An effective trigger for energy release of vinylheptafulvene-based solar heat batteries

Article abstract of DOI:10.1039/c7cc01050h

Stoichiometric copper(i) tetrakis(acetonitrile) is found to activate the thermal ring-closure reaction of a series of high-energy vinylheptafulvene isomers to the corresponding low-energy and photoactive dihydroazulenes, allowing the release of energy upon request.

Full text of DOI:10.1039/c7cc01050h

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COMMUNICATION
Marilyn M. Olmstead, Alan L. Balch, Josep M. Poblet, Luis Echegoyenet al.
Reactivity differences of Sc
first methanofullerene derivatives of Sc
3
N@C2n (2n
=
68 and 80). Synthesis of the
3
N@D5h-C80
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DOI: 10.1039/C7CC01050H
JournalꢀNameꢀ
COMMUNICATIONꢀ
ꢀ
Anꢀeffectiveꢀtriggerꢀforꢀenergyꢀreleaseꢀofꢀvinylheptafulvene-basedꢀ
solarꢀheatꢀbatteriesꢀ
Receivedꢀ00thꢀJanuaryꢀ20xx,ꢀ
Acceptedꢀ00thꢀJanuaryꢀ20xxꢀ
a,b
b
b
b
MartinaꢀCacciarini,* ꢀAlexandruꢀVlasceanu, ꢀMartynꢀJevric, ꢀandꢀMogensꢀBrøndstedꢀNielsen ꢀꢀ
DOI:ꢀ10.1039/x0xx00000xꢀ
ꢀ
ꢀ
www.rsc.org/ꢀ
Stoichiometricꢀcopper(I)ꢀtetrakis(acetonitrile)ꢀisꢀfoundꢀtoꢀactivateꢀ strainedꢀ macrocyclesꢀ bearingꢀ twoꢀ DHAꢀ unitsꢀ haveꢀ recentlyꢀ
1
3,23
theꢀ thermalꢀ ring-closureꢀ reactionꢀ ofꢀ aꢀ seriesꢀ ofꢀ high-energyꢀ beenꢀ explored.
ꢀ Importantly,ꢀ inꢀ theꢀ caseꢀ ofꢀ aꢀ strainedꢀ
vinylheptafulveneꢀ isomersꢀ toꢀ theꢀ correspondingꢀ low-energyꢀ andꢀ macrocycle,ꢀoneꢀVHFꢀunitꢀrevertedꢀwithinꢀhoursꢀbackꢀtoꢀDHA,ꢀ
photoactiveꢀdihydroazulenes,ꢀallowingꢀtheꢀreleaseꢀofꢀenergyꢀuponꢀ whichꢀisꢀinterestingꢀforꢀimmediateꢀenergyꢀrelease,ꢀconversely,ꢀ
request.ꢀ
itꢀtookꢀweeksꢀforꢀfullꢀdischargeꢀofꢀtheꢀsecondꢀVHF,ꢀpotentiallyꢀ
13
interestingꢀforꢀlong-termꢀneeds. ꢀToꢀdate,ꢀitꢀhasꢀbeenꢀpossibleꢀ
toꢀtuneꢀVHFꢀhalf-livesꢀfromꢀmillisecondsꢀtoꢀyears,ꢀbutꢀforꢀsomeꢀ
ofꢀtheꢀlong-livedꢀVHFs,ꢀtheꢀmainꢀdrawbacksꢀareꢀinstabilityꢀandꢀ
theꢀneedꢀtoꢀfindꢀanꢀefficientꢀtriggerꢀtoꢀreleaseꢀtheꢀenergyꢀofꢀ
theꢀsystemꢀuponꢀdemand.ꢀ
Theꢀ designꢀ ofꢀ functionalꢀ organicꢀ materialsꢀ forꢀ solarꢀ energyꢀ
conversionꢀ andꢀ storageꢀ hasꢀ attractedꢀ theꢀ attentionꢀ ofꢀ
scientistsꢀinterestedꢀinꢀactivelyꢀfacingꢀtheꢀenergyꢀcrisisꢀandꢀtheꢀ
imminentꢀ endꢀ ofꢀ fossilꢀ fuelꢀ reserves.ꢀ Oneꢀ suchꢀ possibilityꢀ isꢀ
representedꢀ byꢀ photochromicꢀ moleculesꢀ asꢀ candidatesꢀ forꢀ
harvestingꢀ andꢀ storingꢀ solarꢀ energyꢀ inꢀ metastableꢀ
ꢀ
Inꢀaꢀpreviousꢀcommunicationꢀweꢀreportedꢀonꢀtheꢀeffectsꢀofꢀ
19
Lewisꢀacidsꢀ(LA)ꢀuponꢀthisꢀreactionꢀdynamic. ꢀOnꢀoneꢀhand,ꢀaꢀ
ringꢀ openingꢀ occurredꢀ whenꢀ 1-DHAꢀ wasꢀ treatedꢀ inꢀ theꢀ darkꢀ
withꢀaꢀstrongꢀLAsꢀsuchꢀasꢀAlCl3,ꢀwhileꢀtheꢀTBRꢀwasꢀdrivenꢀbyꢀ
additionꢀofꢀexcessiveꢀamountsꢀofꢀLAsꢀsuchꢀasꢀZn(II)ꢀandꢀAg(I)ꢀ
saltsꢀ inꢀ 1,2-dichloroethaneꢀ (DCE).ꢀ Hereꢀ weꢀ bringꢀ theꢀ studyꢀ aꢀ
majorꢀ stepꢀ forward,ꢀ showingꢀ theꢀ strongꢀ effectꢀ ofꢀ copper(I)ꢀ
tetrakis(acetonitrile)ꢀ saltsꢀ onꢀ aꢀ seriesꢀ ofꢀ DHAꢀ derivativesꢀ
1-9
photoisomerisationꢀ products. ꢀ Suchꢀ systemsꢀ haveꢀ beenꢀ
termedꢀ solarꢀ heatꢀ batteries.ꢀ Amongꢀ others,ꢀ theꢀ
dihydroazulene/vinylheptafulveneꢀ (DHA/VHF)ꢀ pairꢀ isꢀ aꢀ
photo/thermoswitchꢀ thatꢀ hasꢀ beenꢀ purposelyꢀ developedꢀ
10-13
towardsꢀ energyꢀ storageꢀ overꢀ theꢀ pastꢀ fewꢀ years.
