Synthesis, characterization, and optical properties of 2-amino-4-aryl-6-(9, 9′-spirobifluoren-2-yl)pyrimidines

Article abstract of DOI:10.1007/s00706-011-0507-5

A series of 2-amino-4-aryl-6-(9,9′-spirobifluoren-2-yl)pyrimidines have been synthesized by the reaction of guanidine and chalcones under basic conditions. The physical and optical properties indicated that these compounds generally show good blue light e

Full text of DOI:10.1007/s00706-011-0507-5

Monatsh Chem (2011) 142:907–916
DOI 10.1007/s00706-011-0507-5
ORIGINAL PAPER
Synthesis, characterization, and optical properties
of 2-amino-4-aryl-6-(9,90-spirobifluoren-2-yl)pyrimidines
•
Yingbo Shi Qiancai Liu Jie Tang
•
Received: 23 November 2010 / Accepted: 14 April 2011 / Published online: 19 May 2011
Ó Springer-Verlag 2011
Abstract A series of 2-amino-4-aryl-6-(9,90-spirobifluo-
ren-2-yl)pyrimidines have been synthesized by the reaction
of guanidine and chalcones under basic conditions. The
physical and optical properties indicated that these com-
pounds generally show good blue light emissions and
excellent thermal stabilities. Intermolecular hydrogen
bonds and interactions have strong influences on their
properties.
dispirobifluorenes, and pyrene-substituted spirobifluorenes
[7–12]. Pyrimidine derivatives combined with a spirobi-
fluorene subunit could be useful in such materials as a
result of their high electron affinity and lack of ortho–ortho
C–H interactions. For example, good efficiency, stability,
and excellent solubility of 2,7-bis[2-(4-t-butylphenyl)pyr-
imidin-5-yl]-9,90-spirobifluorene (TBPSF) render it a pure
blue light emitter [13]. On the other hand, the 2-amino
group and nitrogen on the pyrimidine ring could be used as
probes for the recognition of different species on the basis
of host–guest interactions such as hydrogen bonding and
van der Waals interactions with other functional groups.
Aminopyrimidine derivatives have been used in supramo-
lecular assembly [14], as fluorescent probes [15, 16], and in
studying in vitro antibacterial activity [17–20].
Keywords Synthesis ꢀ Pyrimidine ꢀ Spirobifluorene ꢀ
Fluorescence
Introduction
Organic p-conjugated oligo- and poly(aryl/heteroaryl)
systems have attracted numerous attention due to their
potential utilization as components of organic light-emit-
ting devices (OLEDs) for flat displays and lightening [1].
In organic electroluminescent materials, non-planar struc-
tures of precursors can effectively prevent the formation of
crystals [2] and increase molecular amorphism.
We envisioned that novel compounds with unique
properties should be accessible by combining spirobifluo-
rene with various pyrimidine subunits. It is worthwhile to
develop a strategy for the preparation of novel and versatile
functionalized pyrimidine-based oligo(arylenes) by well-
defined synthetic routes. This prompted us to explore these
types of new compounds which could be potentially used
as precursors for organic light-emitting diodes (OLEDs)
[13]. The spirobifluorene motif was chosen because of its
high stability and good luminescence efficiency as descri-
bed above; other aryl groups such as phenyl, thienyl, and
naphthyl were used to investigate the influence of substit-
uents on the motif’s fluorescence properties. Furthermore,
the whole system might be further used as a fluorescent
sensor for biologically active compounds such as peptides,
nucleic acids, and proteins by introducing suitable sub-
stituents on the pyrimidine skeleton. In this paper, we
report the synthesis, characterization, and optical properties
of 2-amino-4-aryl-6-(9,90-spirobifluoren-2-yl)pyrimidines
6a–6e (Scheme 1).
Materials with spirobifluorene moieties have been
considered promising candidates for blue-light-emitting
materials in both small-molecule- and polymer-based
devices [3–5]. Tour et al. reported spirobifluorene deriva-
tives as electroluminescent materials in 1996 [6]; subseq-
uently numerous research results have been reported
about blue-light-emitting materials comprising spirobiflu-
orene derivatives, such as anthracene-spirobifluorenes,
Y. Shi ꢀ Q. Liu (&) ꢀ J. Tang
Department of Chemistry, East China Normal University,
Shanghai 200062, China
e-mail: qcliu@chem.ecnu.edu.cn
123

908
Y. Shi et al.
OCH3
S
Scheme 1
NH2
N
6a
6b
, Ar=
, Ar=
6d
6e
, Ar=
, Ar=
N
Ar
6c, Ar=
Cl
6a-6e
Results and discussion
conducted by refluxing for 24 h to afford 6a–6e. The
products generally show high decomposition temperatures
or melting points which depend strongly on the substituents
present; the melting point of 6b is the lowest, whereas that
of 6e is the highest (Table 2).
