TheoreticalInvestigationonMonomerandSolventSelectionforMolecularImprintingof ?Copiah olnCommunityCollege,11Co ircle,Natchez,Mississippi39120,United?DepartmentofChemistryandBiochemistry,JacksonStateUniversity,1400J.R.LynchStreet,Jackson,Mississippi39217,United::Theaimofthisworkistoserveasaguidelinefortheinitialselectionofmonomerandsolventforthesynthesisofthe poundbasedmolecularlyimprintedpolymers,MIPs.Reporteddataludeevaluationofsixsystemswiththeabilitytoformnoncovalentlybondedmonomer?temtecomplexes.Thesesystemsarerepresentedbythefollowingaliphaticandaromaticmolecules:acrolein,acrylonitrile,2,6bisacrylamide,4ethylenebenzoicacid,methylmethacrylate,and2vinylpyridine.Cavemodelsforselectedmonomersarealsopresentedandsupportedbybindingenergyysisundervariousconditions.Solvente?ectsonmonomer?temtebindingenergyhavebeenstudiedforfoursolvents:acetone,acetonitrile,chloroform,andmethanol.Additionally,systemssuchas2,4dinitrotoluene(2,4DNT),2,6dinitrotoluene(2,6DNT),pentachlorophenol(PCP),and3,6dichloro2methoxybenzoicacid(Dicamba)havebeenusedtostudyselectivityofacroleinbasedMIPtowarddetection.Thedensityfunctionaltheory,DFT,methodhasbeenusedforallstructural,vibrationalfrequency,andsolventcalculations.numberofnecessarysearchsynthesesperformedfortheselectionofthebestcompoundforaparticularexperiment.Computationallybasedevaluationextractsthemostusefulsubstancesoutofthepoolofpossiblesystemsquicklyandcostimprinting,MI,isanexperimentaltechniqueforcreatingreceptorstructuresonapolymersurfacethatcanselectivelybindtomoleculesofinterest.MIhasabroadspectrumofextraction,3,4detection,5,6anddrugdelivery.7,8AspresentedinFigure1,themolecularimprintingprocess9canbedividedintoFigure1.MIPprocess:(A)selfassembly;(B)polymerization;(C)solventextraction.threemainstages.Duringthe?rststage(monomerselfassembly)themoleculeofinterest,thetemte,issurroundedbymonomerspositionedtoinctwithfunctionalgroupsofthetemte.Thesecondstage(polymerization)occurswhenmonomerspolymerizewithcrosslinkingagentstoformacavearoundthetemte.Duringthe?nal,third,stage(extraction),thetemteisremoved,byasolventextractionprocess,fromtheformed .Theemptypossessesthecharacter

ofthefunctionalgroups.TheformedMIPisreadytorebindthetemteforitsdetection,separation,orextraction.pounds,especially2,4,6trinitrotoluene,10,11arethegroupofhighlyenergeticmaterialsforwhichdetectionisindemandduetosecurity5,12aswellasenvironmental6reasons. causinganimmediatedanger,asanexplosivematerial,thissubstancec