First synthesis of diindeno[1,2-g:1′,2′-s]rubicene derivatives and their evaluation as semiconductors

Article abstract of DOI:10.1071/CH11375

Solution-processable derivatives 4ad of the novel diindeno[1,2-g:1′, 2′-s]rubicene ring system have been prepared in three steps from 1,5-dichloroanthraquinone. Charge extraction by linearly increasing voltage measurements indicates that 4ad have bulk mobilities 10-7cm2V-1s-1. Consistent with these low mobility values, field-effect transistors fabricated from 4ad show poor performance. X-ray crystallographic analyses indicate that in the crystalline state, molecules of compounds 4bd pack in a manner that hinders π-π stacking, thus preventing strong electronic coupling between molecules that is essential for high charge mobility semiconductor performance.

Full text of DOI:10.1071/CH11375

CSIRO PUBLISHING
Aust. J. Chem. 2012, 65, 145–152
Full Paper
http://dx.doi.org/10.1071/CH11375
First Synthesis of Diindeno[1,2-g:19,29-s]rubicene
Derivatives and their Evaluation as Semiconductors
A
A
B
Mark Bown, Christopher J. Dunn, Craig M. Forsyth,
A
A
A C
,
Peter Kemppinen, Th. Birendra Singh, Melissa A. Skidmore,
and Kevin N. Winzenberg
A
A
Ian Wark Laboratory, CSIRO Molecular and Health Technologies,
Clayton South, Vic. 3168, Australia.
B
School of Chemistry, Monash University, Clayton, Vic. 3800, Australia.
C
Corresponding author. Email: melissa.skidmore@csiro.au
Solution-processable derivatives 4a–d of the novel diindeno[1,2-g:10,20-s]rubicene ring system have been prepared in
three steps from 1,5-dichloroanthraquinone. Charge extraction by linearly increasing voltage measurements indicates that
4a–d have bulk mobilities ,10ꢀ7 cm2 Vꢀ1 sꢀ1. Consistent with these low mobility values, field-effect transistors
fabricated from 4a–d show poor performance. X-ray crystallographic analyses indicate that in the crystalline state,
molecules of compounds 4b–d pack in a manner that hinders p–p stacking, thus preventing strong electronic coupling
between molecules that is essential for high charge mobility semiconductor performance.
Manuscript received: 21 September 2011.
Manuscript accepted: 7 December 2011.
Published online: 23 January 2012.
such as 2,[3] rubrene,[4] picene,[5] and dithieno[2,3-d:2030-d0]
benzo[1,2-b:4,5-b0] dithiophene 3.[6]
Introduction
There is great interest in organic field-effect transistors (OFETs)
due to their potential application in optoelectronic devices
such as displays, organic radiofrequency identification (RFID)
tags, biosensors and integrated circuits.[1] For example,
OFETs are expected to enable the cost-effective production of
flexible electronic components and fabrication of devices over
large areas and on lightweight flexible substrates.[2] To fully
realise the potential of OFETs in organic electronics, new
semiconductor materials that display high charge mobility
(.1 cm2 Vꢀ1 sꢀ1) are required. These materials should be sta-
ble, solution processable and accessible in high purity from
industrially scalable processes using readily available starting
materials. There are several polycyclic aromatic semiconductors
that have shown charge mobility (m) .1 cm2 Vꢀ1 sꢀ1 when
fabricated into OFETs (Fig. 1), for example pentacene deriva-
tives such as 1and structurally related heteroaromatic analogues
A common attribute of each of these materials in the
crystalline state is significant p–p stacking between adjacent
molecules, which enables strong electronic coupling between
molecules, a necessary criterion for ensuring high charge
mobility.[7] The recent report of the successful use of derivatives
of the polycyclic aromatic hydrocarbon (PAH) rubicene[8] as
p-type semiconductors in bilayer organic solar cells prompted us
to consider the use of this little-explored PAH in the design of
other polycyclic semiconductors.[9] In particular, we envisaged
that annelation of indane rings to rubicene to form the 9,19-
dihydrodiindeno[1,2-g:10,20-s]rubicene ring system would
enable us to access soluble derivatives by means of attachment
of appropriate substituents at positions 9 and 19, exemplified by
compounds 4a–d in Scheme 1. Furthermore, as Wudl has shown
rubicene derivatives crystallizing in columnar stacks and with
Si(i-Pr)3
Si(Et)3
C6H13
S
S
S
S
S
S
C6H13
1
2
3
S
Si(i-Pr)3
Si(Et)3
Fig. 1. Polycyclic aromatic semiconductors.
Journal compilation Ó CSIRO 2012
www.publish.csiro.au/journals/ajc

146
M. Bown et al.
p–p overlap between adjacent molecules in the stack,[10] we
thought the planarity and extended p conjugation in this
previously unreported 11-ring system could augur well for the
discovery of diindeno[1,2-g:10,20-s]rubicene derivatives with
crystal packing conducive to the high charge mobility required
for effective semiconductor behaviour.
Results and Discussion
The synthetic route to our target compounds is shown in
Scheme 1. Treatment of the 2-bromo-9,9-dialkylfluorenes
6a–d with n-butyl lithium, followed by reaction with 1,5-
dichloroanthraquinone 5 afforded the diol derivatives 7a–d.