Synthesis
Generally 2-amino-4,6-diarylpyrimidines could be synthe-
sized from either chalcones, 1,3-dicarbonyl compounds, or
b-alkynone condensation with guanidine salt under reflux
or microwave-assisted conditions [21–28]. They can also
be synthesized by palladium-catalyzed cross-coupling
reaction of 4,6-dihalogenated pyrimidines and arylboronic
acids [29, 30]. However, the syntheses from 1,3-dicarbonyl
compounds and b-alkynones such as ArC:CCOAr0 are
evidently more difficult and complex than those from
chalcones. The synthetic routes for compounds 6a–6e are
illustrated in Scheme 2 and used the reaction of chalcones
and aldehydes, which is transition metal catalyst free.
Compounds 6a–6e were synthesized starting with 9,90-
spirobifluorene (3), which was obtained by the reaction of
the Grignard reagent of 2-bromobiphenyl (1) with 9-flu-
orenone initially to form tertiary alcohol 2, followed by the
ring closure in HOAc with acid as catalyst [31]. The aldol
condensation of 2-acetyl-9,90-spirobifluorene (4), formed
by Friedel–Crafts acylation of 3 [32, 33], with aromatic
aldehydes under basic conditions afforded chalcones 5a–5e
in excellent isolated yields (80–90%). The ring closure of
chalcones and guanidine nitrate in the presence of base was
The structures of the compounds described above were
assigned by NMR spectroscopy, mass spectrometry, and
elemental analyses. In addition, the structures of 6a, 6b,
and 6e were further confirmed by X-ray diffraction
(Fig. 1).
Single-crystal X-ray determination
As a result of the good solubilities of 6a, 6b, and 6e in
organic solvents, crystals that were of sufficient quality for
X-ray structure determination were obtained from CH2Cl2/
EtOH. Single-crystal X-ray analyses of 6a, 6b, and 6e
confirmed the substitution patterns in accordance with their
NMR spectra. The results are shown in Fig. 1 and Tables 1
and 2.
It is quite interesting that strong hydrogen bonds
between the 2-aminopyrimidine skeleton and aromatic
pendants on the pyrimidine ring, p–p interactions, and
C–Hꢀꢀꢀp effects in 6a, 6b, and 6e were found, which might
have a strong impact on the conjugate planes (Fig. 1,
Table 1). In the case of 6e, there are four hydrogen bonds
Mg/Et2O,
9-Florenone,
Reflux,
O
HCl/HOAc,
Reflux
CH3COCl
NH4Cl(aq)
OH
AlCl3,CS2
Br
1
4
3
2
O
5a,6a,Ar=
5b,6b,Ar=
5c,6c,Ar=
OCH3
5d,6d,Ar=
5e,6e,Ar=
NH
NaOH,ArCHO, THF
and EtOH(1:1),
25°C for 12h.
. HNO3
NH2
H2N
Ar
S
6a-e
NaOH,THF,Reflux,
24h
Cl
5a-e
Scheme 2
123

Properties of 2-amino-4-aryl-6-(9,90-spirobifluoren-2-yl)
909
Fig. 1 Crystal structures, hydrogen bonds, p–p interactions, and C–Hꢀꢀꢀp effect of 6a, 6b, and 6e
larger steric hindrance which might be responsible for the
lowest yield.
Table 1 Hydrogen bonds and dihedral angles between the aryl and
pyrimidine rings of 6a, 6b, and 6e
The intermolecular hydrogen bonds, p–p interactions,
and C–Hꢀꢀꢀp effects found in this kind of compound could
be considered as sites for selective recognition of different
species towards supramolecular assembly and fluorescent
probe studies [7, 8].
Hydrogen bond data
(length and angle)
Dihedral angle
(°) between
the aryl and
pyrimidine ring
˚
6a
6b
6e
N1A–H1BAꢀꢀꢀN2, 2.15 A, 165.71°
38.62
58.96
17.08
˚
N3A–H3CAꢀꢀꢀN1, 2.18 A, 167.35°
UV–vis and fluorescence spectra
˚
N3A–H3BAꢀꢀꢀN1, 2.44 A, 158.84°
˚
N3A–H3CAꢀꢀꢀS1, 2.97 A, 102.17°
The UV–vis spectra of compounds 6a–6e are shown in
Fig. 2. These spectra exhibited similar absorption peaks at
280–360 nm as a result of the compounds’ structural
similarities. The absorptions from p ? p* transitions for
6a–6d in CH2Cl2 (DCM) are centered at 344–345 nm,
between the two molecules, which could explain why the
melting point of 6e is the highest. Comparing the dihedral
angles between the aryl and pyrimidine rings, 6b has a
123