ꢀ Itsꢀ keyꢀ
featureꢀisꢀbeingꢀaꢀsystemꢀinꢀwhichꢀtheꢀtwoꢀcomponentsꢀcanꢀbeꢀ
interconvertedꢀbyꢀtwoꢀdifferentꢀstimuliꢀ(T-typeꢀphotoswitch).ꢀ
Indeedꢀ lightꢀ triggersꢀ theꢀ ring-openingꢀ ofꢀ 1-DHAꢀ toꢀ theꢀ highꢀ
(
Figureꢀ1)ꢀforꢀinducingꢀtheꢀTBRꢀandꢀhenceꢀenergyꢀreleaseꢀfromꢀ
theꢀVHFꢀtoꢀtheꢀDHAꢀformꢀasꢀaꢀmeanꢀtoꢀaddressꢀenergyꢀreleaseꢀ
uponꢀ demand.ꢀ Gratifyingly,ꢀ usingꢀ stoichiometricꢀ amountsꢀ ofꢀ
theꢀcopperꢀpromoterꢀturnedꢀoutꢀextremelyꢀefficient.ꢀ
1
4,15
energyꢀphoto-isomerꢀ1-VHF,
cyclizationꢀofꢀ1-VHFꢀ(TBR,ꢀthermalꢀbackꢀreaction)ꢀregeneratesꢀ
-DHAꢀ (Schemeꢀ 1)ꢀ withꢀ half-livesꢀ rangingꢀ fromꢀ 218ꢀ minꢀ (inꢀ
ꢀandꢀaꢀthermallyꢀinducedꢀretro-
1
ꢀ
16
CH3CN),ꢀ 545ꢀ minꢀ (inꢀ CH2Cl2)ꢀ toꢀ 2333ꢀ minꢀ (inꢀ cyclohexane). ꢀ
Theꢀ TBRꢀ isꢀ alsoꢀ accompaniedꢀ byꢀ aꢀ releaseꢀ ofꢀ energyꢀ andꢀ anꢀ
importantꢀchallengeꢀisꢀtoꢀbeꢀableꢀtoꢀpromptꢀthisꢀprocessꢀuponꢀ
demand,ꢀideallyꢀbyꢀapplyingꢀaꢀcertainꢀexternalꢀstimulus.ꢀRecentꢀ
functionalꢀmodificationsꢀofꢀtheꢀparentꢀcoupleꢀ1-DHA/VHFꢀhaveꢀ
shownꢀtheꢀabilityꢀtoꢀimproveꢀtheꢀperformanceꢀofꢀtheꢀsystemꢀinꢀ
termsꢀ ofꢀ energyꢀ densityꢀ andꢀ ofꢀ tuningꢀ theꢀ lifetimeꢀ ofꢀ theꢀ
correspondingꢀ VHFꢀ formꢀ byꢀ substitutionsꢀ atꢀ positionsꢀ 1,ꢀ 3,ꢀ 4ꢀ
andꢀ 7ꢀ ofꢀ theꢀ dihydroazuleneꢀ coreꢀ (seeꢀ Schemeꢀ 1ꢀ forꢀ
NC
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
CN
Ph
light
7
1
2
3
CN
CN
4
heat
Ph
(
TBR)
Ph
NC
CN
1-DHA
1-VHF s-cis
s-trans
Schemeꢀ 1.ꢀ Parentꢀ DHA/VHFꢀ photochromicꢀ systemꢀ 1ꢀ andꢀ theꢀ
twoꢀconformersꢀofꢀVHFꢀ(s-cisꢀandꢀs-trans).ꢀ
ꢀ
Inꢀourꢀpreviousꢀwork, ꢀweꢀdescribedꢀhowꢀtheꢀadditionꢀofꢀlargeꢀ
17
19
numbering). ꢀ Inꢀ addition,ꢀ bothꢀ acyclicꢀ compoundsꢀ andꢀ
.
excessꢀ(10-250ꢀequiv.)ꢀofꢀetherealꢀZnCl2 (Et2O)2ꢀorꢀAgOTfꢀinꢀDCEꢀ
couldꢀ enhanceꢀ theꢀ rateꢀ ofꢀ theꢀ TBRꢀ fromꢀ 1-VHFꢀ toꢀ 1-DHA.ꢀ
However,ꢀ ZnCl2ꢀ tendedꢀ toꢀ precipitateꢀ outꢀ ofꢀ solutionꢀ inꢀ
completeꢀabsenceꢀofꢀEt2Oꢀandꢀforcedꢀtheꢀuseꢀofꢀcomplicatedꢀ
solventꢀ mixtures.ꢀ Hydratedꢀ AgOTfꢀ gaveꢀ cloudyꢀ solutions,ꢀ
preventedꢀ onlyꢀ byꢀ theꢀ useꢀ ofꢀ theꢀ presumablyꢀ etherateꢀ formꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ1ꢀꢀ
Pleaseꢀdoꢀnotꢀadjustꢀmarginsꢀ

ChemComm
Page 2 of 4
COMMUNICATIONꢀ
JournalꢀNameꢀ
ꢀ
Ag(Et2O)3OTf.ꢀInꢀaddition,ꢀthisꢀenhancementꢀofꢀtheꢀTBRꢀdidꢀnotꢀ
occurꢀinꢀpolarꢀsolventsꢀcontainingꢀaccessibleꢀloneꢀpairs,ꢀsuchꢀasꢀ
acetonitrile,ꢀacetone,ꢀethylꢀacetateꢀandꢀethanol.ꢀWeꢀthereforeꢀ
turnedꢀ ourꢀ attentionꢀ toꢀ otherꢀ stableꢀ LAs,ꢀ commerciallyꢀ
availableꢀandꢀofꢀgoodꢀsolubilityꢀinꢀpolarꢀsolvents,ꢀandꢀthusꢀweꢀ
selectedꢀ Cu(CH3CN)4BF4ꢀ andꢀ Cu(CH3CN)4PF6,ꢀ whichꢀ wereꢀ
previouslyꢀ usedꢀ extensivelyꢀ byꢀ Sauvageꢀ andꢀ co-workersꢀ forꢀ
coordinationꢀwithꢀphenanthrolinesꢀandꢀtheꢀtemplate-assistedꢀ
t1/2ꢀ(min)ꢀ
View Article Online
DOI: 10.1039/C7CC01050H
ꢀ
DHA/
VHFꢀ
Me COꢀꢀ Me COꢀ+ꢀ
2
2
CH Cl ꢀ
2
2
CH Cl
2
+ꢀCu(I)ꢀ
2ꢀ
3
CH CN
Cu(I)ꢀꢀ
ꢀ
16ꢀ
16
218 ꢀ
1ꢀ
422ꢀ
15.1ꢀ
-ꢀ
115ꢀ
0.9ꢀ
545
18-22ꢀ
ꢀ
22ꢀ
2
ꢀ
1.1ꢀ
-ꢀ
<ꢀ0.5
2.5
2
2
20
3ꢀ
4ꢀ
n.d.ꢀ
