E
E M E N T S
R E S E A R C H
UNC CHEMISTRY
SAVING ENERGY
Solar energy breakthroughs to greener chemical processes
Researchers in UNC’s Department of Chemistry are making bold strides toward a more energy-efficient future. Through innovative approaches that range from advanced material design to the use of light and catalysts, UNC chemists are uncovering new ways to reduce energy usage on a macro and micro level, while harnessing resources more effectively. These discoveries advance fundamental science and lay the groundwork for technologies that can impact everything from consumer products to global energy systems. Read on to discover the latest developments from UNC Chemistry, and to check in with a few of our alums.
The Communications Team
Dave DeFusco
Mandy Melton
Amie Solosky
RESEARCHERS BOOST FLEXIBLE ORGANIC SOLAR PANEL EFFICIENCY BY TURNING DOWN THE HEAT
NEW UNC PROFESSOR DEVELOPS WEARABLE DEVICES MONITORING THE BODY’S CHEMISTRY
RESEARCHERS UNCOVER UNUSUALLY LONG-LIVED 'POLAR STATES' IN PROMISING SOLAR MATERIALS
UNC RESEARCHERS USE CHEMICAL ‘GLUE’ TO POWER SOLAR FUEL BREAKTHROUGH
CHEMISTS UNLOCK ROUTE TO TINY MOLECULAR SHAPES THAT COULD POWER NEXT-GEN MEDICINES
UNC CHEMISTS DISCOVER HOW TO SPEED UP KEY REACTION FOR CLEAN ENERGY
CHEMISTS CAN DISCOVER NEW MATERIALS
MORE QUICKLY WITH AI
Everydayitemslikecartires,plasticbags andfoamcushionscomefrommaterials calledpolymersthatcantakeyearsto developandtest.ResearchersatCarnegie MellonUniversityandtheUniversityofNorth CarolinaatChapelHillhavedevelopeda newapproachtocreatebetterrubber-like materialsmorequicklybycombining artificialintelligencewithhumanexpertise.
Typicallywhenresearchersmakea materialstronger,itbecomeslessflexible, whileflexiblematerialstendtobeweaker. Tofixthisproblem,theteamcreateda machinelearningmodelthatworksin tandemwithhumanchemists.Machine learning—asubsetofAIresearch— involvesteachinganartificialintelligenceto performaspecifictask.Inoneexperiment, theresearcherscollaboratedwiththeAI
tooltocreateapolymerthatisbothstrong andflexible.
“Therearesomanyapplicationsfor polymers:construction,carparts,footwear, moldings,coatings,”saidOlexandr(Oles)
Isayev,CarlandAmyJonesProfessorin InterdisciplinaryScience “Wheneveryou makeoneforaspecificapplication,it needscertainproperties,anditcan’t usuallywithstandforceandexpandatthe sametime.Thesenewmaterialshave excellentproperties.Theycandoboth.”
Thegroupinputthepropertiesitwantedin apolymerintothedesigntool.Then,the modelsuggestedaseriesofexperiments thatUNC-ChapelHillchemistsconducted usingautomatedsciencetools.The researcherstestedtheproducedmaterials
FrankLeibfarthshowsoneofthenewpolymerscreatedusingAI
andprovidedfeedbacktothemodel,soit couldmakeadjustments.
“TheAIsystemsuggestsanexperiment,and aftertheexperiment’sbeenmade,we measuretheproperties,andweiterate,” Isayevsaid “Youcandynamicallyadjustand helpthemachinenavigatetofindmaterials withthedesiredproperties.”
FrankLeibfarth,professorofchemistryatUNC-ChapelHill,saidworkinginthisnewwaywasabreath offreshair.
“Inourhuman-augmentedapproach,wewereinteractingwiththemodel,notjusttakingdirections,” Leibfarthsaid “Thisallowedustocombinethebestaspectsofhuman-andmachine-guided processestocometotheoptimalsolution”
Leibfarthalsosaidhewasexcitedforthepotentialapplicationsforthepolymer
“Materialslikethiscouldbeusedinrunningshoes,medicaldeviceslike3Dprinteddentalimplants, anddurablepartsforcars,”Leibfarthsaid
“We’reatthisreallyinterestingtimeinchemistryandchemicalengineeringoffindingoutwhat’sthe beststrategytogoafterthenextgreatmaterial,”saidDylanAnstine,aformerpostdoctoralfellowin CarnegieMellon’sDepartmentofChemistry,whoisnowanassistantprofessorofchemical engineeringandmaterialsscienceatMichiganStateUniversity.“It’sclearthat’sgoingtoinvolve expertexperimentalchemistsandexpertcomputationalchemistsusingthebestdatasciencetools wecan.Wewerereallyteasingapartwhatthatrelationshiplookslike.”
Themachinelearningmodelalsosavedtheresearcherssignificanttimeandmoneybyrulingout methodsandchemicalsthatwouldnotwork.Theresearchershavemadetheprogramopensource, soanylabcanhaveaccesstothistool.Ifadoptedinotherlabs,thetoolcouldreducethecostand timerequiredforotherdiscoveries.
Thisapproachcouldacceleratethedevelopmentofadvancedmaterialsformedicaldevices, footwearandelectronics BycombiningAIpredictionswithhumanexpertise,theresearchershope theycansolvecomplexmaterialschallengesmoreeffectively
Anstine,IsayevandLeibfarthpublished“DesignofTough3DPrintableElastomerswithHuman-inthe-LoopReinforcementLearning”inAngewandteChemiealongwithCarnegieMellongraduate studentsFilippGusevandFilippNikitin aswellasUNC-ChapelHillresearchers JohannRapp,KellyYun,Meredith Borden,andVitallBhat.Theirworkwas fundedbytheAirForceResearch LaboratoryandtheNationalScience Foundation.
RESEARCHERS BOOST
FLEXIBLE ORGANIC SOLAR PANEL EFFICIENCY BY TURNING DOWN THE HEAT
AteamofresearchersledbyJordanShanahan,aPh.D.studentintheDepartmentofChemistry, demonstratedawaytomakeanimportantstepinorganicsolarcellmanufacturinghappenata temperatureof80degreesCelsius,or176degreesFahrenheit,lowerthannormal.