Reduction of compounds 7a–d with sodium hypophosphite
hydrate/sodium iodide solution in acetic acid gave the 9,10-bis
(2-fluorenyl)anthracenes 8a–d in good yield. In the final step,
ring closure of 8a–d was achieved in N,N-dimethylacetamide,
employing 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and bis
(tricyclohexylphosphine)palladium(II) chloride[11] in a sealed
ampoule at 1408C for 64 h, affording compounds 4a–d in good
yield (63–81 %). These compounds are the first reported deri-
vatives of the diindeno[1,2-g:10,20-s]rubicene ring system. The
selectivity of this cyclization can be attributed to the increased
steric hindrance in the palladium complex blocking the alter-
native cyclization at position 10. The diindeno[1,2-g:10,20-s]
rubicene derivatives are magenta or dark purple crystalline
solids that are stable in air. The structures of 4a–d were con-
O
Cl
R
R
Cl
OH
5
Cl
O
ꢀ
n-BuLi, THF
ꢂ78°C
R R
HO
Cl
Br
R
R
R ꢁ n-octyl 6a
R ꢁ n-hexyl 6b
R ꢁ n-pentyl 6c
R ꢁ n-butyl 6d
R ꢁ n-octyl 7a
R ꢁ n-hexyl 7b
R ꢁ n-pentyl 7c
R ꢁ n-butyl 7d
1
firmed by H and 13C NMR spectroscopy, mass spectrometry
and elemental analysis. Compounds 4a–d possess high thermal
stability; thermal gravimetric analyses showed that compounds
4a–d are stable to 314, 340, 350 and 3708C with melting points
of 205, 252, 345 and 4218C respectively.
NaH2PO2·xH2O,
NaI, AcOH
Reflux
Table 1 shows key data for the photophysical properties of
the diindeno[1,2-g:10,20-s]rubicene derivatives 4a–d. The UV-
vis absorption spectra for 4a–d show four significant maxima
(labs) at 353, 488, 556 and 597 nm; compounds 4a–d show an
emission wavelength (lem) at 705 nm. The absorption and
photoluminescent spectra of 4a are shown in Fig. 2; 4b–d
displayed almost identical spectra. Cyclic voltammetry (CV)
was used to measure the HOMO and LUMO energy levels of
4a–d in dichloromethane referenced to the half-wave potential
(E1/2) of the ferrocene/ferrocenium couple. They exhibited
identical voltammograms with a reversible reduction, two
reversible oxidations, and no sweep-rate dependence. The
HOMO energy levels in films of 4a–b were measured using
photoelectron spectroscopy in air (PESA). UV-vis spectroscopy
was used to determine the band gap, thus enabling LUMO levels
to be calculated. The small discrepancies between HOMO levels
measured by PESA and CV can be explained by the difference in
aggregation between molecules in solution v. the solid state. The
LUMO was calculated to be ꢀ3.3 eV with a band gap of 2.0 eV
for derivatives 4a–b, and the LUMO was calculated to be
ꢀ3.2 eV with a band gap of 2.0 eV for derivatives 4c–d.
The photophysical properties of compounds 4a–d indicate
that they are promising candidates for consideration as
R
R
R
R
Cl
Pd(PCy3)2Cl2,
DBU, DMAc
140°C
Cl
R
R
R
R
R ꢁ n-octyl 4a
R ꢁ n-hexyl 4b
R ꢁ n-pentyl 4c
R ꢁ n-butyl 4d
R ꢁ n-octyl 8a
R ꢁ n-hexyl 8b
R ꢁ n-pentyl 8c
R ꢁ n-butyl 8d
Scheme 1. General synthesis of diindeno[1,2-g:10,20-s]rubicene deriva-
tives 4a–d.
Table 1. Photophysical properties of compounds 4a–d
abs [nm]A
l
em [nm]A
E
[V]
onset
HOMOB,C [eV]
LUMOC [eV]
Band gapB [eV]
ox
4
l
a
b
c
353, 488, 556, 597
353, 488, 556, 597
353, 488, 556, 597
353, 488, 556, 597
705
705
705
705
0.55
ꢀ5.35 (–5.67)
ꢀ5.33 (–5.56)
ꢀ5.33
ꢀ3.33 (–3.75)
ꢀ3.32 (–3.64)
ꢀ3.23
2.0
2.0
2.1
2.1
0.53
0.53
0.46
d
ꢀ5.26
ꢀ3.20
AIn CH2Cl2 10 mg in 1 mL.
BElectrochemical, referenced to E1/2 of the ferrocene/ferrocenium couple.
CPhotoelectron spectroscopy in air (PESA); band gaps were determined from UV absorption.

Diindeno[1,2-g:10,20-s]rubicene Derivatives
147
semiconducting materials. The HOMO–LUMO energy levels
and the band gap indicate that these compounds may have
application as ambipolar semiconductors in transistors.