n.d.ꢀ
>4d ꢀ
synthesisꢀofꢀmechanicallyꢀinterlockedꢀmolecules. ꢀ
ꢀ
675ꢀ
70-75ꢀ
346,ꢀ
5,ꢀ35-
38ꢀ
140,ꢀ
18
160 ꢀ
18
ꢀ
572 ꢀ
-ꢀ
H
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
NC
NC
5ꢀ
10%ꢀ
10%ꢀ
69,ꢀ534ꢀ
77,ꢀ
5455
1
3ꢀ
O
dischargeꢀ dischargeꢀ
inꢀ24ꢀhꢀ inꢀ2-3ꢀhꢀ
O
O
O
CN
H
CN
Nextꢀ weꢀ changedꢀ theꢀ solventꢀ toꢀ dichloromethaneꢀ (DCM),ꢀ aꢀ
non-competitiveꢀmedium,ꢀwhichꢀhadꢀaꢀdrasticꢀeffect.ꢀAdditionꢀ
ofꢀ 1-10ꢀ equiv.ꢀ ofꢀ Cu(I)ꢀ toꢀ theꢀ orangeꢀ solutionꢀ ofꢀ 1-VHFꢀ (λmaxꢀ
475ꢀnmꢀinꢀDCM)ꢀresultedꢀinꢀaꢀcolourꢀchangeꢀtoꢀpink-violetꢀandꢀ
aꢀred-shiftꢀinꢀtheꢀlongest-wavelengthꢀabsorptionꢀupꢀtoꢀ520ꢀnmꢀ
(1ꢀ equiv.)ꢀ orꢀ 545ꢀ nmꢀ (10ꢀ equiv.)ꢀ wasꢀ measured,ꢀ stronglyꢀ
4
H
CN
NC
H
CN NC
NH
2
O
OCH
CN
3
HN
H
H
CN
Ph
ꢀ
indicatingꢀ complexationꢀ (Figureꢀ 2).ꢀ Indeedꢀ theꢀ half-life ofꢀ 1-
Ph
VHFꢀinꢀDCMꢀshortenedꢀtoꢀ18-22ꢀminꢀatꢀroomꢀtemperatureꢀinꢀ
theꢀpresenceꢀofꢀ1ꢀequiv.ꢀofꢀCu(I),ꢀwhileꢀitꢀwasꢀ545ꢀminꢀwithoutꢀ
theꢀ metalꢀ ionsꢀ presentꢀ (Tableꢀ 1).ꢀ Additionꢀ ofꢀ catalyticꢀ (0.2ꢀ
5
ꢀ
2
3
ꢀ
Figureꢀ1.ꢀDHAsꢀ2-5ꢀstudiedꢀinꢀtheꢀpresentꢀworkꢀinꢀadditionꢀtoꢀ1ꢀ equiv.)ꢀCu(I)ꢀfurnishedꢀaꢀhalf-lifeꢀofꢀ83-91ꢀmin,ꢀbutꢀifꢀrunningꢀaꢀ
2,ꢀ 3ꢀ andꢀ 5ꢀ asꢀ racemicꢀ mixtures,ꢀ 4ꢀ asꢀ mixtureꢀ ofꢀ secondꢀ cycleꢀ (i.e.ꢀ irradiatingꢀ theꢀ cuvetteꢀ alreadyꢀ inꢀ theꢀ
(
diastereomers).ꢀꢀ
ꢀ
presenceꢀofꢀtheꢀCu(I)ꢀpromoter)ꢀtheꢀhalf-lifeꢀincreasedꢀtoꢀ223ꢀ
min,ꢀ suggestingꢀ aꢀ photo-degradationꢀ ofꢀ theꢀ complexꢀ (seeꢀ
23
Weꢀ initiallyꢀ switchedꢀ theꢀ solventꢀ ofꢀ theꢀ studiesꢀ fromꢀ DCEꢀ toꢀ ESI). ꢀTheꢀuseꢀofꢀ10ꢀequiv.ꢀofꢀCu(I)ꢀenhancedꢀtheꢀspeedꢀofꢀtheꢀ
acetone,ꢀ aꢀ moreꢀ polarꢀ solventꢀ thatꢀ accordingꢀ toꢀ previousꢀ ring-closureꢀtoꢀ9ꢀmin.ꢀTheꢀstrongꢀcomplexationꢀeffectꢀwasꢀalsoꢀ
16
resultsꢀ shouldꢀ enhanceꢀ theꢀ speedꢀ ofꢀ theꢀ TBR, ꢀ andꢀ atꢀ theꢀ evidencedꢀ byꢀ theꢀ observationꢀ ofꢀ veryꢀ differentꢀ irradiationꢀ
sameꢀtimeꢀisꢀcontainingꢀtwoꢀloneꢀpairsꢀonꢀoxygenꢀcapableꢀofꢀ timesꢀ toꢀ fullyꢀ convertꢀ theꢀ DHAꢀ toꢀ theꢀ VHFꢀ form,ꢀ inꢀ theꢀ
interactingꢀ withꢀ copper.ꢀ Solutionsꢀ ofꢀ 1-DHAꢀ inꢀ acetoneꢀ wereꢀ presenceꢀ(5ꢀmin)ꢀorꢀinꢀtheꢀabsenceꢀ(2ꢀmin)ꢀofꢀCu(I).ꢀThereforeꢀ
irradiatedꢀatꢀtheirꢀabsorptionꢀmaximumꢀ(365ꢀnm),ꢀresultingꢀinꢀ coordinationꢀpresumablyꢀoccursꢀtoꢀaꢀsignificantꢀdegreeꢀinꢀbothꢀ
aꢀ quantitativeꢀ conversionꢀ toꢀ theꢀ correspondingꢀ 1-VHF.ꢀ Thenꢀ DHAꢀandꢀVHFꢀforms,ꢀalthoughꢀweꢀexpectꢀtheꢀloneꢀpairꢀdonorꢀ
UV-Visꢀ absorptionꢀ spectraꢀ wereꢀ acquiredꢀ underꢀ differentꢀ strengthꢀ ofꢀ theꢀ nitrilesꢀ beingꢀ muchꢀ higherꢀ forꢀ theꢀ VHFꢀ onꢀ
conditions,ꢀ i.e.ꢀ atꢀ temperaturesꢀ ofꢀ 25°Cꢀ andꢀ 35°C,ꢀ andꢀ inꢀ orꢀ accountꢀ ofꢀ theꢀ electronꢀ donorꢀ propertiesꢀ ofꢀ theꢀ
withoutꢀ theꢀ presenceꢀ ofꢀ 1-4ꢀ equivalentsꢀ ofꢀ aꢀ Cu(I)(CH3CN)4ꢀ vinylheptafulvene.ꢀ Effortsꢀ toꢀ determineꢀ anꢀ accurateꢀ
21
salt. ꢀTheꢀhalf-livesꢀofꢀtheꢀVHFsꢀwereꢀdeterminedꢀbyꢀfittingꢀtheꢀ associationꢀ constantꢀ forꢀ theꢀ complexꢀ 1-VHF@Cu(I)ꢀ usingꢀ theꢀ
