[PDF] Facile intra- and intermolecular charge transfer control for efficient

View - Download Facile intra- and intermolecular charge transfer control for efficient

Previous PDF

Next PDF

PAPER

Kyung-Ryang Wee et al .

Facile intra- and intermolecular charge transfer control for efficient mechanofluorochromic material

Materials Advances

rsc.li/materials-advancesISSN 2633-5409Volume 2

Number 16

21 August 2021

Pages 5265...5502

€ 2021 The Author(s). Published by the Royal Society of Chemistry

Mater. Adv.

, 2021, 2 2 , 5371

Facile intra-and intermolecular chargetransfer

control foreffcient mechanofluorochromic material†

Min-Ji Kim,Mina Ahnand Kyung-Ryang Wee*

A seriesof donor...acceptor...donor (D...A...D)pyrene(Py) 2,7-position-basedcompounds( CN,F,H,Me, andOMe) weredesigned andsynthesized todemonstr atefacile intra-and intermolecularcharge transfer controlby anelectron push...pulleffect foran efficientmechano fluorochromic (MFC)material . An examinationofthe photophysical properties ofCN-OMerevealed thatthe locallyexcited (LE)and intramolecularcharge transfer(ICT) stateof thecompounds weremodulated finelyby theelectron push...pullsubstituent effect.In addition,it isnotewor thythat theCNemission originatedonly fromthe LE statedespite theD...A...D molecularsystem. Moreover,we confirmedthat theselective LEand/or ICT state modulationaffects intra-and intermolecular chargetransfer controlinthesolid-state emission.In particular,this intra-and intermolecular chargetransfer controlisdirectlydomin atedby MFC phenomena,which meansthat themolecular electronpush...pull substituenteffect isdepend enton MFC behavior.As aresult, thisstudy showsthat asthe electron-withdrawing groupability increases, the intramolecularinteractions becomeinsufficient andinduce strongintermolecu larD...A interactionsfor stabilizing molecules,leadingto highMFC efficiencythat isreversibly repeatedseveral times.

Introduction

Mechanofluorochromic (MFC)organic materialsbased onan electron donor(D) andelectron acceptor(A) areattracting considerable attentionbecause oftheir uniqueoptical charac- teristics andvarious applicationssuch asmechanical sensors, deformationdetectors ,securityinks,memory chips,andoptical datas toragedevices. 1...6

MFCor ganicmaterials canconvertthe

emissionwavel engthunderexternalphy sicalstimul i(grinding, pressing,crushing ,orrubbing)inthes olid -stateandcanre turn to theirorigin alstatebyanneali ngorsolvent fumi ng;this phenomenoncanbesw itchedre peat edly.MFCorgani cmaterials dependgrea tlyonthetrans form ationof themolecularpacking mode,whic hcanoccur between thecrystal linestateand

amorphousstateor betweentwo diff erentcrystallin estate s.A complicatedintermolecu larinteractionaffectsthemol ecularpackingmode, suchasp...p, hydrogenbonding,a nddipole...

dipoleintera ctions,makingitdifficultto predictthe prop erties of MFCorga nicmaterials. 7...10

Hence,alt houghthedevelopmen t

of anexce llentMFCorganicma terialis meaningful,ther eisno clearstra tegyfortherati onalmole cularde signofMFCorga nic materials.Recentl y,itwasreportedthat the twisted conformation,

11...14

thea lkylchainlen gth,

15...17

andth eD...A structure

9,18...20

directlyaffectth eperformanc eofMFC organic materials.However, aprototypical stra tegyisrequiredtodesign newMF Corgani cmaterials(e.g., simple,planar, andD...A...D structures)thatmeetth ebasic concepts mentione daboveand aren otlimite dtotheseinflu enci ngfactors.Si ncethesolid-state opticalproper tieslargelydependon themolecular packing mode,the properti esoftheMFCorganic mate rialcan be predictedifthemo lec ularpa ckingmodecanbeeasily controlled.Therefore,in ordertocontrolthe mol ecularpackin g modefo rdesign ingnewMFCorganic materia ls,itis necessaryto understandthecorrel ationbe tweenintra-andintermol ecular interactions. This paperpresents anovel strategyfor thefacile intra-and intermolecular controlusing triphenylamine(TPA) andpyrene (Py) units.TPA isa verypopular buildingblock forconstructing optoelectronic materialsbecause ofits excellentelectron donor and holetransport properties.21...24

The nonplanarmolecular

structure ofTPA caninduce MFCproperties (i.e., facilitateDepartmentof Chemistryand Instituteof NaturalScience, DaeguUnivers ity,

