triethylamineꢀ andꢀ CuCl ·2H O.ꢀ Theꢀ crystalsꢀ ofꢀ 3ꢀ
wereꢀcollectedꢀwithꢀaꢀyieldꢀofꢀ49%ꢀbasedꢀonꢀMo.ꢀ ꢀ
consistsꢀ ofꢀ oneꢀ molybdenumꢀ oxideꢀ chainꢀ ofꢀ [Mo15
O
47] ,ꢀ fourꢀ
+
2
2
[Cu(bipy)] ꢀ cations,ꢀ andꢀ twoꢀ waterꢀ moleculesꢀ (Fig.ꢀ 2).ꢀ Com‐
poundꢀ 2ꢀ showedꢀ aꢀ 3Dꢀ (4,4)‐connectedꢀ frameworkꢀ withꢀ theꢀ

ꢀ
HongchengꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ36ꢀ(2015)ꢀ1811–1817ꢀ
1813ꢀ
4
2
4
2
(
6 8 )(8 12 )ꢀ topology,ꢀ whichꢀ isꢀ constructedꢀ fromꢀ δ‐
ꢀ
octamo‐
sionꢀofꢀcycloocteneꢀwasꢀreachedꢀafterꢀ8ꢀhꢀreactionꢀatꢀtheꢀlowꢀ
temperatureꢀofꢀ35ꢀ°C.ꢀ ꢀ
lybdatesꢀ[20,21],ꢀcopperꢀcations,ꢀandꢀbixꢀligands.ꢀTheꢀstructureꢀ
ofꢀ2ꢀhasꢀbeenꢀreportedꢀinꢀtheꢀliteratureꢀ[14].ꢀTheꢀmainꢀfeatureꢀ
ofꢀ thisꢀ compoundꢀ isꢀ thatꢀ itsꢀ 3Dꢀ frameworkꢀ isꢀ penetratedꢀ byꢀ
copper‐organicꢀ polymericꢀ chainsꢀ toꢀ formꢀ aꢀ 3Dꢀ polythreadedꢀ
frameworkꢀ(Fig.ꢀ1(b)).ꢀTheꢀunitꢀcellꢀofꢀ2ꢀshowsꢀtheꢀpresenceꢀofꢀ
Catalystꢀ 2ꢀ wasꢀ alsoꢀ active,ꢀ andꢀ 92%ꢀ conversionꢀ ofꢀ cy‐
cloocteneꢀwasꢀ achievedꢀ afterꢀ 10ꢀ h.ꢀBothꢀtheꢀ copperꢀ complex‐
ꢀ
modifiedꢀPOMꢀcatalystsꢀexhibitedꢀmuchꢀhigherꢀactivityꢀthanꢀtheꢀ
referenceꢀsampleꢀ3ꢀ(39%ꢀconversionꢀofꢀcycloocteneꢀafterꢀ10ꢀh).ꢀ
Inꢀaddition,ꢀtheꢀrelativelyꢀinertꢀterminalꢀolefinꢀofꢀ1‐octeneꢀcanꢀ
beꢀalsoꢀconvertedꢀrapidlyꢀtoꢀtheꢀcorrespondingꢀepoxideꢀ(77%ꢀ
conversion,ꢀnearlyꢀ100%ꢀepoxideꢀselectivity,ꢀreactionꢀtimeꢀ12ꢀ
h)ꢀwhenꢀ1ꢀwasꢀusedꢀasꢀcatalyst.ꢀItꢀshouldꢀbeꢀmentionedꢀhereꢀ
thatꢀ someꢀ byproductsꢀ likeꢀ 1,2‐octanediolꢀ andꢀ 1‐octanalꢀ wereꢀ
