Diarylethene Molecular Photoswitches: Concepts and Functionalities PDF
Preview Diarylethene Molecular Photoswitches: Concepts and Functionalities
DiaryletheneMolecularPhotoswitches Diarylethene Molecular Photoswitches Concepts and Functionalities Masahiro Irie Author AllbookspublishedbyWiley-VCH arecarefullyproduced.Nevertheless, MasahiroIrie authors,editors,andpublisherdonot Professoremeritus warranttheinformationcontainedin KyushuUniversity thesebooks,includingthisbook,to Japan befreeoferrors.Readersareadvised tokeepinmindthatstatements,data, illustrations,proceduraldetailsorother itemsmayinadvertentlybeinaccurate. LibraryofCongressCardNo.:appliedfor BritishLibraryCataloguing-in-Publication Data Acataloguerecordforthisbookis availablefromtheBritishLibrary. Bibliographicinformationpublishedby theDeutscheNationalbibliothek TheDeutscheNationalbibliotheklists thispublicationintheDeutsche Nationalbibliografie;detailed bibliographicdataareavailableonthe Internetat<http://dnb.d-nb.de>. ©2021WILEY-VCHGmbH,Boschstr. 12,69469Weinheim,Germany Allrightsreserved(includingthoseof translationintootherlanguages).No partofthisbookmaybereproducedin anyform–byphotoprinting, microfilm,oranyothermeans–nor transmittedortranslatedintoa machinelanguagewithoutwritten permissionfromthepublishers. Registerednames,trademarks,etc. usedinthisbook,evenwhennot specificallymarkedassuch,arenotto beconsideredunprotectedbylaw. PrintISBN:978-3-527-34640-0 ePDFISBN:978-3-527-34642-4 ePubISBN:978-3-527-82286-7 oBookISBN:978-3-527-82285-0 Typesetting SPiGlobal,Chennai,India Printedonacid-freepaper 10 9 8 7 6 5 4 3 2 1 v Contents Preface ix 1 Introduction 1 1.1 GeneralIntroduction 1 1.2 DiscoveryofDiaryletheneMolecularPhotoswitches 4 References 12 2 ReactionMechanism 15 2.1 BasicConcepts 15 2.2 TheoreticalStudy 20 2.3 ReactionDynamics 22 2.3.1 CyclizationReaction 22 2.3.2 CycloreversionReaction 27 References 29 3 PhotoswitchingPerformance 31 3.1 QuantumYield 31 3.1.1 PhotocyclizationQuantumYield 31 3.1.2 SolventEffectonCyclizationQuantumYield 42 3.1.3 PhotocycloreversionQuantumYield 44 3.2 ThermalStability 49 3.3 FatigueResistance 53 3.4 FluorescenceProperty 60 3.4.1 Turn-OffModePhotoswitching 61 3.4.2 Turn-OnModePhotoswitching 76 3.5 ChiralProperty 80 References 86 4 PhotoswitchableCrystals 93 4.1 Dichroism 93 4.2 X-RayCrystallographicAnalysis 97 4.3 QuantumYield 101 4.4 MulticoloredSystemsandNano-LayeredPeriodicStructures 106 vi Contents 4.5 FluorescentCrystals 108 4.6 PhotomechanicalResponse 110 4.6.1 SurfaceMorphologyChange 112 4.6.2 ReversibleShapeChange 113 4.6.3 BendingResponseofMixedCrystals 116 References 121 5 Memory 125 5.1 Single-MoleculeMemory 125 5.2 Near-FieldOpticalMemory 128 5.3 Three-DimensionalOpticalMemory 130 5.4 ReadoutUsingInfraredAbsorption,RamanScattering,andRefractive IndexChanges 132 References 134 6 Switches 137 6.1 Single-MoleculeConductancePhotoswitch 137 6.2 OpticalSwitchBasedonRefractiveIndexChange 141 6.3 Magnetism 141 References 146 7 SurfaceProperties 149 7.1 SurfaceWettability 149 7.2 SelectiveMetalDeposition 151 7.3 SubwavelengthNanopatterning 154 References 155 8 PolymersandLiquidCrystals 157 8.1 Polymers 157 8.2 LiquidCrystals 175 References 178 9 Applications 183 9.1 OrganicField-EffectTransistors(OFETs) 183 9.2 MetalOrganicFrameworks(MOFs) 185 9.3 Super-ResolutionFluorescenceMicroscopy 188 9.3.1 ControlofCycloreversionQuantumYield 189 9.3.2 FatigueResistance 191 9.3.3 PhotoswitchingwithSingle-WavelengthVisibleLight 192 9.3.4 Super-ResolutionBioimaging 195 9.4 ChemicalReactivityControl 197 9.5 BiologicalActivity 201 9.6 ColorDosimeters 204 References 209 Contents vii A SynthesisProceduresofTypicalDiarylethenes 213 A.1 1,2-Bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene 213 A.2 1,2-Bis(2-ethyl-6-phenyl-1-benzothiophene-1,1-dioxide-3-yl)- perfluorocyclopenetene 215 References 217 Index 219 ix Preface Molecules capable of reversible photoswitching between two isomers having different absorption spectra are called photochromic molecules or molecular photoswitches.Thetwoisomersdifferfromeachothernotonlyintheirabsorption and fluorescence spectra, but also in their refractive indices, dielectric constants, oxidation/reductionpotentials,andgeometricalstructures.Thesephotoswitchable bistable molecules are applied to