910
Y. Shi et al.
Table 2 Crystal data for compounds 6a, 6b, and 6e
6a
6b
6e
Empirical formula
Molecular weight
Description
C35H23N3ꢀCH2Cl2
568.47
C39H25N3ꢀCH2Cl2
618.53
C33H21N3S
491.59
Colorless diamond
0.47 9 0.29 9 0.27
173(2)
Colorless diamond
0.874 9 0.507 9 0.314
296(2)
Colorless diamond
0.264 9 0.127 9 0.091
296(2)
Size (mm3)
Temperature (K)
Crystal system
Space group
Monoclinic
P-1
Monoclinic
P2(1)/n
Monoclinic
C2/C
˚
a (A)
9.3186(4)
8.9752(3)
23.2902(3)
11.8235(2)
17.7942(2)
90
˚
b (A)
12.4707(5)
13.2568(4)
106.758
32.4381(12)
11.3700(4)
90
˚
c (A)
a (°)
b (°)
c (°)
93.777
103.38
100.20
102.681
90
90
3
˚
V (A )
1425.33(9)
2
3141.43(19)
4
4822.59(12)
8
Z
Calculated density (mg m-3
)
1.325
1.308
1.354
Scan mode
u- and x-scans
588
u- and x-scans
1,280
u- and x-scans
2,048
F(000)
Absorption coefficient (mm-1
)
0.259
0.241
0.163
h range (°)
Index ranges
1.62–25.01
-11 B h B 11
-14 B k B 14
-15 B l B 15
16,654
1.99–25.00
-10 B h B 10
-38 B k B 36
-13 B l B 13
35,929
1.78–25.01
-27 B h B 27
-14 B k B 14
-21 B l B 21
37,598
Reflections collected
Independent reflections
Data/restraints/parameters
GOF on F2 (all)
4,993 [R(int) = 0.0237]
4,993/0/397
1.050
5,534 [R(int) = 0.0213]
5,534/0/416
1.030
4,260 [R(int) = 0.0509]
4,260/0/334
1.021
Final R (I [ 2r(I))
R indices (all data)
R1 = 0.0622, wR2 = 0.1752
R1 = 0.0751, wR2 = 0.1887
0.9335 and 0.8881
0.837
R1 = 0.0604, wR2 = 0.1641
R1 = 0.0663, wR2 = 0.1716
1 and 0.884977
0.533
R1 = 0.0424, wR2 = 0.1004
R1 = 0.0690, wR2 = 0.1178
1 and 0.873919
0.198
Transmission (ratio of max to min)
-3
˚
Largest diff. peak (e A
)
-3
˚
Largest diff. hole (e A
)
-0.510
-0.825
-0.309
GOF goodness of fit
whereas that of 6e is centered at 358 nm, i.e., with a 10-nm
red shift relative to those of 6a–6d (Table 3).
rotation of naphthyl and thienyl groups and reduce the non-
radiative transition between the molecules, thus improving
the quantum yields.
Their solution fluorescence spectra indicate that the
emissions of compounds 6a–6e (Fig. 3) are smooth and
pure blue emissions could be obtained with peaks at
399–406 nm (Table 3). The emission wavelength of 6a
was the smallest (399 nm), whereas that of 6e was the
largest (406 nm). The differences of quantum yields among
compounds 6a–6e were studied with 9,10-diphenylanthra-
cene as reference. The results indicated that 6b and 6e
show good quantum yields (C60%), whereas that of 6a was
the lowest (37%, Table 3). This might be explained by the
steric hindrance of the naphthyl ring of 6b and four
hydrogen bond systems of 6e, which could prevent the free
The solid emissions of 6a–6e (Fig. 4) peaked at
418–442 nm with a red shift of ca. 10–36 nm relative to
their solution emissions. This behavior might be due to the
effects of hydrogen bonds, p–p interactions, and C–Hꢀꢀꢀp
effects formed in the solid state.
