Synthesis of rigid oligofluorene stars

Article abstract of DOI:10.1055/s-2007-990807

In this paper we present the synthesis of a tetrahedral oligofluorene-functionalized adamantane, via an iterative synthetic approach, using Suzuki coupling methodology. Tetraphenyladamantane with two fluorene units on each arm were successfully synthesized. These tetrahedral oligofluorene adamantane cores exhibited good optical and thermal properties. One problem in this synthesis of these materials was that the homocoupling of the core became more prevalent as the molecular size increased. This is possibly a common defect in many controlled synthesis of large polyarenes. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2007-990807

PAPER
3323
Synthesis of Rigid Oligofluorene Stars
had Jeeva, Stephen C. Moratti*b
a
Synthesis of
R
h
igid Oligoflu
e
orene Star
z
a
Liquid Crystal Group, Department of Chemistry, University of York, York, Yorkshire, YO10 5DD, UK
Department of Chemistry, University of Otago, PO Box 56, Dunedin, New Zealand
E-mail: smoratti@chemistry.otago.ac.nz
b
Received 18 July 2007
MALDI-TOF mass spectroscopy can be a very useful tool
with which to look for defects such as missing end-
groups. However, not all impurities might be picked up,
especially if they are of much higher molecular weight
Abstract: In this paper we present the synthesis of a tetrahedral oli-
gofluorene-functionalized adamantane, via an iterative synthetic
approach, using Suzuki coupling methodology. Tetraphenylada-
mantane with two fluorene units on each arm were successfully syn-
thesized. These tetrahedral oligofluorene adamantane cores than expected. Size-exclusion chromatography (SEC) is
exhibited good optical and thermal properties. One problem in this another important method with which to analyse the puri-
synthesis of these materials was that the homocoupling of the core
ty of such materials. While it is not sensitive enough to
became more prevalent as the molecular size increased. This is pos-
find small differences in molecular structure, larger de-
sibly a common defect in many controlled synthesis of large poly-
fects such as those arising from dimerisation or a missing
arenes.
arm should be readily seen. Unfortunately, these tech-
Keywords: Pd-coupling, ipso-substitution, conjugation, organo-
niques are not always applied in the analysis of these types
metallic reagents, silylation
of molecules.
To our knowledge, there are very few star-shaped oligo-
1
0
fluorene derivatives and the other examples are mostly
Conjugated polymers and oiligomers in their pristine
states are usually wide-to-medium band-gap semi-con-
10b
based on hyperbranched type polymers, on star-shaped
polyphenylene6h or on polyphenylene vinylene oligo-
mers. Unfortunately, no SEC analysis was reported for
any of these examples, which would have helped to vali-
date the purity of the materials.
6b
1
ductors. Metallic conductivity can often be induced by
2
doping the polymer with strong oxidants or acids. These
materials have a wide range of uses in fields such as light
emission, photovoltaics and organic transistors. Control
of morphology, such as crystallinity and aggregation is of- In this paper we present a repetitive divergent synthetic
ten important for the production of good thin films. One strategy with which to prepare a series of well-defined
of the most popular synthetic methods with which to syn- star-shaped, conjugated oligofluorene derivatives, with
thesize conjugated polymers is Suzuki–Miyaura cross- tetraphenyladamantane as the core. Adamantane is an
3
–5
coupling using palladium catalysis.
ideal nucleus for tetrahedral systems due to its rigid Td
symmetry, all-hydrocarbon nature, and thermal stability.11
The adamantane core is used here not only to maintain the
rigidity but also to give extra core volume, thus disrupting
the packing of the tetrahedral stars by its size.11
Since the last decade, tetrahedral organic materials de-
rived from several core compounds such as tetraphenyl-
6
6b
methane,
tetraphenylsilane,
tetraphenyladaman-
6
b,i,j,7
8
9
tane,
silsesquioxane and star-shaped porphyrins
have attracted much attention. They have been investigat- The synthesis of 1,3,5,7-tetrakis(4-iodophenyl)adaman-
ed as light-emitting materials, electronically active mate- tane (3) was performed according to literature methods
rials and as a molecular caltrop in scanning probe using a Friedel–Crafts reaction followed by iodination
1
0
11,12
microscopy. The extended tetrahedral shape of such ma- (Scheme 1).
