Chemistry of Materials
ARTICLE
was purified through column chromatography (SiO2; petroleum ether)
to yield 2 as a white solid (2.56 g, 71%); mp 249 ꢀC.
6.277 (m, 1H, J = 1.4,7.8 Hz). 13C NMR (75 MHz, DMSO-d6, δ):
154.445, 154.076 (d, JC,P = 2.9 Hz), 150.926, 139.544, 133.343 (d,
JC,P =11.9 Hz), 132.887, 131.967 (d, JC,P =11.1 Hz), 132.365 (d, JC,P =
1H NMR (400 MHz, DMSO-d6, δ): 8.02(d, 2H, J = 7.6 Hz),
7.434ꢀ7.491 (m, 4H), 7.321ꢀ7.281 (t, 4H, J = 8.8 Hz), 7.148 (d, 2H,
J = 7.6 Hz), 6.265 (d, 2H, J = 2.4 Hz). 13C NMR (75 MHz, DMSO-d6,
δ): 156.6, 151.1, 137.6, 131.4, 129.1, 128.7, 127.8, 123.6, 123.1, 122.4,
121.4, 117.1, 54.3. HRMS (m/z): 488 [M+]. Elemental anal. Calcd (%)
for C25H14Br2O: C, 61.26; H, 2.88; O, 3.26. Found: C, 61.33; H, 2.91;
O, 3.42.
104.6 Hz), 131.812 (d, JC,P =9.8 Hz), 131.601 (d, JC,P =2.8 Hz),
128.326 (d, JC,P =5.5 Hz), 128.179, 128.006, 123.545 (d, JC,P =94.6 Hz),
126.002, 125.635 (d, JC,P =13.1 Hz), 125.397, 124.690, 123.955,
120.084, 117.203 (d, JC,P =13.1 Hz), 116.843, 53.928. 31P NMR (400
MHz, CDCl3, δ): 28.6. HRMS (m/z): 532 [M+]. Elemental anal. Calcd
(%) for C37H25O2P: C, 83.44; H, 4.73; O, 6.01. Found: C, 83.51; H,
4.79; O, 6.23.
Through column chromatography (SiO2; ethyl acetate/petroleum
ether, 2:1) to yield SFX2070PO as a white solid (0.4 g, 13%).
1H NMR (400 MHz, DMSO-d6, δ): 7.864 (d, 2H, J = 7.6), 7.54ꢀ7.47
(m, 6H), 7.413ꢀ7.351 (m, 12H), 7.324ꢀ7.277 (m, 8H), 7.229 (m, 2H),
7.13 (d, 2H, J = 7.55), 6.613 (m, 2H). 13C NMR (75 MHz, DMSO-d6,
Biphenyl(spiro[fluorene-9,90-xanthen]-2-yl) Phosphine Oxide (SFX2PO).
n-BuLi (1.6 M in hexane, 3.40 mL, 8.50 mmol) was added dropwise to a
stirred solution of 2 (2.61 g, 4.07 mmol) in anhydrous THF (200 mL)
under a nitrogen atmosphere at ꢀ78 ꢀC. After the solution was stirred
at ꢀ78 ꢀC for an additional 3 h, chlorodiphenylphosphine (CDPP)
(1.58 mL, 8.59 mmol) was added to provide a clear, pale-yellow solution.
The mixture was warmed gradually to room temperature under stirring
and further reacted overnight. The reaction was quenched through the
addition of water (200 mL) and the mixture was then extracted with
ethyl acetate (2 ꢁ 100 mL). The combined extract was dried (MgSO4)
and then concentrated under reduced pressure. The rude product was
dissolved in dichloromethane (50 mL) and then 30% aqueous hydrogen
peroxide (5 mL) was added. The mixture was stirred at room tempera-
ture for 3 h and then extracted with dichloromethane (3 ꢁ 50 mL). The
collected organic phase was dried (MgSO4) and then concentrated
under reduced pressure. The residue was purified through column
chromatography (SiO2; ethyl acetate/methanol, 50:1) to yield SFX2PO
as a white solid (2.56 g, 49%).
δ): 154.111, 153.392 (d, JC,P = 2.9 Hz), 139.374, 132.81 (d, JC,P
=
103.23), 132.422 (d, JC,P = 2.6 Hz), 132.318, 132.262, 132.150, 131.623
(d, JC,P = 9.7 Hz), 129.309, 129.079 (d, JC,P = 11.9 Hz), 128.191 (d, JC,P
105.3 Hz), 125.649, 125.508 (d, JC,P = 2.6 Hz), 121.137, 118.129 (d, JC,P
=
=
12.7 Hz), 53.747. 31P NMR (400 MHz, CDCl3, δ): 28.5. HRMS (ESI,
m/z): 732 [M + H]+. Elemental anal. Calcd (%) for C49H34O3P2: C,
80.32; H, 4.68; O, 6.55. Found: C, 80.41; H, 4.76; O, 6.69.
Theoretical Calculations. Computations on the electronic
ground state of the compounds were performed using Becke’s three-
parameter density functional in combination with the nonlocal correla-
tion functional of Lee, Yang, and Parr (B3LYP).16,17 6-31G(d) basis sets
were employed. The ground-state geometries were fully optimized at the
B3LYP level. All computations were performed using the Gaussian 03
package.18
Device Fabrication. For device fabrication, all of the PO com-
pounds were recrytallized for three to four times from their CH2Cl2/
ethyl acetate solutions until their purification excess 99% determined
with High Performance Liquid Chromatography (HPLC) (99.3% for
SFX2PO, 99.2% for SFX27PO, 99.4% for SFX20PO and 99.1% for
SFX2070PO). All the devices were fabricated onto prepatterned indiumꢀ
tin oxide (ITO) with a sheet resistance of 10 Ω/square. The substrates
were ultrasonic cleaned sequentially with detergent, acetone, ethanol,
and deionized water, then dried in an oven, and finally treated in an
ultraviolet-ozone chamber. After the organic deposition, 100-nm-thick
Al was covered directly on the organic layers serving as cathode. The
cathode areadefines an active devicearea of 2 ꢁ 2 mm2 through a shadow
mask. Currentꢀvoltage-luminance (JꢀVꢀL) characteristics were mea-
sured with a PR650 spectrascan spectrometer and a Keithley 2400
programmable voltageꢀcurrent source. EQE was determined with the
method mentioned in the literature.19 All the measurements were
carried out in the ambient environment without encapsulation.