alsoꢀ detectedꢀ whenꢀ theꢀ reactionꢀ timeꢀ wasꢀ furtherꢀ prolongedꢀ
(dataꢀnotꢀgiven).ꢀ
Theꢀ epoxidationꢀ ofꢀ styreneꢀ wasꢀ alsoꢀ investigatedꢀ overꢀ theꢀ
aboveꢀcatalystsꢀ(Tableꢀ2).ꢀWhenꢀchloroformꢀwasꢀchosenꢀasꢀtheꢀ
solvent,ꢀtheꢀcatalyticꢀactivityꢀofꢀtheseꢀthreeꢀcatalystsꢀdecreasedꢀ
inꢀtheꢀorderꢀofꢀ1ꢀ>ꢀ2ꢀ>ꢀ3.ꢀAꢀsignificantꢀamountꢀofꢀbyproductsꢀ
likeꢀbenzaldehydeꢀandꢀpenylacetaldehydeꢀwereꢀobservedꢀoverꢀ
theseꢀcatalysts,ꢀthusꢀconsiderablyꢀdecreasingꢀtheꢀselectivityꢀtoꢀ
4–
I
aꢀ[δ‐Mo O26] ꢀ anion,ꢀtwoꢀCu ꢀ(Cu1ꢀandꢀCu2)ꢀcationsꢀandꢀtwoꢀ
bix1ꢀ(Z‐type)ꢀandꢀbix2ꢀ(U‐type)ꢀligandsꢀ(Fig.ꢀ2(c)).ꢀ
8
Theꢀ referenceꢀ sampleꢀ ofꢀ compoundꢀ 3ꢀ exhibitedꢀ aꢀ 3Dꢀ su‐
pramolecularꢀframeworkꢀbasedꢀonꢀhydrogenꢀbondꢀinteractionsꢀ
andꢀ π‐πꢀ stackingꢀ interactionsꢀ betweenꢀ theꢀ bixꢀ ligandsꢀ andꢀ
(Hbix)
ꢀ consistsꢀ ofꢀ oneꢀ [(Hbix1)
cation,ꢀandꢀoneꢀlatticeꢀwater.ꢀ
2–
[
3
2
(γ‐Mo
8
O26)] ꢀunitsꢀ(Fig.ꢀ3).ꢀTheꢀmolecularꢀstructureꢀofꢀ
O26)] ꢀ unit,ꢀ oneꢀ (H
bix2)2+ꢀ
2–
2
(γ‐Mo
8
2
3
.2.ꢀ ꢀ Catalyticꢀpropertiesꢀ
Theꢀcatalyticꢀpropertiesꢀofꢀcatalystsꢀ1ꢀandꢀ2ꢀandꢀreferenceꢀ
sampleꢀ3ꢀwereꢀinvestigatedꢀforꢀtheꢀepoxidationꢀofꢀcycloocteneꢀ
andꢀ1‐octeneꢀwithꢀt‐BuOOHꢀasꢀtheꢀoxidant.ꢀAsꢀshownꢀinꢀTableꢀ1,ꢀ
allꢀ catalystsꢀ wereꢀ activeꢀ forꢀ theꢀ epoxidationꢀ ofꢀ olefinsꢀ withꢀ
nearlyꢀ100%ꢀselectivityꢀtoꢀtheꢀcorrespondingꢀepoxides.ꢀAmongꢀ
these,ꢀcatalystꢀ1ꢀshowedꢀtheꢀhighestꢀactivity,ꢀandꢀ96%ꢀconver‐
epoxideꢀ (particularlyꢀ seriouslyꢀ onꢀ theꢀ twoꢀ copperꢀ complex‐
ꢀ
modifiedꢀPOMꢀcatalysts).ꢀChangingꢀtheꢀsolventꢀfromꢀchloroformꢀ