terials does not allow efficient packing in the solid state
Initially, the synthesis of a series of unsubstituted
polyphenylene arms was attempted. However, solubility
was a problem even with the bulky adamantyl core. By us-
ing 9,9-disubstituted fluorenyls, the rigidity, stability and
blue light emission of polyphenylene systems can be pre-
served. The iterative syntheses of these types of molecules
requires a protection–deprotection strategy similar to
those found in dendrimer synthesis. A silyl group was em-
ployed here to activate the growing end of the arms. The
required monomer 7, was synthesised in four steps from
the known compound 4. Lithiation and quenching of 4
with trimethylsilyl chloride produced 5 in good yield,
which was subsequently transformed into the boronic
acid. Since boronate esters are often easier to handle and
use than the parent acid, 7 was produced in quantitative
and consequently, they tend to form glassy or amorphous
states which are ideal for many thin-film technologies
such as organic light-emitting diodes (OLEDs). The mo-
lecular weights of these oligomers can be quite high and it
becomes important to determine the purity and presence
of any defects in the structures. Due to the similar and re-
peating nature of the arms, traditional methods such as
NMR, UV/Vis and IR spectroscopy may not be sensitive
enough to pick up some defect structures.
SYNTHESIS 2007, No. 21, pp 3323–3328
x
x.
x
x
.
2
0
0
7
Advanced online publication: 21.09.2007
DOI: 10.1055/s-2007-990807; Art ID: P08807SS
Georg Thieme Verlag Stuttgart · New York
©

3
324
S. Jeeva, S. C. Moratti
PAPER
I
Br
(
i)
(ii)
I
I
8
0%
7
7%
I
11
Scheme 1 Reagent and conditions: (i) t-BuBr, AlCl , benzene, reflux; (ii) [bis(trifluoroacetoxy)iodo]benzene, I .
3
2
(
i)
(ii)
Br
Br
Br
TMS
H17C8 C8H17
H17C8 C8H17
4
5
O
HO
B
(iii)
B
TMS
TMS
O
HO
H17C8 C H
8
H17C8 C H
8
17
17
7
6
Scheme 2 Reagents and conditions: (i) n-BuLi (1.6 M in hexane), –78 °C; TMSCl, –78 °C; (ii) n-BuLi (1.6 M in hexane), –78 °C, trimethyl
borate, –78 °C; (iii) MgSO (anhydrous), MeOH (anhydrous), pinacol, 30 °C.
4
yield by treatment of 6 with pinacol and used without fur-
ther purification.
R
1
3
The aim was then to couple the fluorenyl unit to the core
and to substitute the silyl group with iodine for subsequent
reaction. This method has been previously used to good
effect in the iterative synthesis of several large, conjugat-
ed molecules. The fluorene units were coupled under Su-
zuki coupling conditions to the core 3, in order to increase
the arm length (n = 1,2), then the TMS group was substi-
tuted with iodine. The structures and purity of the coupled
C8H17
C8H17
n
R
C8H17
8
C H
17
1
13
products were investigated by H and C NMR, elemental
and MALDI-TOF analysis, FT-IR and size exclusion
chromatography (SEC).
n
Thermal and optical properties of the newly synthesised
compounds were also investigated. It should be noted that
the iodo moieties of the tetrahedral macromolecule were
treated as intermediates and, as such, their thermal and op-
tical properties were not investigated due to their lower
stability.
