Novel triarylamine-based aromatic polyamides bearing secondary amines: Synthesis and redox potential inversion characteristics induced by pyridines

Article abstract of DOI:10.1039/c6tc03409h

Novel triarylamine-based aramids with secondary amine moieties are prepared and utilized as electrochemical detectors for pyridines. Their electrochemical behavior with different pyridines was investigated in order to demonstrate the ionic hydrogen bondin

Full text of DOI:10.1039/c6tc03409h

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DOI: 10.1039/C6TC03409H
JournalꢀNameꢀ
ꢀ
ARTICLEꢀ
NovelꢀTriarylamine-basedꢀAromaticꢀPolyamidesꢀBearingꢀ
Secondaryꢀamine:ꢀSynthesisꢀandꢀRedoxꢀPotentialꢀInversionꢀ
CharacteristicsꢀbyꢀPyridines†ꢀ
Receivedꢀ00thꢀJanuaryꢀ20xx,ꢀ
Acceptedꢀ00thꢀJanuaryꢀ20xxꢀ
a,‡,§
a,‡
b,
a,
Hung-JuꢀYen, ꢀJhe-HuangꢀLin, ꢀYuhlongꢀOliverꢀSu, *ꢀGuey-ShengꢀLiou *
DOI:ꢀ10.1039/x0xx00000xꢀ
www.rsc.org/ꢀ
Novelꢀtriarylamine-basedꢀaramidsꢀwithꢀsecondaryꢀamineꢀmoietiesꢀ throughꢀ exhaustꢀ gasesꢀ andꢀ variousꢀ industrialꢀ wastes.ꢀ Theseꢀ
areꢀ preparedꢀ andꢀ utilizedꢀ asꢀ electrochemicalꢀ detectorꢀ forꢀ chemicalsꢀ canꢀ causeꢀ acuteꢀ effectsꢀ onꢀ humanꢀ bodyꢀ whenꢀ
ingested,ꢀinhaled,ꢀorꢀabsorbedꢀthroughꢀskin,ꢀincludingꢀvomiting,ꢀ
nausea,ꢀ coughing,ꢀ asthmaticꢀ breathing,ꢀ headaches,ꢀ andꢀ evenꢀ
cancers.ꢀInꢀaddition,ꢀpyridineꢀmightꢀalsoꢀhaveꢀminorꢀneurotoxic,ꢀ
genotoxic,ꢀandꢀclastogenicꢀeffects.ꢀTherefore,ꢀtheꢀdevelopmentꢀ
ofꢀdetectorꢀforꢀharmfulꢀpyridinesꢀhasꢀbecomeꢀaꢀhighlyꢀdemandꢀ
forꢀhumanꢀhealthꢀandꢀeco-friendlyꢀsociety.ꢀꢀ
pyridines.ꢀTheꢀelectrochemicalꢀbehaviorꢀatꢀdifferentꢀpyridinesꢀwasꢀ
investigatedꢀ toꢀ demonstrateꢀ theꢀ ionicꢀ hydrogenꢀ bondingꢀ
interactionꢀ ofꢀ theꢀ secondaryꢀ amineꢀ withꢀ pyridines,ꢀ resultingꢀ inꢀ
obviousꢀ potentialꢀ inversionꢀ whichꢀ isꢀ alsoꢀ supportedꢀ byꢀ in-situꢀ
absorptionꢀmeasurement.ꢀ
2
3ꢀ
Introductionꢀ
Notably,ꢀsomeꢀimportantꢀworksꢀdoneꢀbyꢀLinschitz ꢀandꢀSmith
Recently,ꢀpolymersꢀwithꢀmolecularꢀrecognitionꢀsitesꢀareꢀhighlyꢀ elucidateꢀtheꢀinteractionꢀbetweenꢀtheꢀreducedꢀcompoundsꢀandꢀ
attractiveꢀandꢀconsideredꢀasꢀsensitiveꢀchemosensorsꢀbecauseꢀofꢀ hydrogenꢀ donors,ꢀ suchꢀ asꢀ alcohol,ꢀ amidesꢀ andꢀ ureas,ꢀ canꢀ beꢀ
1
4
theirꢀ notableꢀ electricalꢀ andꢀ opticalꢀ characterizations, ꢀ makingꢀ monitoredꢀ byꢀ CV.ꢀ Also,ꢀ Su’sꢀ group ꢀ synthesizedꢀ aꢀ seriesꢀ ofꢀ
themꢀ particularlyꢀ properꢀ implicationꢀ forꢀ theꢀ applications.ꢀ Theꢀ phenylenediaminesꢀ thatꢀ couldꢀ formꢀ hydrogenꢀ bondꢀ withꢀ
highꢀ sensitivityꢀ originatesꢀ fromꢀ theꢀ conformationꢀ changesꢀ andꢀ pyridinesꢀ orꢀ alcohols,ꢀ andꢀ theꢀ potentialꢀ shiftꢀ exhibitedꢀ aꢀ
differenceꢀ inꢀ electronꢀ distributionꢀ ofꢀ theꢀ polymerꢀ main-chainꢀ differentꢀ CVꢀ patternꢀ onꢀ theꢀ oxidativeꢀ aspect.ꢀ Theꢀ processꢀ ofꢀ
causedꢀbyꢀtheꢀinteractionꢀbetweenꢀtheꢀrecognitionꢀsiteꢀandꢀtheꢀ potentialꢀshiftꢀcouldꢀbeꢀclassifiedꢀasꢀpotentialꢀinversionꢀwithꢀaꢀ
target.ꢀConsequently,ꢀabsorption,ꢀfluorescence,ꢀconductivity,ꢀorꢀ singleꢀ two-electronꢀ wave,ꢀ whichꢀ isꢀ rareꢀ andꢀ mostlyꢀ observedꢀ
5
6
redoxꢀ potentialꢀ ofꢀ theꢀ polymerꢀ changed.ꢀ Nowadays,ꢀ theꢀ whenꢀ significantꢀ structuralꢀ change, ꢀ largeꢀ solvation ꢀ orꢀ redoxꢀ
2
detectorsꢀ withꢀ highꢀ sensitivityꢀ andꢀ reliabilityꢀ areꢀ urgentlyꢀ potentialsꢀ byꢀ ionicꢀ hydrogenꢀ bonding ꢀ occurredꢀ withinꢀ theꢀ
demandedꢀ dueꢀ toꢀ theꢀ degenerativeꢀ environmentꢀ andꢀ theꢀ multi-electronꢀ transferꢀ reaction.ꢀ Nevertheless,ꢀ theseꢀ
increasingꢀ attentionꢀ ofꢀ theꢀ chemicalꢀ andꢀ biologicalꢀ threats.ꢀ compoundsꢀareꢀveryꢀrare.ꢀ
Particularly,ꢀ significantꢀ effortsꢀ haveꢀ doneꢀ toꢀ seekꢀ newꢀ