Gyeongsan 38453,Republic ofKorea. E-mail: krwee@daegu.ac. kr †Electronic supplementaryinformation(ESI) available:NMR spectra;GC-MS data; X-raycrystallograph icdataofCN,F,andMe; PXRDof CN,F,andMe; absorption andemissionspect raof TPAdonorandpyren eacceptor; absorption and emissionspectra invarious solvents andsolid state;emissionlifetime profile; Lippert...Matagaplots anddipolemomentvalues; femtosecond transient absorption spectroscopicdata; CV;HOMOandLUMO energy;DFT/TD -DFT calculation results.CCD C2060789(CN), 2060790( F), 2060791( Me). ForESI and crystallographicdatain CIFor otherelectronic formatsee DOI:10.103 9/ d1ma00407g

Received 3rdMay 2021,

Accepted 10thJun e2021

DOI: 10.1039/d1ma00407g

rsc.li/materials-advances

MaterialsAdvancesPAPER

Open Access Article. Published on 10 June 2021. Downloaded on 10/23/2023 1:50:56 PM.

This article is licensed under a

Creative Commons Attribution-NonCommercial 3.0 Unported Licence.View Article OnlineView Journal | View Issue

rearrangement ofthe crystalpacking structureupon the application ofme chanicalstimuli). 25-28

As apo lycyclicaromatic

hydrocarbon,Pyisusedwid ely as aclass icflatmoleculeto facilitateahighquan tum yield, longfluorescenc elifetime,high thermalstabil ity,andhighchargeca rriermo bility. 29-32
Theph otophysicalpropertiesofPyde pendonthesubstituti on positionsinthePy ring ,includ ing theactive sitesatthe1-,3-, 6-, and8- positions; 33-38
theK- regionsitesat the4-,5-, 9-,and

10-positions;

39-41
andt heinact ivesitesatthe2-, and

7-positions.

31,42-44

Amongthe various positionsofPy, the

2,7-positionswereselected astheta rgetpositionsfo rth ree

reasons.(i)whe nconstr uctingaplan armolecularstructure with MFCpr operties,substitution atthe2,7-positionsofPyim proves thepl anarityofthemolecu lar struct ure.(ii)Substitution atthe

2,7-positionsofPyissynthe tica lly chal lengingbecauseofthe

presenceofthe noda lplane intheHOMOan dLUMO, 45,46
so thereare fewrepo rtsonth estructure-prop erty relatio nshipand MFCpr opertiesofPyderivati ves func tionalizedat2,7-positi ons. (iii)Bec ausePypossessesa lar geplanarp-conjugatedaromatic system,ithas str ongp-pstacking,causing thequenched emissioninthe sol idstate , 32,47
butth eprobl emcanbeover- come,and various fluorescence statescanbeinducedthrough theap propriatecombinationof TPAandPy.Cyano-substi tute d organicmolecu leshavebeenfoundto exhibit obvious emission colorchan gesundermecha nicalstimu li. 48-52

On theothe rhand,

furtherunders tandingoftheinteractionsbe twee ntheMF C propertiesandsing le-molec ulephotophysicalpropertiesfor cyano-substitutedorg anicmolecules couldbekey in the application of anefficien tMFCmaterial. Therefore,thecorrelation betweenthe electron push-pulls ubstituenteffectandM FCproperties wasa lso investigated byexpanding thesubstituted Rgroup (R =CN, F, H,

Me, andOMe)a tt hepara-position ofTPA .

In thisstudy, toprove theelectron push-pullsubstituent effect onthe singlemolecular photophysicalproperties and MFC properties,Py 2,7-position-basedD-A-D compoundswere designed andsynthesized. Interestingly,femtosecond transient absorption (fs-TA)spe ctroscopic resultsshow edthatthe emission originofP y2,7-p osition- basedD-A-Dcompoundswascontrolled by theelectron push-pullsubstitue nteffect.X-raycrystal lographic analysis revealedthe se photophysicalproper tiesandMFC propertiestobeclose ly relat ed.Theseresultsa rehelpful forbetter understandingtheinflue nceofthe electron push-pullsubstituent effectontheMF Cph enomenon andprovide structuralinsight intoth edes ignofnewPy2,7-posit ionD- A-Dcom pound-based

MFC materials.