As a preliminary step to assessment of 4a–d in OFET
devices, we attempted to measure the bulk mobility of these
compounds using the (photo) charge extraction by linearly
increasing voltage (CELIV) technique.[12] We were
disappointed to observe that 4a–d showed bulk mobilities
,10ꢀ7 cm2 Vꢀ1 sꢀ1, which indicated that these particular com-
pounds were unlikely to demonstrate sufficient charge mobility
to enable high performance in transistor devices. Consistent
with this view, we were unable to demonstrate transistor
performance from OFET devices fabricated from 4a–d.
1
PL
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
UV-vis
In an effort to rationalize the poor semiconductor perfor-
mance of these compounds, single-crystal X-ray crystallographic
studies of 4b–d were undertaken to determine crystal packing.
The single crystal structures of 4b, 4c and 4d are presented in
Figs. 3 and 4. The three structures each have a near-planar
polycyclic core with the four alkyl chains lying approximately
perpendicular to the plane. For both 4c and 4d, the molecules are
sited on a crystallographic inversion centre that relates both
halves of the molecule. In the case of 4c, the asymmetric unit
comprises two half-molecules. The structure of 4b has two
unique molecules, one located on an inversion centre and one
complete molecule in the asymmetric unit. Most significantly,
these X-ray crystallographic studies have shown that the mo-
lecular packing of these compounds hinders effective p–p
stacking of the polycyclic aromatic cores. For example, in the
structures of compounds 4b, 4c and 4d, adjacent molecules have
their polycyclic core planes approximately perpendicular (inter-
planar angles: 4b, 83.0(1)8; 4c, 85.1(1)8; 4d, 83.0(1)8) (Fig. 4).
As a result, the aromatic core of each molecule is sandwiched
between the alkyl chains of its two nearest neighbours; the
closest contact between the aromatic cores being an edge-on
300
400
500
600
700
800
900
Wavelength λ [nm]
Fig. 2. Absorption (solid) and photoluminescent (dashed) spectra of 4a at
room temperature in CH2Cl2.
(a)
(b)
C(30)
C(28)
C(29)
C(27)
C(26)
C(13)
C(12)
C(14)
C(15)
C(11)
C(10)
C(6)
C(9)
C(8)
C(1)
C(5)
C(4)
C(7)
C(16)
C(17)
C(21)
C(18)
C(19)
C(22)
C(23)
C(3)
C(2)
C(20)
C(24)
C(25)
C(24)
C(23)
C(20)
C(11)
C(22)
C(21)
C(6)
C(9)
C(8)
C(10)
C(5)
C(4)
C(7)
C(12)
C(13)
C(1)
C(14)
C(15)
C(25)
C(26)
C(3)
C(16)
C(17)
C(2)
C(18)
C(28)
C(27)
C(19)
Fig. 3. Molecular diagrams of 4c and 4d as shown with 50 % thermal ellipsoids and hydrogen atoms as spheres of arbitrary size; (a) side view; (b) top view.
Only one of the two unique molecules of 4c is shown; the molecular diagrams of the second molecule, along with that of 4b, are shown in the Supplementary
Material.

148
M. Bown et al.
Fig. 4. Molecular packing of 4c, and 4d (above) and 4b (below) showing the polycyclic aromatic core surrounded by alkyl chains from adjacent molecules.
˚
Only the major components of disordered groups are shown. The interplanar separations of the aromatic cores are ,7.5 and 7.7 A for 4c and 4d respectively,
˚
whereas in 4b, there is a closer contact between terminal C6 rings of the parallel polycyclic ring planes of ,3.4 A.
˚
˚
C–HꢁꢁꢁC type (HꢁꢁꢁC separation: 4b, 3.09 A; 4c, 2.94 A; 4d,
to 4a–d, the long n-hexyl chains of the Si-n-hexyl-substituted
sexithiophene occupy and create a large free volume between
adjacent molecules; consistent with our results no field-effect
transistor (FET) activity was observed.[14]
˚
2.81 A) between the terminal C6 ring and one of the central-ring
C atoms. Furthermore, in 4c and 4d, the extended molecular
packing shows layers of parallel molecules with an approximate
˚
interplanar separation of 7.5–7.7 A (Fig. 4), which is too distant
for any p–p stacking interaction. However, there is a subtle
difference in the packing of molecules in 4b, where the two
perpendicular molecules are also individually arrayed into an
offset stack (Fig. 4). The interplanar separation in this case is
Conclusion
We have successfully established an efficient synthetic route to
the previously unknown diindeno[1,2-g:10,20-s]rubicene ring
system. Compounds 4a–d, derivatives of this novel polycyclic
ring system have been prepared and demonstrate photophysical
properties consistent with those required for a potential semi-
conductor. Unfortunately, CELIV measurements indicate that
4a–d have very low bulk charge mobilities, which make them
unsuitable for application in OFETs. X-ray crystallographic
analyses indicate that in the crystalline state, molecules 4b–d
pack in a manner that hinders p–p stacking, thus preventing
strong electronic coupling between molecules that is essential
for high charge mobility semiconductor performance. Further
research on the use of diindeno[1,2-g:10,20-s]rubicene derivatives
˚
,3.4–3.6 A but there is only a small amount of overlap between
the edges of the terminal C6 rings. The packing of these diindeno
[1,2-g:10,20-s]rubicene derivatives is unlike that of 5,13-di-t-
butylrubicine,[13] which has an array of face-to-face p-stacked
pairs of molecules. The packing is, however, similar to 3,30-
dihexylsilylene-2,20:5,200:50,2000:500,20000:5000,200000-sexithiophene,
with two Si-n-hexyl substituents. The molecular backbones of
the Si-n-hexyl-substituted sexithiophene stack along the a axis
in a slipped herringbone motif having a large minimum
˚
distance between the neighbouring backbones of 12.72 A,
indicating negligible p–p stacking interactions. Analogous

Diindeno[1,2-g:10,20-s]rubicene Derivatives
149
as semiconductors will require structural modifications that
enable the molecules to pack with effective p–p stacking.
