Macromolecules
Article
1
ArH). 31P{1H} NMR (162 MHz, C6D6): δ 74.0. Note: H NMR
spectroscopy indicates minor impurity signals at 8.14 and 4.20 ppm in
addition to Cp2ZrCl2. However, when the expected reactivity of
Cp2ZrCl2 with PhMgBr and ArLi reagents was accounted for, the
crude product could be reacted in subsequent synthetic steps to
produce compound 3 and 4 as described below.
pentane to remove excess ethyl acetate and dried in vacuo with mild
heating (ca. 50 °C). H NMR (400 MHz, CDCl3): δ 7.66−7.75 (m,
1
7H, ArH), 7.44−7.51 (m, 7H, ArH), 7.35−7.40 (m, 8H, ArH), 7.27−
7.35 (m, 4H, ArH), 6.21−6.23 (m, 1H, vinylicH), 6.15−6.16 (m, 1H,
vinylicH), 2.95 (s, 1H, allylicH), 2.89 (s, 1H, allylicH), 2.67−2.72 (m,
1H, benzylic-CH), 1.60−1.71 (m, 2H, norbornene CH2), 1.51 (d,
2
2JHH = 8.5 Hz, 1H, one H of norbornene CH2), 1.42 (d, JHH = 8.5
Synthesis of 1-Phenyl-2,3-bis(para-biphenyl)benzophosphole
Oxide (3). A 1:1 mixture (0.65 g, 0.85 mmol) of 1-chloro-2,3-
bis(para-biphenyl)benzophosphole and Cp2ZrCl2 was dissolved in 10
mL of THF. The solution was cooled to −78 °C, and phenyl-
magnesium bromide (0.93 mL, 3.0 M solution in Et2O, 2.8 mmol)
was added dropwise. The reaction mixture was stirred for 1 h at −78
°C, followed by 1 h at 0 °C, and then 12 h at room temperature
before the addition of 20 mL of distilled water. The mixture was
cooled to 0 °C, and 15 mL of 30% aqueous H2O2 was added. After 6
h of stirring at room temperature, the crude reaction mixture was
extracted with CH2Cl2 (3 × 50 mL), and then, the organic layers were
combined and washed with saturated aqueous Na2S2O3 (3 × 20 mL),
dried with MgSO4, and gravity-filtered in air, and the solvent was
removed from the filtrate in vacuo. The crude product was further
purified by flash chromatography using a gradient of 20:1 CH2Cl2/
ethyl acetate to 10:1 CH2Cl2/ethyl acetate to yield 3 as a bright-
yellow solid (0.383 g, 85%). Solid 3 was washed with 10 mL of
pentane to remove excess ethyl acetate and dried in vacuo with mild
Hz, 1H, one H of norbornene CH2). 13C{1H} NMR (176 MHz,
CDCl3): δ 151.1 (d, 4JCP = 2.7 Hz, ArC), 149.4 (d, 2 or 3JCP = 21.5 Hz,
ArC), 143.7 (d, 2 or 3JCP = 26.9 Hz, ArC), 141.4 (ArC), 140.33 (ArC),
140.32 (ArC), 140.29 (ArC), 137.6 (vinylicCH), 137.1 (vinylicCH),
1
2 or 3
134.0 (d, JCP = 95.7 Hz, ArC), 133.4 (d,
J
= 15.0 Hz, ArC),
CP
1
2 or 3
132.9 (ArCH), 132.4 (d, JCP = 106.2 Hz, ArC), 131.9 (d,
J
=
CP
2 or 3
9.7 Hz, ArC), 131.0 (d,
J
= 10.9 Hz, ArCH), 129.64 (ArCH),
CP
129.59 (d, 4JCP = 5.8 Hz, ArCH), 129.11 (d, 2 or 3JCP = 9.4 Hz, ArCH),
129.12 (d, 2 or 3JCP = 10.8 Hz, ArCH), 129.0 (ArCH), 128.7 (ArCH),
2 or 3
128.3 (d,
J
CP
= 12.6 Hz, ArCH), 127.8 (ArCH), 127.7 (ArCH),
127.4 (ArCH), 127.1 (ArCH), 127.0 (ArCH), 126.9 (ArCH), 126.6
1
(d, JCP = 102.4 Hz, ArC), 124.0 (d, 2 or 3JCP = 10.8 Hz, ArCH), 47.9
(norbornene CH), 45.9 (norbornene CH2), 44.0 (norbornene CH),
42.4 (norbornene CH), 33.78 (norbornene CH2), 33.77 (norbornene
CH2). 31P{1H} NMR (162 MHz, CDCl3): δ 39.5. Anal. calcd for
C45H35PO: C, 86.79%; H, 5.67%. Found: C, 83.84%; H, 5.49%. Note:
combustion results consistently yielded low carbon values despite the
apparent purity of the sample (see 1H NMR spectrum in Figure
S34).25 UV−vis (THF): λmax = 269 (ε = 4.05 × 104 M−1 cm−1) and
360 nm (ε = 1.31 × 104 M−1 cm−1). HRMS (EI): m/z calcd for
C45H35PO: 622.24255; found: 622.24177 (Δppm = 1.3). mp: 121−
128 °C. PL (solid state): λex = 398 nm, λem = 510 nm, Φ = 57%, τ =
5.7 ns. PL (2.0 μM in THF): λex = 292 and 359 nm; λem = 493 nm, Φ
= 16% (λex = 290 nm); and Φ = 12% (λex = 360 nm); τ = 1.9 ns.