H17C8
R
C8H17
n
n
H17C8
H17C8
8
9
n = 1, R = TMS
n = 1, R = I
10 n = 2, R = TMS
1
1 n = 2, R = I
The synthesis of compounds 8 and 10 (Figure 1) were car-
ried out via Suzuki coupling as shown in Scheme 2. It was
found that the best yields and purity were obtained with
Pd(PPh ) as the catalyst and tetraethylammonium hy-
R
Figure 1
3
4
droxide (20% v/v in H O) as the aqueous basic medium
2
with toluene solvent. In order to achieve maximum cou- Unfortunately, the progress of the reaction could not be
pling, the boronic ester 7 was added in excess to the reac- followed by TLC, due to streaking on the plate; for this
tion mixture, which was then heated for 24 hours. reason the product could also not easily be purified by col-
Synthesis 2007, No. 21, 3323–3328 © Thieme Stuttgart · New York

PAPER
Synthesis of Rigid Oligofluorene Stars
3325
umn chromatography. In addition, the similar R values of itative agreement with the general view that rigid-rod
f
the product and boronic ester precluded their separation.
macromolecules have a larger hydrodynamic volume than
flexible ones of the same molecular weight.16 The large
peak is assumed to be the desired coupled product, while
the smaller peak (on the high molecular size side) is be-
lieved arise from an impurity which may have formed by
the self-coupling of two iodo-cores during the Suzuki cou-
pling reaction. The presence of homo-coupling in these
types of reaction has also been previously reported.17 It
was discouraging that the amount of homo-coupling in-
creased with the size of the molecules. Indeed, attempts at
a third generation rigid star failed due to excessive side-
reactions. The impurity could not be separated by normal
chromatography on silica gel due to the very similar po-
larities. However, preparative SEC on BIORAD bio-
beads SX-1 gel successfully separated out the first peak in
each case.
Therefore, in order to remove the excess of boronic ester
7
, an end-capping technique was used, i.e. an excess of
bromobenzene was used to couple with the unreacted bo-
ronic ester 7 to form a very nonpolar coupled product
which was easily separable from the star. Compound 8
was then eluted using chloroform to give a pale-yellow
glassy solid in 60–70% yield. The moderate yield could be
due to the fact that compound 8 streaked on silica and was
difficult to recover cleanly from the column, even with
highly polar solvents.
Iodination of 8 was performed by modifying a standard
procedure and is shown in Scheme 3. Standard
1
4,15
conditions
°C) gave some unwanted proteo-desilation, which we
(dropwise addition of ICl in CH Cl at
2 2
0
found could be prevented by the use of solid sodium bicar-
bonate as an acid scavenger. Aqueous work-up was fol-
lowed by column chromatography to give a quantitative
yield of 9 as a light-red glassy solid. Complete substitu-
As can be seen in Figure 3, MALDI-TOF analysis also
verified the structure of products 8 (m/z = 2282) and 10
(
m/z = 3836). The small fragmentation peak at m/z =
2209.5 in the spectrum of 8 suggests that a TMS group
m/z = 74) was lost, either in the synthesis or under the
1
tion of 9 was confirmed by H NMR; the spectra con-
(
tained neither a TMS peak nor multiplets due to proteo-
desilation. The synthesis of compounds 10 and 11 was
carried out using similar conditions to those mentioned
above for the synthesis of compounds 8 and 9, respective-
ly.
MALDI analysis conditions. No parent ions could be seen
in the MALDI spectra of either iodo-substituted com-
pounds 9 or 11, probably due to facile loss of iodine.
Thermal gravimetric analysis (TGA) was performed in or-
der to study the potential thermal stability of compounds
The 1H and 13C NMR spectra of the compounds 8–11
8
and 10. As expected, the compounds proved very stable
were too complex to definitively confirm the structure.
1
The H aromatic region (d = 7.0–8.0 ppm) was particular-
ly difficult to assign, as the peaks were usually too close
to each other to integrate individually; the peaks were
1
therefore considered to be a multiplet. The H NMR spec-
tra of these compounds also contain broad peaks with
shifts corresponding to the alkyl chains; such peak broad-
ening is common for large molecules due to slow relax-
ation and inhomogeneity. Elemental analysis and mass
spectra data fit the theoretical values, which helps confirm
the purity.
SEC was performed in order to check the purity of the
compounds 8 and 10 (Figure 2). The molecular weights of
both, determined by referencing their retention times to a
polystyrene standard, were higher than the expected value
from MALDI-TOF measurements. This finding is in qual-
Figure 2 SEC analysis of the crude coupling products before prepa-
rative SEC. Peaks around 20 minutes are due to solvent.