THF (10 mL), under N2 at ꢀ788C, the solution was stirred at
ꢀ788C for 40 min and 1,5-dichloroanthraquinone 5 (0.57 g,
2.1 mmol) was added under a blanket of N2. The solution was
slowly warmed to room temperature and stirred for 16 h.
Hydrochloric acid (3 M, 10 mL) was slowly added and the
solution stirred for 10 min. The reaction mixture was extracted
with dichloromethane (2 ꢂ 50 mL). The combined organic
phases were washed with water (50 mL ꢂ 3), the solvent
removed under vacuum, the residue redissolved in dichloro-
methane and dried using a DryDiskÒ. Column chromatography
of the residue (silica, 10 % EtOAc/petroleum spirits 40–608C)
gave the title compound as pale yellow gum (1.8 g, 63 %). m/z
(HR-ESIMS, CDCl3/MeOH) 1163.5388 [M þ Ag]þꢃ. Calc. for
C72H90O2Cl2107Ag 1163.5369. dH (400 MHz, CDCl3) 7.92
(2H, m), 7.86 (2H, dd, J 8.0, 2.0), 7.58 (2H, d, J 8.0), 7.40–
7.13 (12H, m), 4.43 (2H, s), 2.06 (8H, m), 1.31–1.12 (40H, m),
0.87 (12H, t, J 8.0), 0.68 (8H, m). dC (100 MHz, CDCl3) 150.97,
150.91, 146.87, 142.24, 140.69, 140.08, 134.47, 132.77, 130.84,
129.25, 128.6, 127.11, 126.8, 124.85, 122.82, 120.38, 119.69,
119.45, 74.66, 55.25, 40.59, 40.51, 31.89, 31.85, 30.21, 30.18,
29.42, 29.34, 29.27, 23.96, 23.85, 22.65, 14.13.
Methods and Materials
1
Unless otherwise specified, all H and 13C NMR spectra were
recorded on a Bruker AV400 spectrometer at 400 and
100.6 MHz respectively, or a Bruker AV200 spectrometer at 200
and 50 MHz respectively, using CDCl3 solutions. Chemical
shifts (d) are measured in ppm, coupling constants (J) in Hz.
TLC was performed on 0.25-mm thick plates precoated with
Merck Kieselgel 60 F254 silica gel, and visualized by UV light
(254 and 366 nm). Positive-ion EI mass spectra were measured
on a ThermoQuest MAT95XL mass spectrometer using an
ionization energy of 70 eV. Positive-ion electrospray mass
spectra (ESIMS) were acquired with a Micromass Q-TOF II
mass spectrometer using a cone voltage of 35 eV and a capillary
voltage of 3.0 kV. High resolution positive-ion electrospray
mass spectra (HR-ESIMS) were obtained with a resolution of
5000–10000 using perfluorokerosene (PFK) as the reference
compound. The sample was introduced by direct infusion at a
rate of 5 mL minꢀ1 using NaI as an internal calibrant. Micro-
analyses were performed by Campbell Microanalytical Labo-
ratory, University of Otago, Dunedin, New Zealand.
The following compounds were prepared by the above
procedure.