socontaminatesoilandgroundwater.6Hence,ithasbeenproposedtoapplytheMIPtechniqueforthedetectionandpossibleremovalofthethetheoreticalmodelfortheevaluationofthebindingenergiesbetweenthemonomerandtemteforbothDNT13and14specieshasbeendesigned.ThepresentedmodelallowsustopredictqualitativelyandtativelypossibleinteractionsintheMIPsystem.Theoreticaldatareportedinbothmanuscriptshavebeenveri?edbyexperimentalFTIRspectra.Theabovementionedmodelhasbeenutilizedinthecourseofthisworktoperformtheoreticalcalculationsofsixselectedaromaticandaliphaticmonomers,forselectionofthebestonefortheimprintingof .AspresentedinFigure2,studiedmonomersludeacrolein,acrylonitrile,2,6bisacrylamide,4ethylenebenzoicacid,methylmethacrylate,and2vinylpyridine.Thee?ectsofthefourmostcommonsolventsacetonitrile,chloroform,andmethanol)onthe1:1monomer?temteandselectedcave?temtesystemshavealsobeenreported.Additionally,theselectivityofacroleinbasedMIPReceived:December26, January16,Published:January23,?2013AmericanChemical dx. |J.Phys.Chem.A2013,117,Figure2.Structuresoforganictowarddetectionofhasbeenstudiedusingacavemodelinctingwith2,4DNT,2,6DNT,PCP,andDicambamolecules,aspossiblecompetitors.Overall,thisworkaimstoprovideaguidelineforthemonomerandsolventselectionprocessforthemolecularimprintingofnitroaromaticcompounds,aswellasaninsightintoMIPselectivity.COMPUTATIONALThisstudyutilizespreviouslydeveloped1:1modelforimprinting,14whereinctswithasinglemonomermoleculethroughhydrogenbonding.Althoughthemonomercanformthreepossibleisomers(ortho,meta,andpara)withrespecttothemethylgroupof,themodelisbasedonthelowestenergyorthocomplex,AspresentedinFigure3,monomer(acrolein)inctswithmethylandtheorthonitrogroupofthemoleculethroughhydrogenbonds.Twocavemodelsmadeofthealiphaticandaromaticmonomers(underlinedinTable1)havebeendesignedto

studysolvente?ectsonthebindingenergy.Thecavein?rstsixdimersaroundthetemte.Figure4bshowsanemptyacroleincave.Thesecondcaveisbuiltfromeightaromatic2vinylpyridinemolecules,formingfourdimersaround,aspresentedinFigure4c.Figure4dshowsanempty2vinylpyridinecave.ThestudyontheselectivityofMIPtowardthemoleculehasbeenperformedusingapreviouslyoptimizedacroleave,reportedinFigure4b.ThegeometryofthecavehasbeenptomimictherealsolidstatepolymericstructureofformedMIP.Bindingenergiesoffourspecies,selectedduetotheirpresenceingroundwaterandsoilandstructuralsimilaritiesto,havebeencalculated.ThereportedinFigure5.Thedensityfunctionaltheory,15DFT,methodwiththeB3LYP16?18functionalhasbeenappliedtooptimizeallselectedspeciesandtheircomplexeswith2,4,6trinitrotolueneandtoperformsolventstudies.Nosymmetryconstraintswereimposedduringthegeometryoptimizationprocesses.Geometrysearchesforavarietyofpossiblecon?gurationswereperformedtoobtaintheglobalminimum,whichhasbeenveri?edbyDFTvibrationalfrequencycalculations.ThestandardPoplebasisset,631G(d,p),wasusedinthisstudy.19Basissetsuperpositionerror,20,21BSSE,hasbeenludedincalculationsofthetotalbindingenergyof1:1complexesandtheircomponents.Thee?ectofthesolventonthestudiedsystemswasmodeledbytheCPCMmodel.22CalculationspresentedinthisworkhavebeencarriedoututilizingtheGaussian0323suiteofprograms.RESULTSANDSix,themostpopular,monomersusedformolecularimprinting,MI,havebeenselectedforcomputationalstudyofmonomer?tem