Organic amorphous material N,N,N,N′-tetraaryl(Ar12Ar2 2)-1,1′-biphenyl-4,4′-diamine

Article abstract of DOI:10.1002/jccs.200100155

A series of N,N,N,N′-tetraaryl(Ar¹₂Ar² ₂)-1,1′-biphenyl-4,4′-diamine were synthesized by the Pd(0) catalyzed C-N bond formation methodology. The physical properties, including glass transition temperature (Tg), melting point (Mp) and oxidation potential were measured. For Ar¹ = 2-naphthyl and Ar² = 3-toly (4f) and Ar² = 3-ethylphenyl(4h), the DSC charts indicate that they have Tg, but no observable Mp. These two compounds are amorphous in solid state. The X-ray powder diffraction pattern of 4f further confirmed that it is truly amorphous throughout the temperature range in which it is solid. Therefore, we have demonstrated that a low molecular weight organic solid can be amorphous. This is an important aspect in the preparation of morphologically stable amorphous thin film. Other compounds with Ar¹ = Ph, 1-naphthyl while Ar² = 3-toly or 3-ethylphenyl are normal compounds with both Tg and Mp when prepared in their glassy state by rapid cooling of their melt. The oxidation potentials for compounds with Ar¹ = 1-naphthyl and 2-naphthyl and identical Ar² are exactly the same. The molecular structural features must be important factors for an organic solid to be in the amorphous state.

Full text of DOI:10.1002/jccs.200100155

JournaloftheChineseChemicalSociety, 2001, 48, 1059-1064
1059
OrganicAmorphousMaterial
N,N,N,N -tetraaryl(Ar1 Ar2 )-1,1 -biphenyl-4,4 -diamine
2
2
B. C. Maitia, S. Z. Wanga (
D. J. Huangb (
), C. P. Chenga* (
) and C.-I. Chaob (
),
)
aDepartmentofChemistry,NationalTsingHuaUniversity,Hsin-chu,Taiwan300,R.O.C.
bOpticalDevicesDepartment,Opto-Electronics&SystemsLaboratories,
IndustrialTechnologyResearchInstitute,Hsinchu,Taiwan300,R.O.C.
A se ries of N,N,N,N -tetraaryl(Ar1 Ar2 )-1,1 -biphenyl-4,4 -diamineweresynthesizedbythePd(0)cata-
2
2
lyzedC-Nbondformationmethodology.Thephysicalproperties,includingglasstransit iontemperature(Tg),
meltingpoint(Mp)andoxidationpotentialweremeasured.ForAr1 = 2-naphthyl and Ar2 = 3-toly (4f) and Ar2
= 3-ethylphenyl (4h), theDSCchartsindicatethattheyhaveTg, butnoobservableMp. Thesetwocompounds
areamorphousinsolidstate.TheX-raypowderdiffractionpatternof4f furtherconfirmedthatitistrulyamor-
phous through out the tem per a ture range in which it is solid. There fore, we have dem on strated that a low mo-
lecularweightorganicsolidcanbeamorphous. Thisisanimportantaspectinthepreparationofmorphologi-
cally sta ble amor phous thin film. Other com pounds with Ar1 = Ph, 1-naphthyl while Ar2 = 3-toly or 3-
ethylphenyl are nor mal com pounds with both Tg and Mp when pre pared in their glassy state by rapidcooling
oftheirmelt.TheoxidationpotentialsforcompoundswithAr1 = 1-naphthyl and 2-naphthyl and iden ti cal Ar2
areexactlythesame.Themolecularstructuralfeaturesmustbeimportantfactorsforano r ganic solid to be in
the amor phous state.