dataꢀwithꢀanꢀexponentialꢀfunction.ꢀControlꢀexperimentsꢀwereꢀ UV-Visꢀdilutionꢀmethodꢀwereꢀinꢀvain,ꢀbecauseꢀtheꢀresultsꢀwereꢀ
alsoꢀ runꢀ withꢀ Ag(CH3CN)4BF4,ꢀ inꢀ lightꢀ ofꢀ theꢀ previousꢀ studiesꢀ compromisedꢀbothꢀbyꢀtheꢀfastꢀTBR,ꢀwhichꢀisꢀoccurringꢀwithinꢀ
reportedꢀwithꢀAg(OTf).ꢀTheꢀresultsꢀindicatedꢀaꢀdropꢀofꢀtheꢀhalf- theꢀdilutionꢀtimeꢀscale,ꢀandꢀbyꢀanꢀextendedꢀoverlapꢀofꢀtheꢀ1-
lifeꢀinꢀacetoneꢀfromꢀ422ꢀminꢀtoꢀ115ꢀminꢀatꢀ25ꢀ°Cꢀwithꢀ1ꢀequiv.ꢀ VHFꢀ andꢀ 1-VHF+Cu(I)ꢀ absorptionꢀ spectra.ꢀ Forꢀ theꢀ TBR,ꢀ itꢀ isꢀ
24
ofꢀCu(I)ꢀ(Tableꢀ1),ꢀtoꢀ64ꢀminꢀatꢀ35ꢀ°Cꢀstillꢀwithꢀ1ꢀequiv.ꢀandꢀtoꢀ particularlyꢀimportantꢀtoꢀnoteꢀthatꢀcalculationsꢀhaveꢀshown ꢀ
9ꢀ minꢀ withꢀ 4ꢀ equiv.ꢀatꢀ 35ꢀ °C.ꢀ Theꢀ TBRꢀ isꢀ henceꢀ evenꢀ fasterꢀ thatꢀ theꢀ C(CN) ꢀ inꢀ theꢀ transitionꢀ stateꢀ structureꢀ carriesꢀ aꢀ
4
2
thanꢀ inꢀ theꢀ moreꢀ polarꢀ solventꢀ acetonitrileꢀ (half-lifeꢀ ofꢀ 218ꢀ significantꢀ negativeꢀ chargeꢀ andꢀ theꢀ seven-memberedꢀ ringꢀ aꢀ
16
min). ꢀ Onlyꢀ aꢀ slightꢀ improvementꢀ wasꢀ registeredꢀ uponꢀ positiveꢀcharge.ꢀThus,ꢀcopperꢀcomplexationꢀmayꢀstabilizeꢀthisꢀ
additionꢀofꢀmoreꢀthanꢀaꢀstoichiometricꢀamountsꢀofꢀCu(I)ꢀandꢀ stateꢀ(seeꢀESI).ꢀꢀ
noꢀ effectꢀ wasꢀ recordedꢀ inꢀ theꢀ presenceꢀ ofꢀ Ag(CH3CN)4BF4.ꢀ
ꢀ
Interestingly,ꢀ theꢀ introductionꢀ ofꢀ aꢀ copper-scavengerꢀ
Sinceꢀ itꢀ isꢀ knownꢀ thatꢀ Ag(I)ꢀ canꢀ enhanceꢀ theꢀ ringꢀ closureꢀ inꢀ allowedꢀ theꢀ cycleꢀ toꢀ beꢀ repeated.ꢀ Hence,ꢀ uponꢀ additionꢀ ofꢀ
19
DCE, ꢀtheꢀabsenceꢀofꢀsuchꢀanꢀeffectꢀsuggestsꢀthatꢀtheꢀnitrilesꢀ ethylenediamineꢀtoꢀtheꢀsolutionꢀofꢀ1-VHFꢀwithꢀCu(I)ꢀaꢀvisibleꢀ
mayꢀcoordinateꢀstrongerꢀtoꢀCu(I).ꢀꢀ
ꢀ
naked-eyeꢀ colourꢀ changeꢀ occurred,ꢀ fromꢀ pinkꢀ toꢀ orangeꢀ
(Figureꢀ2),ꢀatꢀtheꢀsameꢀtimeꢀbringingꢀbackꢀtheꢀrateꢀofꢀtheꢀTBRꢀ
Tableꢀ1.ꢀHalf-livesꢀ(t1/2)ꢀatꢀ25ꢀ°CꢀofꢀtheꢀTBRꢀ(VHFsꢀtoꢀDHAs)ꢀinꢀ toꢀtheꢀpre-copperꢀlevel.ꢀIfꢀethylenediamineꢀisꢀaddedꢀafterꢀtheꢀ
neatꢀsolventꢀorꢀinꢀtheꢀpresenceꢀofꢀCu(CH3CN)4BF4ꢀ(1ꢀequiv.ꢀperꢀ TBRꢀisꢀcompletedꢀ(i.e.ꢀtheꢀ“energyꢀstored”ꢀhasꢀbeenꢀreleased),ꢀ
DHAꢀunitꢀ(1-4),ꢀ>2ꢀequiv.ꢀperꢀDHAꢀunitꢀ(5)).ꢀꢀ
ꢀ
theꢀCu(I)ꢀisꢀseizedꢀandꢀuncomplexedꢀ1-DHAꢀrecovered.ꢀꢀ
ꢀ
2
ꢀ|ꢀJ.ꢀName.,ꢀ2012,ꢀ00,ꢀ1-3ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
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Pleaseꢀd Co hꢀ ne omt ꢀ Ca do j mu smt ꢀmarginsꢀ
JournalꢀNameꢀ
ꢀCOMMUNICATIONꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Neverthelessꢀ itꢀ wasꢀ notꢀ possibleꢀ toꢀ evaluateꢀVitehweAꢀrtibclienOdnilningeꢀ
DOI: 10.1039/C7CC01050H
constantꢀ ofꢀ theꢀ 2-VHF@Cu(I)ꢀ complexꢀ dueꢀ toꢀ theꢀ extremelyꢀ
fastꢀ TBR.ꢀ Theꢀ half-lifeꢀ wasꢀ barelyꢀ measurableꢀ atꢀ ambientꢀ
temperature,ꢀchangingꢀfromꢀ15ꢀminꢀinꢀneatꢀacetoneꢀtoꢀ0.9ꢀminꢀ
inꢀ theꢀ presenceꢀ ofꢀ Cu(I).ꢀ Inꢀ thisꢀ case,ꢀ bothꢀ aꢀ nitrileꢀ andꢀ anꢀ
amideꢀ offerꢀ potentialꢀ bindingꢀ groupsꢀ forꢀ complexationꢀ withꢀ
25
copper, ꢀ butꢀ weꢀ doꢀ notꢀ haveꢀ anyꢀ experimentalꢀ evidenceꢀ onꢀ
whichꢀisꢀtheꢀoneꢀdrivingꢀtheꢀeffect.ꢀOnꢀgoingꢀexperimentsꢀareꢀ