chemosensoryꢀ systemsꢀ forꢀ harmfulꢀ materials,ꢀ whichꢀ haveꢀ theꢀ
potentialꢀ toꢀ causeꢀ harmꢀ toꢀ humans,ꢀ animals,ꢀ orꢀ theꢀ
environment,ꢀeitherꢀbyꢀitselfꢀorꢀthroughꢀinteractionꢀwithꢀotherꢀ
factors.ꢀꢀ
Therefore,ꢀ thisꢀ workꢀ weꢀ introducedꢀ aꢀ newꢀ polymericꢀ
chemosensor withꢀ potentialꢀ inversionꢀ characteristic,ꢀ whichꢀ isꢀ
designedꢀforꢀpyridinesꢀsensingꢀviaꢀchangesꢀinꢀelectrochemistryꢀ
andꢀ opticalꢀ absorption.ꢀ Triphenylamine-basedꢀ polymersꢀ withꢀ
secondaryꢀ amineꢀ wereꢀ chosenꢀ andꢀ synthesizedꢀ dueꢀ toꢀ theirꢀ
Pyridineꢀandꢀitsꢀderivativesꢀareꢀkeyꢀchemicalsꢀasꢀsolventsꢀandꢀ well-knownꢀ photo-ꢀ andꢀ electroactiveꢀ propertiesꢀ andꢀ featuredꢀ
intermediatesꢀ forꢀ producingꢀ agriculturalꢀ chemicals,ꢀ additives,ꢀ ionicꢀ hydrogen-bondingꢀ abilityꢀ withꢀ pyridines.ꢀ Theseꢀ targetꢀ
dyes,ꢀ drugs,ꢀ andꢀ etc.ꢀ However,ꢀ theseꢀ toxicꢀ andꢀ foul-smellingꢀ polymersꢀ exhibitꢀ severalꢀ advantages:ꢀ facileꢀ preparationꢀ byꢀ theꢀ
substancesꢀ wouldꢀ intrudeꢀ intoꢀ humanꢀ livingꢀ environmentꢀ polycondensationꢀofꢀdiamineꢀmonomerꢀwithꢀvariousꢀcommercialꢀ
compounds,ꢀ highꢀ thermalꢀ stability,ꢀ andꢀ theꢀ abilityꢀ toꢀ interactꢀ
withꢀ pyridinesꢀ accompaniedꢀ withꢀ potentialꢀ inversionꢀ andꢀ
intenseꢀ absorptionꢀ changeꢀ originatedꢀ fromꢀ ionicꢀ hydrogen-
bonding.ꢀ
ResultsꢀAndꢀDiscussionꢀ
MonomerꢀSynthesisꢀ
Considering the preferential reactivity of N,N’-diaryl-p-
phenylenediamines 1, the secondary amine attached to the
nitrobenzene is more acidic than another one attached to
benzene/methoxybenzene, thus facilitates the deprotonation and
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ1ꢀꢀ
Pleaseꢀdoꢀnotꢀadjustꢀmarginsꢀ

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ARTICLEꢀ
JournalꢀNameꢀ
further nucleophilic substitution of 4-fluoronitrobenzene. IR spectra of these synthesized compounds are ViilelwuAsrttricalteeOdnlinine
Therefore,
diamine
N,N-bis(4-nitrophenyl)-N’-phenylbenzene-1,4- Figure S1 and S2. The nitro groups of cDoOmI:p1o0u.1n0d39s/C26TeCx0h3ib40it9eHd
-1
(2-H)
and
N-(4-methoxyphenyl)-N’,N’-bis(4- two characteristic bands at around 1580 and 1305 cm for -NO
2
nitrophenyl)benzene-1,4-diamine (2-OMe) can be readily asymmetric and symmetric stretching, respectively. After
prepared through the CsF-mediated aromatic nucleophilic reduced to diamine monomers 3, the characteristic absorption
substitution reaction of N-(4-nitrophenyl)-N’-phenyl-1,4- bands of the nitro group disappeared and the primary and
phenylenediamine (1-H) and N-(4-methoxyphenyl)-N’-(4- secondary amino groups showed typical absorption pair at 3400-
-
1
1
13
nitrophenyl)benzene-1,4-diamine
fluoronitrobenzene in high yield (>75%), respectively (Scheme NMR spectra of the compounds 1-3 are illustrated in Figure S4-
). N,N-Bis(4-aminophenyl)-N’-phenylbenzene-1,4-diamine (3- S13, and the results are in perfect agreement with the proposed
H) and N,N-bis(4-aminophenyl)-N’-(4-methoxyphenyl)benzene- molecular structures. The model compounds M were also
,4-diamine (3-OMe) were then synthesized from the dinitro prepared by the condensation of diamines 3 with two equivalent
(1-OMe)
with
4- 3330 cm . H, C NMR, the 2D H-H COSY and C-H HSQC
1
1
compounds 2 and 2-OMe by Pd/C-catalyzed hydrazine reduction amounts of benzoyl chloride for getting simplified structural
of, respectively. Elemental analysis, NMR and FT-IR information of their corresponding polyamides (Scheme 2). Their
1
spectroscopic techniques were utilized to confirm the structures FT-IR and H NMR spectra are shown in Figure S3 and S14,
of dinitro compounds 2 and target diamine monomers 3. The FT- respectively.
