data of 6 and 15 were corrected for absorption by numerical
integration based on real crystal shape. The diffraction data of
15 carries internal signs of twinning, which we were unable to
rationalize. This (or an imperfect absorption correction) is
probably responsible for the relatively high final R and four
residual peaks of electron density (2.84 to 4.34 eÅϪ3) at
distances of 0.96 to 0.99 Å from both bromine atoms. The
structures were solved by direct methods and refined by full-
matrix least squares against F 2 of all data, using SHELXTL
software.
(Journals Grant for International Authors) for funding visits by
I. F. P. to Durham; B. P. L. thanks Sony Europe plc for provid-
ing a CASE studentship; A. P. M. thanks the Leverhulme
Foundation for a fellowship. M. R. B. and A. P. M. thank
Durham County Council under the Science and Technology
for Business and Enterprise Programme SP/082 for funding the
purchase of equipment used in this work.
References
1 Review: Y. Shirota, J. Mater. Chem., 2000, 10, 1.
2 Reviews: (a) A. Kraft, A. C. Grimsdale and A. B. Holmes, Angew.
Chem., Int. Ed., 1998, 37, 402; (b) U. Mitschke and P. Bäuerle,
J. Mater. Chem., 2000, 10, 1471.
Photoluminescence measurements
Photoluminescence spectra were recorded using a Jobin-Yvon
Horiba Fluorolog 3–22 Tau-3 spectrofluorimeter with a 0.5–2
nm bandpass using a Xenon lamp. Spectra were recorded using
conventional 90Њ geometry with an excitation at 355 nm. The
film PLQY were measured using a Jobin-Yvon Fluoromax
spectrofluorimeter equipped with an integrating sphere.36 The
standards for PLQY were quinine sulfate (Φ = 0.577 in 0.1 M
H2SO4) and β-carbolene (Φ = 0.60 in 0.5 M H2SO4), and
excitation was at 350 nm in both cases.
3 Review: D. Fichou, J. Mater. Chem., 2000, 10, 571.
4 Review: M. Thelakkat and H.-W. Schmidt, Polym. Adv. Technol.,
1998, 9, 429.
5 (a) Z. Peng, Z. Bao and M. E. Galvin, Chem. Mater., 1998, 10, 2086;
(b) C. Wang, M. Kilitziraki, L.-O. Pålsson, M. R. Bryce,
A. P. Monkman and I. D. W. Samuel, Adv. Funct. Mater., 2001, 11,
47; (c) C. Wang, G.-Y. Jung, A. S. Batsanov, M. R. Bryce and
M. C. Petty, J. Mater. Chem., 2002, 12, 173.
6 (a) J. K. Kim, J. W. Yu, J. M. Hong, H. N. Cho, D. Y. Kim and
C. Y. Kim, J. Mater. Chem., 1999, 9, 2171; (b) J. A. Irvin, C. J.
DuBois and J. R. Reynolds, Chem. Commun., 1999, 2121; (c)
C. Wang, M. Kilitziraki, J. A. H. MacBride, M. R. Bryce,
L. Horsburgh, A. Sheridan, A. P. Monkman and I. D. W. Samuel,
Adv. Mater. (Weinheim, Ger.), 2000, 12, 217; (d ) A. P. Monkman,
L.-O. Pålsson, R. W. T. Higgins, C. Wang, M. R. Bryce and
J. A. K. Howard, J. Am. Chem. Soc., 2002, 124, 6049.
7 (a) X. Zhang, A. S. Shetty and S. A. Jenekhe, Acta Polym., 1998, 49,
52; (b) X. Zhang and S. A. Jenekhe, Macromolecules, 2000, 33, 2069.
8 K. R. J. Thomas, J. T. Lin, Y-T. Tao and C. H. Chuen, J. Mater.
Chem., 2002, 12, 3516.
9 (a) T. Kanbara, T. Kushida, N. Saito, I. Kuwayiama, K. Kubota and
T. Yamamoto, Chem. Lett., 1992, 583; (b) C. C. Wu, Y. T. Lin,
H. H. Chiang, T. Y. Cho, C. W. Chen, K. T. Wong, Y. L. Liao,
G. H. Lee and S. M. Peng, Appl. Phys. Lett., 2002, 81, 577.
10 R. Gompper, H. Mair and K. Polborn, Synthesis, 1997, 696.
11 (a) M. T. Bernius, M. Inbasekaran, J. O’Brien and W. Wu, Adv.
Mater. (Weinheim, Ger.), 2000, 12, 1737; (b) S. Destri, M. Pasini,
C. Botta, W. Porzio, F. Bertini and L. Marchio, J. Mater. Chem.,
2002, 12, 924; (c) Review: U. Scherf and E. J. W. List, Adv. Mater.
(Weinheim, Ger.), 2002, 14, 477; (d ) D.-H Hwang, J.-D Lee,
J.-M. Kang, S. Lee, C.-H. Lee and S.-H. Jin, J. Mater. Chem., 2003,
13, 1540.
12 (a) S. W. Chang, J.-M. Hong, J. W. Hong and H. N. Choi, Polym.