Melting points were recorded on a Thermoscientific 9300
digital melting-point apparatus and a Mettler Toledo DSC821
and are uncorrected. UV-Vis spectra were recorded on a Hewlett
Packard HP 8453 diode array UV-vis spectrometer. For films,
the UV-vis absorptivity was calculated by dividing the mea-
sured absorbance by the film thickness. Fluorescence spectra
were recorded on a Perkin Elmer LS50B fluorimeter. Thermal
gravimetric analysis was carried out on a Mettler Toledo TGA/
SDTA851 and differential scanning calorimetry (DSC) was
performed on a Mettler Toledo DSC821. Photo electron spec-
troscopy in air (PESA) measurements were recorded with a
Riken Keiki AC-2 PESA spectrometer with a power setting of
5 nW and a power number of 0.5. Samples for PESA were
prepared on glass substrates. The electrochemistry measure-
ments were carried out using a Powerlab ML160 potentiostat
interfaced via a Powerlab 4/20 controller to a PC running Echem
for Windows ver. 1.5.2. The measurements were run in nitrogen-
purged dichloromethane with tetrabutylammonium hexa-
fluorophosphate (0.2 M) as the supporting electrolyte. The
voltammograms were recorded using a standard three-electrode
configuration with a glassy carbon (2 mm diameter) working
electrode, a platinum wire counter-electrode and a silver wire
pseudo reference electrode. The silver wire was cleaned in
concentrated nitric acid and then in concentrated hydrochloric
acid to generate the Ag/Agþ reference. Voltammograms were
recorded with a sweep rate of 50–200 mV sꢀ1. The sample
concentration was 1 mM. All potentials were referenced to the
E1/2 of the ferrocene/ferrocenium couple. Crystals of 4b, 4c and
4d suitable for X-ray crystallographic analysis were grown from
CH2Cl2/hexane using vapour diffusion techniques. Alkyl fluor-
enes 6a–d were synthesized from literature procedures.[15]
1,5-Dichloro-9,10-bis(9,9-dihexylfluoren-2-yl)-9,10-
dihydroanthracene-9,10-diol 7b
Obtained as a pale yellow glassy solid after chromatography
(silica, 10 % EtOAc/petroleum spirits 40–608C) (68 %). m/z
(HR-ESIMS, CDCl3/MeOH) 967.5013 [M þ Na]þꢃ. Calc. for
C64H74Cl2O2Na 967.4964. dH (400 MHz, CDCl3) 7.91 (1H, bs),
7.86 (2H, dd, J 2.4, 7.2), 7.67 (2H, m), 7.58 (1H, s), 7. 56 (1H, s),
7.39–7.23 (10H, m), 7.13 (2H, bs), 4.41 (2H, s), 2.06 (8H, m),
1.14 (24H, m), 0.87–0.78 (12H, m), 0.66 (8H, m). dC (100 MHz,
CDCl3) 150.96, 150.89, 146.86, 142.22, 140.67, 140.07, 134.45,
132.74, 130.84, 129.23, 128.58, 127.1, 126.79, 124.83, 122.8,
120.36, 119.68, 119.42, 74.65, 55.23, 40.57, 40.45, 31.61,
31.57, 29.79, 29.71, 23.80, 23.74, 22.57, 22.52, 14.07, 14.02.
1,5-Dichloro-9,10-bis(9,9-dipentylfluoren-2-yl)-9,10-
dihydroanthracene-9,10-diol 7c
Obtained as a pale yellow glassy solid after chromatography
(silica, 10 % EtOAc/petroleum spirits 40–608C) (88 %). m/z
(HR-ESIMS, CDCl3/MeOH) 911.4352 [M þ Na]þꢃ. Calc. for
C60H66Cl2O2Na 911.4338. dH (400 MHz, CDCl3) 7.87 (4H, m),
7.56 (2H, d, J 8.0), 7.38–7.21 (10H, m), 7.10 (2H, m), 4.35
(2H, s), 2.03 (8H, m), 1.10 (16H, m), 0.77–0.63 (20H, m). dC
(100 MHz, CDCl3) 150.93, 150.88, 146.87, 142.16, 140.64,
140.06, 134.44, 132.70, 130.82, 129.25, 128.58, 127.09,
126.77, 124.79, 122.77, 120.34, 119.66, 119.41, 74.64, 55.20,
40.46, 40.33, 32.29, 32.21, 23.42, 23.4, 22.35, 22.29, 14.01,
13.95.
1,5-Dichloro-9,10-bis(9,9-dibutylfluoren-2-yl)-9,10-
dihydroanthracene-9,10-diol 7d
Obtained as a white glassy solid after chromatography
(silica, 10 % EtOAc/petroleum spirits 40–608C) (64 %). m/z
(HR-ESIMS, CDCl3/MeOH) 832.3808 [M þ Na]þꢃ. Calc. for
C56H58Cl2O2 832.3814. dH (400 MHz, CDCl3) 7.89–7.84 (4H,
m), 7.65 (2H, m), 7.56 (2H, d, J 8), 7.38–7.23 (10H, m), 7.10
(2H, m), 4.34 (2H, s), 2.07 (8H, m), 1.13 (8H, m), 0.77–0.69
(20H, m). dC (50 MHz, CDCl3) 150.9, 146.9, 142.15, 140.64,
140.07, 134.43, 132.67, 130.83, 129.26, 128.59, 127.09, 126.78,
General Synthesis Procedure for 1,5-Dichloro-9,10-bis
(9,9-dialkylfluoren-2-yl)-9,10-dihydroanthracene-
9,10-diol 7a–d
1,5-Dichloro-9,10-bis(9,9-dioctylfluoren-2-yl)-9,10-
dihydroanthracene-9,10-diol 7a
n-BuLi (1.6 M in hexanes, 3.6 mL, 5.8 mmol) was added to a
solution of 2-bromo-9,9-dioctylfluorene 6a (3.0 g, 6.4 mmol) in

150
M. Bown et al.
124.79, 122.81, 120.35, 119.66, 119.41, 74.64, 55.13, 40.25,
40.08, 26.01, 23.16, 23.02, 13.94, 13.88.
0.85–0.67 (20H, m). Compound was not soluble enough for
13C NMR.