toꢀacetonitrileꢀdidꢀnotꢀchangeꢀtheꢀactivityꢀorderꢀofꢀtheꢀcatalysts,ꢀ
butꢀ theꢀ selectivityꢀ toꢀ epoxideꢀ decreasedꢀ notablyꢀ withꢀ theꢀ in‐
(
a)
(b)
ꢀ
4
n–
Fig.ꢀ1.ꢀ(a)ꢀViewꢀofꢀtheꢀinfinite‐trackꢀCu(bipy)ꢀchain‐modifiedꢀ[Mo15
O
47
]
n
ꢀinꢀcompoundꢀ1;ꢀ(b)ꢀTheꢀ3Dꢀpolythreadedꢀsupramolecularꢀstructureꢀalongꢀ
I
+ꢀ
theꢀgivenꢀdirectionsꢀinꢀcompoundꢀ2ꢀ(greenꢀrepresentsꢀpenetratedꢀ[Cu 2(bix2)]
n
chains).ꢀ
(a)
(b)
(c)
Fig.ꢀ2.ꢀBallꢀandꢀstickꢀrepresentationꢀofꢀtheꢀmolecularꢀunitꢀ(a)ꢀandꢀ[Mo15
lecularꢀunitꢀofꢀcompoundꢀ2ꢀ(allꢀhydrogenꢀatomsꢀandꢀlatticeꢀwaterꢀmoleculesꢀwereꢀomittedꢀforꢀclarity).ꢀ
O
47
]
4n–ꢀchainsꢀ(b)ꢀofꢀcompoundꢀ1;ꢀ(c)ꢀBallꢀandꢀstickꢀrepresentationꢀofꢀtheꢀmo‐
n

1814ꢀ
HongchengꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ36ꢀ(2015)ꢀ1811–1817ꢀ
(a)
(b)
ꢀ
Fig.ꢀ3.ꢀ(a)ꢀBallꢀandꢀstickꢀrepresentationꢀofꢀtheꢀmolecularꢀunitꢀofꢀcompoundꢀ3;ꢀ(b)ꢀ3Dꢀsupramolecularꢀframeworkꢀinꢀcompoundꢀ3.ꢀ
creaseꢀ ofꢀ benzaldehydeꢀ selectivity.ꢀ Veryꢀ highꢀ benzaldehybeꢀ
selectivityꢀ(upꢀtoꢀ96%)ꢀwasꢀfoundꢀoverꢀtheꢀcopper‐freeꢀcatalystꢀ
FT‐IRꢀandꢀXRDꢀmeasurementsꢀwereꢀcarriedꢀoutꢀtoꢀinvesti‐
gateꢀ theꢀ structuralꢀ stabilityꢀ ofꢀ catalystꢀ 1.ꢀ Theꢀ FT‐IRꢀ spectraꢀ
showedꢀthatꢀthereꢀwasꢀnoꢀobviousꢀdifferenceꢀbetweenꢀtheꢀusedꢀ
catalystꢀ(afterꢀtheꢀ5thꢀreactionꢀofꢀ1‐octeneꢀepoxidaiton)ꢀandꢀtheꢀ
3.ꢀTheseꢀresultsꢀsuggestꢀthatꢀtheꢀcatalyticꢀperformanceꢀofꢀtheseꢀ
POM‐basedꢀcatalystsꢀwasꢀsolventꢀdependentꢀ[22].ꢀ
Toꢀverifyꢀtheꢀheterogeneityꢀofꢀtheꢀcatalyticꢀprocess,ꢀaꢀleach‐
ingꢀtestꢀwasꢀperformedꢀforꢀtheꢀepoxidationꢀofꢀ1‐octeneꢀoverꢀtheꢀ