O2N
NO2
H2N
NH2
N
N
Nucleophilic
Substitution
H
N
Nucleophilic
Substitution
R
NH2
R
Reduction
TEA, DMSO
CsF, DMSO
Pd/C, EtOH,
Hydrazine
N
H
N
H
NO2
F
NO2
F
NO2
NH
NH
R
R
1
2
3
R: -H, -OMe
ꢀ
Schemeꢀ1.ꢀSyntheticꢀroutesꢀtoꢀdiamineꢀmonomersꢀ3-Hꢀandꢀ3-OMe.ꢀ
ꢀ
-
1
groupꢀ atꢀ aroundꢀ 3330ꢀ cm ꢀ (amideꢀ andꢀ secondaryꢀ N-Hꢀ
H
2
N
NH
2
H
N
H
N
-1
stretching)ꢀandꢀ1655ꢀcm ꢀ(amideꢀcarbonyl).ꢀFigureꢀS16ꢀshowsꢀ
aꢀ typicalꢀ setꢀ ofꢀ Hꢀ spectrumꢀ ofꢀ PA-Hꢀ inꢀ DMSO-d
peaksꢀ couldꢀ beꢀ readilyꢀ assignedꢀ toꢀ theꢀ hydrogenꢀ ofꢀ theꢀ
recurringꢀ unit.ꢀ Theꢀ resultsꢀ identifiedꢀ byꢀ IRꢀ andꢀ NMRꢀ
spectroscopicꢀtechniquesꢀdemonstratedꢀwellꢀagreementꢀwithꢀ
theꢀproposedꢀmolecularꢀstructures.ꢀꢀ
Cl
O
N
O
O
N
1
Condensation
6
;ꢀ allꢀ theꢀ
+
2.0
DMAc, -20 oC, 2h
NH
NH
R
R
3
M
R: -H, -OMe
ꢀ
Schemeꢀ2.ꢀSyntheticꢀroutesꢀtoꢀmodelꢀcompounds.ꢀ
ꢀ
PolymerꢀSynthesisꢀꢀ
Aromaticꢀ polyamidesꢀ (Aramids)ꢀ PA-Hꢀ andꢀ PA-OMe
ꢀ
containingꢀsecondaryꢀamineꢀwithꢀdifferentꢀsubstituentsꢀwereꢀ
preparedꢀ byꢀ reactingꢀ diaminesꢀ 3-Hꢀ andꢀ 3-OMeꢀ withꢀ
commerciallyꢀ availableꢀ diacidꢀ chlorideꢀ viaꢀ low-temperatureꢀ
polycondensation,ꢀ respectivelyꢀ (Schemeꢀ 3).ꢀ Theꢀ
polymerizationꢀreactionꢀproceededꢀhomogeneouslyꢀandꢀtheꢀ
highꢀ molecularꢀ weightsꢀ polymersꢀ canꢀ affordꢀ toughꢀ andꢀ
flexibleꢀfilmsꢀviaꢀsolutionꢀcastingꢀ(asꢀshownꢀinꢀtheꢀinsetꢀfigureꢀ
ofꢀ Schemeꢀ 3).ꢀ Dueꢀ toꢀ theꢀ strongꢀ intra-ꢀ andꢀ inter-chainꢀ
hydrogenꢀ bondingꢀ andꢀ weakꢀ stericꢀ hindranceꢀ forꢀ closeꢀ
packing,ꢀtheꢀprecipitatedꢀpolyamidesꢀshowedꢀaꢀrelativelyꢀlowꢀ
solubility.ꢀ Theꢀ precipitatedꢀ polyamidesꢀ onlyꢀ canꢀ dissolveꢀ inꢀ
Schemeꢀ3.ꢀSynthesisꢀandꢀstructureꢀofꢀpolyamidesꢀPA-HꢀandꢀPA-
OMe.ꢀ
ꢀ
BasicꢀPolymerꢀPropertiesꢀꢀ
Theꢀ thermalꢀ behaviorꢀ ofꢀ theꢀ obtainedꢀ polyamidesꢀ wasꢀ
evaluatedꢀbyꢀTGAꢀandꢀTMA,ꢀandꢀtheꢀresultsꢀareꢀsummarizedꢀ
inꢀTableꢀS2.ꢀTypicalꢀTGAꢀcurvesꢀofꢀpolyamidesꢀareꢀdepictedꢀinꢀ
FigureꢀS17.ꢀAllꢀtheꢀpreparedꢀpolymersꢀmanifestꢀinsignificantꢀ
2 4
H SO ꢀ withꢀ inherentꢀ viscositiesꢀ inꢀ theꢀ rangeꢀ ofꢀ 0.95-1.02ꢀ
dL/g,ꢀ indicatingꢀ theꢀ formationꢀ ofꢀ highꢀ molecularꢀ weightꢀ
polymersꢀ(TableꢀS1).ꢀNevertheless,ꢀtheꢀhighꢀperformanceꢀthinꢀ
filmsꢀstillꢀcanꢀbeꢀobtainedꢀbyꢀspin-coatingꢀorꢀinkjet-printingꢀ
processesꢀ ofꢀ theꢀ as-preparedꢀ polymerꢀ solutionꢀ withoutꢀ theꢀ
o
