The dithieno[3,2-b:2′,3′-d]phosphole system: A novel building block for highly luminescent π-conjugated materials

Article abstract of DOI:10.1002/anie.200461301

Like a bolt from the blue, the blue photoluminescence of novel phospholebased materials is extraordinarily intense. The optoelectronic properties show great stability and broad flexibility with respect to wavelength, intensity, and tuneability. The specia

Full text of DOI:10.1002/anie.200461301

Angewandte
Chemie
Phospholes
The Dithieno[3,2-b:2’,3’-d]phosphole System:
A Novel Building Block forHighly Luminescent
p-Conjugated Materials**
Thomas Baumgartner,* Toni Neumann, and
Bastian Wirges
The incorporation of phosphorus centers into polymeric
materials has recently attracted a great deal of attention.[1]
The versatile reactivity and electronic properties of phospho-
rus offer considerable promise for the development of new
functional materials with novel properties. Exploring the use
of phosphole in this context should be of particular interest, as
materials possessing the structurally related pyrrole and
thiophene moieties are already well-established in the field
of molecular electronics.[2] For example, thiophene-based
materials show significant potential for application in elec-
tronic devices such as photovoltaic cells, organic and polymer
light-emitting diodes (OLEDs, PLEDs), polymeric sensors,
and TFT-based flat-panel displays.[3]
Careful consideration of the HOMO–LUMO gap, which
strongly influences the optical and electronic properties of
these materials, is essential for their utility.[4] The ability to
fine-tune the electronic structure of the p-conjugated system
is therefore highly desirable in order to achieve the required
material properties. Recent work by RØau and co-workers
incorporating the phosphole moiety into extended thiophene-
containing p-conjugated systems (1, see Scheme 1), has
demonstrated the advantageous electronic features of the
phosphorus situated in this system.[1e,5] Due to the pyramid-
alization of the phosphorus center, orbital interaction with the
conjugated p system is reduced. As a result, the lone pair at
the phosphorus atom only functions as an n-dopant for the p
system. Conveniently, the doping mode can be inverted easily
from n- (electron donor) to p-type (electron acceptor) by
simple chemical modifications such as oxidation or complex-
ation at the phosphorus center.[1e,5] Although these intriguing
features as well as theoretical calculations[6] strongly support
the advantages of incorporating phosphole moieties into
polymeric systems, only three examples of phosphole-con-
taining macromolecules have been reported to date.[1e,7]
We now report on the synthesis and optoelectronic
properties of novel dithieno[3,2-b:2’,3’-d]phospholes[8] and
the preparation of a well-defined dithienophosphole-contain-
Scheme 1. Synthesis of dithienophosphole derivatives and precursors:
a) 2nBuLi, 2tBuMe2SiCl, THF, ꢀ788C (6: R=SitBuMe2); b) 2nBuLi,
R’PCl2, Et2O, ꢀ788!RT (2: R=H, R’=Ph, 4: R=H, R’=4-tBuC6H4);
c) 2n-BuLi, (4-vinylphenyl)PCl2, TMEDA, Et2O, ꢀ788!RT (7: R=Sit-
BuMe2, R’=4-vinylphenyl); d) BH3·SMe2 (1m in CH2Cl2), CH2Cl2, RT
(E=BH3; 8: R=H, R’=Ph, 9: R=H, R’=4-tBuC6H4); e) H2O2 (30%
in H2O), pentane, RT (E=O; 10: R=H, R’=Ph, 11: R=H, R’=4-
tBuC6H4, 12: R=SitBuMe2, R’=4-vinylphenyl).
a synthetic target since the annelation of aromatic rings has
been found to be a powerful approach for tuning the band gap
of conjugated materials.[4,9] This is further supported by a
recent theoretical investigation in which thiophene-based,
fused tricyclic polymers were found to have a much more
favorable band gap than the related polythiophenes.[10] The
incorporation of the phosphole moiety into a rigid, tricyclic
dithieno system should therefore lead to a significantly higher
degree of p conjugation than that reported for comparable
systems.[11]
To verify the synthetic accessibility of the dithienophosp-
hole system as well as to explore its optoelectronic properties,
we initiated our studies on model compounds and function-
alized monomers. Dithienophospholes 2 and 4 are accessible
by reaction of 3,3’-dibromo-2,2’-dithiophene (3) with nBuLi,
then subsequent addition of the corresponding dichlorophos-
phine at low temperatures, followed by purification by
filtration over neutral alumina (yields: 2: 70%, 4: 72%).
