CC BY-NC-ND 4.0 · Organic Materials 2021; 03(02): 381-389
DOI: 10.1055/a-1528-6301
Original Article

Dithienothiazine Copolymers – Synthesis and Electronic Properties of Novel Redox-Active Fluorescent Polymers

a  Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
,
Thomas J. J. Müller
a  Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
› Institutsangaben
Funding Information The authors gratefully acknowledge the Ernst Jäger Foundation (scholarship for Jennifer Nau) and the Deutsche Forschungsgemeinschaft (Mu 1088/9-1) for the financial support.
 


Abstract

Dithienothiazine copolymers are efficiently obtained by Suzuki polymerization or in situ lithiation–Negishi polymerization in good to excellent yields. Gel permeation chromatography was applied to characterize the dispersities and degrees of polymerization of these novel materials. Thermogravimetric analysis shows that the copolymers are stable towards side-chain cleavage up to 200 °C. The materials are deep red to black amorphous solids or resins and their absorption and emission spectra in solution reveal broad absorption bands in the visible and orange to deep red luminescence upon UV excitation. According to the optical band gaps these novel copolymers qualify as a new class of low band gap organic semiconductors.


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Introduction

Organic macromolecules with π-conjugated ligation throughout the backbone, so-called π-conjugated polymers, can become electrical (semi)conductors upon doping with oxidants (p-doping) or reductants (n-doping).[1] Although conjugated organic polymers have been known for more than 150 years, it was not before the early 1960s that their conductivity was first discovered.[2] In the past decades, they have conquered numerous applications, such as molecular electronics,[3] photocatalysis,[4] biomedical applications,[5] and organic photovoltaics.[6] Among these π-conjugated polymers, regioregular narrow band gap polymers containing alternating donor and acceptor moieties have aroused interest for use in plastic electronics.[7]

As donor components, ensuring high lying HOMO energies and generation of stable radical cations upon oxidation with triarylamines[8] and thiophene motifs[9] have received significant prominence as hole transporters. Furthermore, S,N-containing tricycles, such as 3,7-disubstituted phenothiazines, exhibit fully reversible one-electron oxidations at low potentials,[10] extraordinarily stable radical cations,[11] and pronounced luminescence. For instance, organic light-emitting diodes[12] as well as redox switchable luminophores[13] have been developed based on oligomeric and polymeric phenothiazines.

Just very recently, we have introduced dithieno[1,4]thiazines, electron-density enriched congeners of phenothiazines,[14] which even have lower oxidation potentials with higher radical cation stability, as novel types of donors for organic chromophores and electrophores.[15] The paramount practical advantage of dithieno[1,4]thiazines over phenothiazines is their ready functionalization in the α,α'-positions of the thieno cores. Based upon versatile transformations by lithiation-electrophilic trapping sequences,[16] halogenated and organometallic build blocks became accessible, which were employed to the efficient synthesis of dithienothiazine dimers, trimers and homopolymers.[17] Here, we report on the synthesis and characterization of dithienothiazine copolymers based upon Suzuki and Negishi polymerization as well as on the electronic properties of these polymers.


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Results and Discussion

Synthesis and Polymer Characterization

For ensuring high solubility in common organic solvents, we decided to introduce p-phenoxy to an aliphatic swallow tail in the 4H-dithieno[2,3-b:3',2'-e][1,4]thiazine 1 (conveniently we will abbreviate this unit as syn,syn-dithienothiazine since the sulfur atoms are in a synsyn relationship). Starting with a TIPS-protected precursor that is obtained in good yield via (5 + 1)-Buchwald–Hartwig cyclization, compound 1 is directly formed by one-pot fluoride-induced desilylation and Williamson ether synthesis, whereas for the diiodo derivative 2 the TIPS-protected precursor is first selectively iodinated followed by one-pot desilylation–etherification synthesis ([Scheme 1]).[17]

Zoom Image
Scheme 1 Synthesis of syn,syn-dithienothiazine starting materials 1 and 2.

With dithienothiazine monomers 1 and 2 in hand, we synthesized dithienothiazine copolymers 4 by Suzuki polymerization of diiodo dithienothiazine 2 and (hetero)aryl bis(boronate) 3 ([Scheme 2]) and by Negishi polymerization in situ dilithiated dithienothiazine 1 and diiodo(hetero)arene 5 ([Scheme 3]) as dark red to black solids or resins in good to excellent yields.

Zoom Image
Scheme 2 Suzuki polymerization synthesis of dithienothiazine copolymers 4.
Zoom Image
Scheme 3 Negishi polymerization synthesis of dithienothiazine copolymers 4.

