CC-2009-3801

Luminescencevapochromicpropertiesofaplatinum(II)complexwith5,50-bis(trimethylsilylethynyl)-2,20-bipyridinew

JunNi,Li-YiZhang,Hui-MinWenandZhong-NingChen*

Received(inCambridge,UK)21stJanuary2009,Accepted29thApril2009FirstpublishedasanAdvanceArticleontheweb19thMay2009DOI:10.1039/b901248f

Aplatinum(II)complexof5,50-bis(trimethylsilylethynyl)-2,20-bipyridinedisplaysunusuallyreversiblecolourandluminescencechangeswhenexposedtospecificorganicvapours,correlatedwellwithPtÁÁÁPtdistancesaswellasp–pandC–HÁÁÁ(CRC)interactionsinthestackingofsquare-planarplatinum(II)moieties.

Thedevelopmentofchemicalsensormaterialscapableofdetectingvolatileorganiccompounds(VOCs)intheenvironmentandtheworkplaceisofgreatsignificancetohumans.Ofparticularinterestarenaked-eyeperceivablechemosensorsthatshowtunable,andreversiblecolourandluminescencechangesinthevisibleandnearinfraredspectralregionuponexposuretovapoursofVOCs.1–20VOC-inducedspectroscopicvariationsandcolorimetricresponsesoccurfrequentlyincomplexescontainingd6,1d8,3–10,17ord10metalions,2,11–16,18,19andareusuallyassociatedwithachangeinmetal–metalcontacts,3,4,6–9,12,14–16ortheappearanceofotherweakinter-actionsincludingaromaticp–pstacking,1–2,5,18hydrogenbonding,2,5,20solvent–metalbonds,10,11,19orreversibleisomer-izationprocesses.13Here,wereportunusualluminescencevapochromismofabis(s-acetylide)platinum(II)complex(1)thatexhibitsselectiveandreversiblecolourchangestoavarietyofVOCswithanemissionshiftfrom562to747nm,correspondingtoavapochromicresponseshiftof185nm.

StateKeyLaboratoryofStructuralChemistry,FujianInstituteofResearchontheStructureofMatter,TheChineseAcademyofSciences,Fuzhou,Fujian350002,China.E-mail:czn@fjirsm.ac.cnwElectronicsupplementaryinformation(ESI)available:Detailedsyntheticproceduresandcharacterizationforcompounds1–3.CCDC7109–710905.ForcrystallographicdatainCIForotherelectronicformatseeDOI:10.1039/b901248f

Fig.1Stackingpatternsofadjacentplanarplatinum(II)moietiesin1Á1.5(CHCl3)Á0.5(H2O)(left)and1ÁCH2Cl2(right),showingstaggeredpackingfortheformerandantiparallelpackingforthelatter.

Thisjournalis

󰀃c

TheRoyalSocietyofChemistry2009Chem.Commun.,2009,3801–3803|3801

Cl2C–HÁÁÁp(CRC)interactionsbetweenCH2Cl2andethynylinthelatter(Fig.S13,ESIw).5b,cFor3ÁH2O(Fig.S15,ESIw),whichcontainsfreeCRCHgroups,significanthydrogenbondingCRC–HÁÁÁN(dHÁÁÁN=

,yC–HÁÁÁN=146.1(5)1)isoperatingbetween2.70(1)A

CRCHof5,50-diethynyl-2,20-bipyridineandtheNatomof5-ethynyl-2,20-bipyridine.TheshortestPtÁÁÁPtdistanceis

in3ÁH2O,precludingthepresenceofanybeyond6.0A

metallophilicinteraction.

Uponirradiationofthesolid-state1ÁVOCwith300nmolexo500nm,theyexhibitbrightyellowtoredluminescenceatambienttemperature.AsshowninFig.2,1ÁVOCcontainingsolvateacetone,CH2Cl2,n-hexaneorEt2Oemitbrightyellow,orange,pinkandredluminescence,respectively.Fig.3depictstheemissionspectraof1ÁVOCwiththeemissionmaximaat562(610sh)nmforacetone,608(563sh)nmforCH2Cl2,617nmforn-hexane,650nmforEt2O,660nmforethylacetate,729nmforCHCl3and747nmforTHF.Ongoingfrom1Áacetoneto1ÁTHF(Fig.3),theemissionat562nmisstepbystepred-shiftedto747nmwithadramaticvapoluminescentresponseshift(185nm).