Both compounds exhibit signals in the 31P NMR spectrum (2:
d = ꢀ21.5 ppm; 4: d = ꢀ22.5 ppm) that are shifted signifi-
cantly upfield from those of related phospholes, for example,
ing polymer built on
a polystyrene backbone. The
dithieno[3,2-b:2’,3’-d]phosphole 2 (Scheme 1) was chosen as
[*] Dr. T. Baumgartner, T. Neumann, B. Wirges
Institut für Anorganische Chemie, RWTH-Aachen
Professor-Pirlet-Strasse 1, 52074 Aachen (Germany)
Fax: (+49)241-8096244
E-mail: thomas.baumgartner@ac.rwth-aachen.de
[**] We thank Prof. Dr. J. Okuda for his generous support of this work.
Financial support from the Fonds der Chemischen Industrie and
BMBF is gratefully acknowledged. We also thank Prof. Dr. U. Englert
for the X-ray data collection, Dr. K. Beckerle for analytical assistance,
and both for helpful discussions.
1
those reported by RØau et al. (d31P = 11–45 ppm).[1e] The H
and 13C NMR data, on the other hand, are not significantly
different than data previously reported for related dithieno
systems.[12] To our satisfaction, both 2 and 4 display strong,
Angew. Chem. Int. Ed. 2004, 43, 6197 –6201
DOI: 10.1002/anie.200461301
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
6197

Communications
blue photoluminescence, and should thus have the desired
The vinylphenyl-functionalized monomer 7 is accessible
in a two-step reaction starting from 3,3’,5,5’-tetrabromo-2,2’-
bithiophene (5). In the first step, the silyl functionalities were
introduced by treating 5 with two equivalents of nBuLi and
then adding tert-butyl(dimethyl)silyl chloride in THFat
ꢀ788C to provide 6 in almost quantitative yield. The silyl-
functionalized dithiophene 6 was then treated with another
two equivalents of nBuLi in Et2O at ꢀ788C, and dichloro(4-
vinylphenyl)phosphane[14] was then added in the presence of
an excess of TMEDA to afford the vinylphenyl-functionalized
dithienophosphole 7 in good yields (ca. 80%) after filtration
over neutral alumina. The dithienophosphole monomer 7
exhibits a resonance in the 31P NMR spectrum of d =
ꢀ26.4 ppm that is shifted slightly upfield from those observed
optoelectronic properties (vide infra). We were able to obtain
light-yellow crystals of 2 suitable for X-ray structure analy-
sis[13] from a concentrated pentane/toluene (1:1) solution
cooled to ꢀ308C. As expected, the rigid tricyclic
dithienophosphole is planar and displays an anti configuration
of the two thiophene moieties and the phosphole unit (see
Figure 1). The high degree of p conjugation is apparent in the
1
for 2 and 4. The H and 13C NMR data confirm the expected
structure and are very similar to those recorded for 2 and 4.
As previously noted, it should be possible to alter the
electronic structure, thus inverting the doping mode of the
phosphole, by either oxidation or complexation of the
phosphorus atom. We therefore investigated the reaction of
the dithienophospholes 2 and 4 with borane (applied as
BH3·SMe2) to afford the phosphole–borane adducts 8 and 9,
and hydrogen peroxide to give the phosphole oxides 10 and
11, all in almost quantitative yields.[15] The NMR data for the
borane adducts show downfield resonances in the 31P NMR
spectrum (d(31P) = 13.5 (8), 14.6 ppm (9)) in correlation with
the electron-withdrawing effect of the BH3 group. This is even
more pronounced in the case of the oxide functionality
(d(31P) = 18.8 ppm (10),[8] 19.1 (11)). The same effect was
observed for the silyl-functionalized phosphole oxide 12
(d(31P) = 14.7 ppm) that was synthesized in an analogous
manner.[15] The 1H and 13C NMR data for all compounds show
a similar trend, and fall within the range of values previously
reported for related phospholes.[1e,5]
Figure 1. Molecular structure of 2 (50% probability level) in the solid
state. Selected bond lengths [Š] and angles [8]: P1–C3 1.8193(14), P1–
C6 1.8218(14), P1–C11 1.8367(13), C3–C4 1.3842(19), C5–C6
1.3817(18), C4–C5 1.4397(19); C6–C7 1.4228(18), C7–C8 1.364(2); C3-
P1-C6 89.25(6), C3-P1-C11 103.82(6), C6-P1-C11 99.92(6).
ꢀ
ꢀ
shortened single bonds {C2 C3 1.427(2), C4 C5 1.440(2),
As indicated earlier, the dithienophosphole derivatives
exhibit a strong blue photoluminescence. Fluorescence
ꢀ
C6 C7 1.423(2) Š) as well as the elongated double bonds
ꢀ
ꢀ
ꢀ
ꢀ
(C1 C2 1.365(2), C3 C4 1.384(2), C5 C6 1.382(2), C7 C8
1.364(2) Š) of the fused ring system. It is interesting to note
that the bond shortening/elongation is significantly more
pronounced in 2 than in the thienyl-substituted phosphole
1,[5a] supporting the positive effects of the rigid ring system on
spectroscopy reveals the dependence of the optical properties
on the electronic structure of the phosphorus center (Table 1).
