161025 mbar and capped with aluminium to prevent oxida-
tion. LEDs were tested under vacuum using a Keithley source
measure unit and a calibrated photodiode. Typical device areas
were 2 mm2. Current±voltage measurements were made in
steps of 0.1 V at intervals of 300 ms. Device ef®ciencies were
deduced from measurements of the light emitted in the forward
direction following Greenham et al.11 The electroluminescence
spectrum was measured with a CCD spectrometer.
dC(CDCl3; 250 MHz) 56, 120, 122, 138, 153, 173, 174, and 190;
m/z (APCIz) 417.4 (MHz 100%).
Tetramethyl 1,4-phenylenedimethylenediphosphonate9
A
solution of 1,4-bis(chloromethyl)benzene (10.00 g,
57.1 mmol) in trimethyl phosphite (37.5 cm3, 35.65 g,
287.30 mmol) was heated at re¯ux for 15 h. Excess trimethyl
phosphite was removed by distillation and the crude product
was distilled under reduced pressure to give a clear colourless
oil of tetramethyl 1,4-phenylenedimethylenediphosphonate
which solidi®ed on cooling (11.95 g, 65%) bp 217±220 ³C at
0.15 mmHg (Found: C, 44.67; H, 6.08. C12H20P2O6 requires C,
44.73; H, 6.26%); nmax(KBr disc)/cm21 1037, 1044 (POCH3),
and 1259 (PLO); lmax(CH2Cl2)/nm (log e) 213sh (2.33), 258
(2.40), 265 (2.45), 270 (2.34), and 273sh (2.25); dH(CDCl3;
2-Chloro-4,6-dimethoxy-1,3,5-triazine (2)
A freshly prepared solution of sodium methoxide in methanol
(1 M, 100 cm3) was added dropwise to an ice cold solution of
2,4,6-trichloro-1,3,5-triazine (9.20 g, 50.0 mmol) in toluene
(100 cm3) under argon whilst maintaining the reaction
temperature at 0 ³C. The reaction mixture was stirred at 0 ³C
for 2 h with the progress of the reaction being monitored by
GC±MS. The cold reaction mixture was ®ltered, and the
residue washed well with cold dichloromethane. The ®ltrate
was collected and the solvent completely removed to yield a
white crystalline solid (8.49 g). The residue was puri®ed by
column chromatography over silica using ethyl acetate±light
petroleum (1 : 3) as eluent and two bands were collected and the
solvent completely removed. The front running band contained
2,4-dichloro-6-methoxy-1,3,5-triazine6a which was isolated as a
white solid (0.89 g, 10%) dH(CDCl3; 200 MHz) 4.14 (3H, s,
OCH3); m/z (GC±MS) 181.0 (MHz 100%). The second eluting
band contained 2 which was isolated as a white solid (7.20 g,
82%) mp 75±76 ³C (lit.,7 75±76 ³C) (Found: C, 34.50; H, 3.36;
N, 24.12. C5H6ClN3O2 requires C, 34.21; H, 3.44; N, 23.93%);
200 MHz) 3.16 (4 H, d, 2JPCH ~20 Hz, CH2) 3.68 (6 H, d,
2
3JPOCH~11 Hz, OCH3), and 7.27 (4 H, s, ArH); dC(CDCl3;
250 MHz) 32 (d, J~9 Hz), 53 (t, J~3 Hz), and 130; m/z
(ETOF CIz ) 323.1 (MHz 100%).