twoꢀcopperꢀcomplex‐modifiedꢀPOMꢀcatalysts.ꢀAsꢀshownꢀinꢀFig.ꢀ
8
0
70
4
,ꢀbothꢀcatalystꢀ1ꢀandꢀcatalystꢀ2ꢀshowꢀveryꢀhighꢀstabilityꢀagainstꢀ
6
0
0
Catalyst 1
leachingꢀ ofꢀ theꢀ activeꢀ species.ꢀ Besides,ꢀ itꢀ wasꢀ alsoꢀ foundꢀ thatꢀ
theseꢀcatalystsꢀareꢀrecyclable,ꢀandꢀnoꢀlossꢀinꢀcatalyticꢀactivityꢀ
wasꢀ detectedꢀ afterꢀ fiveꢀ reactionꢀ cyclesꢀ (Fig.ꢀ 5).ꢀ Theseꢀ resultsꢀ
suggestedꢀthatꢀtheꢀcopperꢀcomplex‐modifiedꢀPOMꢀcompoundsꢀ
areꢀtrulyꢀheterogeneousꢀcatalystsꢀunderꢀtheꢀreactionꢀconditionsꢀ
employed.ꢀ
5
40
30
20
10
0
Catalyst 2
Tableꢀ1ꢀ ꢀ
Epoxidationꢀofꢀolefinsꢀcatalyzedꢀbyꢀcatalystsꢀ1,ꢀ2,ꢀandꢀ3.ꢀ
0
2
4
6
8
10
12
tꢀ
Timeꢀ Conversion
Reaction time (h)
Catalystꢀ
Substrateꢀ
Productꢀ
(
°C)ꢀ (h)ꢀ
35ꢀ
(%)ꢀ
96ꢀ
92ꢀ
39ꢀ
77ꢀ
44ꢀ
43ꢀ
Fig.ꢀ 4.ꢀ Kineticꢀ profilesꢀ ofꢀ theꢀ epoxidationꢀ ofꢀ 1‐octeneꢀ withꢀ t‐BuOOHꢀ
overꢀtheꢀcatalysts.ꢀ(×)ꢀLeachingꢀexperimentsꢀofꢀtheꢀcatalystsꢀindicating
conversionꢀofꢀ1‐octeneꢀwithꢀtheꢀcatalystsꢀremovedꢀafterꢀ4ꢀhꢀatꢀreactionꢀ
temperature.ꢀ Reactionꢀ conditions:ꢀ 1‐octeneꢀ 1.0ꢀ mmol;ꢀ t‐BuOOHꢀ 1.0ꢀ
mmol;ꢀcatalystꢀ0.005ꢀmmol;ꢀchloroformꢀ2.0ꢀmL;ꢀtemperatureꢀ61ꢀ°C.ꢀAllꢀ
selectivitiesꢀforꢀtheꢀepoxideꢀwereꢀnearlyꢀ100%.ꢀ
1
ꢀ
ꢀ 8ꢀ
10ꢀ
10ꢀ
12ꢀ
12ꢀ
12ꢀ
2
ꢀ
O
35ꢀ
35ꢀ
61ꢀ
61ꢀ
61ꢀ
ꢀ
ꢀ
3
ꢀ
1
ꢀ
O
2
ꢀ
ꢀ
ꢀ
3ꢀ
Reactionꢀconditions:ꢀsubstrateꢀ1.0ꢀmmol;ꢀt‐BuOOHꢀ1.0ꢀmmol;ꢀcatalystꢀ
.005ꢀmmol;ꢀchloroformꢀ2.0ꢀmL.ꢀAllꢀselectivitiesꢀforꢀtheꢀepoxideꢀwereꢀ
nearlyꢀ100%.ꢀ
8
6
4
0
0
0
0
Tableꢀ2ꢀ ꢀ
Epoxidationꢀofꢀstyreneꢀoverꢀtheꢀthreeꢀcatalystsꢀafterꢀ12ꢀhꢀreactionꢀtime.