I
TMS
AD
AD
4
H17C8 C8H17
4
H17C8 C8H17
8
9
I
TMS
AD
AD
2
2
4
H17C8 C8H17
4
H17C8 C8H17
10
11
Scheme 3 Reagents and conditions: (i) Pd(PPh ) (12 mol%), Et NOH (20% in H O), toluene (degassed, N ), 90 °C, 24 h; (ii) ICl (1.0 M in
3
4
4
2
2
CH Cl ), NaHCO , 0 °C→r.t., overnight. AD = Adamantyl.
2
2
3
Synthesis 2007, No. 21, 3323–3328 © Thieme Stuttgart · New York

3
326
S. Jeeva, S. C. Moratti
PAPER
All reagents were used as received from commercial suppliers, in-
cluding Pd(PPh ) (Aldrich) and polystyrene (average molecular
3
4
weight ~280,000 by GC, Aldrich). Moisture-sensitive reactions
were conducted in oven- or flame-dried glassware. Temperatures
refer to the bath temperature unless specified otherwise. Flash chro-
matography was performed using Merck 9385 silica gel 60 (0.040–
0
.063 nm). Yields refer to isolated quantities of analytically pure
material unless specified otherwise. FT-IR spectra were measured
1
13
with Perkin–Elmer Spectrum RX I FT-IR spectrometer. H and
C
NMR were recorded on Bruker DPX-400 (400 MHz) or Bruker
DRX-500 (500 MHz) instruments. Elemental analyses were per-
formed with an Exeter Analytical CE-440 elemental analyzer.
UV/Vis absorptions were measured using dilute THF solutions in a
1
.0 cm path-length quartz cuvette on a Hewlett–Packard 8452A di-
ode array spectrophotometer. Photoluminescence (PL) and excita-
tion spectra were recorded on an Aminco–Bowman Series 2
luminescence spectrometer under an ambient atmosphere. DSC and
TGA were performed using a Perkin–Elmer Pyris 1 instrument.
SEC was carried out with the aid of a Viscotek Model 200 differen-
Figure 3 MALDI-TOF spectra of 8 and 10.
and no loss was seen below 400 °C. Differential scanning tial refractometer. MALDI-TOF analysis of the tetrahedral samples
calorimetry (DSC) measurements of compounds 8 and 10 were performed on a 4700 proteomics analyzer with TOF/TOF op-
tics (Applied Biosystem); DHB was used as a matrix. GPC = gel-
exhibited small endothermic peaks on first heating at
permeation chromatography; PD = polydispersity; M = peak mo-
9
9 °C and 170 °C, respectively. However, both failed to
p
1
1,12
11,12
22
lecular weight. The compounds 2,
as described in the literature.
3,
and 4 were prepared
give any transitions on cooling or on a second consecutive
thermal run; it may be that the first transitions were related
to a small amount of trapped solvent, which can be very
difficult to remove from these materials.
7-Bromo-9,9-dioctyl-9H-fluorene-2-yl)trimethylsilane (5)8
(
2,7-Dibromo-9,9-dioctyl-9H-fluorene (4; 17.1 g, 31.2 mmol) was
dissolved in anhydrous Et O (250 mL) and cooled to –78 °C. n-
2
The UV/Vis absorption of compounds 8 and 10 were mea-
sured in THF solution (Table 1). The absorption maxi-
mum is red-shifted as the effective conjugated lengths of
BuLi (21.5 mL; 1.6 M in hexane, 34.3 mmol) was added dropwise
via syringe at –78 °C and the mixture was stirred for 3 h at –10 °C.
The solution was cooled to –78 °C and TMSCl (5.2 mL, 140.5
the respective oligofluorene branches were increased, mmol) was added dropwise via syringe. The solution was stirred
with 8 and 10 exhibiting maximum absorptions at 328 nm overnight at r.t. then H O (100 mL) was added to quench the reac-
2
tion. The organic layer was taken, washed with H O (2 × 200 mL)
and 350 nm respectively. The UV/Vis spectrum of thin
films of compounds 8 and 10 were very similar to those in
solution, showing that there was no apparent aggregation
or crystallisation in the solid state. These compounds all
formed good films upon casting and are thus suitable for
2
and the mixture was dried (MgSO ) and evaporated to give the
4
product 5. Yield: 17.5 g (95%); pale-yellow oil.