Insolartechnology,sometimesasmall tweakcanmakeabigdifference.Fora specialtypeofsolarpanelmadefromthin, flexible,plastic-likematerials,researchers atUNC-ChapelHillhavefoundthattweak: uselessheat.
InanewstudypublishedintheJournalof theAmericanChemicalSociety,ateamof researchersintheCarolinaDepartmentof Chemistryshowedawaytomakean importantstepinorganicsolarcell manufacturinghappenatatemperatureof 80degreesCelsius,or176degrees Fahrenheit,lowerthannormal.Thatgentler approachnotonlypreventsdamagetothe materialbutalsomakesthesolarcellswork better,achievingthebestperformance everreportedforthistypeofmaterial
“Wefiguredoutawaytolowerthe temperaturewhereinsteadofthedevice performancedecreasing,wegeta performanceboost,”saidJordan Shanahan,leadauthorofthestudyanda Ph.D.chemistrystudentatUNC.
Theseflexiblesolarpanels,calledorganic photovoltaics(OPVs),aremadefromtwo mainingredients:alight-absorbing material thedonorpolymer apartner material,theacceptor,thathelpscarry awaytheelectricchargescreatedby sunlight.
Tomakethelight-absorbingmaterial stable,scientistsoftenneedtoremovetiny chemical“sidechains”fromitsstructure. Thismakesthematerialpackmoretightly andletselectricitymovemoreeasily.
Traditionally,thisremovalprocessisdone byheatingthematerialtoveryhigh temperatures around220degreesCelsius, or428degreesFahrenheit.Butthere’sa catch:highheat-inducedstresscanruin thefine,evenblendneededforgood performance Shanahanandco-authors, includingDr.WeiYou,senior authorofthepaperandCaryC. BoshamerDistinguished ProfessorofChemistryand AppliedPhysicalSciences,found awaytoremovethoseside chainsatjust140degrees Celsius,or284degrees Fahrenheit,orevenlowerby addingasmallamountofacid directlyintothematerialbefore heating. Aftertestingdifferenttypesand amountsofacid,theydiscovered that5%diphenylphosphate workedbest.Theacidspeedsup thesidechainremovalwithout harmingtherestofthesolarcell Theresearchersalsofoundthey couldpredicthowfastthe processwouldhappenbasedon threesimplefactors:howstrong theacidis,howmuchacidis addedandthetemperature used.Thismakesiteasierfor otherscientiststofine-tunethe process,almostlikefollowinga recipe.
“Loweringthetemperaturekeptthetwo ingredientsmoreideallymixed,whichled tobetterperformance,”saidProfessor You.“Withthisnewacid-assistedmethod, oursolarcellsreachedabout4.5% efficiency thehighesteverreportedfor thistypeofmaterialsidechainfree”
JordanShanahan
Inearlierwork,theresearchers hadshownthatremovingside chainscouldmakeelectricity movethroughthematerialtwoto fivetimesfaster.Thenewmethod keepsthatbenefitbutavoidsthe damagecausedbyhighheat. Importantly,thenewlow-heat processdoesn’tmakethesolar cellslessstable.Boththehighheatandlow-heatmethods producedmaterialsthatcould handlehighertemperaturesover time.Thedifferenceisthatthe low-heatversionstartedoff workingbetter. Theresearchteambelievesthis mildapproachcouldbeusedto improvemanykindsoforganic electronicdevices.
“It’sanewtoolthatwehope otherscanutilizetoachievebetter performanceandstabilitywith thesematerialsbaseddevices.” saidProfessorYou
WeiYou
NEW UNC PROFESSOR DEVELOPS WEARABLE DEVICES MONITORING THE BODY’S CHEMISTRY
NetzArroyo,whojoinedUNCinJulyafterahighlysuccessfultenureatJohnsHopkinsUniversitySchoolof Medicine,isanexpertincreatingelectrochemicalbiosensors tiny,highlysensitivedevicesthatcan continuouslymonitormoleculesinthebody
Imagineatiny,wearableorimplantable devicethatcouldtrackyourbody’s chemistryinrealtime,tellingyouwhether yourmedicationisworking,ifyou’relowon acriticalnutrientorevenhowyourfitness routineisaffectingyourhealth.ForDr.Netz Arroyo,thenewestassociateprofessorin Carolina’sDepartmentofChemistry,thisis notsciencefiction,it’shiseverydaywork
Arroyo,whojoinedUNCinJulyafterahighly successfultenureatJohnsHopkins UniversitySchoolofMedicine,isanexpertin creatingelectrochemicalbiosensors tiny, highlysensitivedevicesthatcan continuouslymonitormoleculesinthe body.Hisresearchblendschemistry, engineeringandbiologytodeveloptools
TheArroyoLabandhisteamdesign sensorsthatmimicthebody’snatural abilitytodetectspecificmolecules.These devicescanmeasureimportant compoundslikedrugs,proteinsandother chemicalsignalswithoutneedingablood drawortriptothelab. thatcouldtransformhowweunderstand, trackandimprovehealth
“Wewanttomakeitpossibleforpeopleto getdetailed,real-timeinformationabout theirbodies,”saidArroyo.“Thatinformation canempowerbetterdecisionsaboutdiet, exercise,treatments—really,everythingthat affectshealth.”
Thepotentialapplicationsarewideranging:
Bettermedicationmanagementby showingexactlyhowmuchofadrugis inthebodyatanymoment Personalizedhealthmonitoring,with wearabledevicesthatgiveadetailed chemicalsnapshotofyourwell-being. Smarterdrugdeliverysystemsthat respondautomaticallytochangesin thebody.
Hisgroup’srecentworkhasevenrevealed surprisingdetailsabouthowmedicines spreadthroughthebrain,anddeveloped newtoolsfortrackingHIVtreatmentand cancerbiomarkersinrealtime.