All compounds show a maximum excitation wavelength in the
UV region, whereas the emission spectra show a maximum
wavelength in the visible blue region. The dithienophosphole
derivatives exhibit Stokes shifts of 70–80 nm similar to the
related systems reported by RØau et al. (70–90 nm).[1e] It is
interesting to note that the silyl-functionalized dithieno-
phosphole monomer 7 shows a significant red shift of about
ꢀ
ꢀ
the p conjugation. The endocyclic P C bonds P1 C3
(1.8193(14) Š) and P1 C6 (1.8218(14) Š) are only slightly
ꢀ
ꢀ
shorter than the exocyclic P1 C11 bond (1.8367(13) Š) due to
minimal hyperconjugation of the phosphorus lone pair with
the p system, which affords a reduced aromatic phosphole
unit. This structural feature strongly supports the role of the
phosphorus center as a dopant for the p-conjugated system,
which is potentially interesting for the optoelectronic proper-
ties of the material.
Table 1: Optical spectroscopy data for 2, 4, and 7–14.
[c]
Cmpd.
lex [nm][a]
lem [nm][b]
lge
f
2 (4)
8 (9)
10 (11)
7
338 (336)
346 (346)
366 (363)
352
379
352 (374)
374 (352)
415 (408)
424 (423)
453 ( 450)
422
461
424 (452)
458 (456)
4.38 (4.50)
4.35 (4.47)
4.33 (4.45)
4.57
4.48
4.87 (–)
4.92 (–)
0.779 (0.881)
0.690 (0.753)
0.565 (0.590)
0.687
0.579
0.743 (–)
0.572 (–)
To gain access to polymeric systems we functionalized the
phosphorus center of the dithienophosphole with a vinyl-
phenyl group. We also investigated silyl functionalization of
the dithienophosphole ring to provide increased solubility for
the targeted polymer. An additional benefit with respect to
the optoelectronic properties was anticipated, as the silyl
center provides an acceptor component expected to further
extend the delocalized p system, thus optimizing the elec-
tronic structure of the dithienophosphole.[11]
12
13[d]
14[d]
[a] lmax for excitation in CH2Cl2. [b] lmax for emission in CH2Cl2.
[c] Relative to quinine sulfate (0.1m H2SO4 solution); excitation at
365 nm. [d] Values for thin film in brackets.
6198
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
Angew. Chem. Int. Ed. 2004, 43, 6197 –6201

Angewandte
Chemie
10–15 nm for the maximum excitation and emission wave-
(Scheme 2). The material obtained after precipitation into
lengths (lex = 352, lem = 422 nm) compared to the model
degassed pentane was a white amorphous solid. Analysis by
gel permeation chromatography (GPC) revealed a high
molecular weight of Mn = 147650 gmolꢀ1 with a relatively
narrow polydispersity (PDI) of 2.46. Analysis of the smart
polystyrene 13 by differential scanning calorimetry (DSC)
showed a glass transition temperature of Tg = 114.28C (cf.
native polystyrene: < 1008C[19]) and a thermal decomposition
temperature of 428.28C. The 31P NMR spectrum for 13 shows
a broad signal at d(31P) = ꢀ25.0 ppm (cf.: d = ꢀ26.4 ppm for
7), confirming the existence of dithienophosphole units within
the polymeric material. 1H and 13C NMR data revealed a ratio
of ca. 1:30 for dithienophosphole/styrene as was expected
from the reaction conditions.
The smart polymer 13 exhibits a very strong blue photo-
luminescence upon irradiation with UV light. The maximum
of the excitation and emission wavelengths of 13 (lex =
352 nm; lem = 424 nm; dissolved in CH2Cl2) nicely match the
values observed for the vinylphenyl-functionalized monomer
7 (Figure 2), supporting the expected side-chain functional-
compounds 2 (lex = 338, lem = 415 nm) and 4 (lex = 336, lem
=
408 nm), supporting the electron-accepting character of the
silyl center. The same trend is observed when the doping
mode of the phosphorus center is inverted to p-type in the
borane adducts 8 and 9 and the phosphole oxides 10–12. In
correlation with the low-field shift of the 31P NMR resonan-
ces, the maximum wavelengths for excitation and emission
experience a red shift of about 10 nm for the borane adducts
and an even stronger red shift of about 30 nm (excitation) and
40 nm (emission) for the phosphole oxides. In the case of the
silyl-functionalized phosphole oxide 12, a cumulative effect of
both electron-accepting centers (Si and P) is observed (see
Table 1). It should be mentioned that the observed photo-
luminescence is very intense, particularly for the borane
adducts and the phosphole oxides. More importantly, the
quantum yields for all compounds range between 55 and
almost 90%, which is unprecedented for phospholes[1e] and
dithieno systems.[12a,16] Therefore, the optoelectronic data
strongly emphasize the potential of the dithienophosphole
system for applications in optoelectronic devices such as blue-
light-emitters and sensory materials.