INTRODUCTION
Organicelectroluminescent(OEL)devicesbasedon
da tion of the OEL de vices was at trib uted to the mor pho log i-
calchangeresultingfromtheinstabilityoftheamorphousor-
ganic lay ers used in the OEL de vices.6 One tac tic to in crease
theglasstransitiontemperatureistoincreasethemolecular
weightoftheholetransportmaterialsbyplasmapolymeriza-
tion, but ef fi ciency of the OLED with this mod i fied hole
transportlayerisdegradedandlifetimeisnotimproved.7 The
other ap proach is to syn the size triarylamine with high MW
which is ex pected to have high Mp and Tg (which is about 2/3
of Mp).8 For ex am ple, a large num ber of oligomeric triaryl-
amines,9 starburst triarylamines,10 and silanamines11 have
been syn the sized. Some of these ma te ri als have high Tg as
ex pected. One ex treme of the high MW ap proach is to use
polymericmaterial.12 This ap proach suf fers from the draw-
back of dif fi cul ties in syn the sis and pu ri fi ca tion. The com-
pletelyamorphousandultra-purethinfilmsappeartoprovide
the long de vice life time, high ef fi ciency and emissive bright-
ness.13 We are cu ri ous about whether it is pos si ble to pre pare
anamorphousorganicsolidbychangingthemolecularshape
throughsimplesubstitution.Itisnoteworthythatthemorpho-
log i cal sta bil ity of amor phous thin film is not the only con-
cern in the life-time of OLED de vice. It has been dem on-
strated by Z. D. Popovic et al.14 that the sta bil ity of the AlQ3
cation radical is a major degradation mechanism in the
multi-layersoflowmolecularweightorganicmaterialshave
at tracted much at ten tion be cause of their great po ten tial for
use in full color flat-panel dis play. The ad van tage of OEL de-
vices over in or ganic ones are their var i ous emis sion col ors,
lowdrivevoltageandhighefficiency.1 These de vices are cur-
rentlyusedinavarietyofopto-electronicdevices, mostnota-
bly as light emit ting di odes.2 In the sim plest bilayer con fig u-
ra tion, an OEL de vice con sists of an elec tron trans port layer
and a hole trans port layer. The most widely used elec tron
trans port ma te rial is AlQ3(Q:8-hydroxyquinolinate) which
has a high glass tran si tion tem per a ture Tg 175 C. N,N -Di-
phenyl-N,N -bis(3-methylphenyl)-1,1 -biphenyl-4,4 -
diamine. (TPD; Tg: 60 C) and 4,4 ,4 -tris[m-tolylphenyl-
amino]-triphenylamine (MTDATA; Tg: 75 C)3,14a have been
used widely in the hole trans port ing layer in OEL de vices due
to their high car rier mo bil ity and amor phous film form ing
propertyandeaseofpurification.4 How ever, both TPD and
MTDATA have lim ited sta bil ity in their amor phous thin film
state be cause of their low glass tran si tion tem per a ture. For
example,themorphologyofvapordepositedTPDfilmchanges
evenatambienttemperature.5 It was re ported that the deg ra-
DedicatedtoProfessorSheng-liehLiuontheoccasionofhisninetiethbirthday.

1060 J. Chin. Chem. Soc., Vol. 48, No. 6A, 2001
Maiti et al.
long-termperformanceoftheOLEDdevice.
outintheprocessofpurificationduringpreparation. There-
fore, 4f is a sta ble amor phous solid.
To fur ther con firm the amor phous prop erty of 4f, vari-
abletemperatureX-raypowderdiffractionpatternsof4e and
4fwere in ves ti gated. From Fig. 2(a), 4e is amor phous at 25
Caspreparedfromitsmelt.Whenthetemperatureincreased
to 80 and 120 C, 4e re mained in the same amor phous state.
At 190 C, 4e trans formed to a crys tal line state. When the
tem per a ture re turned to 25 C, 4e stayed in the crys tal line
state. How ever, 4f is amor phous all the time in the tem per a-
ture range in ves ti gated from 25 C to 200 C back to 25 C.
We have tried to cool down the melt of 4f slowly over a pe riod
of4h;nocrystallinepowderdiffractionpatternwasdetected.
We tried to an neal 4f at 180 C for var i ous time du ra tions
from 2 hr to 10 days. The X-ray dif frac tion pat terns were
iden ti cal to those in Fig. 2(b) re gard less of the an neal ing pe-
riod. Com pound4f may have an ex tremely slow crys tal for-
ma tion rate so that we were un able to in duce it into a crys tal-
line state. There fore, for all prac ti cal pur poses4f can be con-
sideredaspureamorphousmaterial.
RESULTSANDDISCUSSION
A se ries of triarlyamines were syn the sized with the re-
centlyreportedmethodologyofC-Nbondformation.15 The
syn the sis pro ce dure is given in Scheme I. Lith ium diarly-
amide (2) and 4,4 -dibromo-1,1 -biphenyl (3) re acted in the
pres ence of 1.0 mole % of PdL2 (L = P(o-tolyl)3)intolueneto
pro duce triarylamines 4 af ter 3 h at 100 C in good yields.