Arroyo’simpactisn’tlimitedtothelab bench In2025,hebecameinterimeditorin-chiefofECSSensorsPlus,an internationaljournalthatpublishescuttingedgeresearchonsensingtechnologies He hasbeenrecognizedasa“RisingStarin Sensing”byACSSensorsandhasearned awardsforbothresearchandteaching, includingJohnsHopkins’CecilH.Robinson TeachingAwardin2024
Hisscientificreachspanscollaborationson everythingfromCOVID-19antibody trackingtonewmaterialsforimproving sensorperformance.Inthepasttwoyears alone,he’sco-authoredstudiesonbrain drugmapping,rapidprototypingof biosensorsandDNA-baseddevicesthat candetectproteinsandgeneticmaterial withincredibleprecision.
Beyondhisresearch,Arroyoiscommitted tobuildingadiverseandwelcoming scientificcommunity.Hislabactivelyworks toensurethatpeoplefromallbackgrounds haveaccesstoresearchopportunitiesand thateveryvoiceisrespected.
“Creativityandinnovationcomefrom diversity,”hesaid.“Differentperspectives arewhatallowustosolvehardproblemsin newways”
Arroyoearnedhisundergraduatedegreein chemicalsciencesfromTecnológicode MonterreyinMexico,hisPh.D.inanalytical chemistryfromtheUniversityofTexasat Austin,andcompletedapostdoctoral fellowshipattheUniversityofCalifornia,Santa Barbara HejoinedthefacultyatJohns Hopkinsin2019andquicklybuiltareputation asacreativeresearcherandinspiringteacher beforemakingthemovetoChapelHill.
NetzArroyo
AshesettlesintohisnewroleatUNC,Arroyois lookingforwardtoexpandinghisresearchand collaborations.Hisgoalisclear:tocreate technologiesthatbringlaboratory-level chemicalanalysisintoeverydaylife.
“Forpatients,athletes,doctorsandanyone interestedinunderstandingtheirownbiology,” hesaid,“thefutureasIenvisionitisonewhere chemistryquietlyworksinthebackground, helpingpeoplelivehealthier,moreinformed lives.”
-DaveDeFusco
RESEARCHERS UNCOVER UNUSUALLY LONG-LIVED 'POLAR STATES' IN PROMISING SOLAR MATERIALS
Above,aperovskitesolarcell.AnewstudyledbyCarolinachemistLinaQuanandpublishedin NatureCommunications,revealedasurprisingandpotentiallygame-changingproperty:when perovskitesarehitwithlight,theycanform“polarstates”thatlastanunusuallylongtime upto microseconds,ormillionthsofasecond.
Intheracetocreatecheaper,more efficientsolarpanels,scientistshavebeen focusingonaclassofmaterialscalled metalhalideperovskites Thesematerials canconvertsunlightintoelectricitywith highefficiency,areinexpensivetoproduce andcanbemadeintothin,flexiblefilms.
Butresearchershavelongbeenpuzzledby certainbehaviorsinsideperovskitesthat couldholdthekeytoevenbetter performance.
AnewstudyledbyCarolinachemistLina QuanandpublishedinNature Communications,revealedasurprisingand potentiallygame-changingproperty:when perovskitesarehitwithlight,theycanform “polarstates”thatlastanunusuallylong time uptomicroseconds,ormillionthsofa
second.Thatmightnotsoundlikemuch, butintheworldofelectronicsandenergy conversion,it’salifetime.
“Thisisthelongest-livedphotoinduced polarstateeverseeninthisclassof materials,”saidQuan,seniorauthorofthe paperandanassistantprofessorinUNC’s DepartmentofChemistry.“Itopensup excitingnewpossibilitiesforhowwecan designsolarcellsandotheroptoelectronic devices.”
Apolarstatehappenswhenpositiveand negativechargesinamaterialseparate andcreateabuilt-inelectricfield.In perovskites,shininglightcantriggerthis chargeseparation Thelongerthatstate lasts,themoretimethematerialhasto
tocollectandmovethosechargesto wherethey’reneeded,whetherthat’sto produceelectricityinasolarcellorto createlightinanLED.
“Untilnow,scientiststhoughttheselightinducedpolarstatesinperovskiteswere tooshort-livedtobeuseful,”saidQuan.“But ourteam’sexperimentsshowedthatunder certainconditions,theeffectcanlast thousandsoftimeslongerthansimilar effectsinothermaterials.”
Theresearchersusedultrafastlaserpulses toexcitetheperovskiteandthenmeasured howitsstructureandelectricalproperties changedovertime.Thistechniqueallowed themtocapturefleetingchangeson timescalesrangingfromfemtoseconds quadrillionthsofasecond to microseconds.
Theyfoundthatoncethepolarstate formed,itpersistedfarbeyondtheinitial flashoflight.Thepersistenceappearedto belinkedtosubtledistortionsinthe perovskite’scrystalstructure distortions thattrapthechargesinplacewithout completelyimmobilizingthem.
“It’slikethelightleavesafaintbutlonglastingfingerprintinthematerial’s structure,”saidQuan
Ifscientistscancontrolandharnessthese long-livedpolarstates,theycouldbuild perovskitesolarcellsthatcaptureand delivermoreofthesun’senergy.Theeffect mightalsobeusefulinothertechnologies, suchas:
LEDswithhigherbrightnessand efficiency
Lightsensorsthatcandetectveryfaint signals
Datastoragedevicesthatencode informationusinglight
Perovskitescanbemadeatlow temperaturesusinginexpensive manufacturingmethods,unliketraditional siliconwhichrequireshigh-temperature, energy-intensiveprocessing Thiscould makeadvancedsolarandlighting technologiesfarmoreaffordable.
“Thisfindinggivesusawholenewdesign ruleforperovskite-basedtechnology,”said Quan “It’sareminderthatthesematerials stillhavealotofsecretstoreveal.”
LinaQuan
UNC RESEARCHERS USE CHEMICAL ‘GLUE’ TO POWER SOLAR FUEL BREAKTHROUGH
AndreOrr,aPh.D.candidateintheDepartmentofChemistry,istheleadauthorofastudysupported bytheDepartmentofEnergy-fundedCenterforHybridApproachesinSolarEnergyandLiquidFuels (CHASE)thatattemptstotackleabigquestion:Howdowecaptureandusesunlighttorecycle carbondioxide,amajorgreenhousegas,intovalue-addedproductsandfuels?