The favorable properties of macromolecules in terms of
processability (e.g. as thin films) would be an added benefit
for future materials applications. We therefore investigated
the possibility of generating a polymer that would display the
extraordinary blue photoluminescence of the model com-
pounds by incorporating the dithienophosphole system as
side-chain functionalities. Radical polymerization of func-
tionalized styrene seemed to be the method of choice since it
is usually not affected by the presence of phosphine cen-
ters.[14b] To reduce the steric bulk in the polymeric material
caused by the dithienophosphole ring system, which could
potentially terminate the polymerization process at an early
stage, we targeted the copolymer 13 by using styrene as
solvent for the reactions (7/styrene ca. 1:30, Scheme 2). The
resulting “dilution” of the dithienophosphole centers in the
polymeric material was expected to also enhance the opto-
electronic properties, due to the great distance between the
emitting centers, reducing the potential for quenching proc-
esses that could occur at higher densities.[17] The polymer-
ization was performed in a sealed ampule under vacuum at
1108C for 16 h using a catalytic amount of 2,2,6,6-tetrame-
Figure 2. Excitation (A) and emission (E) spectra of 7 and 13 in
CH2Cl2.
ization. The dithienophosphole-containing polymer 13 can be
oxidized conveniently with hydrogen peroxide (in analogy to
the model compounds) to afford the phosphole oxide
containing polymer 14. It should be mentioned that the
same oxidation process is observed within a day when
a solution of 13 is exposed to air, whereas the solid
material does not show any significant signs of
oxidation—even after several weeks.
thylpiperidinyl-1-oxy (TEMPO)[18]
as
the
initiator
We were also interested in the optoelectronic
properties of a thin film of 13 with regards to
applications as a PLED material. A thin film was
obtained from a concentrated solution of 13 in CH2Cl2
by slow evaporation of the solvent. Relative to the
properties of the CH2Cl2 solution, the very intense
blue photoluminescence of the thin film of 13 is red-
shifted approximately 20 nm for excitation and
roughly 30 nm for emission (lex = 374 nm; lem
452 nm). Surprisingly, the emission wavelength for a
=
Scheme 2. Synthesis of the dithienophosphole-containing polymer 13: cat.
TEMPO, 1108C, 16 h. TBDMS=tert-butyl(dimethyl)silyl.
Angew. Chem. Int. Ed. 2004, 43, 6197 –6201
www.angewandte.org
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
6199

Communications
filtrate was evaporated to dryness, and 2 and 4 were obtained as light-
yellow solids (2: 1.1 g, 70% yield; 4: 1.2 g, 72% yield).
thin film of the oxidized polymer (14, lem = 456 nm) almost
matches that observed for the nonoxidized material 13,
whereas the value for the excitation wavelength is blue-
shifted to 352 nm in 14 (cf. 374 nm for 13; Figure 3). With
2: 31P{1H} NMR (162.0 MHz, 258C, CDCl3): d = ꢀ21.5 ppm;
1H NMR (400 MHz, 258C, CDCl3): d = 7.31 (br, 2H; o-Ph), 7.26–7.23
3
(m., 5H; Ar-H), 7.14 ppm (d, J(H,H) = 5.0 Hz, 2H; Ar-H); 13C{1H}
NMR (100.6 MHz, 258C, CDCl3): d = 146.6 (d, J(C,P) = 8.0 Hz; Ar),
141.7 (d, J(C,P) = 2.3 Hz; Ar), 133.5 (d, J(C,P) = 15.3 Hz; Ar), 132.2
(d, 2J(C,P) = 20.5 Hz; o-Ar), 129.1 (s; p-Ph), 128.5 (d, 3J(C,P) =
7.6 Hz; m-Ar), 126.4 (d, 2J(C,P) = 19.6 Hz; o-Ar), 126.0 ppm (d,
3J(C,P) = 6.2 Hz; m-Ar); MS (70 eV): m/z (%): 272 (100) [M+], 239
(90) [MꢀS]+, 195 (40) [MꢀPh]+; elemental analysis calcd (%) for
C14H9PS2: C 61.75, H 3.33, S 23.55; found: C 61.77, H 3.45, S 23.38.