tecomplexformationoccurringduringimprintingof2,4,6 .Studyreportsbindingenergy,BE,hydrogenbondingdistancesandmonomer? BEa?ectedbythepresenceofsolvent.Thisworkreferstopreviouslyreportedmodels13,14designedformodelingofmonomerselfassemblyprocessoccurringduringmolecularimprintingofselectednitrocoumpounds,wherethemoste?ectivebindingsiteforthefunctionalmonomer(acrylicormethacrylicacid)involvesthemethylgroupandorthopositionednitrogroupofthenitroaromatic’smolecule.Asacontinuation,thisworkpresentssummaryofmonomer?temtebindingpropertiesforaliphatic(acrolein,acrylonitrile,methylmethacrylate),andaromatic(2,6bisacrylamide,4ethylenebenzoicacid,and2vinylpyridine)functionalmonomersinctingwith2,4,6.Bindingenergies,BE,andbindingdistancesforallsixstudiedcomplexes,calculatedinagasphase,andselectedcalculatedinthegasphase,decreasefrom7.03kcal/molfor2ethylenebenzoicacid to3.10kcal/molforthe2vinylpyridNTin ctingsystems.Gasphasecalculatedbindingenergieshavebeencorrectedbycounterpoisecorrectioncalculations.BSSElowersthevalueofBEforabout2.5kcal/mol,which,accordingtoGrabowski,24classi?esthemamongweakhydrogeninctions.Monomer?temteFigure3.1:1model ctingwithmonomer

TakingintoaccountafactthattheMIpolymerizationprocessoccursinasolution,itiscrucialtomimicsolventTable1.BondingPropertiesofStudiedMonomer?TemteComplexes luding:BindingEnergies,BE,CalculatedinaGasPhaseasWellasSelectedSolvents,andHydrogenBindingDistancesaBEinagasCOHCHOC≡NHCHOCHONHONOringHOHOCOCmethylCOHCHOCHOringNHCHOCHOaCalculationsperformedattheB3LYP/631G(d,p)leveloftheory.Energiesinkcal/mol,anglesinFigure5.Structuresofselectedorganicmoleculespresentinacetone,acetonitrile,ormethanolresultsindisintegrationofthecomplex(nomonomer?temteinctionisobserved).Hence,thosethreesolventsmaynotbethebestmediumforimprintingwith2,6bisacrylamideor4ethylenebenzoicFigure4.Cavemodelofencapsulatedinpolymerandemptycave(modelsforacroleinand2vinylpyridine).environmentomputationalstudies.Oneofthegoalsofthisworkistoprovidesolventysisforthepolymerizationprocess,andoverallhelpwithselectionofthebestsolventforimprintingof pounds.UsingtheCPCM22solvationmodelattheDFTleveloftheory,weattempttoinstigateandtemteduringselfassembly.Acetone,acetonitrile,chloroform,andmethanolhavebeenselectedforindividualstudyoftheirin?uenceonBE.AspresentedinTable1,introductionofsolventdramaticallychangesthevalueofBEwhencomparedtoonecalculatedinthegasphase.Themostspectaculare?ectonbindingenergycanbeobservedfortheethylenebenzoicacid?systems,whereadditionof