Inasteptowardacleanerenergyfuture, UNC-ChapelHillchemistryresearchers havediscoveredanewwaytoattach powerfulcarbondioxide-reducing moleculestosiliconsurfacesthatcould helpscientistsharnesssunlighttoturn carbondioxideintousefulfuelsand chemicals essentiallystoringsolarenergy inliquidform
SupportedbytheDepartmentofEnergyfundedCenterforHybridApproachesin SolarEnergyandLiquidFuels(CHASE),the researchteamtackledabigquestioninthe ACSAppliedMaterials&Interfacesstudy, “ImmobilizingaLehn-TypeCatalystwith NitrocyclocondensationChemistries:CO ReductiononSiliconHybrid Photoelectrodes”:Howdowecaptureand usesunlighttorecyclecarbondioxide (CO₂),amajorgreenhousegas,intovalueaddedproductsandfuels? 2
Toturnsunlightandcarbondioxideintofuel, researchersatCHASEarebuildingspecial surfaceswherematerialslikesiliconcan
absorbsunlightandcreatetheelectricity neededtopowerchemicalreactions.These reactionsarehelpedalongbytinymolecules calledcatalysts,whichturnCO₂intouseful fuels.Butthere’sachallenge.Thosecatalysts don’teasilystayattachedtothesilicon.The UNCteamfoundawaytofixthatusinga specialchemical“glue”madethrougha reactioncallednitrocyclocondensation (NCC).Thisgluenotonlykeepsthecatalyst stucktothesiliconduringthereaction,but alsomakessureelectricitycanflow smoothlybetweenthetwo,helpingthe systemworkmoreefficiently
“Attachingmoleculestosiliconinawaythat survivestheharshconditionsneededto reduceCO₂hasalwaysbeenachallenge,” saidAndreOrr,firstauthorofthestudyanda Ph.D.chemistrystudentworkinginthe laboratoriesProfessorsJamesCahoonand MatthewLockett “Manypreviousattempts hadlimitedstabilityorweren’tflexible enoughtoincorporatedifferentkindsof molecularcatalysts.”
Theirmethodborrowsfromearlierstudiesthat usedNCCreactionstobindmoleculesonto siliconinhighlycontrolledlabenvironments, likeultrahighvacuumchambers.Untilnow,no onehadshownthatNCCchemistrieswere suitablefortheconditionsneededtogenerate solarfuels,eg,immersedinaliquidunder illuminationwithsunlight
“Wetookthatchemistryandapplieditin solution,meaningwecannowwecanperform NCCreactionsatamuchmorepractical scale,”saidOrr.
AndreOrr
Siliconisthesamematerialusedinmostsolar panels.It’scheap,abundantandgreatat absorbingsunlight Thecleansurfaceneeded forattachingmoleculesishighlyreactive, easilyformingathininsulatinglayer,silicon oxide,thatcannotefficientlytransferenergy fromthematerialtotheattachedcatalyst.
Underartificialsunlight,theircatalyst-coated siliconconvertedCO₂intocarbonmonoxidewith 23%efficiency,aperformancethatoutshines similarsystemspreparedwithothermethods.
“Thisworkgivesresearchersatoolkitformaking moredurableandefficientsolarfueldevices,” saidDr.MatthewLockett,seniorauthorofthe studyandanassociateprofessorintheUNC DepartmentofChemistry.“Therealimpactis thatitopensthedoortoattachingmanykinds ofcatalystsinamuchsimplerway.”
MatthewLockett
Thatflexibilityisimportantbecausedifferent catalystscanmakedifferentproducts notjust carbonmonoxide,butpotentiallymethane, ethylene,alcoholsorevenjetfuel
“Theabilitytomixandmatchcatalystsand surfaceswiththistechniquecouldhelpus custom-buildsolarreactorstofitawiderange ofliquidenergyneeds,”saidLockett.
Topreparetheirmodifiedphotoelectrodes, whicharespecialmaterialsthatuselightto generateelectricityanddrivechemical reactions,freshlycleanedsiliconwasplaced inaspecialliquidthatpromotedtheNCC reaction,formingstrongnitrogen-silicon bonds.Theydemonstratedtheutilityofthe NCCreactionontwoverydifferentmolecules: Aredoxreportermolecule akindof electrochemicalindicatortotrackreaction completiononthesurfaceandtheabilityof thenewlyformedinterfacetotransfer electronsfromsilicontotheattached molecules. carbonmonoxide,akeybuildingblockforfuels andindustrialchemicals
TheUNCteamisnowexploringhowtoimprove theamountofcatalystthatcanbepackedonto thesurface,testmorecomplexcatalyststhat producericherchemicalproductsandscalethe processforlargersolardevices.
“We’rejustscratchingthesurface literally,” saidOrr.
CHEMISTS UNLOCK ROUTE TO TINY MOLECULAR SHAPES THAT COULD POWER NEXT-GEN MEDICINES
ResearchersintheDepartmentofChemistryhavediscoveredanewwaytomaketworaremolecular shapes,calledspiro[2.2]pentanesandvinylcyclopropanes,moreeasilyandwithmoredesignflexibility. Theformercanmakeadrugbindmoretightlyandpreciselytoitstargetinthebodyand,insome cases,addingonehasmadeadrugdozensoftimesmorepotent.
Somemolecularshapesaresosmalland tensethatmakingthemisliketryingto bendasteelspringintoaperfectsquare withoutsnappingit.Ifchemistscanpullit off,theseunusualshapescantransform thewaymedicineswork.
ResearchersintheDepartmentof ChemistryatUNC-ChapelHillhave discoveredanewwaytomaketwosuch rareshapes,calledspiro[2.2]pentanesand vinylcyclopropanes,moreeasilyandwith moredesignflexibility.Theresearch,ledby Ph.D.studentCharlesReeceTeeplesand AssociateProfessorSidneyWilkerson-Hill, wasrecentlypublishedinthejournal OrganicLetters.
Spiro[2.2]pentaneslookliketwotiny trianglessharingasinglecorner arigid, compactstructurethatscientistscan attachtootherchemicalpieces.Because oftheirlockedshape,theycanmakea drugbindmoretightlyandpreciselytoits targetinthebody.Insomecases,adding onehasmadeadrugdozensoftimesmore potent.