General Synthesis Procedure for 9,9,19,19-Tetraalkyl-4,19-
dihydrodiindeno-[1,2-g:10,20-s]rubicene 4a–d
General Synthesis Procedure for 1,5-Dichloro-9,10-bis
(9,9-dialkylfluoren-2-yl)anthracene 8a–c
9,9,19,19-Tetraoctyl-9,19-dihydrodiindeno
[1,2-g:10,20-s]rubicene 4a
1,5-Dichloro-9,10-bis(9,9-dioctylfluoren-2-yl)
anthracene 8a
1,5-dichloro-9,10-bis(9,9-dioctylfluoren-2-yl)anthracene 7a
(0.95 g, 0.93 mmol), bis(tricyclohexylphosphine)palladium(II)
chloride (0.20 g, 0.27 mmol), 1,8-diazabicyclo[5.4.0]undec-7-
ene (10 mL) and N,N-dimethylacetamide (23 mL) were placed
in an ampoule, with a stirring bead. The ampoule was degassed
by three freeze–evacuate–thaw cycles, sealed under vacuum
(,0.05 mmHg) and then heated with stirring at 1408C for 65 h.
The ampoule was cooled, opened and the solution poured into
methanol (100 mL). The resulting red precipitate was collected
by filtration and washed with methanol. Column chromatogra-
phy (silica, 10 % CH2Cl2/petroleum spirits 40–608C) gave the
title compound as a dark maroon powder (0.56 g, 64 %). mp
A mixture of potassium iodide (4.1g, 27.3 mmol) and sodium
hypophosphite hydrate (4.2 g, 47.6 mmol) in acetic acid
(30 mL) was heated gently until the solids had dissolved. The hot
solution was added to diol 7a (1.2 g, 2.2 mmol) and the resulting
suspension heated at reflux for 4 h. The cooled suspension was
filtered and the collected solid washed with water (100 mL)
followed by MeOH (100 mL) to give the title compound as a
yellow powder of sufficient purity for further reaction. mp 161–
1628C. m/z (HR-ESIMS, CDCl3/MeOH) 1022.6282 [M]þꢃ
.
Calc. for C72H88Cl2 1022.6263. dH (400 MHz, CDCl3) 7.83
(4H, dd, J 8.0, 2.4), 7.69 (4H, d, J 8.8), 7.50 (4H, d, J 6.8), 7.41–
7.34 (10H, m), 7.14 (2H, dd, J 7.2, 1.2), 2.0 (m, 8H), 1.22–1.08
(m, 40H), 0.83 (m, 20H). dC (100 MHz, CDCl3) 151.03, 151.01,
150.15, 150.12, 141.04, 140.66, 139.73, 137.85, 133.90, 131.68,
131.66, 130.07, 129.54, 127.57, 127.14, 126.88, 126.82, 126.29,
124.48, 122.81, 119.78, 118.91, 114.99, 55.19, 40.75, 40.55,
31.84, 30.11, 30.05, 29.38, 29.36, 29.25, 29.21, 24.01, 23.82,
22.61, 14.09.
203–2068C. m/z (HR-ESIMS, CDCl3/MeOH) 950.6730 [M]þꢃ
.
Calc. for C72H86 950.6764. Found: C 90.88, H 9.18. Calc.:
C 90.89, H 9.11 %. dH (400 MHz, CDCl3) 8.69 (2H, d, J 8.8),
8.20 (2H, s), 8.25 (2H, s), 8.12 (2H, d, J 6.8), 7.86 (4H, m), 7.43–
7.33 (6H, m), 2.15 (8H, m), 1.10 (40H, m), 0.91–0.68 (20H, m).
dC (50 MHz, CDCl3) 151.41, 151.19, 141.12, 140.39, 139.51,
138.92, 138.46, 133.76, 133.69, 128.86, 126.98, 126.85, 125.39,
124.50, 122.86, 119.90, 119.56, 118.05, 113.04, 55.29, 40.73,
31.77, 30.10, 29.70, 29.22, 23.86, 22.54, 14.00.
The following compounds were prepared by the above
procedure.
The following compounds were prepared by the above
procedure.
1,5-Dichloro-9,10-bis(9,9-dihexylfluoren-2-yl)
anthracene 8b
Obtained as a yellow powder (83 %). mp 202–2038C. m/z
(HR-ESIMS, CDCl3/MeOH) 933.4947 [M þ Na]þꢃ. Calc. for
C64H74Cl2Na 933.4909. dH (400 MHz, CDCl3) 7.83 (4H, m),
7.68 (2H, M), 7.50 (2h, d, J 6.8), 7.40–7.34 (10H, m), 7.14 (1H, d
7.2 J), 7.12 (1H, d, J 6.8), 1.99 (8H, m), 1.66–1.07 (24H, m),
0.79–0.65 (22H, m). dC (400 MHz, CDCl3) 151.02, 151.01,
150.16, 150.12, 141.05, 140.68, 139.74, 139.72, 137.85,
133.9, 131.67, 131.66, 130.1, 129.56, 127.57, 127.16, 126.91,
126.83, 126.28, 124.49, 122.81, 119.81, 119.79, 118.94, 118.92,
55.22, 55.19, 40.76, 31.62, 31.6, 29.74, 29.68, 29.64, 23.91,
23.76, 22.56, 22.51, 22.49, 14.03.