The start ing diarylamine 1 weresynthesizedbyCuI-catalyzed
Ullmanncondensationreaction16 in good (80-90%) iso lated
yield. To make sure of the na ture of all com pounds, we have
com pletely as signed their1H and 13C NMR spec tra, in ad di-
tiontothehighresolutionmassspectrumandelementalanal-
y sis. By us ing the same meth od ol ogy we also syn the sized
starburst mol e cule MTDATA in an iso lated yield of 93%
which is much better than re ported in the lit er a ture.3a The
yields and phys i cal prop er ties are sum ma rized in Ta ble 1.
Compounds 4a, 4c and 4dareconventionallyabbreviatedas
TPD, 1-NPB and 2-NPB, re spec tively. These are com monly
used as hole-transport ma te ri als in OLED. The yields re-
ported here are better than those in the lit er a ture.
A pos si ble mo lec u lar pic ture in an amor phous com-
pound like 4f is that a small num ber of mol e cules of 4f can
pack tightly to form a pack ing group. Ad di tional mol e cules
can’t be packed as tightly. There fore these ad di tional mol e-
cules pre fer to form an other tight pack ing group and so on. In
other words, only a short or der ex ists in 4f. The at trac tive in-
ter ac tions among these pack ing groups are not con stant and
may vary over some range. The size of each pack ing group is
too small to yield a typ i cal sharp X-ray pow der dif frac tion
pat tern in the solid state. On tem per a ture in crease, the in di-
vid ual mol e cule in each pack ing group may be ex cited to en-
gage in mo tions such as ro ta tional, tor sional and/or small am-
pli tude translational mo tions to re lease strains in the amor-
Scheme I SyntheticprocedureforTriaryamines
Br
Br
Ar
Ar
'
Ar
'
n-BuLi
Ar
3
NH
N
N Li
N
Ar '
Pd(P(o-tolyl)3]2
o
Ar
Ar
Ar'
C
3-4 h
Toluene/100
4
2
1
Usually, solid or ganic com pounds can be pre pared in
the amor phous state by rapid cool ing of their melts. The DSC
chart (Fig. 1) of 4e, which was pre pared in the amor phous
state by the above method, in di cates the pres ence of Tg at
93.4 C and Mp at 215.3 C. The on set of the crys tal line for-
mationtemperatureTcisca160 C. On the other hand, in the
DSC chart of 4f, (Fig. 1) which was also pre pared in the
amor phous state, only Tg was ob served; there was no Mp and
Tc. It in di cates that4f does not have a crys tal line state. The
DSCanalysesof4f were car ried out re peat edly four times by
varyingthetemperaturefrom20to300 C then back to 20 C
at a rate of 5 C/min. The DSC charts were re pro duc ible for
eachrepetition. ThisfurtherindicatesthatevenaboveTg, no
crys tal line phase is formed. In ad di tion, the DSC chart in di-
cates that 4f was in an amor phous state when it pre cip i tated
Fig. 1. DSC charts of com pound 4e and 4f.

AmorphousSolidofLowMolecularWeightDiamine
J. Chin. Chem. Soc., Vol. 48, No. 6A, 2001 1061
Table 1. Products of Pd[P(o-tolyl)3]2 Catalyzed Arylation of Aromatic Secondary Aminesa and Their Mp
and Tg and Redox Potential
d
Entry
Ar
Ar
Productb
Yield/%c
Mp/ C
Tg/ C
Eox
1
2
3
4
5
6
7
8
Phenyl
Phenyl
3-Tolyl
3-Ethylphenyl
Phenyl
Phenyl
3-Tolyl
3-tolyl
3-Ethylphenyl
3-Ethylphenyl
4a8
4b
87
76
93
86
93
85
73
81
167
44
210
265
215
---f
60
---g
98
96
93
86
72
59
0.78
0.80
0.83
0.83
0.81
0.81
0.81
0.81
1-Naphthyl
2-Naphthyl
1-Naphthyl
2-Naphthyl
1-Naphthyl
2-Naphthyl
4c18
4d18
4ee
4f
4g
4h
189
---f
a All reactions were carried out with 1 mole % of catalyst at 100 C for 3-4 h. For the reactions in entries 1-8,
1 equivalent of arylbromide and 3 equivalent of lithiumamide was used.
b All isolated products characterized by 1H and 13C-NMR spectroscopy, elemental analysis and HR-MS. New
compounds were further characterized by 2D spectrum.
c Isolated Yield.
d First reversible oxidation potentials are reported.
e Thayamanavan, S.; Barlow, S.; Marder, S. R. Chem. Mater. 1997, 9, 3231.
f Glass transition temperature was observed but no melting point observed.
g Melting point was observed but no glass transition was detected above 20 C.