1H NMR (400 MHz, DMSO-d6, δ): 8.139 (t, 1H, J = 2.2,7.8 Hz), 8.06
(d, 1H, J = 7.6 Hz), 7.573ꢀ7.387 (m, 13H), 7.316 (t, 1H, J = 7.6 Hz),
7.251 (t, 4H, J = 8.0 Hz), 7.120 (d, 1H, J = 7.6 Hz), 6.834 (m, 2H), 6.282
(d, 2H, J = 7.6 Hz). 13C NMR (75 MHz, DMSO-d6, δ): 155.359,
154.972 (d, JC,P = 11.9 Hz), 151.160, 143.480, 138.373, 133.233, 133.115
(d, JC,P = 102.9 Hz), 132.539 (d, JC,P = 2.2 Hz), 132.263, 132.145, 131.850
(d, JC,P = 9.9 Hz), 129.857 (d, JC,P = 114.7 Hz), 128.957, 129.179 (d, JC,P
=
11.9 Hz), 128.560 (d, JC,P = 9.1 Hz), 127.640, 125.827, 124.243,
124.144, 122.004, 121.354 (d, JC,P = 13.4 Hz), 117.380, 54.263. 31P
NMR (400 MHz, CDCl3, δ): 29.2. HRMS (m/z): 532 [M+]. Elemental
anal. Calcd (%) for C37H25O2P: C, 83.44; H, 4.73; O, 6.01. Found: C,
83.53; H, 4.76; O, 6.19.
Spiro[fluorene-9,90-xanthene]-2,7-diylbis(biphenylphosphine oxide)
(SFX27PO). The synthetic method was similar to that of SFX2PO. The
residue was purified through column chromatography (SiO2; petroleum
ether/ethyl acetate/ethanol, 2:2:1) to yield SFX27PO as a white solid
(2.02 g, 45%).
1H NMR (400 MHz, DMSO-d6, δ): 8.225 (dd, 2H, J = 2.4,7.9 Hz),
7.551ꢀ7.639 (m, 6H), 7.408ꢀ7.512 (m, 18H), 7.248ꢀ7.269 (m, 4H),
6.847ꢀ6.887 (m, 2H), 6.314 (d, 2H, J = 7.6 Hz). 13C NMR (75 MHz,
DMSO-d6, δ): 155.231 (d, JC,P = 12.1 Hz), 151.159, 142.132, 133.772,
’ RESULTS AND DISCUSSION
132.909 (d, JC,P = 102.9 Hz), 132.613 (d, JC,P = 2.6 Hz), 132.401 (d, JC,P
=
11.2 Hz), 131.856 (d, JC,P = 9.8 Hz), 129.589, 129.210 (d, JC,P = 11.9
Hz), 128.938 (d, JC,P = 66.6 Hz), 127.418, 124.414, 123.463, 122.385
(d, JC,P = 12.3 Hz), 117.528, 54.511; 31P NMR (400 MHz, CDCl3, δ):
29.1. HRMS (ESI, m/z): 732[M + H]+. Elemental anal. Calcd (%) for
C49H34O3P2: C, 80.32; H, 4.68; O, 6.55. Found: C, 80.45; H, 4.74;
O, 6.74.
Synthesis and Morphological Stability. The spiro-PO com-
pounds were conveniently prepared through a three-step proce-
dure of lithiation, phosphorization and oxidation with moderate
yields (Scheme 2). The structural characterization was estab-
lished on the basis of highly resolved mass spectrometry and
NMR spectroscopy (see the Supporting Information). The mole-
cular structures were further confirmed by X-ray Crystallography
(Figure 1). It indicated that the adjacent molecules of SFX27PO
Biphenyl (Spiro[fluorene-9,90-xanthen]-20-yl)phosphine oxide (SFX20PO)
and Spiro[fluorene-9,90-xanthene]-20,70-diylbis(diphenylphosphine
oxide) (SFX2070PO). The synthetic method used was similar to that of
SFX2PO. The residue was purified through column chromatography
(SiO2; ethyl acetate/Petroleum ether, 1:1) to yield SFX20PO as a white
solid (0.7 g, 32%);
were bridged by water molecules through the PꢀH O hydrogen-
3 3 3
bonding interactions to generate a 1D chain structure along c axis
(Figure 1a). For SFX20PO, two types intermolecular CꢀH
π
3 3 3
1H NMR (400 MHz, DMSO-d6, δ): 7.919 (d, 2H, J = 7.6 Hz), 7.519
(m, 2H), 7.438 (m, 1H), 7.41ꢀ7.36 (m, 7H), 7.34ꢀ7.28 (m, 7H), 7.23
(m, 2H), 7.09 (d, 2H, J = 7.6 Hz), 6.89ꢀ6.85 (m, 1H), 6.608 (m, 1H),
interactions (3.585 and 3.668 Å) were observed (Figure 1b),
which connected adjacent molecules into a 1D chain structure
along a axis. But for SFX2070PO, the asymmetric unit cell
5333
dx.doi.org/10.1021/cm201654c |Chem. Mater. 2011, 23, 5331–5339