The novel dithienothiazine copolymers 4 were characterized by IR spectroscopy and gel permeation chromatography (GPC).[18] For the THF-soluble copolymers 4a, 4b, 4c, 4e, 4f, and 4h, 1H and 13C NMR spectra were recorded showing broad, poorly resolved signals, yet, showing approximate integral ratios that support the corresponding proposed ligation. For some polymers prepared by the Negishi polymerization protocol, residual TMEDA stemming from the lithiation of monomer 1, which cannot be completely removed by multiple suspension–sonication cycles and extensive high vacuum drying, is discernable in the NMR spectra. MALDI TOF mass spectra rather revealed several molecular peaks for short oligomers with various end groups, such as pinacolyl boryl or iodo substituents.

GPC in THF with polystyrene as a standard[19] allows determining the number average molecular weight (M n), the weight average molecular weight (M w), the molecular weight of the detector signal maximum (M p) as well as the dispersity Đ M = M w/M n and the degree of polymerization DP. For the interpretation the globular structure of polystyrene chains in comparison to the bacillary nature of poly(dithienothiazines) has to be taken into account, overestimating the molecular weights of poly(dithienothiazines). The GPC data of the copolymers 4 are summarized in [Table 1].

Table 1

Molecular weight distributions of the copolymers 4 according to GPC (eluent THF, flow rate 1 mL/min, T = 293 K)

Polymer

Molecular weight [Da]

Dispersity

Degree of polymerization

M 0 [a]

M n [b]

M w [c]

M p [d]

Đ M [e]

DP[f]

4a [g]

714.1

3.76 · 103

6.22 · 103

9.47 · 103

1.65

8.7

4a [h]

5.93 · 103

8.96 · 103

6.74 · 103

1.51

12.5

4b [h]

714.1

3.74 · 103

6.14 · 103

1.64 · 103

1.64

8.6

4c [h]

742.2

4.24 · 103

7.27 · 103

1.78 · 103

1.71

9.8

4d [g]

790.2

1.04 · 104

1.65 · 104

1.61 · 104

1.59

20.9

4e [h]

715.1

8.41 · 103

1.41 · 104

1.72 · 104

1.68

19.7

4f [h]

715.1

4.44 · 103

6.02 · 103

3.79 · 103

1.35

8.4

4g [g]

772.2

2.46 · 103

2.95 · 103

2.46 · 103

1.20

3.8

4h [g]

919.5

1.01 · 104

1.37 · 104

1.50 · 104

1.36

14.9

a M 0: molecular weight of the repeating unit.


b M n: number average molecular weight.


c M w: weight average molecular weight.


d M p: molecular weight of the detector signal maximum.


e Đ M = M w/M n: dispersity.


f DP = M w/M 0: degree of polymerization.


g Suzuki polymer synthesis.


h Negishi polymer synthesis.


The average molecular weights of the dithienothiazine copolymers 4 fall into a range between 3000 and 18000 g/mol. In the GPC traces of copolymers 4a, 4b, 4c, 4g, 4e, and 4f, lower oligomers are also visible ([Figure 1]).

Zoom Image
Figure 1 Representative GPC traces of copolymers 4a (left) and 4h (right) (eluent THF, flow rate 1 mL/min, T = 293 K).

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Thermal Properties

The copolymers 4a and 4dh were furthermore investigated by thermogravimetric analysis for obtaining an insight into their thermal stability ([Table 2]). Our interest was focused on the stability of the N-substituent towards thermal cleavage. After extrusion of solvent residues above 100 °C, all investigated copolymers 4 are thermally stable up to a temperature of 205 °C. While copolymer 4f starts to decompose at 205 °C, copolymer 4d only starts to decompose above 275 °C. In the range of 350 to 395 °C, the pyrolytic cleavage of the solubilizing swallowtail proceeds. This is indicated, depending on the corresponding copolymer 4, by a loss of weight between 40.97 and 50.60%, in accordance with the proportional molecular weight of the swallowtail. At temperatures between 450 and 500 °C, the pyrolytic cleavage of the swallowtail ceases.

Table 2

Thermogravimetric analysis of copolymers 4

Decomposition

Copolymer

Start [°C]

Maximum [°C]

End [°C]

Weight loss [%]

Molecular mass percentage of the swallowtail [%]

4a

235

360

495

47.12

47.1

4d

275

365

500

40.97

42.6

4e

250

395

485

50.60

47.0

4f

205

350

480

48.05

47.0

4g

220

380

450

43.53

43.6

4h

230

380

450

44.61

45.9[a]

a With concomitant cleavage of the phenothiazine's hexyl chain.