focusingꢀonꢀchelatingꢀtheꢀamidoꢀgroupꢀinsteadꢀofꢀtheꢀnitrile,ꢀtoꢀ
expandꢀ theꢀ researchꢀ onꢀ thisꢀ promisingꢀ candidateꢀ forꢀ theꢀ
developmentꢀ ofꢀ fastꢀ responsiveꢀ materials.ꢀ Resultsꢀ becameꢀ
Figureꢀ2.ꢀUV-VisꢀabsorptionꢀspectraꢀinꢀCH2Cl2ꢀatꢀ25ꢀ°Cꢀofꢀ1-DHAꢀ evenꢀmoreꢀinterestingꢀwhenꢀmovingꢀtoꢀDCMꢀasꢀtheꢀsolvent.ꢀAnꢀ
-5
-5
blackꢀ curve,ꢀ 6.2x10 ꢀ M),ꢀ 1-VHFꢀ (redꢀ curve,ꢀ 6.2x10 ꢀ M),ꢀ 1- unexpectedꢀvalueꢀofꢀTBRꢀofꢀ1.1ꢀminꢀwasꢀrecordedꢀforꢀ2-VHFꢀinꢀ
(
VHF+Cu(I)ꢀ(pinkꢀcurve,ꢀ1-VHF:ꢀ4.3x10 ꢀM,ꢀCu(I):ꢀ4.7x10 ꢀM),ꢀ1- neatꢀ DCM,ꢀ whichꢀ whenꢀ comparedꢀ toꢀ 2.5ꢀ minꢀ inꢀ CH3CNꢀ andꢀ
-5
-5
VHF+Cu(I)+ꢀexcessꢀofꢀethylenediamineꢀ(redꢀbrokenꢀcurve).ꢀꢀ
ꢀ
15.1ꢀ minꢀ inꢀ acetoneꢀ suggestsꢀ aꢀ differentꢀ ring-closureꢀ
mechanismꢀfromꢀthatꢀofꢀtheꢀ1-VHF.ꢀIndeedꢀforꢀtheꢀelectrocyclicꢀ
Recyclabilityꢀ experimentsꢀ wereꢀ performedꢀ toꢀ estimateꢀ cyclizationꢀ fromꢀ 1-VHFꢀ toꢀ 1-DHAꢀ aꢀ zwitterionicꢀ TSꢀ wasꢀ
ꢀ
whetherꢀ theꢀ systemꢀ efficiencyꢀ wasꢀ compromisedꢀ byꢀ theꢀ hypothesizedꢀandꢀsupportedꢀbyꢀanꢀempiricalꢀlinearꢀcorrelationꢀ
demetallatingꢀagent,ꢀandꢀtoꢀcompareꢀtheꢀkineticsꢀofꢀtheꢀTBRꢀ betweenꢀtheꢀlogarithmꢀofꢀtheꢀrateꢀconstantꢀandꢀtheꢀDimroth-
16
afterꢀsomeꢀcycles.ꢀTheꢀVHFꢀhalf-livesꢀafterꢀconsecutiveꢀcyclesꢀ Reichardtꢀsolventꢀpolarityꢀparameter, ꢀasꢀwellꢀasꢀbyꢀHammettꢀ
26
areꢀ reportedꢀ inꢀ Figureꢀ 3.ꢀ Everyꢀ fullꢀ cycleꢀ wasꢀ constitutedꢀ byꢀ correlationsꢀ obtainedꢀ fromꢀ variouslyꢀ substitutedꢀ VHFs. ꢀ
fourꢀsteps:ꢀ(i)ꢀirradiationꢀatꢀ365ꢀnmꢀofꢀ1-DHAꢀtoꢀ1-VHFꢀuntilꢀnoꢀ Furtherꢀstudiesꢀareꢀonꢀgoingꢀonꢀthisꢀsubstrate,ꢀbutꢀadditionꢀofꢀ
1
-DHAꢀ isꢀ left,ꢀ (ii)ꢀ additionꢀ ofꢀ ca.ꢀ 1ꢀ equiv.ꢀ ofꢀ Cu(I)ꢀ solutionꢀ inꢀ 1ꢀequiv.ꢀofꢀCu(I)ꢀtoꢀaꢀsolutionꢀofꢀ2-VHFꢀgaveꢀanꢀinstantaneousꢀ
DCM,ꢀ (iii)ꢀ recordingꢀ ofꢀ theꢀ UV-Visꢀ absorptionꢀ spectraꢀ ofꢀ theꢀ andꢀcompleteꢀTBRꢀ(fullꢀrecoveryꢀofꢀ2-DHAꢀwithinꢀlessꢀthanꢀ30ꢀsꢀ
TBRꢀ untilꢀ noꢀ 1-VHFꢀ isꢀ left,ꢀ (iv)ꢀ additionꢀ ofꢀ aꢀ stoichiometricꢀ afterꢀtheꢀcopperꢀaddition).ꢀ
amountꢀofꢀethylenediamineꢀinꢀDCMꢀtoꢀbringꢀtheꢀsystemꢀbackꢀ
ꢀ
Onꢀ theꢀ otherꢀ hand,ꢀ whenꢀ theꢀ amideꢀ isꢀ replacedꢀ byꢀ anꢀ
toꢀ theꢀ pre-copperꢀ status.ꢀ Afterꢀ subsequentꢀ copperꢀ imidateꢀgroup,ꢀasꢀitꢀisꢀforꢀcompoundꢀ3,ꢀweꢀneitherꢀsucceededꢀ
addition/demetallationꢀ cycles,ꢀ theꢀ half-lifeꢀ ofꢀ 1-VHFꢀ didꢀ notꢀ toꢀ induceꢀ aꢀ completeꢀ TBR,ꢀ norꢀ toꢀ limitꢀ theꢀ decompositionꢀ
22
changeꢀ significantlyꢀ (fluctuationsꢀ likelyꢀ originateꢀ fromꢀ smallꢀ previouslyꢀreported. ꢀBesides,ꢀanꢀextendedꢀoverlappingꢀofꢀtheꢀ
variationsꢀinꢀtheꢀexactꢀamountꢀofꢀtheꢀaddedꢀethylenediamine,ꢀ UV-Visꢀ absorptionꢀ spectraꢀ ofꢀ 3-VHFꢀ andꢀ 3-DHAꢀ preventsꢀ theꢀ
seeꢀESI).ꢀ
possibilityꢀ ofꢀ selectedꢀ irradiationꢀ andꢀ likelyꢀ provokesꢀ otherꢀ
photo-inducedꢀprocesses.ꢀStillꢀaꢀblue-shiftꢀwasꢀdetectedꢀuponꢀ
additionꢀ ofꢀ Cu(I),ꢀ butꢀ noꢀ TBRꢀ toꢀ aꢀ DHAꢀ formꢀ wasꢀ evidencedꢀ
neitherꢀinꢀacetoneꢀnorꢀinꢀDCM.ꢀꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Asꢀ forꢀ theꢀ dimericꢀ systemꢀ 4-VHF-VHF,ꢀ theꢀ half-lifeꢀ inꢀ