Selectivityꢀ(%)ꢀ
O
O
Conversionꢀ
Catalystꢀ
Solventꢀ
(%)ꢀ
20
0
O
ꢀ
ꢀ
1
ꢀ
chloroformꢀ
98ꢀ
77ꢀ
67ꢀ
91ꢀ
70ꢀ
21ꢀ
37ꢀ
40ꢀ
63ꢀ
9.0ꢀ
11ꢀ
2.5ꢀ
48ꢀ
47ꢀ
10ꢀ
73ꢀ
77ꢀ
96ꢀ
15ꢀ
13ꢀ
26ꢀ
17ꢀ
10ꢀ
1.3ꢀ
2
ꢀ
1
2
3
4
5
3
ꢀ
Run number
1
ꢀ
acetonitrileꢀ
2
ꢀ
Fig.ꢀ 5.ꢀ Recyclingꢀ experimentsꢀ ofꢀ catalystꢀ 1ꢀ forꢀ theꢀ conversionꢀ ofꢀ
1‐octeneꢀafterꢀ12ꢀhꢀreaction.ꢀReactionꢀconditions:ꢀ1‐octeneꢀ1.0ꢀmmol;ꢀ
t‐BuOOHꢀ1.0ꢀmmol;ꢀcatalystꢀ0.005ꢀmmol;ꢀchloroformꢀ2.0ꢀmL;ꢀtempera‐
tureꢀ61ꢀ°C.ꢀAllꢀselectivitiesꢀforꢀtheꢀepoxideꢀwereꢀnearlyꢀ100%.ꢀ
3ꢀ
Reactionꢀ conditions:ꢀ styreneꢀ 1.0ꢀ mmol;ꢀ t‐BuOOHꢀ 1.0ꢀ mmol;ꢀ catalystꢀ
ꢀ
0
.005ꢀmmol;ꢀsolventꢀ2.0ꢀmL;temperatureꢀ61ꢀ°C.ꢀ

ꢀ
HongchengꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ36ꢀ(2015)ꢀ1811–1817ꢀ
1815ꢀ
40000
30000
20000
10000
0
(1)
(
1)
Mo 3d5/2
Mo 3d3/2
(
2)
(
2)
4
000 3500 3000 2500 2000 1500 1000 500
245
240
235
B.E. (eV)
Fig.ꢀ8.ꢀXPSꢀspectraꢀofꢀcatalystsꢀ1ꢀ(1)ꢀandꢀ2ꢀ(2).ꢀ
230
225
1
Wavenumber (cm )
Fig.ꢀ6.ꢀFT‐IRꢀspectraꢀofꢀfreshꢀcatalystꢀ1ꢀ(1)ꢀandꢀusedꢀoneꢀafterꢀtheꢀfifth
cycleꢀinꢀ1‐octeneꢀepoxidationꢀ(2).ꢀ
interactionꢀ (i.e.,ꢀ formingꢀ aꢀ coordinationꢀ bond)ꢀ betweenꢀ theꢀ
POMꢀunitsꢀandꢀtheꢀcopperꢀcomplex.ꢀThisꢀinteractionꢀcanꢀchangeꢀ
theꢀnatureꢀofꢀtheꢀactiveꢀMoꢀspecies,ꢀthusꢀresultingꢀinꢀthatꢀtheꢀ
copperꢀ complex‐modifiedꢀ POMꢀ catalystsꢀ (1ꢀ andꢀ 2)ꢀ showedꢀ
differentꢀcatalyticꢀactivityꢀandꢀselectivityꢀforꢀtheꢀepoxidationꢀofꢀ
olefinsꢀcomparedꢀtoꢀtheꢀcopper‐freeꢀPOMꢀcatalystꢀ(3).ꢀInꢀaddi‐
tion,ꢀtheꢀintroducedꢀcopperꢀcomplexꢀcanꢀalsoꢀactꢀasꢀaꢀnewꢀac‐
tiveꢀsiteꢀforꢀtheꢀactivationꢀofꢀt‐BuOOHꢀtoꢀformꢀtheꢀactiveꢀinter‐
mediate,ꢀ likeꢀ theꢀ Cu‐hydroperoxoꢀ species,ꢀ whichꢀ hasꢀ beenꢀ
proposedꢀ inꢀ theꢀ literatureꢀ [16,24–27].ꢀ Thisꢀ mayꢀ beꢀ anotherꢀ
importantꢀ contributionꢀ fromꢀ theꢀ copperꢀ complexꢀ toꢀ theꢀ im‐
provementꢀofꢀtheꢀcatalyticꢀactivityꢀofꢀtheꢀPOM‐basedꢀcatalysts.ꢀ ꢀ
Otherꢀ factorsꢀ suchꢀ asꢀ theꢀ structuralꢀ characteristicsꢀ ofꢀ theꢀ