Incontrast,2and3,whichcontainfreeCRCHgroups,donotdisplayluminescencevapochromicproperties.Theirsolid-stateemissionspectraarecomparablewiththoseinsolutionsatambienttemperature.Asrevealedfromthecrystalstructureof3ÁH2O(Fig.S15,ESIw),theformationofhydro-genbondingbetweenCRCHand2,20-bipyridylin2and3inducesasevereslippageinthestackingofsquare-planarplatinum(II)moieties,sothattherelackanyPt–Ptandp–pinteractionsinthecrystallatticesof2and3.Thisresultsinstrikinglydifferentluminescencepropertiesof2and3fromthoseof1ÁVOC.

Toprobetheselectivityandreversibilityofthevapochromicpropertiesof1tospecificVOCs,solutionsof1wasputonquartzdisks,whichwerepurgedwithN2atambienttemperature.UponexposuretosaturatedvapoursofvariousVOCs,exceptforn-hexane,whichcannotbeadsorbed,thedepositedquartzdisksdisplayedthesameemissionspectra(Fig.3)asthoserecordedfromthecrystalline1ÁVOCwithspecificsolvateVOCsandemitthesamebrightcolourorluminescenceunderambientlightorUVlightirradiation,asshowninFig.4.Uponexposureofthequartzdiskspreparedinadichloromethanesolutionof1tovarioussaturatedVOCvapours,exceptforn-hexane,underambienttemperaturefor10–20min,arapidvapochromicresponsewasobserved,in

Fig.3Emissionspectraofsolid-state1ÁVOCwithvarioussolvateVOCsatambienttemperature.

whichthedepositeddiskschangedfromorangeluminescencetoyellowforacetonevapour,andtoredforEt2O,ethylacetate,CHCl3andTHF,withemissionshiftsto652,660,729and747nm,respectively.Likewise,exposureofthequartzdiskspreparedinaTHFsolutionof1tospecificVOCvapours,exceptforn-hexane,inducedarapidvapochromismtoaffordthecorrespondingemissionof1ÁVOC.Thevapochromicresponseisfullyreversibleandreproduciblewithconversionofoneformtoanotherbyconvenientexposureofaquartzdiskpreparedinonesolutionof1toanothersaturatedVOCvapouratambienttemperature.Inallcases,theconversionofcolourisevendeeperunderUVlight(Fig.4),withnodetectabledegradationafterseveralexposurecycles.For1Áacetone,1ÁCH2Cl2and1Án-hexane,withoutPt–Pt

)contactsinthestackingofsquare-planar(dPt–Pt43.4A

platinum(II)moieties,theemissionmostlikelyarisesfromthe3MLCTexcitedstateinvolvingtheHOMOofaPt(d)orbital,mixedlikelywithsomecharacterfroma3LLCT(ligand-to-ligandchargetransfer)state(Fig.S15,ESIw).5,22,23UponformationofthePt–Ptcontactin1ÁTHFand1Á1.5(CHCl3)Á0.5(H2O),theemissiveoriginbecomesametal-metal-to-ligandchargetransfer(3MMLCT)tripletstateinvolvingaHOMOofds*nature(resultingfroms-overlappingbetweendz2orbitals)withahigherenergythanthatofthedz2orbitalandthus,thereisasmallerHOMO–LUMOenergygap,whichissignificantlyinfluencedbythePtÁÁÁPtdistance(Fig.S17,ESIw).8,23ItisnoteworthythatwithagradualdecreaseoftheshortestPtÁÁÁPt