weightꢀlossꢀupꢀtoꢀ405ꢀ Cꢀunderꢀnitrogenꢀandꢀairꢀatmosphere,ꢀ
andꢀtheꢀcarbonizedꢀresidueꢀ(charꢀyield)ꢀofꢀtheseꢀpolymersꢀinꢀ
o
aꢀ nitrogenꢀ atmosphereꢀ wereꢀ moreꢀ thanꢀ 64ꢀ %ꢀ atꢀ 800ꢀ C,ꢀ
estimatingꢀ LOIꢀ valuesꢀ upꢀ toꢀ 44.ꢀ Theꢀ softeningꢀ temperatureꢀ
(T )ꢀcouldꢀbeꢀeasilyꢀmeasuredꢀinꢀtheꢀTMAꢀthermogramsꢀ(asꢀ
s
shownꢀ inꢀ Figureꢀ S18).ꢀ Theꢀ excellentꢀ thermalꢀ propertiesꢀ
indicatedꢀ thatꢀ theꢀ highꢀ aromaticꢀ contentꢀ andꢀ strongꢀ intra-
precipitation/work-upꢀ stepꢀ orꢀ usingꢀ theꢀ harmfulꢀ H
processingꢀsolvent.ꢀ
2 4
SO ꢀ asꢀ
IRꢀspectraꢀofꢀtheꢀpolyamidesꢀPA-HꢀandꢀPA-OCH3ꢀ inꢀFigureꢀ
S15ꢀ exhibitꢀ characteristicꢀ absorptionꢀ bandsꢀ ofꢀ theꢀ amideꢀ
2
ꢀ|ꢀJ.ꢀName.,ꢀ2012,ꢀ00,ꢀ1-3ꢀ
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JournalꢀNameꢀ
inter-chainꢀhydrogenꢀbondingꢀplayedꢀimportantꢀrolesꢀinꢀtheꢀ
ꢀARTICLEꢀ
/
para-substitutionꢀ changedꢀ fromꢀ hydrogenꢀ atomꢀ toꢀ anꢀ
View Article Online
ox
preparedꢀpolyamides.ꢀ
electron-donatingꢀmethoxyꢀgroup,ꢀcomDOpIo: 1u0n.1d0ꢀ329-/OCM6TeCꢀ0(3E409ꢀH=ꢀ
1
ox
2
0
.77ꢀ V;ꢀ E
ꢀ =ꢀ 1.07ꢀ V)ꢀ exhibitedꢀ lowerꢀ oxidationꢀ potentialsꢀ
Electrochemistryꢀandꢀin-situꢀUV-visꢀabsorptionꢀꢀ
ox
ox
thanꢀthatꢀofꢀcompoundꢀ2-Hꢀ(E
toꢀtheꢀinductiveꢀeffectꢀofꢀtheꢀsubstituent.ꢀ
Asꢀ shownꢀ inꢀ Figureꢀ 1a-1d),ꢀ afterꢀ 4-acetylpyridineꢀ (AcPy;ꢀ
pK ꢀ =ꢀ 3.51)ꢀ orꢀ pyridineꢀ (Py;ꢀ pK ꢀ =ꢀ 5.28)ꢀ wasꢀ addedꢀ toꢀ theꢀ
1 2
ꢀ=ꢀ0.87ꢀV;ꢀE ꢀ=ꢀ1.16ꢀV)ꢀdueꢀ
Allꢀtheꢀpreparedꢀphenylenediaminesꢀrevealꢀtwoꢀreversibleꢀ
oxidationꢀstepsꢀrelatedꢀtoꢀtheꢀradicalꢀcationꢀandꢀdication.ꢀTheꢀ
electrochemicalꢀ behaviorꢀ ofꢀ compoundsꢀ 2,ꢀ 3,ꢀ andꢀ theꢀ
polyamidesꢀ wereꢀ investigatedꢀ byꢀ cyclicꢀ voltammetryꢀ (CV).ꢀ
a
a
solutionꢀ ofꢀ nitro-compoundꢀ 2,ꢀ theꢀ peak/currentꢀ ofꢀ secondꢀ
oxidationꢀ waveꢀ wasꢀ onlyꢀ slightlyꢀ shifted.ꢀ While,ꢀ whenꢀ theꢀ
Py;ꢀpK ꢀ=ꢀ7.48,ꢀFigureꢀ
3 a
eꢀandꢀ1f)ꢀwasꢀadded,ꢀaꢀnewꢀoxidationꢀwaveꢀoccurredꢀatꢀaꢀ
lowerꢀpotentialꢀthanꢀtheꢀfirstꢀredoxꢀcoupleꢀ(beganꢀwithꢀtheꢀ
redꢀ dashedꢀ line).ꢀ Theꢀ finalꢀ CVꢀ curveꢀ (blueꢀ solidꢀ line)ꢀ inꢀ theꢀ
3
Compoundsꢀ(10ꢀμmol)ꢀwereꢀdissolvedꢀinꢀacetonitrileꢀ(CH CN)ꢀ
containingꢀ0.1ꢀMꢀofꢀtetrabutylammoniumꢀperchlorateꢀ(TBAP)ꢀ
asꢀ anꢀ electrolyteꢀ andꢀ usingꢀ glassyꢀ carbonꢀ diskꢀ asꢀ workingꢀ
electrode.ꢀ Inꢀ addition,ꢀ theꢀ polymersꢀ wereꢀ conductedꢀ byꢀ