Theproblemisthey’reveryhardtomake. Their“spring-loaded”structuremeans traditionalmethodsoftenfailoronly producealimitedvariety.TheCarolina teamtackledthechallengebyusing sulfones,whicharecommon,stable molecules,assafestand-insforunstable andhighlyreactiveparticlescalled carbenes.
Theytriedtwodifferentstrategies:
1Combiningsulfonereagentswith methylenecyclopropanes,whichare smallring-shapedmoleculeswithan extrareactivebond.
2.Combiningsulfoneswithstyrenes commonaromaticmolecules—usinga special“cyclopropylsulfone”design.
Thefirstmethodworkedasplanned, creating16typesofspiro[2.2]pentanesin goodamounts,withtheabilitytoswapin differentchemicalfeatures.
Thesecondmethodsurprisedthem
Insteadofspiro[22]pentanes,itproduced vinylcyclopropanes,anotherrareand valuableshapethat’salsousedinmaking medicinesandcomplexnaturalproducts.
“Wewereaimingforoneproduct,butthe chemistrydecidedtotakeadifferentpath,” saidTeeples,leadauthorofthestudy.
“That’spartofwhatmakesresearch exciting.Youdiscoversomethingyou weren’tlookingfor.”
CharlesReeceTeeples
Tounderstandthedetour,theteamran trackingexperimentsthatreplacedcertain hydrogenatomswithaheavierversion calleddeuterium.Thishelpedshowthata
key“atomshuffle”stephappensbeforethe finalringforms.
Eventhoughtheoriginalgoalwastomake morespiro[2.2]pentanes,theunexpected newwaytomakevinylcyclopropanesisjust asexciting,saidTeeples.Bothshapesarein highdemandamongdrugdesignersfor theirprecisionandrigidity,whichcan improvehowamedicineworksinthebody
“Thisresearchgivesmedicinalchemistsa newtool,”saidWilkerson-Hill,whois principalinvestigatoronthestudy.“Itlets usmakecomplexshapesusingsulfone compounds,whicharenotasexplosiveand toxicasthetraditionallyuseddiazo compounds.”
SidneyWilkerson-Hill
Next,theresearchersplantomakethe reactionsevengentlerandmoreselective sotheycanbeusedforsensitiveorlargescaleapplications.
AsTeeplesputit,“Anewmethodtomake theseunusualbuildingblockscanbe enablingtodrugdiscoverycampaigns,as wellasthebroadersyntheticcommunity.”
-DaveDeFusco UNC-ChapelHill
UNC CHEMISTS DISCOVER HOW TO SPEED UP KEY REACTION FOR CLEAN ENERGY
InalabatUNC-ChapelHill,agroupof chemistsmayhaveuncoveredamissing pieceinthepuzzleofhowtomakeclean energymoreefficiently.LedbyProfessor GeraldMeyerandtworesearchersinhis lab,MatthewKessingerandThomas Whittemore,theteamdiscoveredhowto speedupakeychemicalreactioninvolved insplittingwaterintooxygenandhydrogen aprocessusedincleanenergy technologieslikesolarfuels.
“Thisworkhelpsusunderstandhowtobetter designcatalystsforwatersplitting,”said Kessinger,apostdoctoralresearcher “That’s abigsteptowardmakingrenewableenergy systemsthatworkfasterandmorereliably.”
SupportedaspartoftheCenterforHybrid ApproachesinSolarEnergytoLiquidFuels (CHASE),anEnergyInnovationHubfunded bytheU.S.DepartmentofEnergy,Officeof Science,theInorganicChemistrystudy, “DirectEvidenceforBuffer-EnhancedProtonCoupledElectronTransferGenerationofa High-ValentMetal-OxoComplex,”examined howaspecialmetal—ruthenium—reacts whenit’spartofamoleculeattachedtoa thinglass-likesurface.Thismetalcanhelp pullapartwatermolecules,aprocess necessaryforahydrogen-basedeconomy. Butthere’sacatch:Tomakethisreaction happen,themetalnotonlyhastolose electrons tiny,chargedparticles butget ridofprotons,whicharepartofhydrogen atoms.Thisdualaction calledprotoncoupledelectrontransfer,orPCET iscrucial forcleanenergychemistry.Unfortunately,it tendstohappenveryslowly.
“Movingasmallparticlelikeanelectronis easy,butgettingridofachargedatom,like aproton,atthesametimeistricky,”said Whittemore,aPhD studentinthe
DepartmentofChemistry.“That’swhere thingsusuallygetboggeddown.”
Thebreakthroughcamewhenthe researchers,includingcolleaguesfromthe UniversityofFerrarainItalyandNorth CarolinaStateUniversity,addedsomething calledabuffertothereaction Buffersare commoninsciencelabs—theyhelpcontrol theacidityofsolutions butinthiscase,they didsomethingmore.Whenthebuffer concentrationwashigh,theslowstepsinthe reactionseemedtodisappear.Insteadof draggingitsfeet,thereactionspedup by asmuchas10,000times.
“Thatwasawowmoment,”saidKessinger. “Wesawthatwithenoughbuffer,the reactiondidn’tgoinsequentialsteps. Everythinghappenedatonce Itwasmuch faster”
Inchemistryterms,thebufferhelpedthe protonandtheelectronmovetogetherin onesmoothmotion,calleda“concerted” reaction.Thisisbetterthanhavingthem moveseparately,whichtakesmoretimeand energy.
Thisdiscoverymayseemsmall,butithas bigimplications.Incleanenergy technologies,scientistsneedtogenerate catalystswithsufficientenergytobreak watermoleculesapart.Byutilizingconcerted reactions,theteambelievesitcanmakethis chemistrymoreefficient However,getting therehasbeenaslowprocess
Meyersaidtheteam’sfindingoffersdirect evidencethatbuffers thosesimple, everydaychemicals canmakethisstep muchfaster.
“Foralongtime,researchersbelievedthat buffershelpthesereactions,butwedidn’t haveclearaexplanationforwhy,”said Meyer.“Nowwedo.Andthatopensthedoor tosmarter,fastercatalystdesigns.”