construct photonic devices, such as erasable optical memory media and optical switch elements. Although the first finding of photoswitchablemoleculescanbetracedbacktothemiddleofnineteenthcentury, theyarestillawaitingtheirtimetogoonthestageofphotonicsdevicesinwideuse. Digital cameras take photos by using physical phenomena of inorganic materi- als. Photodiodes, such as CCD (charge-coupled device) and CMOS (complemen- tarymetaloxidesemiconductor),detectphotonsbasedonphotovoltaiceffectsand constructphoto-images.Animalsandplantshavenosuchinorganicsemiconduc- tors. In biological systems, molecular photoswitches are extensively employed in photoreceptors.Vision,forexample,usesthecis-to-transphotoisomerizationofreti- naltocontroltheconformationofrhodopsinandinitiatethetransductioncascade togenerateneuralsignals,whilephototaxisofChlamydomonasisactivatedbythe trans-to-cisphotoisomerizationofretinalinthechannelrhodopsin.Inplants,the photoisomerization of phytochromes plays a key role in controlling their biologi- calactivity.Theseingenioususesoforganicmoleculesforthedetectionofphotons inbiologicalsystemsindicatethatmolecularphotoswitcheshavethepotentialtobe appliedintheconstructionofvarioustypesofphoton-workingreagentsanddevices. A characteristic feature of molecules is their small size (∼ 1nm). If a single moleculewouldworkasone-bitmemory,ultimatehigh-density(1Pbit/inch2)opti- calmemorycouldberealized.Conductanceswitchesarekeycomponentsofalmost allelectronicdevices.Fabricationofsingle-moleculephotoswitchesisthefirststep towardmolecularelectronics.Photoswitchingofsingle-moleculefluorescencehas revolutionized fluorescence microscopy imaging. The super-resolution technique realizesaresolutionofafewtensofnanometers.Forsuchapplications,molecular photoswitchesarerequiredtopossesssuperiorproperties,suchasthermalstability of both isomers, fatigue resistance, high sensitivity, rapid response, and reactivity inthesolidstate.Amongthem,thermalstabilityandfatigueresistanceareindis- pensable properties. Although tremendous efforts were made in the 1970–1980s x Preface toprovidethethermalirreversibilitytomolecularphotoswitchesinordertoapply them to optical memory media, all attempts to modify existing photoswitchable molecules failed, because there was no guiding principle on how to prepare such thermallystablemolecularphotoswitches. In1988,theserendipitousdiscoveryofdiarylmaleicanhydrides,whichundergo thermally irreversible photoswitching reactions, paved the way to solve the prob- lem. Inferring from experimental as well as theoretical analysis, the molecular design principle of thermally irreversible molecular photoswitches was estab- lished. This new class of molecular photoswitches is named “Diarylethene.” The well-designed diarylethenes provide outstanding photoswitching performance: ∘ both isomers are thermally stable for more than 470000 years at 30 C, photocy- clization(coloration)/photocycloreversion(decoloration) can be repeated for more than104 cycles,thequantumyieldofcyclizationreactioniscloseto1(100%),and the response times of both photocyclization and photocycloreversion reactions are less than 20ps. Many of the diarylethene derivatives undergo photoswitching reactionseveninthecrystallinephase.Inthisbook,thediscoveryanddevelopment of diarylethenes are described comprehensively from the basic concepts to their applications. Iwishtoexpressmydeepappreciationtomycolleagues,Prof.M.Morimoto,Prof. S.Kobatake,Prof.K.Matsuda,Prof.T.Fukaminato,Prof.K.Uchida,Prof.T.Kawai, Prof. T. Tsujioka, and Dr. K. Uno for their kind help and support to prepare the manuscript. Finally, I also express my thanks to my family, Setsuko, Fumi, and Hisafumifortheircontinualencouragementtocompletethisbook. December2020 MasahiroIrie 1 1 Introduction 1.1 General Introduction Biological systems have developed various kinds of photoactive organs to adapt themselves to environmental electromagnetic radiation, sunlight. In biological systems, lightisusedintwowaysasshowninFigure1.1.Inplants,forexample, photosynthetic systems have evolved to utilize light as an energy source. Carbo- hydrates are produced from water and carbon dioxide in plants by using light as an energy source. Another category is the use of light for information access and transmission. Light is used to