POM‐basedꢀcatalystsꢀmayꢀalsoꢀinfluenceꢀitsꢀcatalyticꢀproperty.ꢀ
Comparedꢀwithꢀtheꢀpolythreadedꢀstructureꢀofꢀcatalystꢀ2,ꢀcata‐
lystꢀ1ꢀhasꢀaꢀmoreꢀopenꢀframework,ꢀwhichꢀisꢀmoreꢀsuitableꢀforꢀ
theꢀdiffusionꢀofꢀtheꢀreactantsꢀtoꢀincreaseꢀtheꢀsubstrateꢀcontactꢀ
withꢀtheꢀcatalystꢀactiveꢀsites,ꢀthusꢀhelpingꢀtoꢀimproveꢀtheꢀcata‐
lyticꢀactivityꢀofꢀcatalystꢀ1.ꢀ
freshꢀoneꢀ(Fig.ꢀ6).ꢀTheꢀXRDꢀpatternsꢀindicatedꢀthatꢀtheꢀcharac‐
teristicꢀdiffractionꢀpeaksꢀforꢀtheꢀusedꢀcatalystꢀwereꢀconsistentꢀ
withꢀtheꢀfreshꢀcatalystꢀ1ꢀ(Fig.ꢀ7).ꢀTheseꢀresultsꢀsuggestedꢀthatꢀ
theꢀmolecularꢀstructureꢀgeometryꢀofꢀcatalystꢀ1ꢀwasꢀkeptꢀduringꢀ
theꢀreactionꢀprocess.ꢀTheꢀhighꢀcatalyticꢀstabilityꢀofꢀtheꢀcopperꢀ
complexꢀ modifiedꢀ POMꢀ compoundsꢀ canꢀ beꢀ attributedꢀ toꢀ theꢀ
formationꢀ ofꢀ theꢀ stableꢀ 3Dꢀ supramolecularꢀ structure.ꢀ Itꢀ wasꢀ
discussedꢀ aboveꢀ thatꢀ theꢀ copperꢀ complexꢀ andꢀ molybdenumꢀ
oxideꢀ clustersꢀ wereꢀ coordinatelyꢀ connectedꢀ viaꢀ theꢀ terminalꢀ
oxygenꢀatomsꢀofꢀtheꢀmolybdenumꢀoxideꢀclusterꢀ(asꢀactiveꢀcoor‐
dinationꢀsites)ꢀandꢀtheꢀcopperꢀions.ꢀ
XPSꢀmeasurementsꢀwereꢀalsoꢀcarriedꢀoutꢀforꢀtheꢀtwoꢀcopperꢀ
complex‐modifiedꢀPOMꢀcatalystsꢀ(Fig.ꢀ8).ꢀTheꢀXPSꢀspectrumꢀofꢀ
catalystꢀ1ꢀshowedꢀtwoꢀpeaksꢀatꢀ235.9ꢀandꢀ232.6ꢀeV,ꢀwhichꢀwereꢀ
assignedꢀtoꢀMoꢀ3d3/2ꢀandꢀMoꢀ3d5/2,ꢀrespectively.ꢀForꢀcatalystꢀ2,ꢀ
aꢀslightlyꢀlowerꢀbindingꢀenergyꢀofꢀtheꢀMoꢀspeciesꢀ(235.3ꢀandꢀ
232.1ꢀeV)ꢀwasꢀdetected.ꢀTheꢀhigherꢀelectropositivityꢀofꢀMoꢀspe‐
ciesꢀ isꢀ associatedꢀ withꢀ theꢀ higherꢀ catalyticꢀ activityꢀ ofꢀ molyb‐
denum‐containingꢀcatalystsꢀ[23].ꢀThisꢀmayꢀbeꢀtheꢀmainꢀreasonꢀ
whyꢀcatalystꢀ1ꢀwasꢀmoreꢀactiveꢀthanꢀ2.ꢀTheꢀhighꢀelectropositiv‐
ityꢀofꢀcatalystꢀ1ꢀoriginatedꢀfromꢀtheꢀnatureꢀofꢀtheꢀmolybdenumꢀ
4.ꢀ ꢀ Conclusionsꢀ
4–
Twoꢀ supramolecularꢀ compoundsꢀ basedꢀ onꢀ molybdenumꢀ
oxideꢀclustersꢀandꢀcopperꢀcomplexesꢀshowedꢀexcellentꢀcatalyticꢀ