–
1
IR (neat): 3039, 2956, 2929, 2884, 2857, 1600–1471, 1248 cm .
1
H NMR (400 MHz, CDCl ): d = 7.63 (d, J = 6.2 Hz, 1 H), 7.57 (d,
3
opto-electronic applications. The emission maxima are J = 7.9 Hz, 1 H), 7.46 (m, 4 H), 1.84 (m, 4 H), 1.35 (m, 20 H), 0.82
(
t, J = 5.0 Hz, 6 H), 0.61 (m, 4 H), 0.31 (s, 9 H).
also shown in Table 1. No excimer in the long wavelength
emission region of 500–600 nm (typical of poly-
2
-(9,9-Dioctyl-7-trimethylsilanyl-9H-fluoren-2-yl)boronic Acid
1
8–20
fluorenes
some controversy over whether these, often unwanted,
emissions are due to aggregation or ketone-type defects.21 mmol) was dissolved in anhydrous THF (100 mL) and cooled to
), was observed in the solid state. There is
8
(
6)
-Bromo-9,9-dioctyl-9H-fluorene-2-yl)trimethylsilane (5; 9 g, 16.4
7
–
78 °C. t-BuLi (20 mL, 1.7 M in pentane, 34.5 mmol) was added
Table 1 Optical Measurements of Compounds 8 and 10
dropwise via syringe (the colour of the reaction mixture changed
from yellow to dark green) and the mixture was stirred for 3 h at
–78 °C. (i-PrO) B (11 mL, 49.9 mmol) was added and the mixture
Compd UVmax in THF UV (thin film) PL (THF) PL (thin film)
3
(
nm, log e)
(nm)
(nm)
(nm)
was stirred overnight at r.t. under an atmosphere of N . H O (40
2
2
mL) was added to quench the reaction and the organic layer was
8
0
322 (5.25)
350 (5.44)
326
344
348
separated and washed with H O (2 × 200 mL). The organic layer
2
was dried (MgSO ) and evaporated to give 6. Yield: 5.2 g (61%);
1
354
350
354
4
pale-yellow oil.
1H NMR of the product was complex due to dimer and trimer for-
mation.
In summary, a new series of rigid, tetrahedral oligofluo-
rene stars have been synthesized. Palladium-catalysed
coupling is shown to give defects due to homo-coupling,
which may be a serious limitation to the assembly of mul-
IR (ATR): 3549, 3027, 2951, 2921, 2855, 1608–1416, 1352, 1246
–1
cm .
tiple arms in the same step. It is important to analyse these 2-(9,9-Dioctyl-7-trimethylsilanyl-9H-fluoren-2-yl)-4,4,5,5-
8
types of materials by a wide variety of methods in order to tetramethyl-1,3,2-dioxaborolane (7)
determine the presence of side-reactions. These stars
To a solution of 2-(9,9-dioctyl-7-trimethylsilanyl-9H-fluoren-2-
yl)boronic acid (6; 5 g, 10 mmol) in anhydrous MeOH (100 mL),
was added anhydrous MgSO (5 g) followed by pinacol (5 g, 40
mmol). The mixture was stirred at 30 °C for 24 h then cooled to r.t.
show good thermal stability and form fluorescent, amor-
phous films.
4
Synthesis 2007, No. 21, 3323–3328 © Thieme Stuttgart · New York

PAPER
Synthesis of Rigid Oligofluorene Stars
3327
and EtOAc (100 mL) was added followed by H O (200 mL). After
stirring for 10 min, the organic layer was separated, dried (MgSO4),
filtered and then evaporated under reduced pressure to give a pale-
131.7, 128.1, 127.6, 127.2, 126.0, 125.98, 125.91, 125.55, 121.50,
121.44, 121.40, 119.96, 119.91, 118.0, 55.2, 55.0, 47.1, 40.3, 40.1,
39.6, 31.9, 30.1, 29.9, 29.6, 29.2, 29.19, 29.13, 29.08, 14.1, –0.86.