Imagineafuturewheresolarpanelsdon’t justgenerateelectricity,theyalsostore energybyturningsunlightintoasustainable fuellikehydrogengas.That’soneofthe dreamsbehindsolarfuelsresearch.Butfor thattohappen,everypieceofthechemical puzzlehastoworkefficiently Thisresearch helpsfillinoneofthosepieces.
“Anywaytospeed-upthesereactions helps,”saidWhittemore.“Ifwecan understandandcontrolthechemistrybetter, wecanhelpmakecleanenergyareality”
GeraldMeyer
CHEMISTS USE LIGHT AND COBALT TO MAKE GREENER, CHEAPER INDUSTRIAL CHEMICALS
Lefttoright,MichaelRodriguez,ProfessorErikAlexanianandMasonFaculakdevelopedanewmethod forproducingtwovaluableclassesofchemicals estersandcarboxylicacids whichshowupin everythingfromfoodadditivestosynthetictextilesandbiodegradablematerials.Usingvisiblelightand acheap,earth-abundantmetalcatalyst cobalt theirprocessisnotonlymoremildand environmentallyfriendlybutefficientenoughforlarge-scaleuse,possiblypavingthewayforcleaner manufacturingofvitalchemicals
Simplemoleculescalledalkenes commonlyproducedduringoilrefining areanabundantandlow-coststarting pointformakingawiderangeofindustrial andconsumerproducts,fromfuelsand plasticstofragrancesand pharmaceuticals.Twoparticularlyvaluable classesofchemicalsareestersand carboxylicacids,whichshowupin everythingfromfoodadditivestosynthetic textilesandbiodegradablematerials.
Whilethesecompoundscanbemade throughvariouswell-establishedmethods, convertingalkenesintoestersandacidsis especiallyappealingbecauseitoffersa directroutefromcheapfeedstocks However,thistypeoftransformation,known
asalkenecarbonylation,typicallyrequires raremetals,highheatandextreme pressure,makingitcostlyanddifficultto scale.Thechallengehasbeenfindinga milder,moresustainablewaytocarryitout.
InarecentJournaloftheAmerican ChemicalSocietystudy,MasonFaculakand MichaelRodriguez,UNCPhD chemistry studentsinthelabofProfessorErik Alexanian,developedanewmethodto produceestersandcarboxylicacidsusing visiblelightandacheap,earth-abundant metalcatalyst:cobalt.Theirprocessisnot onlymoremildandenvironmentally friendlybutefficientenoughforlarge-scale use,possiblypavingthewayforcleaner manufacturingofvitalchemicals
“We’retakingamethodthat’sbeenaroundfor decadesandmodernizing itforasustainablefuture,”saidFaculak,alead authorofthestudy “Theexcitingpartis,we’re doingitwithmaterialsandconditionsthatare muchmorepracticalandaccessibleforindustry andacademia.”
Thechemicalreactionsattheheartofthisstudy —calledalkoxycarbonylationand hydroxycarbonylation turnsimpleoil-andgasbasedmoleculesknownasalkenesintomore usefuloneslikeestersandcarboxylicacids, whicharewidelyusedinproductsfromplastics topharmaceuticals Traditionally,doingthis requiresrareandexpensivemetalslike palladiumorplatinum,extremelyhighheat (over250°F)andcarbonmonoxidegasat pressuresmorethan40timeswhatwe experienceatsealevel Inotherwords,it’scostly, energy-intensiveandhardtoscaleupfor industrialuse
TheUNCteam,however,figuredouthowtocarry outthesereactionsusingcobaltcarbonyl a cheapandabundantmetalcatalyst underlow pressureandmildtemperaturesusingvisible lightasasourceofenergy
“Usinglight,insteadofheat,todrivethisreaction allowsittobemoreselectivewithrespectto chemicalreactivityandalsocompatiblewith morecomplexmolecules,”saidRodriguez,the otherleadauthorofthestudy
Cobaltbyitselfwasn’tenoughtomakethe reactionwork,sotheresearcherscameupwith asmartworkaround:theyaddedtwosimple helpermoleculestoactivatethecobalt.Oneof them,calledDMAP,helpedswapoutcertain partsofthereactingmolecules,whiletheother, triethylammoniumtosylate,helpedmanagethe balancebetweenacidicandbasicconditions animportantpartofkeepingthereactionon track
“Throughjudiciouschoiceofco-catalysts,we developedasystemthatisincrediblyefficient,” saidRodriguez.“Insomecases,withthese
optimizedconditions,weobservedyields approachingthetheoreticalmaximum”
Thereaction,asitturnsout,alsoworkswithout anyaddedsolventinsomecases,which dramaticallycutsdownonchemicalwasteand givesitanexceptionallylowEfactor—a commonmeasureofenvironmentalimpactin industrialchemistry
TheUNCteamtestedtheirmethodondozensof differentalkenesandalcohols,includingsimple industrialfeedstocks,complexmoleculeslike cholesterolandquinine,andnaturalproduct derivativeslikementholandproline.Theseall reactedcleanlyundertheirmildconditions, contrastingwithpreviousmethodsunderwhich complexmoleculesmightdecompose.
“Wewerehappytoseehowbroadthemethod was,”saidFaculak.“Wecouldpaircomplex alcoholswithcomplexalkenesandstillobtain excellentyieldsandselectivity”
Becausetheprocessonlyrequiresone moleculeofalcoholpermoleculeofalkene, ratherthanlargeexcesses,itproducesless wasteandthusismorepracticalforcomplex synthesis,keytraitsformakingmedicinesor finechemicals,wherematerialcostsarehigh ProfessorAlexanian,seniorauthorofthestudy, saidtheteam’sworkrepresentsamajorstep towardmakinggreener,morescalable chemicalreactions.
“Thisresearchshowsthatyoudon’tneed expensivecatalystsorextremeconditionsto makevaluableproductsonlargescales,”said Alexanian.“Byusingvisiblelightandearthabundantcobalt,we’redevelopingmethods thatenablenewreactivityandcouldhelp reshapethewayessentialchemicalsare manufactured,especiallyasindustrieslookto cutcostsandreducetheirenvironmental footprint.”