Thermostabilities of compounds 6a, 6b, and 6e
The thermal properties of 6a, 6b, and 6e were investigated
by thermal gravimetric analysis (TGA) and differential
scanning calorimetry (DSC). Compounds 6a, 6b, and 6e
123

Properties of 2-amino-4-aryl-6-(9,90-spirobifluoren-2-yl)
911
6a
6b
6c
6d
6e
6a
6b
6c
6d
6e
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
-0.1
1.0
0.8
0.6
0.4
0.2
0.0
350
400
450
500
λ / nm
240 260 280 300 320 340 360 380 400 420
/ nm
Fig. 3 Solution fluorescence emission spectra of 6a–6e
(1 9 10-6 M, DCM)
Fig. 2 UV–vis absorption spectra of 6a–6e (1 9 10-6 M, DCM)
exhibited excellent thermal stabilities. The decomposition
temperatures (Td) with 5% weight loss under a N2 atmo-
sphere of 6a, 6b, and 6e are quite high (382 °C for 6a,
383 °C for 6b, 381 °C for 6e). The DSC curves of 6a, 6b,
and 6e showed obviously crystalline melting temperatures
ranging from 180 °C (6b) to 307 °C (6e).
single-electron reduction occurs at -1.43, -1.46, and
-1.44 eV; therefore the HOMO/LUMO energy levels from
CV were estimated as -5.93, -5.87, and -5.79, and
-2.54, -2.51, and -2.53 eV, respectively. Calculation
results show that the HOMO/LUMO energy levels of 6a,
6b, and 6e from density functional theory (DFT) calcula-
tions were estimated as -5.63, -5.62, and -5.63, and
-1.57, -1.59, and -1.66 eV, respectively (Table 4). The
large variations between the experimental and calculated
LUMO data might be due to the different calculation
methods and conditions. The LUMO data from the CV
were calculated from experiential equation and the DFT
calculation was based on Koopmans’ theorem which
ignores the electron gain and loss effect of other electrons.
On the other hand, the HOMO/LUMO energies of 6a, 6b,
and 6e were close to that of tris(8-hydroxyquinoline)alu-
minum(III) (Alq3; -5.62/-2.85 eV) [34]. Thus the
differences of orbital energy among these compounds from
HOMO/LUMO and electrochemistry studies
Cyclic voltammetry (CV) and calculations by Gaussian 03
at B3LYP/6-31G* level are both useful tools for studying
the front orbital energies. Cyclic voltammetry data indi-
cated that 6a, 6b, and 6e have good electrochemical
stabilities in the reduction area, but no reversible process
was observed in the oxidation which might be due to the
amino groups on the pyrimidine rings (Fig. 5).
The oxidation process for 6a, 6b, and 6e occurs at 1.96,
1.90, and 1.82 eV, respectively, whereas the reversible
Table 3 Optical data and thermoanalysis data of 6a–6e
kabs (max) (nm)a
kem,solution (nm)a
kem, solid (nm)b
U (%)c
Tm (°C)d
Td (°C)e
6a
6b
6c
6d
6e
a
344
343
345
345
358
399
404
401
400
406
418
443
416
428
442
37
60
45
43
63
256
180
291
230
307
382
383
–
–
381
In dichloromethane (1.0 9 10-6 M)
b
c
The solid emission spectrum was measured with solid powder
The relative quantum yield U was measured using standard procedures with reference to 9,10-diphenylanthracene (1.0 9 10-6 M in cyclo-
hexane, U = 90%)
d
6a, 6b, and 6e data obtained from differential scanning calorimetry (DSC); 6c and 6d data obtained from a micrographic measuring apparatus
e
Decomposition temperature Td is defined as the temperature at which 5% loss occurs during heating
123

912
Y. Shi et al.
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
-0.1
Conclusion
6a
6b
6c
6d
6e
We have successfully synthesized a series of 2-amino-4-
aryl-6-(9,90-spirobifluoren-2-yl)pyrimidines. Their optical
properties indicated that some of them might be used as
precursors for novel blue-light-emitting materials (with
quantum yields ranging from 37 to 63%). The intermo-
lecular interactions, hydrogen bonds, and C–Hꢀꢀꢀp effects
found in these molecules might be considered as versatile
tools for molecular recognition and luminescent probes.
Further studies are underway to establish the potential
utilization of the title compounds in the fields of OLED
devices and molecular recognition.
350
400
450
500
550
600
/ nm
Experimental
Fig. 4 Solid fluorescence emission spectra of 6a–6e
9,90-Spirobi[9H-fluorene] (3) was prepared according to
[31]. Commercially available reagents, solvents, and other
materials were used without further purification other than
stated below. THF was distilled from Na/benzophenone
prior to use. Petroleum ether refers to the fraction with b.p.
60–90 °C. All operations were performed by standard
Schlenk techniques unless otherwise stated. TLC was car-
ried out by using silica gel 60 GF 254 and visualized under
UV light (254 and 365 nm). Melting points were measured
HOMO/LUMO data lead to good feasibilities as electron
transport materials. The similar electrochemical band gaps
of compounds 6a, 6b, and 6e range from 3.26 to 3.38 eV
(366–379 nm), which are in accordance with their UV–vis
spectra. Both the electrochemical band gaps and theoretical
calculation values (4.23–4.56 eV) are also close to the
energy band gaps of other blue-emitting materials [35].