4: 31P{1H} NMR (162.0 MHz, 258C, CDCl3): d = ꢀ22.5 ppm;
1H NMR (400 MHz, 258C, CDCl3): d = 7.28–7.23 (m., 6H; Ar-H),
7.13 (d, 2J(H,H) = 4.9 Hz, 2H; Ar-H), 1.24 ppm (s, 9H; tBu); 13C{1H}
NMR (100.6 MHz, 258C, CDCl3): d = 152.4 (s; p-Ar), 147.0 (d,
J(C,P) = 8.7 Hz; Ar), 141.6 (d, J(C,P) = 2.1 Hz; Ar), 132.1 (d,
J(C,P) = 20.5 Hz; o-Ar), 129.7 (d, 1J(C,P) = 11.4 Hz; Ar), 126.5 (d,
3
2J(C,P) = 16.9 Hz; o-Ar), 125.9 (d, J(C,P) = 5.7 Hz; m-Ar), 125.7 (d,
3J(C,P) = 8.5 Hz; m-Ar), 34.5 (s; CMe3), 31.0 ppm (s; C(CH3)3). MS
(70 eV): m/z (%) 328 (100) [M+], 271 (50) [M-tBu]+, 195 (90)
[MꢀC10H13]+, 57 (25) [tBu]+; elemental analysis calcd (%) for
C18H17PS2: C 65.83, H 5.22, S 19.53; found: C 65.42, H 5.39, S 19.46.
7: To a solution of 3,3’-dibromo-5,5’-bis(tert-butyldimethylsilyl)-
2,2’-bithiophene (1.11 g, 2 mmol) and TMEDA (1.51 mL, 10 mmol) in
Et2O (50 mL) was added nBuLi (1.6 mL, 4 mmol) dropwise at ꢀ788C.
Subsequently, (4-vinylphenyl)PCl2 (0.41 g, 2 mmol), dissolved in Et2O
(10 mL), was added slowly to the reaction mixture, and the resulting
mixture was allowed to warm quickly to room temperature. The
solvent was then removed under vacuum, and the residue taken up in
pentane (ca. 60 mL) and filtered to remove LiCl. The filtrate was
concentrated and left for crystallization at ꢀ308C. 7 was obtained as
white amorphous powder in 80% yield (0.84 g).
Figure 3. Excitation (A) and emission (E) spectra of 13 and 14 as thin
films.
respect to resistance to light, 13 was found to exhibit fairly
good stability; this is intrinsically important for the lifetime of
optoelectronic devices. Irradiation of a solution of 13 in
CH2Cl2 at 352 nm for 2 h results in a stable emission (intensity
detected at 424 nm) within a loss of at most 3%, suggesting a
potential use in optoelectronic devices. The same is true for a
thin film of the oxidized polymer (14) with a margin of 5%.
In conclusion, we have synthesized novel dithieno[3,2-
b:2’,3’-d]phosphole derivatives in a convenient one- or two-
step synthesis, demonstrating that a broad variety of func-
tionalized systems are accessible by this method. The
optoelectronic properties of the dithienophospholes are
extraordinary with respect to wavelength, intensity, and
tuneability, allowing for the possibility of fine-tuning the
electronic structure by simple chemical modifications. Addi-
tionally, we have shown that it is possible to incorporate the
dithienophosphole moiety into polymeric systems, opening up
potential applications in optoelectronic devices such as blue-
light-emitting PLEDs and polymeric sensors. We are cur-
rently probing the range of dithienophosphole-based sensory
materials by tuning the optoelectronic properties with differ-
ent functionalities and modifications of the phosphorus
center. Furthermore, the incorporation of polymers 13 and
14 into optoelectronic devices is currently under investiga-
tion.
31P{1H} NMR (162.0 MHz, 258C, CDCl3): d = ꢀ26.4 ppm;
1H NMR (500 MHz, 258C, CDCl3): d = 7.32 (br, 2H; Ar-H), 7.31 (s,
2H; Ar-H), 7.26 (s, 2H; Ar-H), 6.65 (dd, 3J(H,H) = 17.7 Hz,
3
J(H,H) = 11.3 Hz, 1H; CH CH2), 5.73 (d, 3J(H,H) = 17.7 Hz, 1H;
=
3
=
=
CH CHH), 5.73 (d, J(H,H) = 11.3 Hz, 1H; CH CHH), 0.93 (s, 18H;
SitBu), 0.31 (s, 6H; SiMe2), 0.30 ppm (s, 6H; SiMe2); 13C{1H} NMR
(125.7 MHz, 258C, CDCl3): d = 148.7 (d, 1J(C,P) = 10.3 Hz; ipso-Ar),
147.0 (s; Ar), 139.8 (d, 2J(C,P) = 6.2 Hz; Ar), 139.5 (d, 1J(C,P) =
=
19.6 Hz; Ar), 138.4 (s; p-Ar), 136.3 (s; CH CH2), 134.3 (d,
2J(C,P) = 16.6 Hz; o-Ar), 132.8 (d, 2J(C,P) = 21.7 Hz; o-Ar), 126.4
3
=
(d, J(C,P) = 8.3 Hz; m-Ar), 114.7 (s; CH CH2), 26.4 (s; SiC(CH3)3),
17.0 (s; SiC(CH3)3), ꢀ4.9 ppm (s; SiMe2); elemental analysis calcd
(%) for C26H37PS2Si2: C 63.83, H 7.46, S 12.17; found: C 63.66, H 7.68,
S 12.14.