UNC CHEMISTRY ALUM TURNS MOLECULAR INSIGHTS INTO BENEFITS FOR P&G CONSUMERS
AtP&G,LaurenMcRaeappliesherbackgroundinchemistryanddatasciencetooptimizematerials forpaperproducts,ensuringtheyperformwell,arecost-effectiveandalignwithconsumerneeds.
WhenLaurenMcRaearrivedatUNC-Chapel Hillin2018tobeginherPh.D.inchemistry, sheimaginedafuturewhereherresearch onsustainablematerialsmighthelpshape thenextgenerationofbatteries.Whatshe didn’tanticipatewashowtheproblemsolvingmindsetthatshehonedinScott Warren’slab learningtothink independently,workcreativelywithdata andcollaborateacrossdisciplines would carryherintooneoftheworld’sleading consumergoodscompanies.
Today,asaseniorscientistinProcter& Gamble’sBaby,FeminineandFamilyCare Analyticaldivision,McRaeisusingthat samemindsettotransformeveryday products Sheappliesherbackgroundin chemistryanddatasciencetooptimize materialsforpaperproducts,ensuringthey performwell,arecost-effectiveandalign withconsumerneeds.
“Alotofmyfocusnowisontechnical efficiency,”saidMcRae.“Howdowemake methodsmoreautomated,feedthose methodsdataandthenusethatdatato generateinsightsthatimprovethe consumerexperience?”
McRae’sdoctoralresearchinCarolina’s DepartmentofChemistrycenteredon crystallinephasesofnewmaterialsthat couldserveassustainablealternativesto lithium-ionbatteries Theworkdemanded bothcomputationalandexperimental approaches,aswellasadeep commitmenttoturningrawdatainto meaningfulinsights.
“ThetypeofthinkingIhadtodoinmyPhD —learninghowtoresearchindependently, solveproblemsinuniquewaysandanalyze dataefficiently hasreallytranslatedwell tothechallengeswefaceatP&G,”shesaid.
ShecreditshertimeinChapelHillnotjust withteachinghertechnicalskillslikecoding inPythontoprocessdata,butwithshaping herabilitytoseethebigpicture Her advisor,AssociateProfessorScottWarren, playedanimportantroleinthatgrowth.
“Hewasreallyhelpfulinhelpingme understandtheresearch,butalsoin helpingmefigureoutwhatIwantedtodo next,”saidMcRae.“Hesupportedallthe differentthingsIexploredinsideand outsideofresearch,andthathasshaped howInowmentorothers”
McRae’sworkisgroundedinmeasurement science,orunderstandinghowthe fundamentalpropertiesofrawmaterials andpolymerstranslateintoproduct performance.HerexperiencewithdatadrivenresearchatUNChasbeencentralto herabilitytodriveinnovationatP&G Inone project,sheworkedalongsideP&G’smass spectrometryteam,whichgenerates massivedatasetsthatcanbetimeconsumingtoanalyze.Byapplying computationaltechniqueslikecluster analysisandmachinelearning,hergroup uncoveredmolecularsignaturesthat correlatedwithconsumerfeedbackabout productperformance
“Inapreviousprojectwhileworkingonhair careproducts,oneconsumerreportedtheir hairfeltsofter,butitwasn’tclearwhich moleculeswereresponsible,”shesaid.
“Usingcomputationalanalysisofthemass specdata,wewereabletoidentifythe moleculescontributingtoperformanceand buildthatinsightbackintoproduct development”
Thatcombinationofcomputationalinsight andexperimentalvalidationhasbecomea hallmarkofMcRae’sapproach.Whether workingonbiodegradablepolymers, femininepadsorfamilycarepaper products,sheemphasizestheimportance oflinkingrawdatatoconsumerexperience.
Inherrolewithpaperproducts,McRae’sexpertise liesinpolymercharacterization understandinghow chemicalandphysicalpropertiesaffecthowa productperformsinreallife.Thechallenge,shesaid, istoconnecteverystageoftheprocess:howthe rawmaterialismade,howitperformsinproduction andhowitultimatelyfeelstotheconsumer
“Themostuniqueandinterestingchallengeis predictingtheconsumerexperiencefromtheraw material,”shesaid “Ifwecanunderstandthe fundamentalchemicalpropertiesupfront,wecan innovatemoreefficientlyandinwaysthathelpus identifymeaningfulsolutionsmuchfaster.”
WhetherMcRaeisanalyzingpolymersfor biodegradabilityorhelpingdesignbabyandfamily careproducts,sheseesscienceasameansto improvedailylife.
“Therearetonsoftechnicalpiecesthatgointo makingaproduct,butultimately,thesingulargoal foreveryonehereistomaketheconsumer experiencebetter,”shesaid.“That’swhatdrivesus.”
-DaveDeFusco UNC-ChapelHill
CHARLOTTE MONTGOMERY’S MOLECULAR DESIGN TWEAKS PAVING THE WAY TO CLEANER ENERGY
CharlotteMontgomerypresentsherthesis
WhenCharlotteMontgomeryarrivedatthe UniversityofNorthCarolinaatChapelHillto pursueherPh.D.inchemistry,shedidn’tplanon helpingsolveoneofthemostcomplicated problemsincleanenergy.Butshelovedpuzzles andintheworldofchemistry,fewpuzzlesare trickier,ormoreimportant,thanhowto efficientlyconvertelectricityintofuel.
Herresearch,“ImpactofPendantAmine BasicityonElectrochemically-Promoted CobaltHydrideFormation:Kineticand MechanisticAnalysis,”recentlypublishedin InorganicChemistryaspartofaspecialissue on“Proton-CoupledElectronTransferin CoordinationChemistry,”tacklesahighly
specific,butcritical,question:howdoes tweakingtinychemicalfeaturesonamolecule affectitsabilitytoformacrucialintermediate calledametalhydride?Andhowcanthat informationbeusedtomakebettercatalysts themoleculesthatspeedupchemical reactions forcleanfuelproduction?
Atfirstglance,thismightseemlikeanobscure detailofacademicchemistry,buttheimpact couldbemassive.Efficientcatalyststhathelp turncarbondioxideintofuelusingrenewable electricityareoneoftheholygrailsofclimate technology Theycouldhelpusstoresolaror windpowerasusableliquidfuel essentially bottlingsunshineforwhenweneedit.