castingꢀfilmꢀ(polymerꢀfilmsꢀareaꢀaboutꢀ0.5ꢀcmꢀxꢀ1.1ꢀcm)ꢀonꢀanꢀ
indium-tinꢀoxideꢀ(ITO)-coatedꢀglassꢀasꢀworkingꢀelectrode.ꢀAsꢀ
shownꢀinꢀFigureꢀ1,ꢀthereꢀareꢀtwoꢀreversibleꢀoxidationꢀredoxꢀ
couplesꢀ forꢀ compoundsꢀ 2-Hꢀ orꢀ 2-OMeꢀ beforeꢀ addingꢀ
pyridines,ꢀwhichꢀisꢀcalledꢀ“normalꢀpotential”,ꢀindicatingꢀtheꢀ
secondꢀoxidationꢀoccursꢀatꢀhigherꢀappliedꢀpotentialꢀthanꢀtheꢀ
firstꢀoneꢀdueꢀtoꢀtheꢀelectrostaticꢀrepulsion.ꢀMoreover,ꢀasꢀtheꢀ
moreꢀbasicꢀ2,4,6-trimethylpyridineꢀ(Me
1
presenceꢀ ofꢀ 1ꢀ equiv.ꢀ (10.0ꢀ µmole)ꢀ ofꢀ Me
oneꢀredoxꢀcoupleꢀatꢀE
3
Pyꢀ exhibitedꢀ onlyꢀ
’ꢀ=ꢀ0.81ꢀandꢀ0.66ꢀVꢀforꢀ2-Hꢀandꢀ2-
OMe,ꢀ respectively,ꢀ whichꢀ areꢀ lowerꢀ thanꢀ theꢀ normalꢀ
ox
2
ox
1
potentialꢀE
ofꢀtheꢀcorrespondingꢀ2-Hꢀandꢀ2-OMe.ꢀꢀ
2-H
2-OMe
AcPy
N
O
Py
N
Me Py
3
N
ꢀ
Figureꢀ1.ꢀCyclicꢀvoltammogramsꢀofꢀ10ꢀμmolꢀ2-Hꢀ(a,c,e)ꢀandꢀ2-OMeꢀ(b,d,f)ꢀinꢀ0.1ꢀMꢀTBAP/CH
3.51],ꢀ(c)(d)ꢀPyꢀ[pK ꢀ=5.28]ꢀandꢀ(e)(f)ꢀMe Pyꢀ[pK ꢀ=7.48].ꢀScanꢀrate:ꢀ100ꢀmV/s.ꢀWorkingꢀelectrode:ꢀglassyꢀcarbonꢀdiskꢀ(areaꢀ=ꢀ0.07ꢀcm ).ꢀ
1 2
Meanwhile,ꢀ toꢀ simplifyꢀ theꢀ structuralꢀ informationꢀ ofꢀ ꢀ andꢀ E .ꢀ Theꢀ firstꢀ oxidationꢀ
3 a
CNꢀwithꢀvariousꢀamountꢀofꢀ(a)(b)ꢀAcPyꢀ[pK ꢀ
2
=
a
3
a
ox
ox
0.74ꢀ V)ꢀ growsꢀ betweenꢀ E
remainedꢀunchanged,ꢀandꢀtheꢀcurrentꢀofꢀsecondꢀoxidationꢀatꢀ
E ꢀ=ꢀ0.92ꢀVꢀgraduallyꢀdecreasedꢀasꢀincreasingꢀtheꢀamountꢀofꢀ
2
polyamides,ꢀ theꢀ modelꢀ compoundsꢀ Mꢀ wereꢀ preparedꢀ andꢀ
usedꢀ forꢀ CVꢀ measurement.ꢀ Asꢀ shownꢀ inꢀ Figureꢀ 2,ꢀ M-Hꢀ
ox
ox
ox
exhibitsꢀtwoꢀreversibleꢀredoxꢀcouplesꢀatꢀE
1
ꢀ=ꢀ0.54ꢀVꢀandꢀE
2
ꢀ
AcPy.ꢀWhenꢀtheꢀAcPyꢀreachedꢀ1ꢀequiv.ꢀ(10.0ꢀµmole)ꢀtoꢀM-H,ꢀ
=
ꢀ0.92ꢀV,ꢀrespectively.ꢀAfterꢀAcPyꢀ(pK ꢀ=ꢀ3.51,ꢀFigureꢀ2a)ꢀwasꢀ
a
theꢀsecondꢀoxidationꢀwaveꢀcompletelyꢀdisappearedꢀandꢀtheꢀ
appearanceꢀofꢀE2 ’ꢀwithꢀlowerꢀoxidationꢀpotentialꢀthanꢀE2 ꢀisꢀ
ox
ox
ox
addedꢀtoꢀtheꢀsolutionꢀofꢀM-H,ꢀaꢀnewꢀoxidationꢀwaveꢀ(E
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
2
’ꢀ=ꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ3ꢀ
Pleaseꢀdoꢀnotꢀadjustꢀmarginsꢀ

Jo uP rl ne aa sl eo ꢀ fd Mo ꢀ an to et rꢀ ai ad l jsu sC t hꢀ me am r ig si nt rsyꢀ C
Page 4 of 5
ARTICLEꢀ
JournalꢀNameꢀ
assignedꢀasꢀtheꢀnewꢀsecondꢀoxidationꢀassociatedꢀwithꢀAcPy.ꢀ
Inꢀaddition,ꢀtheꢀadditionꢀofꢀPyꢀ(pK ꢀ=5.28;ꢀFigureꢀ2cꢀandꢀ2d)ꢀ
aniline,ꢀ respectively,ꢀ forꢀ comparisonꢀ (Figureꢀ S1Vi9ew).ꢀAOrticnlelyOꢀntlhineeꢀ