Synthesis of 5. To 5-(4-bromophenyl)norbornene (1.631 g, 6.576
mmol) in 30 mL of THF at −78 °C was added nBuLi (3.1 mL, 2.5 M
in n-hexane, 7.8 mmol), and the reaction mixture was allowed to stir
for 30 min at −78 °C. 2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-
dioxaborolane (1.7 mL, 8.3 mmol) was added, and the reaction
mixture was allowed to warm to room temperature and then stirred
for 16 h under N2. Distilled water (50 mL) was then added to the
reaction mixture, and the product was extracted with CHCl3 (3 × 50
mL portions). The organic layers were combined, dried with MgSO4,
and filtered, and the volatiles were removed from the filtrate in vacuo.
The crude product was purified by recrystallization from hot hexanes
(ca. 60 °C) to yield 0.702 g (36%) of 5 as a white crystalline solid. 1H
1
heating (ca. 50 °C). H NMR (700 MHz, CDCl3): δ 7.81−7.85 (m,
3
2H, ArH), 7.72−7.75 (m, 1H, ArH), 7.71 (d, JHH = 8.4 Hz, 2H,
3
4
ArH), 7.67 (dd, JHH = 8.2 Hz, JHH = 1.1 Hz, 2H, ArH), 7.44−7.52
3
(m, 8H, ArH), 7.34−7.45 (m, 10H, ArH), 7.31 (dd, JHH = 7.7 Hz,
4JHH = 2.8 Hz, 1H, ArH), 7.27−7.29 (m, 1H, ArH). 13C{1H} NMR
2 or 3
(176 MHz, CDCl3): δ 149.6 (d,
J
= 21.6 Hz, ArC), 143.8 (d,
CP
2 or 3
J
CP
= 26.9 Hz, ArC), 141.5 (ArC), 140.4 (ArC), 140.33 (ArC),
1
2 or 3
140.28 (ArC), 134.0 (d, JCP = 95.7 Hz, ArC), 133.3 (d,
J
CP
=
4
4
15.1 Hz, ArC), 133.0 (d, JCP = 1.4 Hz, ArCH), 132.3 (d, JCP = 2.8
Hz, ArCH), 132.2 (d, 1JCP = 105.8 Hz, ArC), 131.8 (d, 2 or 3JCP = 10.0
Hz, ArC), 131.0 (d, 2 or 3JCP = 10.6 Hz, ArCH), 130.1 (d, JCP = 99.7
1
Hz, ArC), 129.6 (ArCH), 129.5 (d, 2 or 3JCP = 5.8 Hz, ArCH), 129.19
2 or 3
2 or 3
(d,
J
CP
= 10.5 Hz, ArCH), 129.15 (d,
J
CP
= 9.5 Hz, ArCH),
128.96 (d, 2 or 3JCP = 12.3 Hz, ArCH), 128.95 (ArCH), 128.7 (ArCH),
127.8 (ArCH), 127.7 (ArCH), 127.4 (ArCH), 127.1 (ArCH), 127.0
(ArCH), 126.9 (ArCH), 124.1 (d, 2 or 3JCP = 10.8 Hz, ArCH). 31P{1H}
NMR (162 MHz, CDCl3): δ 39.1. Anal. calcd for C38H27PO: C,
86.02%; H, 5.13%. Found: C, 83.98%; H, 5.12%. Note: combustion
results consistently yielded low carbon values despite the apparent
25
1
3
purity of the sample (see H NMR spectrum in Figure S29). UV−
vis (THF): λmax = 268 (ε = 3.92 × 104 M−1 cm−1) and 361 nm (ε =
1.35 × 104 M−1 cm−1). High-resolution mass spectrometry (HRMS)
(EI): m/z calcd for C38H27PO: 530.17993; found: 530.17927 (Δppm
= 1.2). mp: 108−112 °C. PL (solid state): λex = 397 nm, λem = 510
nm, Φ = 67%, τ = 5.9 ns. PL (2.0 μM in THF): λex = 305 and 361
NMR (700 MHz, CDCl3): δ 7.75 (d, JHH = 8.0 Hz, 2H, ArH), 7.29
(d, 3JHH = 7.9 Hz, 2H, ArH), 6.23−6.27 (m, 1H, vinylicH), 6.15−6.19
(m, 1H, vinylicH), 2.97 (s, 1H, allylicH), 2.92 (s, 1H, allylicH), 2.70−
2.76 (m, 1H, benzylicH), 1.72−1.78 (m, 1H, one H of norbornene
CH2), 1.60−1.67 (m, 1H, one H of norbornene CH2), 1.57 (d, 2JHH