Polymerization: To a solution of 7 (0.26 g, 0.5 mmol) dissolved in
styrene (2 mL, 17.5 mmol) in an ampule was added a catalytic amount
of TEMPO. The ampule was then evacuated, sealed, and kept
overnight at 1108C. The resulting yellowish solid obtained after the
reaction mixture had cooled to room temperature was then dissolved
in ca. 10 mL of dichloromethane and precipitated into degassed
pentane. After the solvent had been decanted off and the residue
dried under vacuum, polymer 13 was obtained as a white solid (1.76 g,
ca. 85%). GPC: Mn = 147650 gmolꢀ1
114.28C,
decomp = 428.28C; 31P{1H} NMR (162.0 MHz, 258C,
, PDI = 2.46; DSC: Tg =
T
CD2Cl2): d = ꢀ25.0 ppm; 1H NMR (500 MHz, 258C, CD2Cl2): d =
7.09 (m br, ca. 132H; Ar-H), 6.53 (m br, ca. 88H; Ar-H); 1.84 (m
br, ca. 48H; CHCHH); 1.48 (m br, ca. 96H; CHCHH), 0.98 (br, 18H;
SitBu), 0.35 ppm (br, 12H; SiMe2); 13C{1H} NMR (125.7 MHz, 258C,
CD2Cl2): d = 149.3 (br; Ar), 145.0 (br; Ar), 140.2 (br; Ar), 134.9 (br;
Ar), 132.2 (br; Ar), 128.4 (br; Ar), 128.0 (br; Ar), 126.0 (br; Ar), 45.0
(m br; CHCH2), 40.8 (m br; CHCH2), 26.6 (br; SiC(CH3)3), 17.2 (br;
SiC(CH3)3), ꢀ4.7 ppm (br; SiMe2).
Experimental Section
Dithienophospholes: To a solution of 3 (1.62 g, 5 mmol) in Et2O
(100 mL) was added nBuLi (4 mL, 10 mmol) dropwise at ꢀ788C.
Subsequently, RPCl2 (R = Ph: 0.90 g, 5 mmol; R = 4-tBu-C6H4, 1.18 g,
5 mmol) dissolved in Et2O (10 mL), was added slowly to the reaction
mixture, and the resulting suspension was allowed to warm quickly to
room temperature. The solvent was then removed under vacuum, the
residue taken up in pentane (ca. 60 mL) and filtered over neutral
alumina to remove LiCl and a small amount of brown impurities. The
Received: July 14, 2004
6200 ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
Angew. Chem. Int. Ed. 2004, 43, 6197 –6201

Angewandte
Chemie
7.54 (dd, 3J(H,P) = 11.6 Hz, 3J(H,H) = 8.4 Hz, 2H; o-Ph), 7.40
Keywords: luminescence · optical properties · phosphorus
heterocycles · polymers · thiophene
.
(dd, 3J(H,H) = 8.4 Hz, 3J(H,P) = 2.1 Hz, 2H; m-Ph), 7.34 (dd,
3J(H,H) = 4.9 Hz, 3J(H,P) = 3.1 Hz, 2H; Ar-H), 7.16 (dd,
3J(H,H) = 4.9 Hz, 4J(H,P) = 1.2 Hz, 2H; Ar-H), 1.29 (s, 9H;
tBu); 13C{1H} NMR (125.6 MHz, 258C, CDCl3): d = 150.5 (d,
2J(C,P) = 2.9 Hz; Ar-Ar), 144.9 (d, 4J(C,P) = 10.5 Hz; p-Ph),
139.3 (d, 1J(C,P) = 63.3 Hz; ipso-Ar), 131.8 (d, J(C,P) = 10.5 Hz;
Ar-H), 128.1 (d, J(C,P) = 12.5 Hz; Ar-H), 126.1 (d, J(C,P) =
16.3 Hz; Ar-H), 126.1 (d, J(C,P) = 11.5 Hz; Ar-H), 122.3 (d,
1J(C,P) = 54.7 Hz; ipso-Ph), 35.0 (s; CMe3), 31.0 ppm (s; CH3);
11B NMR (160.3 MHz, 258C, CDCl3): d = ꢀ39.2 ppm. 11: 31P{1H}
NMR (126.0 MHz, 258C, CDCl3): d = 19.1 ppm; 1H NMR
(400 MHz, 258C, CDCl3): d = 7.62 (dd br, 3J(H,P) = 13.2 Hz,
3J(H,H) = 8.5 Hz, 2H; o-Ph), 7.40 (dd br, 3J(H,H) = 8.5 Hz,
4J(H,P) = 3.0 Hz, 2H; m-Ph), 7.26 (dd, 3J(H,H) = 5.0 Hz,
3J(H,P) = 3.4 Hz, 2H; Ar-H), 7.12 (dd, 2J(H,H) = 5.0 Hz,
4J(H,P) = 2.5 Hz, 2H; Ar-H), 1.26 ppm (s, 9H; tBu); 13C{1H}
NMR (100.6 MHz, 258C, CDCl3): d = 155.9 (s; p-Ar), 145.4 (d,
[1] a) F. Mathey, Angew. Chem. 2003, 115, 1616; Angew. Chem. Int.