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Electronic Properties

The electronic properties of the dithienothiazine copolymers 4 were investigated by cyclic voltammetry and absorption and emission spectroscopy. Upon comparison of the cyclic voltammograms of copolymers 4 with the CV of the previously reported dithienothiazine homopolymer,[17] a similar behavior becomes apparent. Only broad oxidation and reduction waves are displayed, which cannot be elaborated further ([Figure 2]).

Zoom Image
Figure 2 Cyclic voltammograms of dithienothiazine copolymers 4e (left) and 4h (right) (recorded in CH2Cl2, T = 293 K, 0.1 m electrolyte [ n Bu4N][PF6]; v = 100 mV/s; Pt working electrode, Ag/AgCl reference electrode and Pt counter electrode).

The solutions of copolymers 4a, 4b, 4c, 4e, 4f, and 4h are orange to red under daylight and they fluoresce with orange to deep red color under the handheld UV lamp ([Figure 3]).

Zoom Image
Figure 3 Solutions of selected dithienothiazine copolymers 4 (recorded in CH2Cl2, T = 293 K, c(4) = 10−6 M, under daylight (top) and under the handheld UV lamp, λ exc = 365 nm).

Absorption and emission spectra of the dithienothiazine copolymers 4 were recorded in dichloromethane or in THF, depending on the solubility ([Table 3], [Figure 4]). For copolymer 4a, the absorption bands essentially are at the same energy in both solvents, dichloromethane and THF. Only the emission maximum experiences a slight redshift upon changing from THF to the polar solvent dichloromethane.

Table 3

Selected absorption and emission data of dithienothiazine copolymers 4

Solvent

λ max,abs [nm] (ε [L mol−1 cm−1])[a]

λ max,em[nm][b]

Stokes shift ∆ [cm−1][c]

ΔE opt(HOMO–LUMO) (E 0-0)[d] [eV (nm)]

4a

CH2Cl2

322 (18100), 461 (5300)

643

6100

2.18 (569)

4a

THF

322 (22200), 461 (6700)

631

5800

2.21 (562)

4b

CH2Cl2

295 (26300), 442sh (3600)

608

6200

2.29 (542)

4c

CH2Cl2

291 (21600), 437 (4000)

637

7200

2.24 (553)

4d

THF

328 (26200), 471 (8700)

628

5300

2.19 (565)

4e

CH2Cl2

336 (21000), 501 (6600)

681

5300

2.03 (610)

4f

CH2Cl2

316 (17600), 465 (3400)

640

5900

2.18 (570)

4g

THF

300 (21600), 747 (11200)

4h

CH2Cl2

297 (42800), 436 (15500)

587

5900

2.40 (516)

a Recorded at T = 293 K, c(4) = 10−5 M.


b Recorded at T = 293 K, c(4) = 10−6 M, λ exc = 470 nm.


c  = λ max,abs −1 - λ max,em −1 [cm−1].


d E 0-0 was determined at the intersection of the corresponding normalized absorption and emission bands.[20]


Zoom Image
Figure 4 Normalized absorption (solid lines) and emission (dashed lines) spectra of copolymers 4a (red lines), 4e (magenta lines), and 4h (yellow lines) (absorption spectra recorded in CH2Cl2, T = 293 K, c(4) = 10−5 m; emission spectra recorded in CH2Cl2, T = 293 K, c(4) = 10−5 m, λ exc = 470 nm).

All copolymers 4 possess two characteristic absorption bands, the higher energy absorptions fall into a range from 291 to 336 nm and lower energy longest wavelength absorption band appears in a broad range from 436 to 747 nm. Expectedly, an electron-withdrawing bridging unit, such as 2,5-pyridylene or 4,7-benzothiadiazolylene, causes a considerable bathochromic shift in comparison to electron neutral or electron-donating bridging units. Therefore, most blueshifted is the absorption band of the electron-rich dithienothiazine–phenothiazine copolymer 4h.

Most distinctly, the emission maxima of the dithienothiazine copolymers 4 appear in a range from 587 to 681 nm, again in agreement with the electronic nature of the bridging unit. In contrast to many simple dithienothiazines with 2,6-diaryl substitution, which are only weakly luminescent,[16a] this novel type of low-band gap polymers is intensely luminescent with orange to deep red color. Furthermore, from the intersection of the absorption and emission spectra, the optical band gap ΔE opt that corresponds to the E 0-0 transition[20] can be estimated for the copolymers 4, and lies in a range between 2.03 and 2.40 eV. Therefore, the dithienothiazine-2,5-pyridine copolymer 4e possesses the smallest and the dithienothiazine–phenothiazine copolymer 4h the largest band gap. Since the typical window for optical band gaps of organic semiconductors encompasses a range from 1.5 to 3.0 eV,[21] all these novel dithienothiazine copolymers qualify as low band gap semiconductors.