Fig. 2. X-ray pow der dif frac tion pat terns of com pound 4e (a) and com pound 4f (b),atvarioustemperatures.

1062 J. Chin. Chem. Soc., Vol. 48, No. 6A, 2001
Maiti et al.
phousstate.Thesemolecularmotionsareresponsibleforthe
pres ence of Tg. Fur ther in crease in tem per a ture leads to the
mo tion of in di vid ual pack ing groups while each pack ing
group remained more or less unchanged. Only the non-
definiteinteractionsamongthepackinggroupsarethermally
ex cited lead ing to soft en ing and melt ing of the solid. Hence
no Mp was ob served.
wtmaterialscanoffertheadvantageofeaseinsynthesis,ease
in pro cess ing into de vices and mor pho log i cal sta bil ity in
thin-filmdevices.
EXPERIMENTAL SECTION
Since the MW of4f and4e is ex actly the same, the find-
ing that 4f is amor phous all the time is un ex pected. The DSC
chart showed that 4h is also amor phous over a wide tem per a-
ture range. How ever, the cor re spond ing 1-naphthyl com-
pound 4gbe haves in the nor mal fash ion with both Tg and Mp.
Comparing4f or 4h with 4d, it is ob vi ous that a pair of in ert
3-methy or 3-ethyl sub stitu ents on the phenyl groups are suf-
fi cient to in flu ence the mo lec u lar pack ing in the solid state
from crys tal line to amor phous. On the other hand, from a se-
ries of three com pounds 4a, 4e and 4f (or 4b, 4g and 4h), it
appearsthatonly2-naphthylgroupsareeffectiveininducing
the amor phous prop erty. It dem on strated that high MW is not
aprerequisiteforanorganicmaterialtobeamorphous17 over
awidetemperaturerange.
There are some re lated triarylamine com pounds be ing
re ported to have Tg and which do not have ob serv able Mp.
Forexample, 1,3,5-tris(2 -antrhacenyl-4 -methoxyphenyl-
amino)benzene,18 has a Tg at 123 C; 2,2-bis(4 -[5 -{4 -
(diphenylamino)phenyl}-1,3,4-oxadiazol-2-yl]-phenyl)hexa-
fluoropropane19 has a Tg at 133.6 C; no Mp was de tected for
these two com pounds. Thomp son et al.20 alsoreportedatotal
ofthirteenasymmetricaltriaryldiamineswithTgandnoMp.
Thereforethephenomenaofcompoundswithglasstransition
points and with out melt ing points may be quite com mon.
Thesecompoundsmaybeamorphoussimilarto4f and 4h. A
better un der stand ing of the amor phous prop erty of sol ids is
called for.
1H and 13C NMR spec tra were re corded on Bruker AC
300, Bruker AC 400 and Bruker AC 600 MHz in stru ments.
Chem i cal shifts are re ported in parts per mil lions (ppm). UV
spectra were measured using a Perkin Elmer Lambda 5
UV/VIS spectrophotometer. El e men tal anal y ses were per-
formed on a Heraeus CHN-O Rapid An a lyzer. High res o lu-
tion mass spec tra were re corded on a JEOL SX-102A spec-
trometer. The glass transition temperatures and melting
points were mea sured us ing a Seiko DSC 5000 dif fer en tial
scan ning cal o rim e ter (DSC). The sam ples were heated at a
rate of 5 C per min ute. The re ported melt ing point (Mp) is
the ini tial tem per a ture of the ob served melt ing tran si tion
peak. Pow der X-ray dif frac tion pat terns were col lected on a
Scintag GEN-4000 diffractometer equipped with a vari able
temperatureaccessory. Cyclicvoltammetry(CV)measure-
ments were car ried out at a plat i num elec trode us ing 0.025
mMsolutionsindrydegassedacetonitrilecontaining25mM
tetrabutylammonium hexafluorophosphate as a sup port ing
elec trode in a three elec trode cell. Ferrocene was used as an
internalreferenceforcalibration.21 It was ob served that, the
mea sured ox i da tion po ten tials var ied in the range of 10-50
V from those mea sured in the ab sence of ferrocene. There-
fore we ex cluded ferrocene from all mea sure ments. Each
diaminecompoundexhibitstwosequentialreversibleoxida-
tion pro cesses. The po ten tials rel a tive to the Ag/AgCl ref er-
ence20 forthefirstoxidationprocessesarelistedinTable1.