Ed. 2003, 42, 1578; b) Z. Jin, B. L. Lucht, J. Organomet. Chem.
2002, 653, 167; c) C.-W. Tsang, M. Yam, D. P. Gates, J. Am.
Chem. Soc. 2003, 125, 1480; d) R. C. Smith, J. D. Protasiewicz, J.
Am. Chem. Soc. 2004, 126, 2268; e) C. Hay, M. Hissler, C.
Fischmeister, J. Rault-Berthelot, L. Toupet, L. Nyulµszi, R.
RØau, Chem. Eur. J. 2001, 7, 4222.
[2] See e.g.: a) Handbook of Oligo- and Polythiophenes (Ed.: D.
Fichou), Wiley-VCH, Weinheim, 1999; b) Conjugated Conduct-
ing Polymers, Vol. 102 (Ed.: H. Kiess), Springer, New York,
1992.
[3] G. Tourillion, Handbook of Conducting Polymers (Ed.: T. A.
Skotheim), Marcel Dekker, New York, 1986, pp. 293 – 350.
[4] J. Roncali, Chem. Rev. 1997, 97, 173.
[5] a) C. Hay, C. Fischmeister, M. Hissler, L. Toupet, R. RØau,
Angew. Chem. 2000, 112, 1882; Angew. Chem. Int. Ed. 2000, 39,
1812; b) C. Hay, D. Le Vilain, V. Deborde, L. Toupet, R. RØau,
Chem. Commun. 1999, 345; c) C. Fave, T.-Y. Cho, M. Hissler, C.-
W. Chen, T.-Y. Luh, C.-C. Wu, R. RØau, J. Am. Chem. Soc. 2003,
125, 9254.
[6] a) D. Delaere, M. T. Nguyen, L. G. Vanquickenborne, Phys.
Chem. Chem. Phys. 2002, 4, 1522; b) D. Delaere, M. T. Nguyen,
L. G. Vanquickenborne, J. Phys. Chem. A 2003, 107, 838; c) J.
Ma, S. Li, Y. Jiang, Macromolecules 2002, 35, 1109.
[7] a) S. S. H. Mao, T. D. Tilley, Macromolecules 1997, 30, 5566;
b) Y. Morisaki, Y. Aiki, Y. Chujo, Macromolecules 2003, 36,
2594.
[8] Dithieno[3,2-b:2’,3’-d]-1-(phenyl)phosphole oxide has been
reported before, see: J.-P. Lampin, F. Mathey, J. Organomet.
Chem. 1974, 71, 239.
[9] a) M. Pomerantz, Handbook of Conducting Polymers, 2nd ed.