CVꢀcurveꢀinꢀtheꢀpresenceꢀofꢀanilineꢀshoDwOsI:ꢀ1a0ꢀs.1l0ig3h9t/Cꢀs6hTiCft0ꢀo34fꢀ0t9hHeꢀ
a
ox
ox
doesn'tꢀshiftꢀtheꢀE
1
ꢀbutꢀfurtherꢀloweredꢀtheꢀE
ꢀasꢀtheꢀPyꢀconcentrationꢀreachedꢀtoꢀ1ꢀequiv.ꢀ
10.0ꢀµmole)ꢀofꢀM.ꢀ
Furthermore,ꢀ whenꢀ Me
2
’ꢀseemingꢀtoꢀ
secondꢀ oxidationꢀ potential,ꢀ whichꢀ isꢀ evenꢀ unobservableꢀ
whenꢀcomparedꢀwithꢀtheꢀpyridineꢀderivativesꢀ(Figureꢀ2b,ꢀ2d,ꢀ
andꢀ 2f).ꢀ Inꢀ addition,ꢀ theꢀ presenceꢀ ofꢀ H-bondingꢀ isꢀ alsoꢀ
ox
mergeꢀwithꢀE
1
(
+
•
supportedꢀbyꢀUV-visꢀspectraꢀofꢀM-OMe ꢀafterꢀaddingꢀMe
3
Py.ꢀ
3
a
Pyꢀ (pK ꢀ =7.48,ꢀ Figureꢀ 2e)ꢀ wasꢀ
Absorptionꢀ spectraꢀ changeꢀ inꢀ Figureꢀ S20ꢀ revealedꢀ thatꢀ theꢀ
addedꢀ toꢀ theꢀ M-Hꢀ solution,ꢀ theꢀ CVꢀ exhibitedꢀ differentꢀ
+•
M-OMe ꢀ exhibitedꢀ aꢀ characteristicꢀ broadꢀ bandꢀ inꢀ theꢀ NIRꢀ
region,ꢀ whichꢀ isꢀ dueꢀ toꢀ IV-CTꢀ excitationꢀ betweenꢀ statesꢀ inꢀ
whichꢀtheꢀpositiveꢀchargeꢀwasꢀcenteredꢀatꢀdifferentꢀnitrogenꢀ
patternsꢀ toꢀ thoseꢀ ofꢀ AcPyꢀ andꢀ Py.ꢀ Theꢀ newꢀ redoxꢀ waveꢀ
ox
.ꢀ Theꢀ
producedꢀ atꢀ aꢀ muchꢀ lowerꢀ potentialꢀ thanꢀ thatꢀ ofꢀ E
1
finalꢀCVꢀcurveꢀ(blueꢀsolidꢀlineꢀofꢀFigureꢀ2e)ꢀwithꢀ1ꢀequiv.ꢀ(10.0ꢀ
1
9ꢀ
+•
ox
2
atoms. AfterꢀMe PyꢀwasꢀaddedꢀtoꢀtheꢀsolutionꢀofꢀM-OMe ,ꢀ
3
µmole)ꢀ ofꢀ Me
3
Pyꢀ showedꢀ onlyꢀ oneꢀ redoxꢀ coupleꢀ atꢀ E
’ꢀ =ꢀ
ox
theꢀ intensityꢀ ofꢀ theꢀ absorptionꢀ peakꢀ atꢀ 660ꢀ nmꢀ graduallyꢀ
increased,ꢀandꢀaꢀbroadꢀbandꢀcenteredꢀatꢀ900ꢀnmꢀinꢀtheꢀNIRꢀ
regionꢀ graduallyꢀ decreasedꢀ inꢀ intensity.ꢀ Afterꢀ addedꢀ theꢀ
0
.48ꢀ V,ꢀ whichꢀ isꢀ apparentlyꢀ lowerꢀ thanꢀ E
1
.ꢀ Also,ꢀ theꢀ finalꢀ
peakꢀ currentꢀ isꢀ aboutꢀ 2ꢀ timesꢀ higherꢀ thanꢀ theꢀ firstꢀ one,ꢀ
indicatingꢀthatꢀtheꢀhydrogenꢀbondingꢀplayedꢀaꢀsignificantꢀroleꢀ
inꢀ stabilizingꢀ theꢀ oxidizedꢀ productꢀ andꢀ furtherꢀ favoredꢀ theꢀ
secondꢀ oxidation.ꢀ Asꢀ theꢀ chemosensorsꢀ requireꢀ highꢀ
selectivityꢀ andꢀ sensitivityꢀ toꢀ theꢀ substrates,ꢀ weꢀ furtherꢀ
measuredꢀtheꢀCVsꢀofꢀmodelꢀcompoundꢀ M-OMeꢀwithꢀequalꢀ
molarꢀ ofꢀ aliphaticꢀ amineꢀ methylamineꢀ andꢀ aromaticꢀ amineꢀ
equiv.ꢀ(1.0ꢀµmole)ꢀofꢀMe
3
Py,ꢀtheꢀcompleteꢀdiappearanceꢀofꢀ
IV-CTꢀ bandꢀ inꢀ NIRꢀ regionꢀ attributableꢀ toꢀ theꢀ H-bondingꢀ
+•
3
formationꢀ betweenꢀ M-OMe ꢀ andꢀ Me Pyꢀ confirmsꢀ theꢀ
phenomenon.ꢀ
M-H
M-OMe
AcPy
N
O
Py
N
Me Py
3
N
ꢀ
3