activityꢀandꢀselectivityꢀforꢀtheꢀepoxidationꢀofꢀolefins.ꢀBothꢀcata‐
lystsꢀ areꢀ heterogeneousꢀ inꢀ natureꢀ andꢀ canꢀ beꢀ easilyꢀ recycledꢀ
withoutꢀdecreaseꢀinꢀactivity.ꢀTheꢀpresenceꢀofꢀrelativelyꢀstrongꢀ
coordinationꢀbondsꢀbetweenꢀtheꢀcopperꢀcomplexꢀandꢀtheꢀmo‐
lybdenumꢀoxideꢀclustersꢀplayedꢀaꢀcriticalꢀroleꢀinꢀfabricatingꢀtheꢀ
stableꢀsupramolecularꢀstructureꢀandꢀinꢀformingꢀanꢀactiveꢀandꢀ
stableꢀheterogeneousꢀcatalystꢀforꢀtheꢀepoxidationꢀofꢀolefins.ꢀ
oxide,ꢀi.e.,ꢀ[Mo15O47] .ꢀ
Furthermore,ꢀ theꢀ introductionꢀ ofꢀ theꢀ copperꢀ complexꢀ intoꢀ
theꢀframeworkꢀofꢀtheꢀPOM‐basedꢀcompoundsꢀalsoꢀconsiderablyꢀ
influencedꢀtheꢀelectropositivityꢀofꢀtheꢀMoꢀspeciesꢀbyꢀaꢀstrongꢀ
▲
Mo
Cu
Referencesꢀ
▲
▲
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(
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/( )
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8
Fig.ꢀ7.ꢀXRDꢀpatternsꢀofꢀfreshꢀcatalystꢀ1ꢀ(1)ꢀandꢀtheꢀusedꢀoneꢀafterꢀthe
fifthꢀcycleꢀinꢀ1‐octeneꢀepoxidationꢀ(2).ꢀ
[

1816ꢀ
HongchengꢀGaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ36ꢀ(2015)ꢀ1811–1817ꢀ
GraphicalꢀAbstractꢀ
Chin.ꢀJ.ꢀCatal.,ꢀ2015,ꢀ36:ꢀ1811–1817ꢀ ꢀ ꢀ doi:ꢀ10.1016/S1872‐2067(15)60919‐6
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Catalyticꢀepoxidationꢀofꢀolefinꢀoverꢀsupramolecularꢀcompoundsꢀofꢀ ꢀ
molybdenumꢀoxideꢀclustersꢀandꢀaꢀcopperꢀcomplexꢀ
+
t-BuOOH
HongchengꢀGao,ꢀYanꢀYan,ꢀXiaohongꢀXu,ꢀJiehuiꢀYu,ꢀHuilingꢀNiu,ꢀWenxiuꢀGao,ꢀ ꢀ
WenxiangꢀZhang,ꢀMingjunꢀJiaꢀ*ꢀ
R4
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ChengdeꢀPetroleumꢀCollege;ꢀJilinꢀUniversity;DaqingꢀOilfieldꢀGeneralꢀHospitalꢀ ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Copperꢀcomplex‐modifiedꢀpolyoxometalatesꢀshowedꢀhighꢀcatalyticꢀactivityꢀandꢀ
stabilityꢀ inꢀ theꢀ catalyticꢀ epoxidationꢀ ofꢀ olefinꢀ withꢀ tert‐butylꢀ hydroperoxideꢀ
(t‐BuOOH)ꢀasꢀoxidant.ꢀ
Copper complexes modified POMs
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