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Conclusions

In summary, we have employed the previously published organometallic synthesis of dithienothiazine homopolymers and oligomers to the generation of dithienothiazine copolymers. Indeed, two complementary polymerizations, Suzuki polymerization and in situ lithiation–Negishi polymerization, were successfully probed to give a series of eight dithienothiazine copolymers in good to excellent yields. The dispersities and degrees of polymerization were determined by GPC measurements of the molecular weight distribution. The copolymers are remarkably stable with respect to thermal cleavage of the solubilizing side chains, which does not proceed up to 200 °C. The copolymers are deep colored amorphous solids or resins that dissolve readily in organic solvents. The absorption and emission spectra not only reveal broad absorption bands in the visible, but also orange to deep red luminescence upon excitation with UV light. The determined optical band gaps qualify these novel copolymers as a new class of potential low band gap organic semiconductors. A more detailed treatment of the electronic structure of dithienothiazine-bridge-dithienothiazine models of the copolymers is currently underway.


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Experimental Section

Reagents, catalysts, and solvents were purchased reagent grade and used without further purification. Monomers 1 and 2 were synthesized according to our previously published protocol.[17] Bisboronate 3d was prepared according to our previously published protocol[22] and bisboronate 3c was prepared from the corresponding 4,7–dibromobenzo[c][1,2,5]thiadiazole[23] by Miyaura coupling.[24] Anhydrous THF was obtained from a drying system (MBraun systemMB-SPS-800) and toluene was dried over MS 3Å for at least 24 h. The reaction progress was monitored qualitatively by using TLC silica gel 60 UV254 sheets obtained by Macherey-Nagel GmbH & Co. KG. The spots were detected with UV light at 254 and 365 nm. The 1H and 13C NMR spectra were determined on a 600 MHz NMR spectrometer. Chemical shifts δ are reported in ppm relative to the internal solvent signals of THF-d8 (1H δ 3.58, 13C δ 67.6). By using DEPT-135 spectra the quaternary C, CH, CH2, and CH3 signals were assigned. Infrared spectra were recorded with neat compounds under attenuated total reflection and the intensities were characterized as strong (s), middle (m), and weak (w). The elemental analyses were carried out in the microanalytical laboratory of the Pharmazeutisches Institut, Heinrich-Heine-Universität Düsseldorf. Absorption and emission spectra were recorded in dichloromethane HPLC grade at 293 K on a Perkin Elmer UV/Vis/NIR Lambda 19 (absorption) and Hitachi F7000 (emission) spectrometer. The cyclic voltammetry experiments were performed under argon in dry and degassed dichloromethane at 293 K using a small-scale set-up with a three-electrode arrangement (2 mm platinum working electrode, platinum wire counter electrode, Ag/AgCl reference electrode) with tetrabutylammonium hexafluorophosphate as the electrolyte. The oxidation potentials were determined against the internal standard decamethylferrocene (E 0/+1 = −95 mV). The potential of this standard was determined against ferrocene (E 0/+1 = 450 mV[25]).

General Procedure for the Suzuki Polymerization (GP1)

In an oven-dried Schlenk flask with a magnetic stir bar, a mixture of 4-(4-((2-decyltetradecyl)oxy)phenyl)-2,6-diiodo-4H-dithieno[2,3-b:3',2'-e][1,4]thiazine (2) (357 mg, 0.40 mmol), diboronic acid/diboronate 3 (0.40 mmol), tetrabutylammonium chloride (111 mg, 0.40 mmol), toluene (16 mL) and a saturated aqueous solution of potassium carbonate (4 mL) was degassed with argon for 20 min (for experimental details, see [Table 4]). Then, tetrakis(triphenylphosphane)palladium(0) (10 mol%, 46.0 mg, 0.04 mmol) was added to the reaction mixture and the reaction mixture was heated under an argon atmosphere at 85 °C (oil bath) for 3 d. After cooling to room temperature, water (20 mL) was added to stop the reaction. The organic layer was separated and the aqueous phase was extracted with dichloromethane (3 × 20 mL). The combined organic layers were dried with anhydrous magnesium sulfate, filtered and the solvent was removed under reduced pressure to give the crude product 4.