(Eds.: T. A. Skotheim, R. L. Elsenbaumer, J. R. Reynolds),
Marcel Dekker, New York, 1998, pp. 277 – 309; b) X. Zhang,
A. J. Matzger, J. Org. Chem. 2003, 68, 9813.
1
2J(C,P) = 24.0 Hz; Ar), 139.0 (d, J(C,P) = 111.9 Hz; Ar), 130.6
2
2
(d, J(C,P) = 11.8 Hz; o-Ar), 128.0 (d, J(C,P) = 14.7 Hz; o-Ar),
126.0 (d, 1J(C,P) = 111.1 Hz; Ar), 125.9 (d, 3J(C,P) = 13.2 Hz; m-
Ar), 125.8 (d, 3J(C,P) = 12.8 Hz; m-Ar), 34.9 (s; CMe3), 30.8 ppm
(s; C(CH3)3). 12: 31P{1H} NMR (162.0 MHz, 258C, CDCl3): d =
14.7 ppm; 1H NMR (500 MHz, 258C, CDCl3): d = 7.70 (dd,
3J(H,P) = 12.8 Hz, 3J(H,H) = 8.2 Hz, 2H; Ar-H), 7.46 (dd,
3J(H,H) = 8.2 Hz, 4J(H,P) = 2.8 Hz, 2H; Ar-H), 7.19 (d,
3J(H,P) = 2.4 Hz, 2H; Ar-H), 6.71 (dd, 3J(H,H) = 17.4 Hz,
3
J(H,H) = 10.7 Hz, 1H; CH CH2), 5.83 (d, 3J(H,H) = 17.4 Hz,
=
3
=
=
1H; CH CHH), 5.35 (d, J(H,H) = 10.7 Hz, 1H; CH CHH),
0.91 (s, 18H; SitBu), 0.28 (s, 6H; SiMe2), 0.27 ppm (s, 6H;
SiMe2); 13C{1H} NMR (125.7 MHz, 258C, CDCl3): d = 150.8 (d,
1J(C,P) = 23.9 Hz; ipso-Ar), 142.8 (d, J(C,P) = 14.3 Hz; Ar),
=
141.4 (d, J(C,P) = 18.2 Hz; Ar), 140.4 (s; p-Ar), 135.9 (s; CH
CH2), 133.3 (d, 2J(C,P) = 15.3 Hz; o-Ar), 131.3 (d, 2J(C,P) =
1
12.4 Hz; o-Ar), 129.0 (d, J(C,P) = 110.2 Hz; ipso-Ar), 126.6 (d,
3J(C,P) = 12.4 Hz; m-Ar), 116.5 (s; CH CH2), 26.2 (s;
=
SiC(CH3)3), 16.8 (s; SiC(CH3)3), ꢀ5.0 (s; SiMe), ꢀ5.1 ppm (s;
SiMe).
[16] G. Barbarella, L. Favaretto, G. Sotgiu, L. Antolini, G. Gigli, R.
Cingolani, A. Bongini, Chem. Mater. 2001, 13, 4112.
[17] B. Valeur, Molecular Fluorescence, Principles and Applications,
Wiley-VCH, Weinheim, 2002.
[18] M. Georges, R. P. N. Veregin, P. M. Kazmaier, G. K. Hamer,
Macromolecules 1993, 26, 2987.
[10] S. Y. Hong, J. M. Song, J. Chem. Phys. 1997, 107, 10607.
[11] T. Baumgartner, Macromol. Symp. 2003, 196, 279.
[12] a) K. Ogawa, S. C. Rasmussen, J. Org. Chem. 2003, 68, 2921; b) J.
Ohshita, M. Nodono, H. Kai, T. Watanabe, A. Kunai, K.
Komaguchi, M. Shiotani, A. Adachi, K. Okita, Y. Harima, K.
Yamashita, M. Ishikawa, Organometallics 1999, 18, 1453.
[13] Crystal data for 2: (C14H9PS2): Mr = 272.30, T= 153(2) K,
monoclinic, space group P2(1)/c, a = 12.740(3), b = 8.2365(16),
c = 11.729(2) Š, a = 90, b = 92.62(3), g = 908, V= 1229.5(4) Š3,
[19] Encyclopedia of Polymer Science and Engineering, Rev. Ed.,
Wiley, New York, 1998.
Z = 4, 1calcd = 1.471 Mgmꢀ3
,
m = 0.534 mmꢀ1
,
l = 0.71073 Š,
2qmax = 56.628, 12358 measured reflections, 3046 [R(int) =
0.0227] independent reflections, GOFon F2 = 1.080, R1 =
0.0317, wR2 = 0.0857 (I > 2s(I)), R1 = 0.0332, wR2 = 0.0868 (for
all data), largest difference peak and hole 0.429 and
ꢀ0.248 eŠꢀ3. The intensity data were collected on a Bruker
SMART D8 goniometer with an APEX CCD detector. The
structure was solved by direct methods (SHELXTL) and refined
on F2 by full-matrix least-squares techniques. Hydrogen atoms
were included by using a riding model. CCDC-244042 contains
the supplementary crystallographic data for this paper. These
data can be obtained free of charge via www.ccdc.cam.ac.uk/
conts/retrieving.html (or from the Cambridge Crystallographic
Data Centre, 12, Union Road, Cambridge CB21EZ, UK; fax:
(+ 44)1223-336-033; or deposit@ccdc.cam.ac.uk).
[14] a) K. Diemert, B. Kottwitz, W. Kuchen, Phosphorus Sulfur Relat.
Elem. 1986, 26, 307; b) M. K. W. Choi, H. S. He, P. H. Toy, J. Org.
Chem. 2003, 68, 9831.
[15] Selected physical data: 9: 31P{1H} NMR (80.9 MHz, 258C,
1
CDCl3): d = 14.6 ppm; H NMR (500 MHz, 258C, CDCl3): d =
Angew. Chem. Int. Ed. 2004, 43, 6197 –6201
www.angewandte.org
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
6201