(E),(E)-3',3@,5',5@-Tetrakis(4,6-dimethoxy-1,3,5-triazin-2-
yloxy)distyrylbenzene (6)
Sodium hydride (60% dispersion in oil; 30 mg, 0.74 mmol) was
added to a solution of tetramethyl 1,4-phenylenedimethylene-
diphosphonate (100 mg, 0.31 mmol) in dry N,N-dimethylfor-
mamide (0.6 cm3) at room temperature under nitrogen. The
mixture was stirred at room temperature for 1 h. Compound 5
(260 mg, 0.62 mmol) was added to the solution and the reaction
mixture was stirred at room temperature for 3 h. Ether (5 cm3)
was added to the reaction mixture which caused precipitation
of a yellow gum. The supernatant was removed and the residue
was repeatedly triturated with ether until the crude product was
a free ¯owing solid. The residue was puri®ed by chromatotron
chromatography using light petroleum±dichloromethane±
triethylamine (50 : 49 : 1) as eluent. The ®rst band was collected
and the solvent completely removed to give 6 as a pale yellow
powder (39.1 mg, 28%) mp 220±221 ³C (Found C, 55.53; H,
4.15; N, 18.23. C42H38N12O12 requires C, 55.88; H, 4.24; N,
18.61%); nmax(KBr disc)/cm21 1366 and 1570; lmax(CH2Cl2)/
nm (log e) 347sh (4.79), 360 (4.79), and 380sh (4.58); dH(CDCl3,
200 MHz) 4.01 (24 H, s, OCH3, 6.97 (2 H, dd,
l
max(CH2Cl2)/nm (log e) 236 (4.63); dH(CDCl3, 200 MHz) 4.09
(3H, s, OCH3); m/z (GC±MS) 176 (MHz 100%).
3,5-Dihydroxybenzaldehyde (4)
Freshly prepared Jones' reagent was added dropwise to an ice
cold solution of 3,5-dihydroxybenzyl alcohol (3) (4.00 g,
28.5 mmol) in distilled acetone (178 cm3) over 6 min. The
reaction temperature was maintained at 0 ³C during the
addition. The mixture was stirred for a further 7 min at 0 ³C
and then poured into diethyl ether (1500 cm3). The organic
layer was washed with saturated sodium bicarbonate solution
(66100 cm3), brine (56120 cm3), dried over anhydrous
sodium sulfate, ®ltered, and the solvent completely removed
to give 4 as a pale brown solid (3.11 g, 79%) mp 161±162 ³C
(lit.,8 162±163 ³C); dH(CD3COCD3; 200 MHz) 6.65 (1 H, dd,
J2',4'~J6',4'~2 Hz, C(4')H), 7.08 (4 H, s, vinyl H), 7.25 (4 H,
d, J4',2'~J4',6'~2 Hz, C(2')H and C(6')H), and 7.49 (4 H, s,
C(4)H); m/z (APCIz) 903 (Mz) and 904 (MHz).
J
2,4~J6,4~3 Hz, C(4)H), 6.88 (2 H, d, J4,2~J4,6~3 Hz, C(2)H
Acknowledgements
and C(6)H), 8.77 (2 H, s, ArOH), and 9.84 (1 H, s, CHO).
We wish to thank the EPSRC Electronic Materials for Displays
Programme and Raychem Ltd. for ®nancial support.
I.D.W.S. is a Royal Society University Research Fellow.
3,5-Bis(4',6'-dimethoxy-1',3',5'-triazin-2-yloxy)benzaldehyde (5)
Sodium hydride (60% dispersion in mineral oil; 1.22 g,
30.4 mmol) was added to a stirred solution of 2-chloro-4,6-
dimethoxy-1,3,5-triazine(5.21 g,29.7 mmol)and3,5-dihydroxy-
benzaldehyde (2.00 g, 14.5 mmol) in anhydrous tetrahydro-
furan (280 cm3) at room temperature under argon. The
reaction mixture was stirred at room temperature for 20 h
and then water (120 cm3) and dichloromethane (400 cm3) were
added. The organic layer was separated, and the aqueous layer
was extracted with dichloromethane (46100 cm3). The com-
bined organic layers were dried over anhydrous sodium sulfate,
®ltered, and the solvent completely removed to give a cream
solid. The residue was puri®ed by precipitation from chloro-
form by the addition of ®ve-fold excess of ether to give 5 as a
white powder (5.66 g, 94%) mp 181±183 ³C (Found: C, 49.25;
H, 3.79; N, 20.26. C17H16N6O7 requires C, 49.04; H, 3.87; N,
20.19%); nmax(KBr disc)/cm21 1712 (CHO); lmax(CH2Cl2)/nm
(log e) 248 (5.43) and 297 (3.35); dH(CDCl3; 500 MHz) 3.99 (12
H, s, OCH3), 7.27 (1 H, dd, J2,4~J6,4~2 Hz, C(4)H), 7.66 (2 H,
d, J4,2~J4,6~2 Hz, C(2)H and C(6)H), and 10.0 (1 H, s, CHO);
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