Table 4

Experimental details of the Suzuki polymerization synthesis of dithienothiazine copolymers 4

Entry

Diboronic acid/diboronate 3

Dithienothiazine copolymer 4 (yield)

1

66.0 mg (0.40 mmol) of 3a

272 mg (92%) of 4a

2

97.0 mg (0.40 mmol) of 3b

204 mg (63%) of 4d

3[a]

155 mg (0.40 mmol) of 3c

290 mg (85%) of 4g

4

214 mg (0.40 mmol) of 3d

374 mg (99%) of 4h

a Reaction time at 85 °C for 4 d.



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General Procedure for the Negishi Polymerization (GP2)

In an oven-dried Schlenk flask with a magnetic stir bar, a mixture of 4-(4-((2-decyltetradecyl)oxy)phenyl)-4H-dithieno[2,3-b:3',2'-e][1,4]thiazine (1) (192 mg, 0.30 mmol), TMEDA (0.10 mL, 0.66 mmol), and dry THF (6 mL) under argon was cooled to −78 °C (dry ice/acetone). Then, n-butyllithium in hexanes (1.58 m, 0.42 mL, 0.60 mmol) was added dropwise over 10 min and stirring at −78 °C was continued for 2 h. Then, a solution of freshly dried zinc bromide (203 mg, 0.90 mmol) in dry THF (1 mL) was added to the reaction mixture, which was then allowed to come to room temperature. After stirring at room temperature for 1 h, tetrakis(triphenylphosphane)palladium(0) (10 mol%, 35.0 mg, 0.03 mmol) and diiodo(hetero)-arene 5 (1.0 equiv, 0.30 mmol) were added and the mixture was stirred at 50 °C (oil bath) for 3 d (for experimental details, see [Table 5]). After cooling to room temperature, brine (15 mL) was added to stop the reaction. The aqueous phase was extracted with dichloromethane (3 × 20 mL). The combined organic layers were dried with anhydrous magnesium sulfate, filtered and the solvent was removed under reduced pressure to give the crude product 4.

Table 5

Experimental details of the Negishi polymerization synthesis of dithienothiazine copolymers 4

Entry

Diiodo(hetero)arene 5

Dithienothiazine copolymer 4 (yield)

1

99 mg (0.30 mmol) of 5a

220 mg (99%) of 4a

2

99 mg (0.30 mmol) of 5b

225 mg (99%) of 4b

3

107 mg (0.30 mmol) of 5c

212 mg (92%) of 4c

4

99 mg (0.30 mmol) of 5d

229 mg (100%) of 4e

5

99 mg (0.30 mmol) of 5e

228 mg (100%) of 4f


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Poly[4-(4-((2-decyltetradecyl)oxy)phenyl)-4H-dithieno[2,3-b:3',2'-e][1,4]thiazin-2,6-yl-alt-1,4-phenylene] (4a)

The crude product obtained according to GP1 was suspended in acetone (25 mL), placed in the ultrasound bath for 25 min and after filtration the residue was dried under reduced pressure to give polymer 4a (272 mg, 92%) as a dark brown solid, Mp 174–180 °C.

Zoom Image

The crude product obtained according to GP2 was suspended in acetone (20 mL), placed in the ultrasound bath for 15 min and after filtration the residue was dried under reduced pressure to give polymer 4a (220 mg, 99%) as a dark brown solid, Mp 174–180 °C.

Zoom Image

IR [cm−1]: 2920 (m), 2850 (w), 1504 (s), 1493 (m), 1483 (w), 1463 (w), 1456 (w), 1427 (w), 1409 (w), 1377 (w), 1276 (w), 1240 (m), 1165 (w), 1103 (w), 1062 (w), 1045 (w), 1024 (w), 997 (w), 977 (w), 947 (w), 839 (w), 808 (m), 765 (w), 721 (w), 692 (w), 681 (w), 665 (w).

1H NMR (THF-d8 , 600 MHz): δ = 6.03–7.80 (m, 10 H), 3.70–3.99 (m, 2 H), 1.81–184 (m, 1 H), 1.29–1.55 (m, 40 H), 0.78–0.97 (m, 6 H).

13C NMR (THF-d8 , 150 MHz): δ = 160.1 (Cquat), 143.4 (Cquat), 139.0 (Cquat), 133.3 (Cquat), 133.2 (Cquat), 131.32 (CH), 131.28 (CH), 127.4 (CH), 126.1 (CH), 116.92 (Cquat), 116.89 (Cquat), 116.1 (CH), 101.6 (Cquat), 72.0 (CH2), 39.4 (CH), 33.1 (CH2), 32.6 (CH2), 31.2 (CH2), 30.85 (CH2), 30.81 (CH2), 30.5 (CH2), 28.1 (CH2), 23.8 (CH2), 14.7 (CH3).