Outofthreeinitiallyselectedaromaticfunctionalmonomersonly2vinylpyridinehasapotentialformolecularimprintingofnitrocoumpoundsinthepresenceofallfourstudiedsolvents.The2vinylpyrid NTcalculatedBEfora1:1ratio te)insolventsolutionamountsto0.56kcal/molforacetonitrileand2.36kcal/molforchloromonomer?inction,reportedinTable1showthefollowingtrends:Allfourstudiedsolventsaresuitableformolecularimprintingof poundtemte.InallcalculatedcasesthevalueofBEdecreasesintheorderacrolein>methylmethacrylate>acrylonitrileformonomer?temtecomplexes.about1.5kcal/mol)whencomparedtoBEsofstudiedaromaticsystems.Cavemodelsforimprinting,usingacroleinand2vinylpyridinemonomers,havebeendesignedtocreatemoreinFigure4.Inthe?rstmodelthemoleculehasbeensurroundedbysixacroleindimersandinthesecondbyfourvinylpyridinedimers.Cave?temtebindingenergiesinagasphaseandsolventshavebeenreportedinTable2.TheysisTable2.BondingEnergies,BE,forStudiedCave?TemteComplexesCalculatedinaGasPhaseandSelectedSolventsaBEina BEin BEin BEin BEincavetemtegasphasemethanolacetonechloroformacetonitrileaCalculationswereperformedattheB3LYP/631G(d,p)leveloftheory.Energiesareinkcal/mol.ofcollecteddatashowsthatintroductionofthechloroformthefortheacroleinecaveand9.47kcal/molforthe2vinylpyridinecave.Introductionofothersolventslowerscave?temtebindingenergiesevenmoresigni?cantly.However,allcomputationallystudiedsolventsseemstobesuitableasamediumforthe imprintingwithacroleinand2Finally,theacroleavemodelhasbeenusedtostudytheselectivityofacrolinbasedMIPtowardthemolecule.AsacroleinbasedMIPisasolidstatepolymer,inourstudythegeometryoftheacroleavemodelhasbeenp.Nosymmetryconstraintshavebeenimposedonthefourspecieschosenfortheselectivitystudy.Thesepollutantshavebeenselectedduetotheirstructuralresemblancetoandallfourspeciesandtheacroleavehavebeencalculatedinagasphase.ThestudyindicatesthatbothDNTmoleculesbindtotheacrole avebutthebindingenergyissigni?cantlysmallerthanfor ,reportedas21.59kcal/mol.Bindingenergiesare10.98and3.73kcal/molfor2,4DNTand2,6DNT,respectively.PCPandDicambadonotbindtotheacroleave;performedcalculationsshowthattheyarestronglyrepelledbythecave.■Onthebasisoftheperformedcalculations,outofthesetoffourstudiedsolventsthemostuniversalsolventforMIPof,regardlessofthetypeofusedfunctionalmonomer,seemstobechloroform.Acetone,acetonitrile,andmethanolareproposedtobeusedforaliphaticmonomerimprintingorfortemteextractionofaromaticmonomers,withtheexceptionof2vinylpyridine.■AUTHOR446■Theauthorsdeclarenocompeting?nancial■ThisprojectissupportedbytheU.S.DepartmentofDefensethroughtheEngineer,ResearchandDevelopmentCenter(Vicksburg,MS),Contract#W912HZ10C0107,andTheMississippiCenterfor putingResearch(MCSR).