acetoneꢀisꢀreducedꢀfromꢀ675ꢀminꢀtoꢀ70-75ꢀminꢀ(withꢀ1-4ꢀequiv.ꢀ
ofꢀCu(I));ꢀmoreover,ꢀinꢀacetoneꢀonlyꢀoneꢀhalf-lifeꢀisꢀdetected,ꢀ
whileꢀinꢀacetonitrileꢀtwoꢀdistinctꢀandꢀsequentialꢀring-closuresꢀ
22
wereꢀ previouslyꢀ observed,ꢀ butꢀ notꢀ differingꢀ drastically. ꢀ Inꢀ
DCMꢀ theꢀ half-livesꢀ ofꢀ theꢀ firstꢀ andꢀ theꢀ secondꢀ TBRꢀ wereꢀ
determinedꢀ toꢀ 346ꢀ minꢀ andꢀ 572ꢀ min,ꢀ respectively.ꢀ Uponꢀ
Figureꢀ3.ꢀRecyclabilityꢀofꢀtheꢀsystemꢀ(irradiation,ꢀCu(I)ꢀaddition,ꢀ additionꢀofꢀ0.5-2.5ꢀequiv.ꢀofꢀCu(I)ꢀperꢀDHAꢀunit,ꢀtheꢀabsorptionꢀ
TBR,ꢀethylenediamineꢀaddition)ꢀreportedꢀasꢀhalf-lifeꢀofꢀ1-VHFꢀ maximumꢀofꢀ4-VHF-VHFꢀwasꢀredshiftedꢀfromꢀ470ꢀnmꢀtoꢀ495-
vsꢀ cycle.ꢀ Atꢀ “cycleꢀ zero”,ꢀ theꢀ half-lifeꢀ isꢀ reportedꢀ withoutꢀ 515ꢀ nm.ꢀ Theꢀ irradiationꢀ timesꢀ forꢀ DHAꢀ toꢀ VHFꢀ ring-openingsꢀ
additionꢀofꢀCu(I)ꢀpromoter.ꢀ
ꢀ
changed,ꢀfromꢀ2ꢀminꢀ(firstꢀringꢀopeningꢀtoꢀDHA-VHF)ꢀandꢀca.ꢀ10ꢀ
minꢀ(secondꢀringꢀopeningꢀtoꢀVHF-VHF),ꢀtoꢀ4ꢀminꢀandꢀmoreꢀthanꢀ
Thenꢀ weꢀ focusedꢀ ourꢀ interestꢀ towardsꢀ aꢀ selectionꢀ ofꢀ 30ꢀ minꢀ inꢀ theꢀ presenceꢀ ofꢀ theꢀ copperꢀ salt.ꢀ Asꢀ expected,ꢀ theꢀ
ꢀ
13,18,22
previouslyꢀ reportedꢀ DHAsꢀ 2-5,
ꢀ forꢀ elucidatingꢀ theꢀ copperꢀ effectꢀ onꢀ theꢀ TBRꢀ wasꢀ extremelyꢀ strongꢀ alsoꢀ onꢀ thisꢀ
influenceꢀ ofꢀ differentꢀ functionalꢀ groupsꢀ andꢀ theꢀ numberꢀ ofꢀ substrate.ꢀ Twoꢀ distinctꢀ half-lives,ꢀ describedꢀ byꢀ aꢀ doubleꢀ
DHAꢀ unitsꢀ withꢀ theꢀ possibilityꢀ forꢀ multipleꢀ nitrilesꢀ toꢀ exponentialꢀ decay,ꢀ wereꢀ alwaysꢀ detectedꢀ whenꢀ varyingꢀ theꢀ
coordinateꢀ simultaneously.ꢀ Weꢀ investigatedꢀ theꢀ effectꢀ ofꢀ theꢀ equivalentsꢀ ofꢀ Cu(I)ꢀ perꢀ DHAꢀ unitꢀ fromꢀ 0.5ꢀ toꢀ 2.5.ꢀ Thusꢀ byꢀ
Cu(I)ꢀadditiveꢀonꢀtheꢀTBRꢀbothꢀinꢀacetoneꢀandꢀDCM.ꢀInꢀacetoneꢀ additionꢀofꢀ0.5ꢀequiv.ꢀofꢀCu(I)ꢀperꢀDHAꢀunit,ꢀweꢀmeasuredꢀtwoꢀ
onlyꢀaꢀslightꢀchangeꢀinꢀtheꢀabsorptionꢀmaximaꢀ(<4ꢀnm)ꢀofꢀtheꢀ distinctꢀhalf-livesꢀofꢀ9ꢀminꢀandꢀ66ꢀmin;ꢀbyꢀadditionꢀofꢀ1.3ꢀequiv.ꢀ
DHAꢀandꢀVHFꢀformsꢀwasꢀdetectedꢀinꢀtheꢀpresenceꢀorꢀabsenceꢀ ofꢀCu(I)ꢀperꢀDHAꢀunitꢀtheꢀhalf-livesꢀdecreasedꢀtoꢀ5ꢀminꢀandꢀ37ꢀ
ofꢀ Cu(I),ꢀ exceptꢀ forꢀ 2-VHF,ꢀ whoseꢀ absorptionꢀ maximumꢀ red- min,ꢀandꢀbyꢀadditionꢀofꢀ2.5ꢀequiv.ꢀofꢀCu(I)ꢀperꢀDHAꢀunitꢀtoꢀ5ꢀ
shiftedꢀ fromꢀ 413ꢀ nmꢀ toꢀ 450ꢀ nmꢀ withꢀ Cu(I)ꢀ (1-3ꢀ equiv.)ꢀ inꢀ minꢀandꢀ23ꢀmin.ꢀꢀ
acetone,ꢀ evidencingꢀ aꢀ strongꢀ complexationꢀ effect.ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ3ꢀ
Pleaseꢀdoꢀnotꢀadjustꢀmarginsꢀ

ChemComm
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COMMUNICATIONꢀ
FinallyꢀweꢀinvestigatedꢀtheꢀeffectꢀofꢀCu(I)ꢀonꢀtheꢀswitchingꢀ
JournalꢀNameꢀ
ꢀ
1
2
ꢀ
View Article Online
Z.-I.ꢀYoshida,ꢀJ.ꢀPhotochem.,ꢀ1985,ꢀ29,ꢀ27.ꢀ
DOI: 10.1039/C7CC01050H
R.ꢀ Boese,ꢀ J.ꢀ K.ꢀ Cammack,ꢀ A.ꢀ J.ꢀ Matzger,ꢀ P.ꢀ Pflug,ꢀ W.ꢀ B.ꢀ
Tolman,ꢀK.ꢀP.ꢀC.ꢀVollhardtꢀandꢀT.ꢀW.ꢀWeidman,ꢀJ.ꢀAm.ꢀChem.ꢀ
Soc.,ꢀ1997,ꢀ119,ꢀ6757.ꢀ
Y.ꢀKanai,ꢀV.ꢀSrinivasan,ꢀS.ꢀK.ꢀMeier,ꢀK.ꢀP.ꢀC.ꢀVollhardtꢀandꢀJ.ꢀC.ꢀ
Grossman,ꢀAngew.ꢀChem.ꢀInt.ꢀEd.,ꢀ2010,ꢀ49,ꢀ8926.ꢀ