MS (MALDI): m/z = 1043.219 ([I-p-ph-(DTT-ph)-I)]+), 1554.675 ([(DTT-p-ph)2-I]+), 1756.602 ([I-p-ph-[(DTT-p-ph)2-I]+), 2269.053 ([(DTT-p-ph)3-I]+), 2471.245 ([I-(p-ph-DTT)3-p-ph-I]+).


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Poly[4-(4-((2-decyltetradecyl)oxy)phenyl)-4H-dithieno[2,3-b:3',2'-e][1,4]thiazin-2,6-yl-alt-1,3-phenylene] (4b)

The crude product obtained according to GP2 was suspended in acetone (15 mL), placed in the ultrasound bath for 15 min and after filtration the residue was dried under reduced pressure to give polymer 4b (225 mg, 99%) as a dark red resin, Mp >300 °C.

Zoom Image

IR [cm−1]: 2958 (w), 2920 (s), 2870 (w), 1597 (w), 1585 (w), 1568 (w), 1533 (w), 1506 (m), 1464 (m), 1456 (w), 1435 (w), 1417 (w), 1377 (w), 1363 (w), 1338 (w), 1257 (m), 1242 (m), 1184 (w), 1165 (w), 1093 (m), 1016 (s), 937 (w), 864 (w), 837 (w), 817 (m), 789 (s), 742 (w), 719 (w), 690 (m), 659 (w).

1H NMR (THF-d8 , 600 MHz): δ = 6.02–7.74 (m, 10 H), 3.70–4.00 (br, 2 H), 1.82–1.85 (br, 1 H), 1.28–1.56 (m, 40 H), 0.80–0.89 (m, 6 H).

13C NMR (THF-d8 , 150 MHz): δ = 160.1 (Cquat), 154.3 (Cquat), 145.5 (Cquat), 137.0 (Cquat), 134.3 (Cquat), 133.3 (CH), 133.1 (CH), 133.0 (CH), 132.6 (Cquat), 132.3 (Cquat), 131.2 (CH), 129.34 (CH), 129.29 (CH), 117.0 (CH), 116.9 (CH), 115.8 (CH), 101.1 (Cquat), 72.0 (CH2), 39.4 (CH), 33.1 (CH2), 32.6 (CH2), 31.2 (CH2), 30.9 (CH2), 30.8 (CH2), 30.5 (CH2), 28.1 (CH2), 26.6 (CH2), 23.8 (CH2), 14.7 (CH3).

MS (MALDI): m/z = 841.248 ([(DTT-m-ph)-I]+), 1043.279 ([I-m-ph-(DTT-m-ph)-I]+), 1555.746 ([(DTT-m-ph)2-I]+), 1757.701 ([I-m-ph-(DTT-m-ph)2-I]+), 2269.150 ([(DTT-m-ph)3-I]+).


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Poly[4-(4-((2-decyltetradecyl)oxy)phenyl)-4H-dithieno[2,3-b:3',2'-e][1,4]thiazin-2,6-yl-alt-2,5-dimethyl-1,4-phenylene] (4c)

The crude product obtained according to GP2 was suspended in acetone (15 mL), placed in the ultrasound bath for 15 min and after decantation of the supernatant the residue was dried under reduced pressure to give polymer 4c (212 mg, 92%) as a dark red resin.

Zoom Image

IR [cm−1]: 2987 (w) 2920 (s), 2872 (m), 1701 (w), 1558 (w), 1504 (s), 1456 (w), 1435 (w), 1379 (w), 1354 (w), 1296 (w), 1278 (w), 1240 (m), 1166 (w), 1072 (w), 1037 (w), 997 (w), 974 (w), 889 (w), 742 (w), 721 (w), 692 (w), 620 (m).

1H NMR (THF-d8 , 600 MHz): δ = 6.01–7.75 (m, 8 H), 3.75–3.95 (br, 2 H), 2.08–2.57 (m, 6 H), 1.75–1.83 (br, 1 H), 1.28–1.52 (m, 40 H), 0.79–0.90 (m, 6 H).

