Photoinduced electron transfer fluorometric Hg(II) chemosensor based on a BODIPY armed with a tetrapod receptor

CULZONI M J; MUÑOZ DE LA PEÑA, A; MACHUCA A; H. GOICOECHEA; BRASCA R; BABIANO R

TALANTA

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2013

0039-9140

FromthegreatvarietyofBODIPYbased-chemosensorsabletodetermineHg2þ, onlyasmallportionhas been appliedtoitsdeterminationinenvironmentaland/orbiologicalsamples.Thelackofstudieson the analyticalperformanceofthelattersensorsmakesinterestingthedevelopmentofinvestigations oriented totheirpossibleanalyticalapplications.ThesynthesisofaBODIPYderivativearmedwitha tetrapodreceptorisdescribed.Theprocedureisbasedonapreviouspublication,andthemodifications performed toimprovethesynthesisincludealternativeprocedureswithdifferentobjectives,asthe consecution ofamultigramsynthesis,improvingthelowyieldsofsomeofthepreviouslyproposed proceduresteps,simplifyingtheexperimentalsteps,achievingthedesiredpurityrequirementsforuse with analyticalpurposes,andenrichingthecharacterizationoftheimpliedstructures.Thecharacteristics of itsselectivitytowardsHg2þ havebeeninvestigated,andtheOFF?ON fluorometric response,based on aphoto-electrontransfer(PET)mechanism,servedasthebaseforthedevelopmentofamethodable to determineHg2þ in environmentalwatersatngmL1 levels. The intrinsic fluorescence oftheBODIPYcoreisinhibitedandtheprobeexhibitsaweak fluorescence (i.e. ?OFF? state duetothedeactivatingPETeffect).Uponcomplexation,Hg2þ interactswiththelone-pair electrons onthenitrogenatomsofthereceptormoietysothattheelectronictransferfromthereceptor to thephoto-excited fluorophoreissloweddownorswitchedoff(i.e. ?ON? state duetothesuppression of thedeactivatingPETeffectbycoordinationoftheanalytetotheprobe). Regardingthecomplexphotostabilityinaqueoussolution,itismandatorytoconducttheexperi- ments atdarknessduetoitsphotodegradation.Thestoichiometrystudiesindicateda1:2relationshipfor the BODIPY-Hg2þ complex.Thehighselectivitytowardsmercuricionsisconsiderablyinfluenced bypH, being necessarytoconducttheexperimentsinapHvaluehigherthan6.Calibrationsampleswere preparedbyaddingappropriateamountsofHg2þ between 20.0?120.0ngmL?1, ataconstantBODIPY concentration of1 mmol L?1. Afteragitatingfor5minatdarkness,phosphatebuffer(pH¼7.50)was added, anditwasdilutedtothemarkwithwater.Fluorescencemeasurementswerecarriedoutat18 1C, excitingat515nm,andobtaining fluorescence emissionat538nm.Themethodhasbeensatisfactory applied toHg2þ determination inenvironmentalwatersamples