Visual frontier molecular orbitals of 6a, 6b, and 6e were
also established (Fig. 6).
1
on an X-4 micrographic measuring apparatus. H and 13C
NMR spectra were measured on a Bruker DRX 500
Fig. 5 Cyclic voltammograms
of 6a, 6b, and 6e. Anodic
10.0
6e
10.0
7.5
6b
6a
7.5
5.0
2.5
0.0
-2.5
7.5
5.0
oxidation of a 2 9 10-3
M
5.0
-1.38V
-1.29V
solution in CH2Cl2 ? 0.1 M
Bu4NPF6, 100 mV/s; cathode
2.5
2.5
-1.42V
0.0
0.0
reduction of a 2 9 10-3
M
-2.5
-5.0
-7.5
-2.5
-5.0
-7.5
solution in tetrahydrofuran
(THF) ? 0.1 M Bu4NPF6,
100 mV/s
-1.82v
-1.79V
-1
-1.68V
-2
-1
1
2
3
-2
1
2
3
-2
-1
1
2
3
E / V vs AgI/Ag
E / V vs AgI/Ag
E / V vs AgI/Ag
Table 4 Electrochemical properties and HOMO/LUMO levels of 6a, 6b, and 6e
Electrochemical data
Calculation data
HOMOcal (eV)f
EOx (V)a
ERed (V)b
HOMO (eV)c
LUMO (eV)d
DEel (eV, nm)e
LUMOcal (eV)f
DEcal (eV)f
6a
6b
6e
a
1.96
1.90
1.82
-1.43
-1.46
-1.44
-5.93
-5.87
-5.79
-2.54
-2.51
-2.53
3.38, 366
3.36, 368
3.26, 380
-5.63
-5.62
-5.63
-1.57
-1.59
-1.66
4.06
4.03
3.97
In CH2Cl2
b
c
d
e
f
In THF
From the onset oxidation potential
From the reduction potential
DEel = |HOMO - LUMO|; k = hm/DEel (eV) = 1,237.5/DEel (nm) from redox data
Using Gaussian 03 B3LYP/6-31G* calculation on models of the CIF documents; DEcal = |HOMO - LUMO|
123

Properties of 2-amino-4-aryl-6-(9,90-spirobifluoren-2-yl)
913
All electrochemical experiments were performed using a
Pt disk electrode (diameter 1 mm), the counter electrode
was a vitreous carbon electrode (diameter 3 mm), and the
reference electrode was AgI/Ag. The redox cyclic vol-
tammograms were measured with a electrochemical
workstation (CH Instruments CHI-840C); the scan rate was
100 mV/s. All solvents were dried. The experiments were
preceded by flushing with dry nitrogen gas for 5 min to
remove oxygen in the system. With n-Bu4NPF6 (0.1 M) as
supporting electrolyte, the oxidation processes were mea-
sured in CH2Cl2 and reduction processes were measured in
THF. All samples were prepared as 2 9 10-3 M solutions.
The ferrocene/ferrocenium (Fc?/Fc) couple served as
internal standard and all reported potentials are referenced
to its reversible formal potential.
The HOMO and LUMO can be calculated according to
the following equations [38]:
HOMO ¼ ½ꢂðEOx ꢂ WÞ ꢂ 4:8ꢃeV
LUMO ¼ ½ꢂðERed ꢂ WÞ ꢂ 4:8ꢃeV
DEel ¼ jHOMO ꢂ LUMOj
Fig. 6 Visual frontier molecular orbitals of compounds 6a, 6b,
and 6e
where W is the onset potential of ferrocene (Fc?/Fc) versus
AgI/Ag and equals 0.6761 V; EOx is the onset potential of
the oxidation process; ERed is the onset potential of the
reduction process; 4.8 is the vacuum energy level of
ferrocene.
spectrometer (1H NMR 500 MHz, 13C NMR 125 MHz).
Elemental analyses were measured on a Vario EL element
analysis instrument. Mass spectra were recorded on an
Angilent 5973 N mass spectrometer.
Density functional theory (DFT) calculations were per-
formed with the hybrid Becke-3 parameter exchange
functional and the Lee–Yang–Parr nonlocal correlation
functional (B3LYP) [39–42] implemented in Gaussian 03
(Revision B.01) using the 6-31G* basis set.
The crystal data were collected by a Bruker SMART
˚
CCD area detector with Mo Ka radiation (k = 0.71073 A).