2
yellow sticky solid (6.5 g, 80%) that was recrystallized (Et O–
MeOH, 1:5) to give pure 7. Yield: 5.2 g, 52%; pale-yellow crystals;
mp 72–73 °C.
2
MS (MALDI-TOF): m/z (C278H384Si ) = 3838.37.
4
Anal. Calcd for C278H384Si : C, 86.45; H, 9.92. Found: C, 86.99; H,
4
1
0.08.
–
1
IR (ATR): 3027, 2951, 2921, 2855, 1608–1416, 1352, 1246 cm .
5
UV/Vis (THF): lmax (e) = 348 (1.95 × 10 ) nm.
1
H NMR (400 MHz, CDCl ): d = 7.81–7.69 (m, 4 H), 7.47 (m, 2 H),
3
UV/Vis (thin film): lmax = 348 nm.
1
0
.97 (m, 4 H), 1.39 (s, 12 H, CH CO), 1.21–1.03 (m, 20 H, CH ),
3
2
.81 (t, J = 7.0 Hz, 6 H), 0.55 (m, 4 H, CH ), 0.31 (s, 9 H).
2
PL (THF): lemission = 406 nm, thin film 409 nm, doped with Ir(acac)
complex (127) 568 nm.
Suzuki Coupling; General Procedure
Arylhalide (0.9 mmol), arylboronic ester (5.5 mmol) and Pd(PPh3)4
12.0 mol%) dissolved in toluene (50 mL, degassed) were placed in
DSC: T = 130 °C, T = 170 °C; TGA decomposition events seen at
c
m
3
04, 450, 568 °C.
(
a one-neck round-bottom flask (250 mL). Et NOH (25 mL) was
GPC (THF): PD = 1.09, M = 5540.
p
4
added and the system was degassed and stirred at 85 °C under an at-
mosphere of N overnight. The system was cooled to r.t. and a solu-
1,3,5,7-Tetrakis(7-phenyl-2-iodo-9,9-dioctyl-9H-fluorene)ada-
mantane (9)
2
tion of PhBr (excess, 100 mg), Pd(PPh ) (10 mg) and Et NOH (2.0
3
4
4
mL) dissolved in toluene (5.0 mL) was added via syringe. The sys-
tem was degassed again and heated at 85 °C under the atmosphere
1,3,5,7-Tetrakis[(9,9-dioctyl-7-phenyl-9H-fluoren-2-yl)trimethyl-
silane]adamantane (8; 400 mg, 0.2 mmol) was dissolved in anhyd-
of N for 24 h. After cooling to r.t., toluene (50 mL) was added fol-
rous CH
mL). NaHCO
10 °C then iodomonochloride (1.0 M in CH Cl , 1 mL, 1.05 mmol)
2
Cl
2
(20 mL) in a dry one-neck round-bottom flask (100
2
lowed by H O (200 mL).
3
(1 g) was added and the mixture was stirred at
2
–
2
2
1
,3,5,7-Tetrakis[(9,9-dioctyl-7-phenyl-9H-fluoren-2yl)trimeth-
was added dropwise and the mixture was stirred at r.t. for 12 h under
an atmosphere of N . The reaction mixture was quenched by adding
aqueous Na (2.0 M, 50 mL) and stirred until the pink colour
of the reaction mixture became colourless. The reaction mixture
was poured into a conical flask and CH Cl (100 mL) was added fol-
lowed by H O (100 mL). The organic layer was extracted, dried
(MgSO ), filtered and evaporated under reduced pressure to give a
red solid that was dissolved in CH Cl and passed through a plug of
ylsilane]adamantane (8)
According to the general procedure described above. The organic
layer was separated, dried (MgSO ), filtered and evaporated under
reduced pressure to give a crude yellow glassy product that was pu-
rified by column chromatography (hexane then CHCl –hexane, 1:4)
to give 8. Yield: 1.2 g (60%); colourless glassy solid.