■Jo,S.H.;Lee,S.Y.;Park,K.M.;Yi,S.C.;Kim,D.;Mun,S.J.Chromatogr.A2010,45,7100?7108.■Pap,T.;Horvath,V.;Tolokan,A.;Horvai,G.;Sellergen,B.J.Chromatogr.A2002,973,1?12.Purif.Technol.2004,38,173?179.Alizadeh,T.;Zare,M.;Ganjali,M.R.;Norouzi,P.;Tavana,Biosens.Bioelect.2010,25,Cormack,P.A.G.;Elorza,A.Z.J.Chromatogr.B2004,804,Politzer,P.;Murray,J.S.;Koppes,W.M.;Concha,M.C.;P.Cent.Eur.J.Energet.Mater.2009,6,Clarkson,J.;Smith,W.E.;Batcheldar,D.N.;Smith,D.A.;Coats,A.M.J.Mol.Struct.2003,648,203?214.Bunte,G.;Hurttlen,J.;Pontius,H.;Hartlieb,K.;Krause,Saloni,J.;Dasary,S.S.R.;Yerramilli,A.;Yu,H.;Hill,G.,Hill,G.,Jr.Polymer2011,52,1206?1216.Molecules;OxfordUniversityPress:NewYork,1994.Lee,C.;Yang,W.;Parr,R.G.Phys.Rev.B1988,37,Simon,S.;Duran,M.;Dannenberg,J.J.J.Chem.Phys.105,Boys,S.F.;Bernardi,F.Mol.Phys.1970,19,83,Frisch,M.J.;Trucks,G.W.;Schlegel,H.B.;Scuseria,G.E.;Robb,M.A.;Cheeseman,J.R.;etal.Gaussian03,revisionC02;Gaussian.:Pittsburgh,PA,2004.Grabowski,S.Annu.Rep.Prog.Chem.Sect.C2006,102,Copiah-LolnCommunityCollege,11Co-L ircle,Natchez,Mississippi39120,UnitedStatesDepartmentofChemistryandBiochemistry,JacksonStateUniversity,1400J.R.LynchStreet,Jackson,Mississippi39217,UnitedStates 丙烯醛、丙烯腈、2,6-雙丙烯酰胺、4-亞乙基苯甲酸、甲基丙烯酸甲酯和2-乙烯基吡啶。還提出四種溶劑的模板結(jié)合能：丙酮、乙腈、氯仿和甲醇。此外，還有2,4-二硝基甲苯(2,4-DNT)、2,62,6-DNT(PCP)3,6-二氯-2Dicamba用于研究基于丙烯醛的MIP對(duì)檢測的選擇性。密度泛函理論（DFT）方法已用于所有結(jié)構(gòu)、.MI1,23,4、5,67,819MIP2,4,6-三硝基甲苯,10,115,126因，需要對(duì)其進(jìn)行檢測。除了造成直接危險(xiǎn)外，作為一種爆炸性物質(zhì)，這種物質(zhì)還會(huì)污染土壤和地下水。6因此，有人建議應(yīng)用MIP技術(shù)來檢測并盡可能去除環(huán)境中的及其衍生物。在型如圖1所示。MIP過程：(A)自組裝；(B)聚合；(C)溶劑萃取。MIPFT-IR香族和脂肪族單體進(jìn)行理論計(jì)算，以選擇最適合印跡的單體。如圖2所示，研究的單體包括丙烯醛、丙烯腈、2,6-雙丙烯酰胺、42-乙烯基吡啶。四種最常見溶劑（丙酮、乙腈、氯仿和甲醇）對(duì)1:1單體的影響。temte和選定的Cave.temteMIP：20111226：20131162013123物理化學(xué)雜志A》針對(duì)的檢測進(jìn)行了研究，使用洞穴模型與2,4-DNT、2,6-DNT、PCP和麥草畏分子（作為可能的競爭者）相互作用?？偟膩碚f，這項(xiàng)工作旨在為硝基芳香族化合物分子MIP2.發(fā)的印跡1:1模型，14其中通過氫鍵與單個(gè)單體分子相互作用。雖然單體相對(duì)于如圖3所示，單體（丙烯醛）與甲基和對(duì)位相互作用。分子的鄰硝基通過氫鍵連接。設(shè)計(jì)了兩個(gè)由脂肪族和芳香族單體制成的洞穴模型（表1中下劃線），用于研究溶劑對(duì)結(jié)合能的影響。.rst模型中的洞穴（圖4a）由十二個(gè)丙烯醛分子組成，在模板周圍形成六個(gè)二聚4b2-乙烯基吡啶分子構(gòu)成，在周圍形成四個(gè)二聚體，如圖4c所示。圖4d顯示了一個(gè)空的2-乙烯基吡啶洞穴。MIP對(duì)分子的選擇性研究是使用先前優(yōu)化的丙烯醛洞進(jìn)行的，如圖4b所示。洞穴的幾何形MIP由于它們存在于地下水和土壤中并且與結(jié)構(gòu)相似而被選擇的。2,4-DNT、2,6-DNT、PCP和麥草畏的結(jié)構(gòu)如圖5所示。密度泛函理論、15DFT、B3LYP16.182,4,6-三硝基何搜索以獲得全局最小值，這已通過DFTPople19BSSE)1:1究系統(tǒng)的影響通過CPCM22Gaussian03233.結(jié)果和討論六種最流行的用于分子印跡的單體，MI，已被選擇用于2,4,6- 生的單體.模板復(fù)合物形成的計(jì)算研究。研究報(bào)告了結(jié)合能、BE、氫鍵距離和單體。BE受溶劑甲基丙烯酸甲酯）和芳香族（2,6-雙丙烯酰胺、4-乙烯苯甲酸和2-乙烯基吡啶）功能單體與2、4,6-梯恩梯。表1報(bào)告了所有六種研究復(fù)合物在氣相中計(jì)算的結(jié)合能、BE和結(jié)合距離以及所選溶劑。在氣相中計(jì)算的BE的呈現(xiàn)值從2-的7.03kcal/mol降低對(duì)于2-乙烯基吡啶.相互作用系統(tǒng)，乙烯苯甲酸-至3.10kcal/mol。氣相計(jì)算的結(jié)合能已通過平衡校正計(jì)算進(jìn)行校正。BSSE使BE值降低約2.5kcal/mol，根據(jù)G