=
8.5 Hz, 1H, one H of norbornene CH2), 1.42 (d, 2JHH = 8.7 Hz, 1H,
one H of norbornene CH2), 1.34 (s, 12H, BPinCH3 groups). 13C{1H}
NMR (176 MHz, CDCl3): δ 149.7 (ArC), 137.5 (vinylicC), 137.3
(vinylicC), 134.9 (ArCH), 127.1 (ArCH), 83.7 (O-C), 48.2 (CH),
45.8 (CH2), 44.0 (CH), 42.4 (CH), 33.6 (CH2), 24.9 (CH3). 11B{1H}
NMR (128 MHz, CDCl3): δ 31.0. Anal. calcd for C19H25BO2: C,
77.04%; H, 8.51%. Found: C, 76.94%; H, 8.59%. UV−vis (THF): λmax
= 234 nm (ε = 2.40 × 104 M−1 cm−1). HRMS (EI): m/z calcd for
C19H25O211B: 296.19476 found: 296.19438 (Δppm = 1.3). mp: 93−
95 °C.
nm; λem = 498 nm, Φ = 9.8% (λex = 310 nm); and Φ = 9.5% (λex
360 nm); τ = 1.5 ns.
=
Synthesis of 1-para-Norbornenephenyl-2,3-bis(para-biphenyl)-
benzophosphole Oxide (4). To a solution of 5-(4-bromophenyl)-
norbornene (0.575 g, 2.31 mmol) in 12 mL of dry THF at −78 °C
was added nBuLi (1.0 mL, 2.5 M in hexanes, 2.5 mmol). After stirring
for 1 h at −78 °C, this solution of 4-(norbornene)phenyllithium was
added dropwise to a 1:1 mixture (0.535 g, 0.700 mmol) of 1-chloro-
2,3-bis(para-biphenyl)benzophosphole (2) and Cp2ZrCl2 in 10 mL of
THF at −78 °C. The reaction mixture was stirred at −78 °C for 30
min, followed by 1 h at 0 °C, and then 16 h at room temperature
before the addition of 20 mL of distilled water. The mixture was
cooled to 0 °C, and 15 mL of 30% aqueous H2O2 was added. After 6
h stirring at room temperature, the crude reaction mixture was
extracted with CH2Cl2 (3 × 40 mL), and then, the organic layers were
combined and washed with saturated aqueous Na2S2O3 (3 × 15 mL),
dried with MgSO4, and gravity-filtered in air, and the solvent was
removed from the filtrate in vacuo. The crude product was further
purified by flash chromatography using a gradient of 20:1 CH2Cl2/
ethyl acetate to 10:1 CH2Cl2/ethyl acetate to yield 4 as a bright-
yellow solid (0.314 g, 72%). Solid 4 was washed with 10 mL of
Polymer Syntheses. Benzophosphole Oxide Homopolymer
(P1). To a solution of 4 (57.7 mg, 0.0926 mmol) in THF (0.6 mL)
in a 4 mL vial was added 43 μL of the Grubbs third-generation
catalyst in THF (21 mM stock solution), and the reaction mixture
was stirred at room temperature for 3 min after which ca. 0.5 mL of
ethylvinyl ether was added. The reaction mixture was then stirred for
an additional 15 min, and the crude reaction solution was
concentrated in vacuo to a volume of ca. 0.5 mL. This solution was
then pipetted into 100 mL of vigorously stirring methanol, and the
resulting light-yellow polymer was collected by vacuum filtration and
dried (43 mg, 74%). 1H NMR (700 MHz, CDCl3): δ 7.48−7.86 (7H,
ArH), 6.78−7.48 (19H, ArH), 4.72−5.37 (2H, vinylicH), 2.13−3.13
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Macromolecules XXXX, XXX, XXX−XXX