9,9,19,19-Tetrahexyl-9,19-dihydrodiindeno
[1,2-g:10,20-s]rubicene 4b
Obtained as a dark rusty maroon powder following column
chromatography (silica, 20 % CH2Cl2/petroleum spirits
40–608C) (67 %). mp 249–2528C. m/z (HR-ESIMS, CDCl3/
MeOH) 838.5488 [M]þꢃ. Calc. for C64H70 838.5478. Found
C 91.45, H 8.41. Calc.: C 91.59, H 8.41 %. dH (400MHz, CDCl3)
8.69 (2H, d, J 8.4), 8.30 (2H, s), 8.25 (2H, s), 8.11 (2H, d, J 6.9),
7.85 (4H, m), 7.43–7.33 (6H, m), 2.16 (8H, m), 1.10 (24H, m),
0.91–0.69 (20H, m). dC (50 MHz, CDCl3) 151.39, 151.17,
141.1, 140.37, 139.49, 138.9, 138.44, 133.73, 133.67, 128.86,
126.96, 126.84, 125.36, 124.48, 122.84, 119.89, 119.55, 118.02,
113.02, 55.26, 40.73, 31.49, 29.75, 23.81, 22.54, 13.93.
1,5-Dichloro-9,10-bis(9,9-dipentylfluoren-2-yl)
anthracene 8c
9,9,19,19-Tetrapentyl-9,19-dihydrodiindeno
Obtained as a yellow powder (87 %). mp 278–2798C. m/z
(HR-ESIMS, CDCl3/MeOH) 877.4294 [M þ Na]þꢃ. Calc. for
C60H64Cl2Na 877.4283. dH (400 MHz, CDCl3) 7.83 (4H, m),
7.68 (2H, d, J 9.2), 7.50 (2H, d, J 6.8), 7.39–7.33 (10H, m), 7.14
(1H, d, J 8.8), 7.12 (1H, d, J 8.8), 2.0 (8H, m), 1.09 (16H, m),
0.86–0.65 (20H, m). dC (50 MHz, CDCl3) 150.99, 150.10,
150.06, 141.03, 140.65, 139.7, 137.81, 133.87, 131.61,
130.06, 129.54, 127.55, 127.13, 126.86, 126.8, 126.24,
124.45, 122.77, 119.77, 118.91, 55.19, 55.16, 40.68, 40.47,
32.3, 32.16, 32.14, 23.54, 23.46, 22.39, 22.33, 14.02, 13.94.
[1,2-g:10,20-s]rubicene 4c
Obtained as a dark purple solid following column chroma-
tography (silica, 30 % CH2Cl2/petroleum spirits 40–608C). mp
344–3468C. m/z (HR-ESIMS, CDCl3/MeOH) 782.4852 [M]þꢃ
.
Calc. for C60H62 782.4821. Found C 92.02, H 7.98. Calc.
C 92.13, H 7.90 %. dH (400 MHz, CDCl3) 8.668 (2H, d, J 8.8),
8.30 (1H, s,), 8.25 (1H, s), 8.11 (1H, J 6.4), 7.85 (4H, m), 7.43–
7.33 (6H, m), 2.15 (8H, m), 1.10 (16H, m), 0.89–0.68 (20H, m).
dC (50 MHz, CDCl3) 151.38, 151.16, 141.1, 140.37, 139.5,
138.9, 138.43, 133.72, 133.66, 128.86, 126.97, 126.84,
125.36, 124.46, 122.83, 119.89, 119.55, 118.00, 113.03,
55.25, 40.69, 32.29, 23.53, 22.29, 13.95.
1,5-Dichloro-9,10-bis(9,9-dibutylfluoren-2-yl)
anthracene 8d
Obtained as a yellow powder (52 %). mp 320–3268C. m/z
(HR-ESIMS, CDCl3/MeOH) 821.36601 [M þ Na]þꢃ. Calc. for
C56H56Cl2Na 821.36565. dH (400 MHz, CDCl3) 7.85 (4H, m),
7.71 (2H, dd, J 1.2, 7.6), 7.53 (2H, d, J 6.8), 7.40 (10H, m), 7.18
(1H, d, J 7.2), 7.15 (1H, d, J 7.2), 2.03 (8H, m), 1.13 (8H, m),
9,9,19,19-Tetrabutyl-9,19-dihydrodiindeno
[1,2-g:10,20-s]rubicene 4d
Obtained as a dark purple, almost black, solid following
column chromatography (silica, 20 % CH2Cl2/petroleum spirits

Diindeno[1,2-g:10,20-s]rubicene Derivatives
151
40–608C). mp 420–4228C (DSC). m/z (HR-ESIMS, CDCl3/
MeOH) 726.4222 [M]þꢃ. Calc. for C56H54 726.4226. Found
C 92.47, H 7.72. Calc.: C 92.51, H 7.49 %. dH NMR (400 MHz,
CDCl3) 8.70 (2H, d J 8.4), 8.31 (2H, s), 8.26 (2H, s), 8.12 (2H, d
J 6.8), 7.87 (4H, m), 7.43–7.33 (6H, m), 2.16 (8H, m), 1.14 (8H,
m), 0.85–0.67 (20H, m). dC (50 MHz, CDCl3) 151.38, 151.16,
141.11, 140.38, 139.5, 138.91, 138.44, 133.68, 128.89, 126.97,
126.84, 125.38, 124.49, 122.85, 119.98, 119.92, 119.55, 118.03,
113.03, 55.19, 40.55, 26.03, 23.11, 13.80.