(acetone)-4.3091(9)Adistancesintheorder4.8406(15)A

(ethylacetate)-3.2363(15)A(n-hexane)-3.6140(17)A

(THF),theluminescenceof1ÁVOCis(CHCl3)-3.2196(5)A

progressivelyred-shiftedintheorder562(610sh)(acetone)-617nm(n-hexane)-660nm(ethylacetate)-729nm(CHCl3)-747nm(THF).Itappearsthattheemissionenergy

Fig.2Photographicimagesofsolidsamplesof(a)1Áacetone,(b)1ÁCH2Cl2,(c)1Án-hexane,(d)1ÁEt2O,(e)1Á0.5(ethylacetate),(f)1Á1.5(CHCl3)Á0.5(H2O),and(g)1ÁTHFunderambientlightandUVlightirradiation(365nm).Fig.4Photographicimagesof1depositedonquartzslicesandexposedtoselectedorganicvapoursunderambientlightandUVlightirradiation(365nm);(a)acetone,(b)CH2Cl2,(d)Et2O,(e)ethylacetate,(f)CHCl3,and(g)THF.

3802|Chem.Commun.,2009,3801–3803Thisjournalis

󰀃c

TheRoyalSocietyofChemistry2009

iscorrelatedwellwiththePtÁÁÁPtdistancesin1ÁVOCwithvarioussolvateVOCs,inwhichtheshorterthePtÁÁÁPtdistance,thelowertheemissionenergyofthe3MMLCTtripletstate.8,23For1Áacetone,1ÁCH2Cl2,1Án-hexaneand1Á0.5(ethylacetate),withveryweakorwithoutPt–Ptinteractions,ared-shiftinemissionenergy(Fig.4)intheorder562(610sh)nm(acetone)-608(563sh)nm(CH2Cl2)-617nm(n-hexane)-660nm(ethylacetate)isprobablyassociatedwithweakintermolecularinteractions,includingp–pstackingbetweenpyÁÁÁpyringsin1Án-hexane

)and1Á0.5(ethylacetate)(dpyÁÁÁpy=3.53A),(dpyÁÁÁpy=3.75A

andsubstantialC–HÁÁÁp(CRC)interactions(videsupra)betweendichloromethaneandethynylin1ÁCH2Cl2.Ithasbeenproposedthatintermolecularp–pstacking,aswellasC–HÁÁÁp(CRC)interactions,wouldlowertheLUMOlevel(p*orbital)oftheligandandthuscauseanappreciableredshiftofthe3MLCT/3MMLCTemission(Fig.S17,ESIw).3a,5,23Insummary,bis(s-acetylide)platinum(II)complex1representsanunusualexamplethathaspotentialapplicationforthedetectionofVOCs.Studiesonthecrystalstructuresof1ÁVOCrevealthatthecolourchangeandemissionresponseof1tospecificVOCsaregovernedbythefactorsincludingPt–Pt,p–pandC–HÁÁÁp(CRC)interactionsinthestackingofthesquare-planarplatinum(II)moieties.

ThisworkwassupportedbytheNSFC(20625101,20773128and20821061),the973project(2007CB815304)fromMSTC,andNSFofFujianProvince(2008I0027).ProfessorZhenyangLinattheUniversityofScienceandTechnologyisthankedforhishelpfuldiscussion.

Crystaldatafor1ÁTHF:C48H46N6OPtSi2,Mr=974.18,monoclinic,spacegroupC2/c,a=28.870(3),b=23.5279(12),

,b=99.285(5)1,V=9088.4(11)A3,Z=8,c=13.5575(9)A

rcalcd=1.424gcmÀ1,m(MoKa)=3.182mmÀ1,T=113.1(1)K,28346reflectionscollected,7886unique(Rint=0.0537),R1=0.0538,wR2=0.1321for6627reflectionswithI42s(I),GOF=1.144.Crystaldatafor3ÁH2O:C38H24N6Pt,Mr=775.72,orthorhombic,

,spacegroupPbcn,a=20.479(5),b=11.794(3),c=12.660(3)A

3À1V=3057.8(13)A,Z=4,rcalcd=1.685gcm,m(MoKa)=

4.631mmÀ1,T=293(2)K,22593reflectionscollected,3511unique(Rint=0.0412),R1=0.0391,wR2=0.1005for2667reflectionswithI42s(I),GOF=1.127.