2
S O
2 2 3
4
2
2
3
2
4
–1
2
2
IR (ATR): 3027, 2951, 2921, 2850, 1600–1464, 1246 cm .
silica to remove colour. Evaporation of the solvent gave 9. Yield:
440 (100%); colourless glassy solid.
1
H NMR (400 MHz, CDCl ): d = 7.76–7.46 (m, 40 H), 2.30 (s,
3
5
2 H), 1.99 (m, 16 H), 1.21–1.08 (m, 40 H), 0.81 (t, J = 5.0 Hz,
4 H), 0.78–0.70 (m, 16 H), 0.31 (s, 36 H).
–
1
IR (ATR): 3027, 2951, 2921, 2855, 1519–1456 cm .
1H NMR (400 MHz, CDCl
2
1
3
3
): d = 7.72–7.44 (m, 40 H), 2.3 (s, 12 H),
.03–1.89 (m, 16 H), 1.24–0.99 (m, 40 H), 0.79 (t, J = 5.3 Hz,
4 H), 0.72–0.57 (m, 16 H).
C NMR (100 MHz, CDCl ): d = 151.5, 150.1, 148.2, 141.3, 140.2,
3
2
2
1
2
39.6, 138.9, 119.9, 118.9, 55.0, 47.4, 40.2, 39.1, 31.7, 29.9, 29.1,
9.0, 23.7, 22.5, 14.0, –0.9.
1
3
C NMR (125 MHz, CDCl ): d = 153.3, 150.8, 148.4, 140.3, 140.2,
3
MS (MALDI-TOF): m/z [C162H224Si ] = 2282.5842.
4
1
39.4, 139.3, 135.8, 132.0, 127.1, 126.0, 125.5, 121.4, 121.3, 120.0,
Anal. Calcd for C162H224Si : C, 85.20; H, 9.89. Found: C, 85.48; H,
9
4
55.3, 47.4, 40.2, 39.2, 31.7, 29.9, 29.1, 23.6, 22.5, 14.0.
.70.
MS (MALDI-TOF): m/z = 2496.76.
5
UV/Vis (THF): lmax (e) = 322 (1.78 × 10 ) nm.
UV/Vis (thin film): lmax = 326 nm.
5
UV/Vis (THF): lmax (e) = 326 (1.62 × 10 ) nm.
UV/Vis (thin film): lmax = 334 nm.
PL (THF): lemission = 346 nm.
PL (THF): lemission = 344 nm.
DSC: T 92 °C, T 99 °C; TGA decomposition events seen at
4
c
m
GPC (THF): PD = 1.09, M = 3000.
p
23 °C and 639 °C.
GPC (THF): PD = 1.14, M = 2990.
p
1,3,5,7-Tetrakis(bis-7-phenyl-2-iodo-9,9,-dioctyl-9H-fluo-
rene)adamantane (11)
1
,3,5,7-Tetrakis[7-phenyl-bis(9,9-dioctyl-9H-fluoren-2-yl)tri-
In a dry one-neck round-bottom flask (100 mL), 1,3,5,7-tetrakis[7-
phenyl-bis(9,9-dioctyl-9H-fluoren-2-yl)trimethylsilane]adaman-
tane (10; 1.2 g, 0.3 mmol) was dissolved in anhydrous CH Cl (20
methylsilane]adamantane (10)
According to the general procedure described above. The organic
2
2
layer was separated, dried (MgSO ), filtered and evaporated under
4
mL). NaHCO (1.0 g) was added and the mixture was stirred at
3
reduced pressure to give a crude yellow glassy product. Purification
by column chromatography (CHCl –hexane, 1:20 then CHCl )
gave a light-brown glassy product (939 mg, 70% crude yield). A
sample (110 mg) was then subject to preparative SEC using BIO-
–
10 °C. Iodomonochloride (1.5 mL, 1.0 M in CH Cl , 1.5 mmol)
2 2
3
3
was added dropwise and the mixture was stirred at r.t. for 12 h under
an atmosphere of N . The reaction mixture was quenched by adding
2
aqueous Na S O (2.0 M, 50 mL) and stirred until the pink colour
2
2
3
RAD SX-1 biobeads (CH Cl ) to give 10 (56 mg).