T.ꢀJ.ꢀKucharski,ꢀY.ꢀTian,ꢀS.ꢀAkbulatovꢀandꢀR.ꢀBoulatov,ꢀEnergyꢀ
Environ.ꢀSci.,ꢀ2011,ꢀ4,ꢀ4449.ꢀ
K.ꢀ Moth-Poulsen,ꢀ D.ꢀ Ćoso,ꢀ K.ꢀ Börjesson,ꢀ N.ꢀ Vinokurov,ꢀ S.ꢀ
Meier,ꢀA.ꢀMajumdar,ꢀK.ꢀP.ꢀC.ꢀVollhardtꢀandꢀR.ꢀA.ꢀSegalman,ꢀ
EnergyꢀEnviron.ꢀSci.,ꢀ2012,ꢀ5,ꢀ8534.ꢀ
K.ꢀ Moth-Poulsen,ꢀ inꢀ Organicꢀ Synthesisꢀ andꢀ Molecularꢀ
Engineeringꢀ(Ed.ꢀM.ꢀB.ꢀNielsen),ꢀWiley,ꢀHoboken,ꢀUSA,ꢀ2014,ꢀ
pp.ꢀ179-196.ꢀ
A.ꢀLennartson,ꢀA.ꢀRoffeyꢀandꢀK.ꢀMoth-Poulsen,ꢀTetrahedronꢀ
Lett.,ꢀ2015,ꢀ56,ꢀ1457.ꢀ
propertiesꢀofꢀmacrocycleꢀ5,ꢀconstitutedꢀbyꢀaꢀconformationallyꢀ
constrainedꢀ double-DHA,ꢀ whichꢀ hasꢀ shownꢀ interestingꢀ
charge/dischargeꢀ propertiesꢀ (fastꢀ andꢀ ultraslowꢀ TBRsꢀ forꢀ theꢀ
twoꢀVHFs)ꢀifꢀcomparedꢀtoꢀtheꢀcorrespondingꢀacyclicꢀstructuralꢀ
3
4
5
13
analogueꢀ4. ꢀTheꢀdecayꢀthatꢀdescribesꢀtheꢀTBRꢀofꢀtheꢀ5-VHF-
VHFꢀstructureꢀturnedꢀoutꢀtoꢀbeꢀveryꢀcomplexꢀinꢀtheꢀpresenceꢀ
ofꢀ Cu(I),ꢀ suggestingꢀ theꢀ presenceꢀ ofꢀ multipleꢀ equilibriaꢀ inꢀ
solutionꢀ (DHA-DHA,ꢀ DHA-VHF,ꢀ VHF-VHFꢀ andꢀ correspondingꢀ
complexesꢀwithꢀcopper),ꢀandꢀtheꢀdataꢀareꢀdifficultꢀtoꢀfitꢀwithꢀaꢀ
simpleꢀ model.ꢀ Althoughꢀ theꢀ veryꢀ firstꢀ partꢀ ofꢀ theꢀ decayꢀ
appearedꢀ asꢀ aꢀ mono-exponentialꢀ functionꢀ inꢀ acetone,ꢀ onlyꢀ aꢀ
qualitativeꢀ evaluationꢀ ofꢀ theꢀ "discharge"ꢀ ofꢀ theꢀ systemꢀ wasꢀ
possibleꢀ(i.e.ꢀpercentageꢀreductionꢀofꢀtheꢀabsorbanceꢀofꢀVHFꢀ
withinꢀtime).ꢀAꢀ10%ꢀdischargeꢀwasꢀobtainedꢀinꢀacetoneꢀinꢀtheꢀ
absenceꢀ ofꢀ Cu(I)ꢀ withinꢀ 24ꢀ h,ꢀ whileꢀ theꢀ presenceꢀ ofꢀ Cu(I)ꢀ (3ꢀ
equiv.)ꢀ inducedꢀ 10%ꢀ dischargeꢀ withinꢀ onlyꢀ 2-3ꢀ h.ꢀ Moreover,ꢀ
afterꢀ 24ꢀ hꢀ inꢀ theꢀ presenceꢀ ofꢀ Cu(I)ꢀ aꢀ 35%ꢀ dischargeꢀ ofꢀ theꢀ
systemꢀ wasꢀ recorded.ꢀ Noꢀ additionalꢀ significantꢀ informationꢀ
couldꢀbeꢀextrapolatedꢀfromꢀtheꢀTBRꢀdataꢀinꢀacetone.ꢀOnꢀtheꢀ
contrary,ꢀwhenꢀmacrocycleꢀ5ꢀwasꢀinvestigatedꢀinꢀDCMꢀwithꢀ2-3ꢀ
equiv.ꢀofꢀCu(I)ꢀperꢀDHAꢀunit,ꢀrecoveryꢀofꢀmoreꢀthanꢀ75%ꢀofꢀ5-
DHA-DHAꢀwasꢀpossibleꢀalreadyꢀafterꢀ22ꢀhꢀatꢀ25ꢀ°Cꢀ(Figureꢀ5).ꢀ
Thisꢀ resultꢀ shouldꢀ beꢀ comparedꢀ toꢀ half-livesꢀ inꢀ theꢀ polarꢀ
solventꢀacetonitrileꢀ(promotingꢀtheꢀTBR)ꢀofꢀ77ꢀminꢀandꢀ5455ꢀ
minꢀ(91ꢀh).ꢀInꢀtheꢀpresenceꢀofꢀCu(I),ꢀtheꢀdecayꢀwasꢀmodelledꢀ
throughꢀaꢀdoubleꢀexponentialꢀdecayꢀgivingꢀhalf-livesꢀofꢀ69ꢀminꢀ
andꢀ534ꢀmin.ꢀThus,ꢀweꢀwereꢀableꢀtoꢀactivateꢀtheꢀsecondꢀTBRꢀofꢀ
6
7
8
9
1
D.ꢀ Zhitomirsky,ꢀ E.ꢀ Choꢀ andꢀ J.ꢀ C.ꢀ Grossman,ꢀ Adv.ꢀ Energyꢀ
Mater.,ꢀ2015,ꢀ1502006.ꢀ
A.ꢀLennartson,ꢀA.ꢀLundin,ꢀK.ꢀBörjesson,ꢀV.ꢀGrayꢀandꢀK.ꢀMoth-
Poulsen,ꢀJ.ꢀChem.ꢀSoc.,ꢀDaltonꢀTrans,ꢀ2016,ꢀ45,ꢀ8740.ꢀ
0 M.ꢀCacciarini,ꢀA.ꢀB.ꢀSkov,ꢀM.ꢀJevric,ꢀA.ꢀS.ꢀHansen,ꢀJ.ꢀElm,ꢀH.ꢀG.ꢀ
Kjaergaard,ꢀK.ꢀV.ꢀMikkelsenꢀandꢀM.ꢀB.ꢀNielsen,ꢀChem.ꢀEur.ꢀJ.,ꢀ
2015,ꢀ21,ꢀ7454.ꢀ
1
1
1
1
1 S.ꢀT.ꢀOlsen,ꢀJ.ꢀElm,ꢀF.ꢀE.ꢀStorm,ꢀA.ꢀN.ꢀGejl,ꢀA.ꢀS.ꢀHansen,ꢀM.ꢀH.ꢀ
Hansen,ꢀJ.ꢀR.ꢀNikolajsen,ꢀM.ꢀB.ꢀNielsen,ꢀH.ꢀG.ꢀKjaergaardꢀandꢀ
K.ꢀV.ꢀMikkelsen,ꢀJ.ꢀPhys.ꢀChem.ꢀA,ꢀ2015,ꢀ119,ꢀ896.ꢀ
2 A.ꢀB.ꢀSkov,ꢀS.ꢀL.ꢀBroman,ꢀA.ꢀS.ꢀGertsen,ꢀJonasꢀElm,ꢀM.ꢀJevric,ꢀ
ꢀ
ꢀ
M.ꢀCacciarini, A.ꢀKadziola,ꢀK.ꢀV.ꢀMikkelsenꢀand M.ꢀB.ꢀNielsen,ꢀ