13C NMR (THF-d8 , 150 MHz): δ = 145.4 (Cquat), 141.8 (Cquat), 134.2 (Cquat), 133.3 (Cquat), 133.2 (Cquat), 132.8 (CH), 131.3 (CH), 131.01 (CH), 130.03 (CH), 129.34 (Cquat), 129.26 (Cquat), 119.9 (CH), 116.8 (Cquat), 115.8 (CH), 101.1 (Cquat), 71.8 (CH2), 47.9 (Cquat), 39.3 (CH), 33.0 (CH2), 32.55 (CH2), 32.50 (CH2), 31.2 (CH2), 30.82 (CH2), 30.78 (CH2), 30.5 (CH2), 28.0 (CH2), 23.7 (CH2), 14.7 (CH3).

MS (MALDI): m/z = 869.280 ([(DTT-2,6-p-xyl)-I]+), 1099.232 ([I-2,6-p-xyl-(DTT-2,6-p-xyl)-I]+), 1610.670 ([(DTT-2,6-p-xyl)2-I]+), 1840.620 ([I-2,6-p-xyl-(DTT-2,6-p-xyl)2-I]+), 2353.052 ([(DTT-2,6-p-xyl)3-I]+), 2582.997 ([I-2,6-p-xyl-(DTT-2,6-p-xyl)3-I]+).


#

Poly[4-(4-((2-decyltetradecyl)oxy)phenyl)-4H-dithieno[2,3-b:3',2'-e][1,4]thiazin-2,6-yl-alt-4,4'-biphenylene] (4d)

The crude product obtained according to GP1 was suspended in acetone (25 mL), placed in the ultrasound bath for 25 min and after filtration the residue was dried under reduced pressure to give polymer 4d (204 mg, 63%) as a sparingly soluble black solid, Mp >300 °C.

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IR [cm−1]: 2920 (s), 2850 (m), 1504 (s), 1490 (s), 1465 (m), 1435 (m), 1411 (w), 1400 (w), 1377 (w), 1298 (w), 1274 (w), 1240 (s), 1165 (w), 1105 (w), 1029 (w), 1001 (w), 839 (w), 808 (s), 763 (w), 719 (w), 694 (w).

MS (MALDI): m/z = 839.445 ([(DTT-4,4'-biph)-B(OH)2]+), 1428.834 ([DTT-4,4'-biph-DTT]+), 2219.263 ([(DTT-4,4'-biph)2-DTT]+), 3008.729 ([(DTT-4,4'-biph)3-DTT]+).


#

Poly[4-(4-((2-decyltetradecyl)oxy)phenyl)-4H-dithieno[2,3-b:3',2'-e][1,4]thiazin-2,6-yl-alt-2,5-pyridyl] (4e)

The crude product obtained according to GP2 was suspended in acetone (20 mL), placed in the ultrasound bath for 15 min and after filtration the residue was dried under reduced pressure to give polymer 4e (229 mg, 100%) as a black solid, Mp >300 °C (dec.).

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IR [cm−1]: 2920 (s), 2850 (m), 1573 (w), 1556 (w), 1531 (w), 1504 (s), 1471 (s), 1417 (m), 1377 (w), 1365 (w), 1292 (w), 1276 (w), 1240 (s), 1186 (w), 1166 (w), 1134 (w), 1101 (w), 1076 (w), 1047 (w), 1022 (w), 997 (w), 975 (w), 964 (w), 945 (w), 918 (w), 893 (w), 839 (w), 813 (w), 765 (w), 742 (w), 721 (w), 692 (w), 667 (w), 615 (w).

1H NMR (THF-d8 , 600 MHz): δ = 6.01–8.59 (m, 9 H), 3.74–3.93 (br, 2 H), 1.83 (br, 1 H), 1.28–1.54 (m, 40 H), 0.80–0.90 (m, 6 H).

13C NMR (THF-d8 , 150 MHz): δ = 160.8 (Cquat), 145.6 (Cquat), 134.0 (Cquat), 133.6 (Cquat), 132.5 (Cquat), 131.43 (CH), 131.37 (CH), 129.4 (Cquat), 117.0 (CH), 116.97 (CH), 116.94 (CH), 101.1 (Cquat), 71.8 (CH2), 39.4 (CH), 33.1 (CH2), 32.6 (CH2), 31.2 (CH2), 30.8 (CH2), 30.5 (CH2), 28.0 (CH2), 23.8 (CH2), 14.7 (CH3).

MS (MALDI): m/z = 1556.659 ([(DTT-2,5-py)2-I]+), 1759.579 ([I-2,5-py-(DTT-2,5-py)2-I]+), 2272.027 ([(DTT-2,5-py)3-I]+), 2474.958 ([I-2,5-py-(DTT-2,5-py)3-I]+), 3189.435 ([I-2,5-py-(DTT-2,5-py)4-I]+).