C(30–32) and C(87–90) were also modelled as disordered
(occupancies fixed at 0.50 : 0.50 and 0.60 : 0.40 respectively)
with restrained C–C bond lengths, C–C–C bond angles and
anisotropic displacement parameters.
9,9,19,19-Tetrapentyl-9,19-dihydrodiindeno
[1,2-g:10,20-s]rubicene 4c
C60H62, FW 783.10. CCDC 842100. Red plate 0.20 ꢂ 0.18 ꢂ
0.05 mm, T ¼ 123(1) K, triclinic P(–1); a ¼ 9.883(2),
˚
b ¼ 13.629(3), c ¼ 17.419(3) A; a ¼ 91.449(6), b ¼ 94.875(9),
X-Ray Crystal Structure Determinations for
9,9,19,19-Tetraalkyl-4,19-dihydrodiindeno-
[1,2-g:10,20-s]rubicene 4b–d
3
g ¼ 109.933(6)8; V ¼ 2194.(7) A , Z ¼ 2, rcalc ¼ 1.185 g cmꢀ3
,
˚
m ¼ 0.066 mmꢀ1
,
Tmin/Tmax ¼ 0.68, Nt ¼ 16463, N ¼ 8167
(Rint ¼ 0.066 (statistics for all single and composite reflec-
tions)), R ¼ 0.078, wR2 ¼ 0.191 (for 4212 reflections with
I . 2sI), R ¼ 0.141, wR2 ¼ 0.251 (all data), GoF ¼ 0.956.
X-ray diffraction data were collected for representative crystals
of 4b–d, covered in viscous oil and mounted onto a glass fibre,
using a Bruker APEXII CCD diffractometer and MoKa radia-
˚
tion, l ¼ 0.71073 A, equipped with an Oxford Cryosystems 700
9,9,19,19-Tetrabutyl-9,19-dihydrodiindeno
[1,2-g:10,20-s]rubicene 4d
temperature controller. Data collection and data reduction were
performed using the Bruker Apex2 v2.0 program suite.[16]
A sphere or hemisphere of diffraction data (Nt) was collected to
2y ¼ 508 using 0.58 correlated images and a combination of f
C56H54, FW 726.99. CCDC 842101. Red plate 0.20 ꢂ 0.17 ꢂ
0.05 mm, T ¼ 123(1) K, monoclinic P21/c; a ¼ 9.7315(12),
3
and v scans. Data were corrected for absorption (SADABS[16]
)
˚
˚
b¼ 15.945(2), c¼ 14.204(2) A; b¼ 109.908(4)8, V¼ 2072.2(4) A ,
Z ¼ 2, rcalc ¼ 1.165 g cmꢀ3, m ¼ 0.065 mmꢀ1, Tmin/Tmax ¼ 0.59,
Nt ¼ 6032, N ¼ 3591 (Rint ¼ 0.079), R ¼ 0.071, wR2 ¼ 0.140
(for 1453 reflections with I . 2sI), R ¼ 0.199, wR2 ¼ 0.193
(all data), GoF ¼ 0.934. One of the butyl arms, C(25–28), was
modelled as disordered with C(27) and C(28) refined in two
positions (occupancies fixed at 0.60 : 0.40 after trial refine-
ment). The geometry of the minor component was restrained
to be similar to that of the major component.
and merged to N unique reflections (Rint as quoted) that were
used for structure solution by direct methods and full matrix
least-squares refinement using SHELX97[17] in conjunction with
the X-SEED interface.[18] Hydrogen atoms were placed in cal-
culated positions and refined using a riding model (C–H
˚
0.954 A, Uiso(H) ¼ 1.5 ꢂ Uiso(C) for CH3 or Uiso(H) ¼ 1.2 ꢂ
Uiso(C) for all other groups). Crystal and refinement details are
listed below. In all cases, the samples appeared visually as well-
formed crystals but gave problematic diffraction data. Several
samples were measured for each compound under differing
conditions, the presented data representing the best in each case.
For compound 4c, several off-lattice reflections were observed
in all samples. For the final dataset, two twin domains, related by
1808 rotation about reciprocal axis 0 0 1, were identified using
CELL_NOW[16] and the images were processed using SAINT1/
TWINABS,[16] resulting in a total of 16463 reflections, of which
4059 were from domain 1, 4055 were from domain 2 and 8349
were composite. Successful refinement of the structure with
HKLF5 gave a twin ratio 0.254.
Supplementary Material
1
Supplementary material containing H and 13C NMR data for
compounds, 7a–d, 8a–d, 4a and additional crystallographic
details of structures 4b–d is available from the Journal’s
website.
Acknowledgements
We thank Dr Roger Mulder and Dr Jo Cosgriff for assistance with NMR
spectroscopy and Mr Carl Braybrook and Dr Jo Cosgriff for mass
spectrometry.
9,9,19,19-Tetrahexyl-9,19-dihydrodiindeno
[1,2-g:10,20-s]rubicene 4b
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