1Z.Liu,Z.Bian,J.Bian,Z.Li,D.NieandC.Huang,Inorg.Chem.,2008,47,8025.

2J.Pang,E.J.-P.Marcotte,C.Seward,R.S.BrownandS.Wang,Angew.Chem.,Int.Ed.,2001,40,4042.

3T.J.Wadas,Q.-M.Wang,Y.-j.Kim,C.Flaschenreim,T.N.BlantonandR.Eisenberg,J.Am.Chem.Soc.,2004,126,16841;P.Du,J.Schneider,W.W.BrennesselandR.Eisenberg,Inorg.Chem.,2008,47,69.

4S.M.Drew,D.E.Janzen,C.E.Buss,D.I.MacEwan,K.M.DublinandK.R.Mann,J.Am.Chem.Soc.,2001,123,8414;C.E.BussandK.R.Mann,J.Am.Chem.Soc.,2002,124,1031;K.A.McGee,B.J.MarquardtandK.R.Mann,Inorg.Chem.,2008,47,9143.

5S.C.F.Kui,S.S.-Y.Chui,C.-M.CheandN.Zhu,J.Am.Chem.Soc.,2006,128,8297;W.Lu,M.C.W.Chan,N.Zhu,C.-M.Che,Z.HeandK.-Y.Wong,Chem.–Eur.J.,2003,9,6155.

s,S.Fuertes,J.A.Loopez,A.MartiınandV.Sicilia,6J.Forniee

Inorg.Chem.,2008,47,7166;M.L.Muro,C.A.DawsandF.N.Castellano,Chem.Commun.,2008,6134.

7V.W.-W.Yam,K.M.-C.WongandN.Zhu,J.Am.Chem.Soc.,2002,124,6506.

8M.Kato,Bull.Chem.Soc.Jpn.,2007,80,287;M.Kato,A.Omura,A.Toshikawa,S.KishiandY.Sugimoto,Angew.Chem.,Int.Ed.,2002,41,3183.

9L.J.Grove,J.M.Rennekamp,H.JudeandW.B.Connick,J.Am.Chem.Soc.,2004,126,1594;L.J.Grove,A.G.Oliver,J.A.KrauseandW.B.Connick,Inorg.Chem.,2008,47,1408.10M.Albrecht,M.Lutz,A.L.SpekandG.vanKoten,Nature,2000,406,970.

11E.J.Fernandez,J.M.Lopez-de-Luzuriaga,M.Monge,M.E.Olmos,J.Perez,A.Laguna,A.A.MohamedandJ.P.

ndez,Jr.Fackler,J.Am.Chem.Soc.,2003,125,2022;E.J.Fernaa

J.M.Lopez-de-Luzuriaga,M.Monge,M.E.Olmos,R.C.Puelles,A.Laguna,A.A.MohamedandJ.P.Jr.Fackler,Inorg.Chem.,2008,47,8069.

12A.Luquin,C.Bariain,E.Vergara,E.Cerrada,J.Garrido,I.R.MatiasandM.Laguna,Appl.Organomet.Chem.,2005,19,1232.

13E.Cariati,X.BuandP.C.Ford,Chem.Mater.,2000,12,3385.14M.A.Mansour,W.B.Connick,R.J.Lachicotte,H.J.GyslingandR.Eisenberg,J.Am.Chem.Soc.,1998,120,1329.

15R.L.White-Morris,M.M.OlmsteadandA.L.Balch,J.Am.Chem.Soc.,2003,125,1033;R.L.White-Morris,M.M.Olmstead,F.Jiang,D.S.TintiandA.L.Balch,J.Am.Chem.Soc.,2002,124,2327.

16H.V.R.Dias,H.V.K.Diyabalanage,M.A.Rawashdeh-Omary,M.A.FranzmanandM.A.Omary,J.Am.Chem.Soc.,2003,125,12072.