The structure solution and refinement was completed by
Bruker SHELXTL [43]. The structures were solved by
direct methods and refined by full-matrix least-squares on
F2 values of all data.
Thermogravimetric analyses (TGA) were performed
with a Thermal analyzer Mettler Toledo TGA851e/SF/
1100 under a nitrogen atmosphere. TGA measurements
were carried out between 20 and 800 °C with a heating rate
of 10 °C/min. The differential scanning calorimetry (DSC)
data were collected from the heat process analysis.
UV–vis spectra were recorded using a Carey-100 UV–
vis spectrophotometer. Photoluminescence spectra were
recorded at room temperature with an HITACHI F-4500
spectrofluorimeter using a xenon lamp. Quantum yields
(Usol) were calculated relative to 9,10-diphenylanthracene
(1 9 10-6 M in cyclohexane, Usol = 90%) by standard
procedures. Usol was determined according to the following
equation [36, 37]:
1-(9,90-Spirobi[9H-fluoren]-2-yl)ethanone (4)
To a two-necked round-bottom flask was added 6.2 g
anhydrous AlCl3, 2.17 g spirobifluorene 3 (6.9 mmol), and
30 cm3 CS2. Then a solution of 0.56 g acetyl chloride
(7.1 mmol) in 10 cm3 CS2 was added dropwise with
stirring within 10 min. The reaction mixture was heated at
reflux for 2 h and then cooled to room temperature,
followed by pouring into in a mixture of 100 cm3 ice-cold
water and 50 cm3 2 N HCl. The mixture was extracted
with dichloromethane (3 9 20 cm3). The combined
organic phase was dried over Na2SO4 and the solvent
was evaporated. The residue was purified by column
chromatography with dichloromethane and petroleum ether
(4:1) to afford 4 in 1.60 g yield (65%). M.p.: 223–224 °C
(m.p. 225 °C [21–28]).
ꢀ ꢁ
2
ðFs ꢁ ArÞ
ðFr ꢁ AsÞ
ns
nr
Usol ¼ Uref ꢁ 100 ꢁ
ꢁ
where subscripts ‘‘s’’ and ‘‘r’’ refer to the sample and
reference, respectively. The integrated area of the emis-
sion peak in arbitrary units is given as F; n is the
refractive index of the solvent (ns = 1.4244 for DCM;
nr = 1.4264 for cyclohexane); and A is the absorbance.
The emission spectra were recorded in solution in
cyclohexane. The solid emission spectrum was measured
from solid powders.
123

914
Y. Shi et al.
General procedure for preparation of 5a–5e
3-(4-Methoxylphenyl)-1-(9,90-spirobi[9H-fluoren]-2-yl)-2-
propen-1-one (5d, C35H24O2)
To a flask was charged 1.79 g 2-acetylspirobifluorene 4
(5 mmol), the appropriate aldehyde (5.1 mmol), a mixture
of THF and EtOH (4:1, 100 cm3), and 10 cm3 30% aq.
NaOH solution. After stirring for 12 h at room temperature,
the solution was neutralized by 2 N HCl, then the mixture
was extracted with dichloromethane (3 9 20 cm3), and the
organic phase was dried over Na2SO4. After filtration and
evaporation of the solvents, the products were purified by
recrystallization from EtOH (80–90% yield).
Yield 88%; m.p.: 179–181 °C; 1H NMR (500 MHz,
CDCl3): d = 8.10 (dd, J = 8.0 Hz, J = 1.5 Hz, 1H),
7.96 (d, J = 8.0 Hz, 1H), 7.92 (d, J = 7.5 Hz, 1H), 7.89
(d, J = 8.0 Hz, 2H), 7.67 (d, J = 15.5 Hz, 1H), 7.51 (d,
J = 8.5 Hz, 2H), 7.42–7.38 (m, 4H), 7.24 (d, J = 15.5 Hz,
1H), 7.18 (t, J = 7.5 Hz, 1H), 7.12 (t, J = 7.5 Hz, 2H),
6.89 (d, J = 8.5 Hz, 2H), 6.74 (t, J = 10.5 Hz, 3H), 3.83
(s, 3H) ppm; 13C NMR (125 MHz, CDCl3): d = 189.95,
161.81, 150.42, 149.33, 148.15, 146.51, 144.69, 142.16,
140.68, 138.22, 130.49, 129.30, 129.14, 128.20, 127.87,
124.50, 124.45, 124.26, 121.13, 120.47, 120.21, 119.99,
114.56, 66.20, 55.63 ppm.