2
2
of the reaction mixture became colourless. The reaction mixture
was poured into a conical flask and CH Cl (100 mL) was added fol-
–1
IR (ATR): 3022, 2951, 2926, 2855, 1600–1400, 1246 cm .
2
2
lowed by H O (100 mL). The organic layer was separated, dried
1
2
H NMR (400 MHz, CDCl ): d = 7.80–7.48 (m, 64 H), 2.37 (s,
3
(
MgSO ), filtered and evaporated under reduced pressure to give a
4
1
4
2 H), 2.16–1.99 (m, 32 H), 1.24–0.87 (m, 80 H), 0.84–0.73 (m,
8 H), 0.32 (s, 36 H).
red glassy compound. The crude material was purified by column
chromatography (hexane–CH Cl , 20:1) to give 11. Yield: 0.5
2
2
13C NMR
40.55, 140.50, 140.3, 140.2, 140.0, 139.9, 139.6, 139.5, 138.1,
(125 MHz, CDCl ): d = 151.7, 151.6, 150.2, 148.0,
(42%); transparent glassy product.
3
1
Synthesis 2007, No. 21, 3323–3328 © Thieme Stuttgart · New York

3
328
S. Jeeva, S. C. Moratti
PAPER
(7) Li, Q.; Jin, C.; Petukhov, P. A.; Rukavishnikov, A. V.;
–
1
IR (ATR): 3027, 2951, 2921, 2855, 1519–1456 cm .
1
Zaikova, T. O.; Phadke, A.; LaMunyon, D. H.; Lee, M. D.;
Keana, J. F. W. J. Org. Chem. 2004, 69, 1010.
8) Lin, W.-J.; Chen, W.-C.; Wu, W.-C.; Niu, Y.-H.; Jen, A.
K.-Y. Macromol. 2004, 37, 2335.
9) Li, B.; Li, J.; Fu, Y.; Bo, Z. J. Am. Chem. Soc. 2004, 126,
H NMR (400 MHz, CDCl ): d = 7.72–7.63 (m, 64 H), 2.3 (s, 12 H),
3
2
1
.03–1.89 (m, 32 H), 1.24–0.99 (m, 80 H), 0.79–0.57 (m, 48 H).
(
(
3
C NMR (125 MHz, CDCl ): d = 153.4, 150.8, 148.3, 140.3, 140.2,
3
1
4
39.4, 135.8, 132.0, 127.2, 126.2, 125.9, 121.4, 121.3, 120.0, 55.1,
7.8, 40.0, 39.1, 31.2, 29.9, 29.1, 23.4, 22.1, 14.1.
3
430.
10) (a) Liu, X.-M.; Chaobin He; Huang, J.; Xu, J. Chem. Mater.
005, 17, 434. (b) Liu, X.-M.; Chaobin He; Hao, X.-T.;
(
GPC (THF): PD = 1.25, M = 5060.
p
2
Tan, L.-W.; Li, Y.; Ong, K. S. Macromol. 2005, 37, 5965.
(c) Han, Y.; Fei, Z.; Sun, M.; Bo, Z.; Liang, W.-Z.
Macromol. Rapid Commun. 2007, 28, 1017.
Acknowledgment
We acknowledge the Aga Khan Foundation for a scholarship (S.J.).
(
(
11) Reichert, V. R.; Mathias, L. J. Macromol. 1994, 27, 7015.
12) Li, Q.; Rukavishnikov, A. V.; Petukhov, P. A.; Zaikova, T.
O.; Jin, C.; Keana, J. F. W. J. Org. Chem. 2003, 68, 4862.
13) Geng, Y.; Trajkovska, A.; Karsus, D.; Ou, J. J.; Culligan, S.
W.; Chen, S. H. J. Am. Chem. Soc. 2002, 124, 8337.
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Synthesis 2007, No. 21, 3323–3328 © Thieme Stuttgart · New York