17R.Pattacini,C.Giansante,P.Ceroni,M.MaestriandP.Braunstein,Chem.–Eur.J.,2007,13,10117.

18S.DasandP.K.Bharadwaj,Inorg.Chem.,2006,45,5257.

19J.Lefebvre,R.J.BatchelorandD.B.Leznoff,J.Am.Chem.Soc.,2004,126,16117.

20L.G.Beauvais,M.P.ShoresandJ.R.Long,J.Am.Chem.Soc.,2000,122,2763.

21C.A.HunterandJ.K.M.Sanders,J.Am.Chem.Soc.,1990,112,5525.

22M.Hissler,E.McGarrah,J.W.B.Connick,D.K.Geiger,S.D.CummingsandR.Eisenberg,Coord.Chem.Rev.,2000,208,115.

23V.M.MiskowskiandV.H.Houlding,Inorg.Chem.,1991,30,4446.

Notesandreferences

zCrystaldatafor1Áacetone:C47H44N6OPtSi2,Mr=960.15,triclinic,

,spacegroupP󰀂1,a=7.097(3),b=15.148(6),c=21.774(9)A

3a=71.79(1),b=86.63(1),g=83.21(1)1,V=2207.4(16)A,Z=2,

rcalcd=1.445gcmÀ1,m(MoKa)=3.274mmÀ1,T=113.1(1)K,134reflectionscollected,7575unique(Rint=0.0506),R1=0.0585,wR2=0.1421for6510reflectionswithI42s(I),GOF=1.158.Crystaldatafor1Á1.5(CHCl3)Á0.5(H2O):C45.50H40.5Cl4.50N6O0.5PtSi2,Mr=1090.,monoclinic,spacegroupC2/c,a=25.299(11),

,b=112.987(8)1,V=10288(8)A3,b=32.774(13),c=13.478(6)AÀ1À1Z=8,rcalcd=1.406gcm,m(MoKa)=3.045mm,T=113.1(1)K,32100reflectionscollected,8887unique(Rint=0.0843),R1=0.0685,wR2=0.1636for6875reflectionswithI42s(I),GOF=1.073.

Crystaldatafor1ÁCH2Cl2:C45H40Cl2N6PtSi2,Mr=987.00,tri-,clinic,spacegroupP󰀂1,a=10.871(2),b=13.095(1),c=16.633(1)A

3,Z=2,a=110.08(1),b=95.31(1),g=98.44(1)1,V=2173.6(5)A

À1À1rcalcd=1.508gcm,m(MoKa)=3.445mm,T=293(2)K,16765reflectionscollected,9783unique(Rint=0.0244),R1=0.0295,wR2=0.0710for8682reflectionswithI42s(I),GOF=1.014.Crystaldatafor1Á0.5(ethylacetate):C46H42N6OPtSi2,Mr=946.13,monoclinic,spacegroupP2/n,a=21.9(15),

,b=104.36(1)1,V=4380(5)A3,b=7.210(4),c=28.56(2)A

Z=4,rcalcd=1.435gcmÀ1,m(MoKa)=3.299mmÀ1,T=293(2)K,31762reflectionscollected,9799unique(Rint=0.10),R1=0.0710,wR2=0.1386for6955reflectionswithI42s(I),GOF=1.061.

Crystaldatafor1Án-hexane:C94H90N12Pt2Si4,Mr=10.32,triclinic,spacegroupP󰀂1,a=15.104(4),b=15.307(4),

,a=90.50(1),b=100.19(1),g=110.16(1)1,c=20.785(6)A

3,Z=2,rcalcd=1.418gcmÀ1,m(MoKa)=V=4427(2)A

3.262mmÀ1,T=293(2)K,27972reflectionscollected,14881unique(Rint=0.0363),R1=0.0405,wR2=0.1006for12150reflectionswithI42s(I),GOF=1.104.

Thisjournalis

󰀃c

TheRoyalSocietyofChemistry2009Chem.Commun.,2009,3801–3803|3803