Bull., 2001, 47, 231; (b) S. Beaupré, M. Ranger and M. Leclerc,
Macromol. Rapid Commun., 2000, 21, 1013; (c) H. N. Cho,
J. K. Kim, D. Y. Kim, C. Y. Kim, N. W. Song and D. Kim,
Macromolecules, 1999, 32, 1476; (d ) M. Ranger, D. Rondeau and
M. Leclerc, Macromolecules, 1997, 30, 7686.
Fabrication of light-emitting devices
A hole-conducting poly(ethylenedioxythiophene) (PEDOT)
layer (30 nm thick) was spun onto an etched ITO glass substrate
(20 Ω/ᮀ), and then baked overnight in a vacuum oven at 50 ЊC
to remove residual water. A dilute solution of compound 16 in
toluene (ca. 0.5 mg cmϪ3) was then drop-cast onto the PEDOT
to form an active layer (ca. 300 nm thick, as confirmed by
AlphaStep measurements). On top of this layer, a cathode of 50
nm thick calcium capped with 50 nm thick aluminium was
deposited by evaporation under high vacuum.
Electrochemical measurements
Cyclic voltammetry experiments were performed on a BAS
CV50W electrochemical analyzer with iR compensation.
Platinum wire, platinum disk (∅ 1.6 mm) and Ag/Agϩ were
used as counter, working, and reference electrodes, respectively.
CV experiments were performed in dry dichloromethane with
Ϫ
0.2 M Bu4NϩPF6 as supporting electrolyte; concentrations of
compounds were ca. 10Ϫ3 MϪ1. The scan rate was varied from
50 to 500 mV sϪ1. The potentials were referenced to Fc/Fcϩ
couple as the internal reference, which showed a potential of
ϩ0.17 V vs. Ag/Agϩ in our conditions.
13 For a review of cross-coupling methodology in oligomer/polymer
synthesis see: (a) A. D. Schluter, J. Polym. Sci., Part A: Polym.
Chem., 2001, 39, 1533; (b) J. Hassan, M. Sévignon, C. Gozzi,
E. Schulz and M. Lemaire, Chem. Rev., 2002, 102, 1359.
Computational procedure
The ab initio computations were carried out with the Gaussian
9837 package of programs at both Hartree–Fock and density-
functional theory levels using Pople’s 6–31G split valence basis
set supplemented by d-polarisation functions on heavy atoms
and p-polarisation functions on hydrogens. DFT calculations
were carried out using Becke’s three-parameter hybrid
exchange functional38 with either Lee–Yang–Parr correlation
functional39 (B3LYP) or Perdew–Wang 1991 gradient-
corrected correlation functional40 (B3PW91). Geometries
were optimised with HF/6-31G(d,p), B3LYP/6-31G(d,p) and
B3PW91/6-31G(d,p) and electronic structures were calculated
at the same levels. Contours of HOMO and LUMO orbitals
were also calculated at HF/6-31G(d,p)//B3LYP/6-31G(d,p)
level and visualisation of frontier orbital populations was
performed using Molekel v.4.2 program.41 No constraints of
bonds/angles/dihedral angles were applied in the calculations
and all the atoms were free to optimise.
14 (a) D. J. Brown and J. M. Lyall, Aust. J. Chem., 1964, 17, 794; (b)
B. W. Arantz and D. J. Brown, J. Chem. Soc., C, 1971, 1889; (c)
H. Schlosser and R. Wingen, U. S. Patent, 5,371,224, 1994.
15 (a) G. Cooke, H. A. de Cremiers, V. M. Rotello, B. Tarbit and
P. E. Vanderstraeten, Tetrahedron, 2001, 57, 2787; (b) J. M.
Schoemaker and T. J. Delia, J. Org. Chem., 2001, 66, 7125; (c)
K.-T. Wong, T. S. Hung, Y. Lin, C.-C. Wu, G.-H. Lee, S.-M. Peng,
C. H. Chou and Y. O. Su, Org. Lett., 2002, 4, 513; (d ) P. M. Murphy,
V. A. Phillips, S. A. Jennings, N. C. Garbett, J. B. Chaires,
T. C. Jenkins and R. T. Wheelhouse, Chem. Commun., 2003, 1160.
16 (a) Compound 6: J. Nasielski, A. Kirsh-Demesmaeker and
R. Nasielski-Hinkens, Tetrahedron, 1972, 28, 3767; (b) Compound 7:
R. M. Wagner and C. Jutz, Chem. Ber., 1971, 104, 2975.
17 A. F. Littke, C. Dai and G. C. Fu, J. Am. Chem. Soc., 2000, 122, 4020.
18 For alternative procedures for alkylation of 2,7-dibromofluorene to
yield 9 see: (a) W.-Y. Wong, K.-H. Choi, G.-L. Lu, J.-X. Shi, P.-Y. Lai
and S.-M. Chan, Organometallics, 2001, 20, 5446; (b) W.-Y. Wong,
G.-L. Lu, K.-H. Choi and J.-X. Shi, Macromolecules, 2002, 35, 3506;
(c) S. H. Lee and T. Tsutsui, Thin Solid Films, 2000, 363, 76; (d )
W.-L. Yu, J. Pei, Y. Cao, W. Huang and A. J. Heeger, Chem.
Commun., 1999, 1837; (e) M. Ranger and M. Leclerc, Chem.
Commun., 1997, 1597.
Acknowledgements
We thank EPSRC for funding; The Royal Society (RS-NASU
Exchange Program) and The Royal Society of Chemistry
19 For alternative procedures of obtaining compound 10 from 9 see: (a)
Ref. 18d.; (b) B. Liu, W.-L. Yu, Y.-H. Lai and W. Huang,
O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 3 0 6 9 – 3 0 7 7
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