Chem.ꢀEur.ꢀJ.,ꢀ2016,ꢀ22,ꢀ14567.ꢀ
3 A.ꢀ Vlasceanu,ꢀ S.ꢀ L.ꢀ Broman,ꢀ A.ꢀ S.ꢀ Hansen,ꢀ A.ꢀ B.ꢀ Skov,ꢀ M.ꢀ
Cacciarini,ꢀA.ꢀKadziola,ꢀH.ꢀG.ꢀKjaergaard,ꢀK.ꢀV.ꢀMikkelsenꢀandꢀ
M.ꢀB.ꢀNielsen,ꢀChem.ꢀEur.ꢀJ.,ꢀ2016,ꢀ22,ꢀ10796.ꢀ
4 J.ꢀDaub,ꢀT.ꢀKnöchelꢀandꢀA.ꢀMannschreck,ꢀAngew.ꢀChem.ꢀInt.ꢀ
Ed.,ꢀ1984,ꢀ23,ꢀ960.ꢀ
5
,ꢀwhichꢀwasꢀ“onꢀpause”ꢀforꢀenergyꢀstorage,ꢀandꢀtoꢀreleaseꢀitꢀ
uponꢀdemand.ꢀAdditionꢀofꢀethylenediamineꢀrestoredꢀtheꢀpre- 15 S.ꢀGierischꢀandꢀJ.ꢀDaub,ꢀChem.ꢀBer.,ꢀ1989,ꢀ122,ꢀ69.ꢀ
1
6 S.ꢀL.ꢀBroman,ꢀS.ꢀL.ꢀBrand,ꢀC.ꢀR.ꢀParker,ꢀM.ꢀÅ.ꢀPetersen,ꢀC.ꢀG.ꢀ
Tortzen,ꢀ A.ꢀ Kadziola,ꢀ K.ꢀ Kilsåꢀ andꢀ M.ꢀ B.ꢀ Nielsen,ꢀ Arkivoc,ꢀ
copperꢀsystemꢀ(seeꢀvideoꢀinꢀESI).ꢀ
Inꢀconclusion,ꢀweꢀhaveꢀshownꢀthatꢀtheꢀring-closureꢀofꢀVHFsꢀ
ꢀ
2
011,ꢀix,ꢀ51.ꢀ
toꢀDHAsꢀcanꢀbeꢀveryꢀwellꢀactivatedꢀbyꢀstoichiometricꢀCu(I)ꢀionsꢀ
bothꢀinꢀacetone,ꢀaꢀcompetitiveꢀLewisꢀbasicꢀsolvent,ꢀandꢀevenꢀ
1
7 M.ꢀCacciarini,ꢀS.ꢀL.ꢀBromanꢀandꢀM.ꢀB.ꢀNielsen,ꢀArkivoc,ꢀ2014,ꢀ
i,ꢀ249.ꢀ
moreꢀeffectivelyꢀinꢀdichloromethaneꢀuponꢀcomplexationꢀofꢀtheꢀ 18 A.ꢀU.ꢀPetersen,ꢀS.ꢀL.ꢀBroman,ꢀS.ꢀT.ꢀOlsen,ꢀA.ꢀS.ꢀHansen,ꢀL.ꢀDu,ꢀ
A.ꢀKadziola,ꢀT.ꢀHansen,ꢀH.ꢀG.ꢀKjaergaard,ꢀK.ꢀV.ꢀMikkelsenꢀandꢀ
M.ꢀB.ꢀNielsen,ꢀChem.ꢀEur.ꢀJ.,ꢀ2015,ꢀ21,ꢀ3968.ꢀ
9 C.ꢀ R.ꢀ Parker,ꢀ C.ꢀ G.ꢀ Tortzen,ꢀ S.ꢀ L.ꢀ Broman,ꢀ M.ꢀ Schau-
Magnussen,ꢀ K.ꢀ Kilsåꢀ andꢀ M.ꢀ B.ꢀ Nielsen,ꢀ Chem.ꢀ Commun.,ꢀ
VHFꢀform.ꢀImportantly,ꢀweꢀhaveꢀprovedꢀthatꢀthisꢀcomplexationꢀ
isꢀreversibleꢀandꢀalsoꢀallowsꢀaꢀfasterꢀreleaseꢀofꢀenergyꢀinꢀtheꢀ
1
caseꢀofꢀtheꢀlong-livedꢀVHFsꢀofꢀmacrocycleꢀ5.ꢀThisꢀisꢀaꢀsignificantꢀ
stepꢀ forwardꢀ forꢀ triggeringꢀ energyꢀ releaseꢀ inꢀ theꢀ DHA/VHFꢀ
solarꢀheatꢀbatteryꢀsystem.ꢀ
2
011,ꢀ47,ꢀ6102.ꢀ
20 C.ꢀ O.ꢀ Dietrich-Buchecker,ꢀ J.-P.ꢀ Sauvageꢀ andꢀ J.-P.ꢀ Kintzinger,ꢀ
TetrahedronꢀLett.,ꢀ1983,ꢀ24,ꢀ5095ꢀꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
2
1 Noꢀ differenceꢀ wasꢀ registeredꢀ changingꢀ theꢀ weaklyꢀ
coordinatingꢀanionꢀfromꢀCu(CH CN) BF ꢀtoꢀCu(CH CN) PF .ꢀ
2 M.ꢀCacciarini,ꢀM.ꢀJevric,ꢀJonasꢀElm, AnneꢀU.ꢀPetersen,ꢀKurtꢀV.ꢀ
3
4
4
3
4
6
ꢀ
2
MikkelsenꢀandꢀM.ꢀB.ꢀNielsen,ꢀRSCꢀAdv.,ꢀ2016,ꢀ6,ꢀ49003.ꢀ
23 R.ꢀSharma,ꢀJ.ꢀD.ꢀKnoll,ꢀP.ꢀD.ꢀMartin,ꢀI.ꢀPodgorski,ꢀC.ꢀTurroꢀandꢀ
J.ꢀJ.ꢀKodanko,ꢀInorg.ꢀChem.,ꢀ2014,ꢀ53,ꢀ3272.ꢀ
4 O.ꢀSchalk,ꢀS.ꢀL.ꢀBroman,ꢀM.ꢀÅ.ꢀPetersen,ꢀD.ꢀV.ꢀKhakhulin,ꢀR.ꢀY.ꢀ
Brogaard,ꢀM.ꢀB.ꢀNielsen,ꢀA.ꢀE.ꢀBoguslavkiy,ꢀA.ꢀStolow,ꢀandꢀT.ꢀI.ꢀ
Sølling,ꢀJ.ꢀPhys.ꢀChem.ꢀA,ꢀ2013,ꢀ117,ꢀ3340.ꢀ
2
2
5 H.ꢀSigelꢀandꢀR.ꢀB.ꢀMartin,ꢀChem.ꢀRev.,ꢀ1982,ꢀ82,ꢀ385.ꢀ
Figureꢀ 5.ꢀ UV-Visꢀ absorptionꢀ spectraꢀ inꢀ CH2Cl2ꢀ atꢀ 25ꢀ °Cꢀ ofꢀ 5- 26 S.ꢀL.ꢀBroman,ꢀM.ꢀJevricꢀandꢀM.ꢀB.ꢀNielsen,ꢀChem.ꢀEur.ꢀJ.,ꢀ2013,ꢀ
-
5
1
9,ꢀ9542.ꢀ
DHA-DHAꢀ (blackꢀ curve,ꢀ 5.7x10 ꢀ M),ꢀ 5-VHF-VHFꢀ (redꢀ curve,ꢀ
-5
-5
.7x10 ꢀM),ꢀ5-VHF-VHF+Cu(I)ꢀ(pinkꢀcurve,ꢀ5-VHF-VHF:ꢀ5.5x10 ꢀ
5
M,ꢀ Cu(I):ꢀ 15.3x10 ꢀ M),ꢀ spectrumꢀ afterꢀ 22ꢀ hꢀ (brokenꢀ blackꢀ
curve,ꢀ>75%ꢀofꢀ5-DHA-DHAꢀrecovered).ꢀ
-5
Notesꢀandꢀreferencesꢀ
4
ꢀ|ꢀJ.ꢀName.,ꢀ2012,ꢀ00,ꢀ1-3ꢀ
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