It is note wor thy that the first re vers ible ox i da tion po-
ten tials (Ta ble 1) in di cate that the same po ten tials are de-
tected for the pair of com pounds in which 1-naphthyl groups
are re placed by 2-naphthyl groups while the other parts are
kept the same (4c and 4d, 4e and 4f, 4g and 4h). This is con-
sis tent with our ex pec ta tion that re plac ing 1-naphthyl group
by 2-naphthyl group in duces only mi nor elec tronic struc ture
modification. Webelievethattheamorphouspropertyof 4f
and 4h in con trast to4e and 4gmustinvolvedelicatemolecu-
larstructuralfeatures.
Inconclusion, wehaveshownthatbysimplyreplacing
the phenyl group in 2-NPB by a 3-tolyl group or 3-ethyl-
phenyl, amor phous sol ids can be ob tained. It dem on strates
thatmoleculeswithlowmolecularwt,suchas 4f and 4h, can
ex ist as amor phous sol ids all the time. These low mo lec u lar
General Synthetic Procedure
Atroomtemperatureundernitrogenatmosphere,4,4 -
dibromo-1,1 -biphenyl, 3, (1 mmol) was added to a so lu tion
of Pd[P(o-tolyl)3]2 (PdL2, 1 mole % rel a tive to the aryl bro-
mide) in 40-50 mL to lu ene which was dis tilled over a Na/
Ph2CO ketyl in di ca tor just be fore use. The re sul tant mix ture
was stirred at that temperature for 10-15 minutes. Then
lithiumamide, 2, (3 mmol), pre pared from n-BuLi and the
correspondingdiarylamine, 1, which was syn the sized by the
standardUllmanncondensation,16 wasaddedundernitrogen
at mo sphere and heated at 100 C for 3-4 hours. When the
startingmaterialshaddisappearedasjudgedbyTLC, thesol-
vent was re moved in a ro tary evap o ra tor and the com pound
wasfilteredthroughasilicagelcolumnbyusingchloroform
as eluent. Af ter re mov ing chlo ro form, the res i due was dis-

Amor phous Solid of Low Molecular Weight Diamine
J. Chin. Chem. Soc., Vol. 48, No. 6A, 2001 1063
solvedintetrahydrofuranandtheproductwasprecipitatedby
theadditionofethanol.Theisolatedyieldsaswellasspectro-
scopic data for all new com pounds in Ta ble 1 are re ported be-
low. For the known com pounds, iso lated yields are col lected
in Ta ble 1, and all spec tro scopic data are con sis tent with
thosereportedinliterature.
4.34; found: C, 88.94; H, 6.34; N, 4.71. HRMS cal cu lated
644.3191; found 644.3186.
Data for N,N -bis(2-naphthyl)-N,N -bis(3-ethylphenyl)-
1,1 -biphenyl-4,4 -diamine (4h)
Light yellow solid, isolated yield 81%. 1H-NMR
(CDCl3, 300 MHz) 1.21 (t,J = 7.63 Hz, 3H); 2.88 (q,J = 7.57
Hz, 2H); 6.93 (d, J = 7.5 Hz, 1H); 6.99 (d, J = 7.89 Hz, 1H);
7.05 (s, 1H); 7.20 (m, 3H); 7.38 (m, 3H); 7.49 (m, 2H); 7.61
(d, J = 7.82 Hz, 1H); 7.75 (m, 2H). 13C-NMR (100 MHz,
CDCl3) 15.54, 28.77, 120.19, 121.99, 122.76, 124.12,
124.23, 124.40, 124.47, 126.22, 126.89, 127,26, 127.52,
128.80, 129.16, 129.98, 134.42, 134.72, 145.43, 145.59,
146.78, 147.57. UV/VIS max (log ) 351 (4.55) 322 (4.534)
Data for N,N -bis(2-naphthyl)-N,N -bis(3-methylphenyl)-
1,1 -biphenyl-4,4 -diamine (4b)
Light yel low solid prod uct, iso lated yield 85%. 1H-
NMR (600 MHz, CDCl3): 2.27 (s, 3H), 6.88 (d, J = 8.0 Hz,
1H), 6.98 (m, 2H), 7.17 (m, 3H), 7.35 (m, 3H), 7.45 (m, 3H),
7.59 (d, J = 7.6 Hz, 1H), 7.75 (d, J = 7.6 Hz, 1H). 13C-NMR
(150 MHz): 21.41 (CH3), 120.30, 121.84, 124.07, 124.26,
124.44, 124.49, 125.29, 126.24, 126.93, 127.30, 127.55,
128.84, 129.13, 130.04, 134.46, 134.80, 139.21, 145.47,
275 (4.45). Emis sion Spec trum
(CHCl3): 444.5 nm. El e-
max
mentalanalysiscalculatedforC48H40N2: C, 89.40; H, 6.25;
N, 4.34; found: C, 89.2; H, 6.19; N, 4.61. HRMS cal cu lated
644.3191; found 644.3184.