Figureꢀ2.ꢀCyclicꢀvoltammogramsꢀofꢀ10ꢀμmolꢀM-Hꢀ(a,c,e)ꢀandꢀM-OMeꢀ(b,d,f)ꢀinꢀ0.1ꢀMꢀTBAP/CH CNꢀwithꢀvariousꢀamountꢀofꢀ(a)(b)ꢀAcPyꢀ
2
[
pK
a
=3.51],ꢀ(c)(d)ꢀPyꢀ[pK
a
ꢀ=5.28]ꢀandꢀ(e)(f)ꢀMe
3
Pyꢀ[pK
a
ꢀ=7.48].ꢀScanꢀrate:ꢀ100ꢀmV/s.ꢀWorkingꢀelectrode:ꢀglassyꢀcarbonꢀdiskꢀ(areaꢀ=ꢀ0.07ꢀcm ).ꢀ
Theꢀshiftꢀofꢀsecondꢀoxidationꢀwaveꢀforꢀmodelꢀcompoundsꢀ
polyamideꢀPA-OMeꢀrevealedꢀtwoꢀreversibleꢀoxidationꢀwavesꢀ
ox
ox
affectedꢀbyꢀtheꢀstrengthꢀofꢀH-bondingꢀindicatesꢀtheꢀdifferentꢀ
forceꢀ betweenꢀ theꢀ secondaryꢀ amineꢀ andꢀ pyridines.ꢀ Theirꢀ
correspondingꢀ polyamidesꢀ alsoꢀ haveꢀ theꢀ similarꢀ
electrochemicalꢀ behaviorꢀ (Figureꢀ 3).ꢀ Theꢀ CVꢀ diagramsꢀ ofꢀ
atꢀ E
1
ꢀ =ꢀ 0.56ꢀ Vꢀ andꢀ E
2
ꢀ =ꢀ 0.93ꢀ V,ꢀ respectivelyꢀ (blackꢀ solidꢀ
,ꢀ theꢀ
ꢀ valueꢀ ofꢀ pyridines.ꢀ
line).ꢀ Afterꢀ addingꢀ theꢀ pyridinesꢀ withꢀ differentꢀ pK
a
ox
2
E
’decreasedꢀ asꢀ increasingꢀ theꢀ pK
2
Especially,ꢀ inꢀ theꢀ presenceꢀ ofꢀ Me Py,ꢀ theꢀ finalꢀ E ’ꢀ isꢀ alsoꢀ
a
ox
3
4
ꢀ|ꢀJ.ꢀName.,ꢀ2012,ꢀ00,ꢀ1-3ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
Pleaseꢀdoꢀnotꢀadjustꢀmarginsꢀ

Page 5 of 5
Jo uP rl ne aa sl eo ꢀ fd Mo ꢀ an to et rꢀ ai ad l jsu sC t hꢀ me am r ig si nt rsyꢀ C
JournalꢀNameꢀ
ꢀARTICLEꢀ
ox
lowerꢀthanꢀE
thanꢀ thatꢀ ofꢀ E
behaviorꢀtoꢀtheꢀstructure-relatedꢀcompounds.ꢀMoreover,ꢀtheꢀ
1
ꢀwithꢀtheꢀpeakꢀcurrentꢀaroundꢀ2ꢀtimesꢀhigherꢀ
accordingly.ꢀTheꢀdisappearanceꢀofꢀIV-CTꢀbandꢀaVtiꢀeawrAoruticnledOꢀ9nl5in0eꢀ
nmꢀcanꢀbeꢀobservedꢀafterꢀeachꢀpryidinDeOꢀIw: 1a0s.1ꢀa0d39d/eCd6.TꢀCB0e3s4id0e9sH,ꢀ
theꢀintensityꢀofꢀtheꢀnewꢀabsorptionꢀbandꢀatꢀaroundꢀ680ꢀnmꢀ
a
isꢀhighlyꢀrelatedꢀtoꢀtheꢀpK ꢀofꢀpyridines,ꢀfurtherꢀprovidesꢀtheꢀ
ox
1
,ꢀ manifestingꢀ aꢀ similarꢀ potentialꢀ inversionꢀ
+•
absorptionꢀ spectraꢀ changeꢀ ofꢀ PA-OMe ꢀ afterꢀ addingꢀ
differentꢀ pyridinesꢀ wasꢀ presentedꢀ inꢀ Figureꢀ 3bꢀ toꢀ illustrateꢀ
theꢀstrengthꢀofꢀH-bondingꢀbetweenꢀPA-OMe ꢀandꢀpyridinesꢀ
additionalꢀsupportꢀforꢀtheꢀpresenceꢀofꢀH-bonding.ꢀ
+•
ꢀ
(a)
H
N
H
N
O
C
O
C
N
N
n
PA-OMe
H
H
3
CO
(b)
Proton Acceptor
pK
a
:
3.51
5.28
7.48
N
N
N
O
ꢀ
Figureꢀ3.ꢀ(a)ꢀTheꢀshiftꢀofꢀsecondꢀpotentialꢀforꢀPA-OMeꢀwithꢀdifferentꢀpK
a
ꢀofꢀpyridinesꢀ(36ꢀμmol)ꢀinꢀ0.1ꢀMꢀTBAP/CH
3
CN.ꢀ(b)ꢀTheꢀabsorptionꢀ
spectraꢀofꢀPA-OMeꢀwithꢀdifferentꢀpK
a
ꢀofꢀpyridinesꢀ(80ꢀμmol)ꢀinꢀ0.1ꢀMꢀTBAP/CH CN.ꢀ(polymerꢀfilmsꢀareaꢀaboutꢀ0.5ꢀcmꢀxꢀ1.1ꢀcm)ꢀ
3
Conclusionꢀ