seek out optimum conditions for their life. Photoresponsive biological systems for vision, phototaxis, and phototropism have evolvedtorecognizesurroundingconditionsandtoaccessexternalinformation.In theformer,photoinducedelectrontransferisakeychemicalreaction.Ontheother hand,photoisomerizationplaysakeyroleinthelatter. Photoisomerizationisoneofthefundamentalreactionsinphotochemistry[1–3]. Trans–cisisomerization,sigmatropicrearrangements,andelectrocyclicrearrange- ments are typical examples. Molecules capable of these reversible photoisomer- ization reactions are called photochromic molecules or molecular photoswitches [4–10]. The two isomers differ from each other not only in their absorption and fluorescence spectra but also in their geometrical structures, oxidation/reduction potentials,refractiveindices,anddielectricconstants. Scheme1.1showstypicalexamplesofphotoswitchablemoleculesandwhenthey were discovered. The three upper molecules, azobenzene [11], spirobenzopyran [12], and bridged imidazole dimer [13], belong to T-type (thermally reversible) molecular photswitches, in which photogenerated right-side colored isomers are thermallyunstableandspontaneouslyrevertbacktoleft-sidecolorlessisomersin thedark.Azobenzeneundergoesalargechangeingeometricalstructureduringthe photoisomerizationreactionfromthetrans-tothecis-form.Thedistancebetween4 and4′carbonatoms(thelongaxisofthemolecule)decreasesfrom0.90to0.55nm and the dipole moment increases from 0.5 to 3.1D [14, 15]. A spirobenzopyran derivative,6-nitro-1′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indoline],converts from a less polar spiro-form to a polar merocyanine-form upon irradiation with UVlight.Itisreportedthatthedipolemomentofthespiro-formis6.2D,whileit DiaryletheneMolecularPhotoswitches:ConceptsandFunctionalities,FirstEdition.MasahiroIrie. ©2021WILEY-VCHGmbH.Published2021byWILEY-VCHGmbH. 2 1 Introduction Energy Photosynthesis (Photoinduced electron transfer) Light Information Photoresponsiveness (Photoisomerization) Vision Phototaxis Phototropism Figure1.1 Theuseoflightinbiologicalsystems. increasesto13.9Dinthemerocyanineform[16].Thebluecolorofthemerocyanine formdisappearsinlessthananhoureveninhigh-Tgpolymermatricesinthedarkat roomtemperature[17].Acolorlessbridgedimidazoledimer,1,8-TPID-naphthalene (TPID: dimer of triphenylimidazolyl radicals), turns green in toluene upon irra- diation with UV light, and the green color disappears in less than a few seconds afterswitchingofftheUVlight[18].Theimidazoledimerexhibitsextremelyquick response. The two lower molecules, furylfulgide [19] and diarylethene [20–22], undergo P-type(thermallyirreversiblebutphotochemicallyreversible)photoswitchingreac- tions.IntheP-typemolecularphotoswitches,photogeneratedright-sidecolorediso- mers are thermally stable and practically never return to the right-side colorless isomersinthedarkatroomtemperature.Althoughmanymolecularphotoswitches havebeensofarreported,P-typechromophoresareveryrare.Thefamilies,furyl- fulgidesanddiarylethenes,aretwosuchrareexamplesexhibitingP-typereactivity. Theprimarydifferencebetweenfurylfulgidesanddiarylethenesisfatigueresistance. Photoinducedcoloration/decolorationcyclesofwell-designeddiarylethenederiva- tives can be repeated more than 104 times maintaining adequate photoswitching ability (see Section 3.3), whereas in most cases the corresponding cycles of furyl- fulgidesarelimitedtolessthan102times. Theinstantpropertychangesofphotoswitchablemoleculesbyphotoirradiation withoutanyadditionalprocessleadtotheiruseinvariousphotoresponsivematerials andphotonicdevices.Whenthebistablemoleculesareincorporatedintomaterials, theelectronicstructurechangescanbeappliedtoopticalmemorymediaandcon- ductancephotoswitches,whilethegeometricalstructurechangescanbeappliedto light-driven actuators and others. Molecular photoswitches used in such applica- tionsarerequiredtofulfillfollowingproperties. 1. Thermalstabilityofbothisomers 2. Fatigue-resistance 3. Highsensitivity 4. Rapidresponse 5. Reactivityinthesolidstate. Molecular photoswitches belonging to the diarylethene family fulfill the above requirements simultaneously. Diarylethenes are derivatives of stilbene. When the phenylringsofstilbenearereplacedwithfive-memberedheterocyclicrings,such
The list of books you might like