“Catalystshavealotofroomforimprovement,”saidMontgomery,“but youdon’tknowhowtofixsomethinguntilyouknowwhyit’sbroken.Ilike studyingthenitty-grittydetails figuringoutwherethebottlenecksare andwhatwecandotoopenthemup.”
AttheheartofMontgomery’sworkisametalcalledcobalt.Specifically, cobaltcomplexes moleculeswhereacobaltatomsitsatthecenter, surroundedbyring-likestructurescalledligands Thesecomplexescan formwhat’sknownasacobalthydride,whereahydrogenatomis attachedtothemetal.
Thatstep,formingametalhydride,iskeyinconvertingcarbondioxide intoenergy-richproductslikeformateorcarbonmonoxide building blocksforsyntheticfuels.Butexactlyhowthehydrogengetstothe cobalt throughwhatsequenceofchemicalsteps isn’talwaysstraightforward.
Toinvestigate,Montgomeryfocusedonwhat’scalleda“pendantamine” anitrogen-containing armhangingoffthesideofthemoleculethatcanhelptransferprotons,akeypartofhydrogen atoms,tothemetal.Importantly,notallpendantaminesarecreatedequal.Somearemorebasic willingtograbprotons andsomeareless.Bychangingthenatureofthispendantamine making itmoreorlessbasic Montgomerycouldessentiallyrewirethemechanismofhydrideformation. “Thisprojectwasreallyinspiredbywantingtounderstandhowthosechangesinbasicitychange thepathwayofthereaction,”shesaid.“Dotheymakeitfaster?Dotheymakeitmoreefficient?And howcanweusethattomakebettercatalysts?”
Montgomerytestedthreevariationsofthependantamine:benzyl(mostbasic),phenyl(least basic)andmethoxyphenyl(somewhereinbetween) Itwasmorethanjustamix-and-match exercise.Eachchangealteredthethermodynamics howmuchenergywasneededorreleased andthekinetics howfastthingshappened.
“Wesawarealmarriagebetweenthermodynamicsandkinetics,”saidMontgomery.“Bychanging thebasicity,wechangedthespeedandefficiencyofthereaction That’shugeifyou’retryingto makefuelsfastandcleanly”
Ofthethree,thebenzylversionsurprisedherthemost.Itturnedouttobethemostreactive, allowingaccesstoavarietyofreactionpathways.Thatluckychoice startingwithbenzyl setthe toneforherwholedissertation.
“Isometimesthinkabouthowmydissertationwould’vebeendifferentifI’dstartedwiththephenyl versioninstead,”shesaid.“Thatonewasn’tbasicenoughtoevenaccesssomeofthepathways. Thewholeprojectmightnothavehappened.”
Montgomerydidn’tjustrelyontrialanderror Sheusedarangeofsophisticatedtoolstofigure outexactlywherethechemicalactionwas happening.Bydesigningaseriesofexperiments thatusedacidsofvaryingstrength,shewasable totrackchangesinthereaction’sbehavior,likea detectivewatchingforsubtleclues.Shethen backedupherexperimentalfindingswith computersimulationsandtheoreticalmodels,
CharlotteMontgomery
whichconfirmedthattheproton thehydrogen wasinitiallyattachingnottothecobaltmetal itself,buttothenitrogenonthependantamine.
“Thattellsussomethingreallyimportant,”shesaid.“Itshowshowcriticaltheligand thepartofthe moleculesurroundingthemetal isincontrollingthereaction.That’sahugeinsightfordesigning bettercatalysts.”
Oneofthemostexcitingoutcomesofherstudyistherealizationthatbytweakingthependant amine,chemistscancontrolwhichproductisformedfromcarbondioxide.Ifthependantamineis verybasicandreactive,ithelpsformacobalthydride,whichinturnmakesformate atypeof liquidfuel.Butiftheamineislessbasic,formateproductioncanbecomelessfavorable.Indifferent systemswithoutapendantaminesite,hydrideformationmaybeshutoffentirelyandadifferent reactionhappens,producingcarbonmonoxide,whichcanbeconvertedintomethanolorethanol
Thatabilitytosteerthereactiononewayoranotherisknownasselectivity.It’sabigdealin chemistry,becauseitmeansyoucanproducethefuelyouwantwithfewerunwanted byproducts ForMontgomery’smentor,Dr JillianDempsey,BowmanandGordonGray DistinguishedTermProfessor,thestudyrepresentsmorethanjustasuccessfuldissertation
“Charlotte’sworkprovidesguidingprinciplesforhowsubtlechangesinmoleculardesigncan completelyreshapeacatalyst’sreactivity,”saidDempsey “Fundamentalsciencelikethisprovide criticalfoundationsforfuturesustainableenergytechnologies”
DempseysaidCharlotte’sdiscoveriesofferexactlythekindofdeepinsightscientistsneedto designbetter,fasterandmoreefficientcatalystsfortomorrow’senergytechnologies.
“Whendevelopingnext-generationcatalysts,thetypesofcatalyststructure-reactivitydetails Charlotterevealedcanprovideanessentialblueprintforwhatsortofdesignchangestomaketo enhanceperformance,”saidDempsey.“Thissortofcriticaldesignputsusonanacceleratedpath towardcatalyststhatoperatewiththerequiredmetricsfornext-generationtechnologies”
AfterfinishingherPh.D.,MontgomeryacceptedapositionatExponent,ascientificand engineeringconsultingfirm,whereshewillapplyherchemistrybackgroundtoreal-worldlegal andbusinesschallenges.
“It’skindofafull-circlemoment,”shesaid.“IdidaninternshipatEstéeLauderasanundergrad andanotheratastartup,AIRCO,workingonsustainableaviationfuelduringgraduateschool. NowatExponent,I’llbeworkingoncasesinvolvingfuels,lubricantsandcosmetics.”
Shefirstconnectedwiththe firmduringIndustryInSight,a professionaldevelopment eventshehelpedorganizeat UNC “I’vealwaysloved problem-solvingand communicatingscience clearly,”shesaid.“Exponent letsmedoboth,whilestill stayingconnectedto chemistry.”
-DaveDeFusco