3.ꢀ (a)ꢀY.ꢀGe,ꢀR.ꢀR.ꢀLilienthalꢀandꢀD.ꢀK.ꢀSmith,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ
996,ꢀ118,ꢀ3976;ꢀ(b)ꢀY.ꢀGe,ꢀL.ꢀMiller,ꢀT.ꢀOuimetꢀandꢀD.ꢀK.ꢀ
1
Inꢀsummary,ꢀthisꢀworkꢀreportsꢀtheꢀsynthesisꢀofꢀtriarylamine-
basedꢀhigh-performanceꢀpolyamidesꢀwithꢀsecondaryꢀamineꢀ
andꢀ theirꢀ electrochemicalꢀ detectionꢀ ofꢀ pyridinesꢀ
characterizedꢀ byꢀ potentialꢀ inversionꢀ resultingꢀ fromꢀ H-
bondingꢀ interaction.ꢀ Pyridinesꢀ withꢀ differentꢀ substituentꢀ
andꢀ pKa’s,ꢀ haveꢀ beenꢀ manifestedꢀ byꢀ theꢀ effectꢀ onꢀ
electrochemicalꢀpropertiesꢀofꢀtheꢀpolyamides.ꢀTheꢀpotentialꢀ
inversionꢀ couldꢀ beꢀ obviouslyꢀ observedꢀ byꢀ CVꢀ diagramsꢀ asꢀ
Me3Pyꢀisꢀapplied,ꢀwhichꢀisꢀalsoꢀsupportedꢀbyꢀin-situꢀUV-visꢀ
absorptionꢀmeasurement.ꢀThus,ꢀtheseꢀresultsꢀdemonstrateꢀ
thatꢀtheꢀtriarylamine-basedꢀpolymersꢀcontainingꢀsecondaryꢀ
amineꢀcanꢀeffectivelyꢀinteractꢀwithꢀprotonꢀacceptorꢀtoꢀformꢀ
ionicꢀ hydrogenꢀ bondingꢀ andꢀ thisꢀ phenomenonꢀ canꢀ beꢀ
successfullyꢀ monitoredꢀ byꢀ cyclicꢀ voltammogramꢀ diagramsꢀ
andꢀabsorptionꢀspectra.ꢀ
Smith,ꢀJ.ꢀOrg.ꢀChem.,ꢀ2000,ꢀ65,ꢀ8831;ꢀ(c)ꢀY.ꢀGeꢀandꢀD.ꢀK.ꢀ
Smith,ꢀAnal.ꢀChem.,ꢀ2000,ꢀ72,ꢀ1860;ꢀ(d)ꢀJ.ꢀBu,ꢀN.ꢀD.ꢀLilienthal,ꢀ
J.ꢀE.ꢀWoods,ꢀC.ꢀE.ꢀNohrden,ꢀK.ꢀT.ꢀHoang,ꢀD.ꢀTruongꢀandꢀD.ꢀK.ꢀ
Smith,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ2005,ꢀ127,ꢀ6423;ꢀ(e)ꢀC.ꢀChan-
Leonor,ꢀS.ꢀL.ꢀMartinꢀandꢀD.ꢀK.ꢀSmith,ꢀJ.ꢀOrg.ꢀChem.,ꢀ2005,ꢀ70,ꢀ
1
0817.ꢀ
4
.ꢀ Y.-C.ꢀChung,ꢀY.-J.ꢀTu,ꢀS.-H.ꢀLu,ꢀW.-C.ꢀHsu,ꢀK.ꢀY.ꢀChiuꢀandꢀY.ꢀO.ꢀ
Su,ꢀOrg.ꢀlett.,ꢀ2011,ꢀ13,ꢀ2826.ꢀ
5.ꢀ (a)ꢀD.ꢀH.ꢀEvansꢀandꢀK.ꢀHu,ꢀJ.ꢀChem.ꢀSoc.ꢀFaradayꢀTrans.,ꢀ1996,ꢀ
2,ꢀ3983;ꢀ(b)ꢀN.ꢀA.ꢀMacías-RuvalcabaꢀandꢀD.ꢀH.ꢀEvans,ꢀJ.ꢀPhys.ꢀ
9
Chem.ꢀB,ꢀ2006,ꢀ110,ꢀ5155.ꢀ
6
ꢀ
.ꢀ P.ꢀHapiot,ꢀL.ꢀD.ꢀKispert,ꢀV.ꢀV.ꢀKonovalovꢀandꢀJ.-M.ꢀSavéant,ꢀJ.ꢀ
Am.ꢀChem.ꢀSoc.,ꢀ2001,ꢀ123,ꢀ6669.ꢀ
Notesꢀandꢀreferencesꢀ
1
.ꢀ (a)ꢀR.ꢀBao,ꢀC.ꢀWang,ꢀL.ꢀDong,ꢀR.ꢀYu,ꢀK.ꢀZhao,ꢀZ.ꢀL.ꢀWangꢀandꢀC.ꢀ
Pan,ꢀAdv.ꢀFunct.ꢀMater.,ꢀ2015,ꢀ25,ꢀ2884;ꢀ(b)ꢀM.ꢀM.ꢀBarsan,ꢀM.ꢀ
E.ꢀGhicaꢀandꢀC.ꢀM.ꢀA.ꢀBrett,ꢀAnalyticaꢀChimicaꢀActa,ꢀ2015,ꢀ
8
81,ꢀ1;ꢀ(c)ꢀS.-Y.ꢀKuo,ꢀH.-H.ꢀLi,ꢀP.-J.ꢀWu,ꢀC.-P.ꢀChen,ꢀY.-C.ꢀHuangꢀ
andꢀY.-H.ꢀChan,ꢀAnal.ꢀChem.,ꢀ2015,ꢀ87,ꢀ4765.ꢀ
2
.ꢀ N.ꢀGuptaꢀandꢀH.ꢀLinschitz,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ1997,ꢀ119,ꢀ6384.ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ5ꢀ
Pleaseꢀdoꢀnotꢀadjustꢀmarginsꢀ