146.81, 147.62. UV/VIS (CHCl3)
(log ): 356 (4.56),
max
329(4.57), 285(4.47). EmissionSpectrum max (CHCl3): 452
nm.ElementalanalysiscalculatedforC46H36N2: C, 89.58; H,
5.88; N, 4.54; found: C, 89.35; H, 5.96; N, 4.86; HRMS cal-
cu lated. 616.2878; found 616.2875.
ACKNOWLEDGMENT
Data for N,N -diphenyl-N,N -bis(3-ethylphenyl)-1,1 -
biphenyl-4,4 -diamine (4f)
We thank the Na tional Sci ence Coun cil of Tai wan for
fi nan cial sup port (NSC 88-2113-M-007-038 and 89-2113-
M-007-027)andtheInstituteofIndustrialResearch.
Light yel low solid, iso lated yield 76%. 1H-NMR (300
MHz, CDCl3) 1.18 (t, J = 7.56 Hz, 3H); 2.56 (q, 7.56, 2H);
6.88 (d, J = 7.46 Hz, 1H); 6.93 (dd,J1 = 8.08 Hz,J2 = 1.97 Hz,
1H); 7.00 (m, 2H); 7.19 (m, 7H); 7.45 (d, J = 8.44 Hz, 2H).
13C-NMR (75 MHz, CDCl3) 15.39, 28.82, 121.96, 122.66,
124.09, 124.27, 127.24, 129.18, 134.75, 145.59, 146.99,
Received January 15, 2001.
Key Words
147.82, 148.00. UV/VIS (CHCl3)
329 (3.53). Emis sion Spec trum
(log ): 352 (3.47),
Amorphous materials; Triarylamine; Lumines-
cence; Phase transitions.
max
(CHCl3) 438 nm. El e-
max
mentalanalysiscalculatedforC40H36N2: C, 88.19; H, 6.66;
N, 5.14; found: C, 87.82; H, 6.79; N, 5.42. HRMS cal cu lated
544.2878; found 544.2872.
REFERENCES
Data for N,N -bis(1-naphthyl)-N,N -bis-(3-ethylphenyl)-
1,1 -biphenyl-4,4 -diamine (4g)
1. (a) Van slyke, S. A.; Tang, C. W. US pat ent 4,539,507,
1985. (b) Tang, C. W.; Van slyke, S. A. Appl. Phys. Lett.
1987, 51, 913. (c) Adachi, C.; Tsutui, T.; Saito, S. Appl.
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Van Slyke, S. A.; Chen, C. H.; Tang, C. W. Appl. Phys.
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(g) Chen, C. H.; Shi, J.; Tang, C. W. Macromol. Sym.
1998, 125, 1.
Light yel low solid, iso lated yield 73%. 1H-NMR (300
MHz, CDCl3) 1.15 (t, J = 7.58 Hz, 3H); 2.52 (d, J = 7.54 Hz,
2H); 6.81 (d,J = 7.49 Hz, 1H); 6.85 (d,J = 7.99 Hz, 1H); 7.02
(d, J = 8.54 Hz, 2H); 7.11 (dd,J1 = 7.84 Hz, J2 = 7.73 Hz, 1H);
7.42 (m, 6H); 7.76 (d,J = 8.11, 1H); 7.88 (d,J = 8.07 Hz, 1H);
7.96 (d, J = 8.33 Hz, 2H). 13C-NMR (75 MHz, CDCl3) 15.35,
28.85, 119.80, 121.58, 121.93, 124.48, 126.06, 126.30,
127.03, 128.35, 129.00, 131.48, 135.42, 143.82, 145.39,
147.60, 148.55. UV/VIS (CHCl3) max (log ) 345 (3.55), 272
(3.36). EmissionSpectrum max (CHCl3):474.5nm. Elemen-
tal anal y sis cal cu lated for C48H40N2: C, 89.40; H, 6.25; N,
2. (a) Kido, J.; Kimura, M.; Nagai, K. Science 1995, 267,
1132. (b) Kido, J. BulletinofElectrochemistry. 1994, 10,
1.

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