3-Phenyl-1-(9,90-spirobi[9H-fluoren]-2-yl)-2-propen-1-one
(5a, C34H22O)
Yield 85%; m.p.: 194–196 °C; 1H NMR (500 MHz, CDCl3):
d = 7.97 (d, J = 8.0 Hz, 1H), 7.93 (d, J = 8.0 Hz, 1H), 7.89
(d, J = 8.0 Hz, 2H), 7.71 (d, J = 15.0 Hz, 1H), 7.60–5.50
(m, 2H), 7.43–7.35 (m, 8H), 7.20 (t, J = 7.5 Hz, 1H), 7.14 (t,
J = 7.5 Hz, 2H), 6.75–6.73 (m, 3H) ppm; 13C NMR
(125 MHz, CDCl3): d = 189.92, 150.46, 149.45, 148.11,
146.70, 144.80, 142.17, 140.63, 137.94, 135.17, 130.61,
129.36, 129.21, 129.21, 129.08, 128.90, 128.66, 128.21,
124.58, 124.56, 124.46, 124.22, 122.42, 122.35, 121.41,
120.46, 120.21, 66.23 ppm.
1-(9,90-Spirobi[9H-fluoren]-2-yl)-3-(2-thienyl)-2-propen-
1-one (5e, C32H20OS)
Yield 90%; m.p.: 149–150 °C; 1H NMR (500 MHz,
CDCl3): d = 8.06 (dd, J = 7.5 Hz, J = 1.0 Hz, 1H),
7.95 (d, J = 8.0 Hz, 1H), 7.91 (d, J = 8.0 Hz, 1H), 7.87
(d, J = 7.0 Hz, 2H), 7.89 (d, J = 15.0 Hz, 1H), 7.41–7.37
(m, 5H), 7.28 (d, J = 3.0 Hz, 1H), 7.19 (m, 2H), 7.11 (t,
J = 7.5 Hz, 2H), 7.04 (t, J = 4.0 Hz, 1H), 6.75 (d,
J = 8.0 Hz, 1H), 6.72 (d, J = 8.0 Hz, 2H) ppm; 13C
NMR (125 MHz, CDCl3): d = 189.31, 150.46, 149.52,
148.10, 146.66, 142.17, 140.63, 137.89, 137.11, 131.95,
129.36, 129.08, 128.89, 128.49, 128.22, 128.17, 124.67,
124.21, 121.17, 121.14, 120.46, 120.15, 66.22 ppm.
3-Naphthyl-1-(9,90-spirobi[9H-fluoren]-2-yl)-2-propen-1-
one (5b, C38H24O)
Yield 80%; m.p.: 237–239 °C; 1H NMR (500 MHz,
CDCl3): d = 8.54 (d, J = 15.0 Hz, 1H), 8.16 (dd,
J = 8.0 Hz, J = 2.5 Hz, 1H), 8.13 (d, J = 8.0 Hz, 1H),
7.99 (d, J = 8.0 Hz, 1H), 7.93 (d, J = 7.0 Hz, 1H),
7.90–7.85 (m, 4H), 7.81 (d, J = 7 Hz, 1H), 7.56–7.38
(m, 8H), 7.18 (t, J = 7.5 Hz, 2H), 7.13 (t, J = 7.5 Hz,
2H), 6.76 (t, J = 7.5 Hz, 3H) ppm; 13C NMR (125 MHz,
CDCl3): d = 189.79, 150.51, 149.48, 148.10, 146.80,
142.18, 141.66, 140.62, 137.93, 137.90, 133.92, 132.68,
131.95, 130.91, 130.87, 129.39, 129.33, 128.92, 128.24,
128.21, 127.16, 126.46, 125.62, 125.35, 125.16, 125.09,
124.62, 124.46, 124.24, 123.72, 121.16, 120.48, 120.31,
66.25 ppm.
General procedure for preparation of 6a–6e
A mixture of chalcone 5a–5e (5 mmol) and guanidine
nitrate (5 mmol) in 100 cm3 THF and EtOH (4:1) was
refluxed, while a solution of sodium hydroxide (0.4 mol) in
10 cm3 water was added portionwise over 2 h. Refluxing
was continued for further 24 h and the solution was neu-
tralized by 2 N HCl. Then the mixture was extracted with
dichloromethane (3 9 20 cm3), and the organic phase was
dried over Na2SO4. After filtration and evaporation of the
solvents, the products were purified by column chroma-
tography using dichloromethane and ethyl acetate (50:1).
