C3CC49555H氧杂

ChemComm

Published on 11 February 2014. Downloaded by NANJING UNIVERSITY on 24/07/2014 09:32:16.

Citethis:Chem.Commun.,2014,50,3579

Received17thDecember2013,Accepted7thFebruary2014DOI:10.1039/c3cc49555h

doc.guandang.net

Turn-onfluorescentprobesfornitricoxidesensingbasedontheortho-hydroxyaminostructureshowingnointerferencewithdehydroascorbicacid

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AliciaBeltra´n,M.IsabelBurguete,DanielR.Aba´nades,DoloresPe´rez-Sala,SantiagoV.Luis*aandFranciscoGalindo*a

Anewfamilyoffluorescentsyntheticmolecularprobesfornitricoxidesensingbasedonortho-hydroxyamino-triarylpyryliumsaltsispresented.

Nitricoxide(NO)hascapturedtheattentionofmanyresearchersduringthelastdecade.InterestinNOderivesfromitsknownbiologicalactivity,inparticularitspivotalroleinvasodilatationoritsfunctionsasaneurotransmitterandanantimicrobialagent.1

FluorescencetechniqueshavebecomeverypopularforNOsensingbecauseoftheirhighsensitivityandspatiotemporalresolu-tionwhencombinedwithmicroscopy.2Thus,theconstructionofsmallfluorescentsensorssuitableforspecificNOdetectioninlivingsystemshasreceivedgreatattention.Anumberoffluorescentprobeshavebeenreportedtodate.ThemostcommonapproachforNOdetectioninvolvestheuseofo-diaminoaromaticsunderaerobicconditions.ThesemoleculesreactwithN2O3(formedfromNOandO2),toyieldfluorescenttriazolederivatives.3

Anotherfamilyofprobes,inthiscasereactingdirectlywithNO,isbasedontransition-metalcomplexes.4Anincreasingnumberofotherstrategieshavebeendescribedintheliterature.5

Furthermore,althoughthepastseveralyearshavewitnessedgreatprogressinthedevelopmentofortho-diaminefluorescentprobes,theystillhavesomeshortcomings.Oneofthemostimpor-tantdrawbacks,isthatdehydroascorbicacid(DHA)reactswitho-diaminoaromaticsandturnsonthefluorescenceofsuchprobesinananalogouswayasN2O3does.AspointedoutbySweedlerandcoworkers,dehydroascorbicacidreactswithortho-diamineprobestogivefluorescentadductswhichareindistinguishablefromthosearisingfromthereactionwithN2O3.6Tosolvethisproblemvariouscorrectionstrategieshavebeendeveloped,includingfreezingofthe

´micaInorga´nicayOrga´nica,Avda.SosUniversitatJaumeI,DepartamentodeQu

´n,Spain.E-mail:francisco.galindo@uji.es,luiss@uji.esBaynats/n,12071,Castello

b

´gicas,C.S.I.C.,RamirodeMaeztu,9,CentrodeInvestigacionesBiolo

28040Madrid,Spain

Electronicsupplementaryinformation(ESI)available:Syntheticproceduresandcharacterizations,fluorometricandabsorptionstudies,andX-raycrystallo-graphicandbiologicalstudies.CCDC977073–977075.ForESIandcrystallo-graphicdatainCIForotherelectronicformatseeDOI:10.1039/c3cc49555h

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medium,7usingenzymesandcapillaryelectrophoresis8andmulti-derivatizationimageanalysis.9Inthisregard,notabledetectionlimitshavebeenreachedusingacontactlesscorrectionmethod(10nM).7Itshouldbenotedthatnottakingintoaccountthisimportantbiologicalinterferingspeciesmayleadresearchersinbiomedicalareastowronglyinterprettherecordeddata.However,developingamoreselectiveprobe,notreactivewithDHA,thusavoidingtheaforementionedcorrectionmethods,continuestobeanimportanttargetofcurrentinterestinthefield.

HereinwepresentthedevelopmentofanewfamilyofsyntheticmolecularprobesforNOinanoxygenatedmediumbasedonthepyryliumcationwhichmeetstheessentialcriteria,namely:(1)theyaresensitivetoNO/O2withoutshowingsignificantinterferencewithotherreactivenitrogen(RNS)andoxygenspecies(ROS),andespe-ciallywithoutshowinginterferencewithdehydroascorbicacid,and(2)theyareobtainedbyasimplemethodologythatallowse cientsynthesisoftheproductinonlytwosyntheticstepsandinhighyieldsfromreadilyavailablestartingproducts.Besides,thesyntheticprocedureallowsforastraightforwardintroductionofstructuralvariantsfavoringafinetuningofthedi erentspectroscopicproper-ties(excitationandfluorescenceemissionwavelengths,emissionquantumyields,andfluorescencelifetimes,etc.).

Thekeyfactortoaccomplishtheabove-mentionedfeaturesistheutilizationoftheortho-hydroxyaminostructureinsteadofthetraditionalortho-diaminoone.

Thesynthesisofcompounds2a–dstartedwiththepreparationoftheintermediates1a–dwithanortho-hydroxynitrosubstructure(Fig.1).Intermediates1a–dwereeasilypreparedbyaddingBF3ÁOEt2toasolutionof4-hydroxy-3-nitrobenzaldehydeandthecorre-spondingacetophenoneinanhydroustoluene.Thesolutionwasrefluxedfor2h.Aftercoolingtoroomtemperature,acetonewasaddedandthesolutionwaspouredintoexcessether.Aprecipitatewasformedwhichwasthenfiltered,washedwithetheranddriedundervacuum.Aseriesofanalysesconfirmedthattheprecipitatewasthehydroxynitropyryliumsalts1a–d.Compounds2a–dwereobtainedbyreductionofthenitrogrouptoanaminogroupbyusingSnCl2Á2H2Oindichloromethaneandexcessofhydrochloricacidundernitrogenatmosphere.Thereactionmixturewasrefluxedfor

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