Results anddiscussion

Synthesis

Scheme 1shows thesynthetic procedurefor aseries ofpyrene- based D-A-Dcompounds. First,direct borylationof pyreneat the 2and 7positions wasperformed in situvia a reactionof [{Ir(m-OMe)cod} 2 ] with4,4 0 -di-tert-butyl-2,2 0 -bipyridine (dtbpy) according toa previousreport. 53

As anelectron donor,the

functional Rgroup (R= CN,F, H,Me, andOMe) atthe parapositionandbr omo-subs titutedtriphenylaminederivatives were

preparedusingpr eviouslyre portedprocedures. 54

Pyrene-based

D-A-Dcomp oundswerethensynt hesizedbyth epallad ium- catalyzedSuzuki-M iyauracouplingreactionusing2 ,7- bis(Bpin)pyrene(pin=OCMe 2 CMe 2

O) withtwo molarra tiosof

OMe).All compound swerepurifiedbysil icagel columnchro- matographywithyiel dsrangin gfrom16to5 3%.Themolecul ar structuresofallprod uct swerede terminedby 1

H- and

13 C{ 1 H}- nuclearmagnet icresonance(NMR )spectroscopy,el emental analysis, andm assspectrometry( Fig.S1-S11,ESI †).Finally, the structures ofCN,F,andMewereauth enticatedbysingle-cr ystal X-ray crystallography(F ig.S12-S14,ESI†). TheE xperimental section andESI†providedetails ofthesyntheticpro cedur esand characterizationdata. Theoretical characterizationand electrochemicalproperties To considerthe opticalproperties ofpyrene derivatives,density functional theory(DFT) andtime-dependent densityfunctional theory (TD-DFT)calculations wereperformed atthe B3LYP

6-31G (d,p)level. Inall thecompounds studied,the highest

occupied molecularorbital (HOMO)was largelydistributed on the TPAmoiety, andthe lowestunoccupied molecularorbital (LUMO) wasstrongly localizedon thePy moiety(Fig. S34and S35-S39, ESI†). Thesechanges inthe orbitaldistributions ofthe HOMOs andLUMOs showedthat chargetransfer occursfrom the TPAto Pyin theexcited state.The experimentalHOMO energy levelscould bedetermined fromthe oxidationonset potentials fromthe cyclicvoltammetry (CV)curves (Fig.S15, ESI†), andthe HOMOenergy levelsof OMe...CNwere estimated to beca.?5.44 to?5.92 eV.Because nocathodic reduction processes weremeasured, theexperimental LUMOenergy levels were estimatedto beca.?2.48 to?2.70 eVfrom theoptical band gapscalculated fromthe edgesof theabsorption spectra and HOMOenergy levels.The calculatedHOMO energylevels ranged from?4.55 to?5.77 eV,and thecalculated LUMO energy levelsranged from?1.39 to?2.01 eV(Table S4,ESI †). The calculatedvalues werehigher thanthe experimentalvalues for allcompounds, butthe tendencieswere similar.These results showthat anincrease inthe electron-donating ability destabilizesthe HOMOmore thanthe LUMO,thereby narrowing thebandgap andproducing ared-shift inthe absorption spectrumfrom CNtoOMe. Theelectron push-pull effect ofthe para-substituents oftriphenylamine onthe HOMO and LUMOlevels isalso explainedas afunction ofthe

Hammett substituentconstants (s

p 55

Fig. S16(ESI

†) shows

that, theHOMO andLUMO energylevels changeaccording to Scheme 1Synthesiso fpyrene2,7-positionsbased D-A-Dcom pounds.

PaperMaterialsA dvances

Open Access Article. Published on 10 June 2021. Downloaded on 10/23/2023 1:50:56 PM.

This article is licensed under a

Creative Commons Attribution-NonCommercial 3.0 Unported Licence.View Article Online € 2021 The Author(s). Published by the Royal Society of Chemistry

Mater. Adv.

, 2021, 2quotesdbs_dbs46.pdfusesText_46

[PDF] le probleme 3 svp

[PDF] le probleme avec le pourcentage

[PDF] Le Problème d'Abraham Ben Erza

[PDF] Le problème d'eau : un enjeu majeur

[PDF] le problème d'infiltration cinema

[PDF] le problème d'infiltration critique

[PDF] le problème d'infiltration film critique

[PDF] le problème d'infiltration horaire

[PDF] Le probleme de Géraldine

[PDF] LE PROBLEME DE L EAU A ALGER A LA FIN DU 20éme siècle

[PDF] le probleme de l'eau

[PDF] Le probleme de la chèvre

[PDF] Le problème du canadair

[PDF] le problème du duc de toscane arbre

[PDF] le problème du fil de fer