3-(4-Chlorophenyl)-1-(9,90-spirobi[9H-fluoren]-2-yl)-2-
propen-1-one (5c, C34H21ClO)
4-Phenyl-6-(9,90-spirobi[9H-fluoren]-2-yl)pyrimidin-2-
amine (6a, C35H23N3)
Yield 86%; m.p.: 190–192 °C; 1H NMR (500 MHz,
CDCl3): d = 8.09 (dd, J = 8.0 Hz, J = 1.0 Hz, 1H),
7.96 (d, J = 8.0 Hz, 1H), 7.92 (d, J = 7.5 Hz, 1H), 7.88
(d, J = 7.5 Hz, 2H), 7.63 (d, J = 14.5 Hz, 1H), 7.47 (d,
J = 8.0 Hz, 4H), 7.42–7.30 (m, 6H), 7.18 (t, J = 7.5 Hz,
Yield 50%; Rf = 0.34; m.p.: 250–254 °C; 1H NMR
(500 MHz, CDCl3): d = 8.16 (dd, J = 8.5 Hz,
J = 1.0 Hz, 1H), 7.97 (t, J = 8.0 Hz, 2H), 7.96 (s, 1H),
7.91 (t, J = 7.5 Hz, 3H), 7.45–7.44 (m, 4H), 7.39 (t,
J = 7.7 Hz, 3H), 7.28 (s, 1H), 7.16–7.11 (m, 3H), 6.77 (d,
J = 7.5 Hz, 2H), 6.73 (d, J = 7.5 Hz, 1H), 5.04 (s, 2H)
ppm; 13C NMR (125 MHz, CDCl3): d = 166.35, 160.00,
163.69, 150.03, 149.46, 148.60, 144.55, 142.12, 141.09,
138.02, 137.64, 130.53, 128.89, 128.71, 128.19, 128.09,
127.46, 127.34, 124.39, 124.30, 123.12, 120.70, 123.11,
1H), 7.12 (t, J = 7.2 Hz, 2H), 6.77–6.74 (m, 3H) ppm; 13
C
NMR (125 MHz, CDCl3): d = 189.92, 150.48, 149.47,
148.08, 146.90, 143.31, 142.18, 140.56, 137.74, 136.52,
133.63, 129.87, 129.48, 129.39, 129.28, 128.28, 128.23,
124.57, 124.48, 124.26, 122.70, 121.23, 120.52, 120.32,
66.21 ppm.
123

Properties of 2-amino-4-aryl-6-(9,90-spirobifluoren-2-yl)
915
120.44, 120.35, 104.44, 104.42, 66.32 ppm; EI-MS:
m/z = 485 (100, M?), 315 (20), 242 (19).
J = 7.5 Hz, 1H), 5.02 (s, 2H) ppm; 13C NMR (125 MHz,
CDCl3): d = 165.80, 163.33, 160.65, 149.98, 149.37,
148.54, 144.60, 143.26, 142.09, 141.02, 137.35, 129.30,
128.72, 128.26, 128.18, 128.06, 127.39, 127.17, 124.40,
124.27, 123.04, 120.71, 120.43, 120.32, 102.57,
66.24 ppm; EI-MS: m/z = 475 (100, M?), 315 (45), 237
(55).
4-(1-Naphthyl)-6-(9,90-spirobi[9H-fluoren]-2-yl)pyrimidin-
2-amine (6b, C39H25N3)
Yield 30%; Rf = 0.38; m.p.: [170 °C; 1H NMR
(500 MHz, CDCl3): d = 8.13 (dd, J = 8.0 Hz, J = 1.0
Hz, 1H), 8.06 (d, J = 8.0 Hz, 1H), 7.95 (d, J = 8.0 Hz,
1H), 7.90–7.84 (m, 5H), 7.52–7.35 (m, 7H), 7.15–7.10 (m,
4H), 6.76 (d, J = 7.5 Hz, 2H), 6.73 (d, J = 7.5 Hz, 1H),
5.13 (s, 2H) ppm; 13C NMR (125 MHz, CDCl3):
d = 168.56, 165.62, 163.38, 150.01, 149.60, 148.54,
144.65, 142.10, 141.09, 137.36, 137.20, 134.04, 130.82,
129.79, 128.76, 128.58, 128.17, 128.14, 127.47, 127.01,
126.88, 126.30, 125.67, 125.38, 124.34, 123.16, 120.73,
120.47, 120.39, 108.87, 108.84, 66.29 ppm; EI-MS:
m/z = 535 (100, M?), 491 (34), 315 (20), 245 (20), 220
(47).
Acknowledgments We are grateful to Shanghai Natural Science
Foundation (09ZR1409400), Shanghai Committee of Science and
Technology of China (10520710100), and the Sino-French Institute of
ECNU for financial support.
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Yield 64%; Rf = 0.34; m.p.: 230–232 °C; 1H NMR
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