#

Poly[4-(4-((2-decyltetradecyl)oxy)phenyl)-4H-dithieno[2,3-b:3',2'-e][1,4]thiazin-2,6-yl-alt-2,6-pyridyl] (4f)

The crude product obtained according to GP2 was suspended in acetone (20 mL), placed in the ultrasound bath for 15 min and after filtration the residue was dried under reduced pressure to give polymer 4f (228 mg, 100%) as a dark brown solid, Mp 95–98 °C.

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IR [cm−1]: 2920 (s), 2850 (m), 2160 (w), 1575 (w), 1558 (m), 1541 (w), 1504 (m), 1442 (s), 1419 (m), 1394 (w), 1377 (w), 1367 (w), 1298 (w), 1242 (m), 1186 (w), 1159 (w), 1109 (w), 1078 (w), 1045 (w), 1026 (w), 1004 (w), 997 (w), 979 (w), 950 (w), 894 (w), 839 (w), 825 (w), 792 (m), 783 (w), 763 (w), 723 (w), 704 (w), 692 (w), 621 (m).

1H NMR (THF-d8 , 600 MHz): δ = 6.02–7.75 (m, 9 H), 3.75–3.95 (br, 2 H), 1.82–1.85 (br, 1H), 1.28–1.57 (m, 40 H), 0.83–0.89 (m, 6 H).

13C NMR (THF-d8 , 150 MHz): δ = 163.0 (Cquat), 151.8 (Cquat), 142.6 (Cquat), 133.7 (Cquat), 133.32 (Cquat), 133.28 (Cquat), 131.4 (CH), 129.6 (Cquat), 129.4 (Cquat), 129.3 (Cquat), 126.1 (Cquat), 117.7 (CH), 117.0 (CH), 116.8 (CH), 104.4 (Cquat), 101.1 (Cquat), 72.0 (CH2), 39.4 (CH), 33.0 (CH2), 32.6 (CH2), 31.2 (CH2), 30.82 (CH2), 30.79 (CH2), 30.5 (CH2), 28.1 (CH2), 23.7 (CH2), 14.6 (CH3).

MS (MALDI): m/z = 1045.221 ([I-2,6-py-(DTT-2,6-py)-I]+), 1557.680 ([(DTT-2,6-py)2-I]+), 1759.602 ([I–2,6-py-(DTT-2,6-py)2-I]+), 2272.054 ([(DTT-2,6-py)3-I]+), 2474.987 ([I-2,6-py-(DTT-2,6-py)3-I]+), 2986.498 ([(DTT-2,6-py)4-I]+), 3189.435 ([I-2,6-py-(DTT-2,6-py)4-I]+).


#

Poly[4-(4-((2-decyltetradecyl)oxy)phenyl)-4H-dithieno[2,3-b:3',2'-e][1,4]thiazin-2,6-yl-alt-4,7-benzo[c][1,2,5]thiadiazolyl] (4g)

The crude product obtained according to GP1 was suspended in acetone (20 mL), placed in the ultrasound bath for 15 min. Then the solid was suspended twice in acetone (2 × 10 mL) and the supernatant was decanted. After filtration the residue was dried under reduced pressure to give polymer 4g (290 mg, 85%) as a sparingly soluble dark green solid, Mp > 300 °C (dec.).

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IR [cm−1]: 2920 (m), 2850 (m), 1506 (m), 1483 (s), 1467 (m), 1426 (s), 1411 (s), 1375 (m), 1352 (w), 1338 (w), 1298 (w), 1240 (m), 1184 (w), 1165 (w), 1103 (w), 1049 (w), 1022 (w), 1008 (w), 864 (w), 837 (m), 819 (m), 788 (w), 765 (w), 719 (w), 638 (w).

MS (MALDI): m/z = 1410.746 ([DTT-(BTD-DTT)]+), 2183.107 ([DTT-(BTD-DTT)2]+), 2955.468 ([DTT-(BTD-DTT)3]+).


#

Poly[4-(4-((2-decyltetradecyl)oxy)phenyl)-4H-dithieno[2,3-b:3',2'-e][1,4]thiazin-2,6-yl-alt-10-hexyl-10H-phenothiazin-3,7-yl] (4h)

The crude product obtained according to GP1 was suspended in acetone (20 mL), placed in the ultrasound bath for 30 min and after filtration the residue was dried under reduced pressure to give polymer 4h (374 mg, 99%) as a dark brown resin, Mp 124–128 °C.

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IR [cm−1]: 2953 (w), 2920 (m), 2850 (w), 1620 (w), 1575 (w), 1571 (w), 1550 (w), 1508 (m), 1469 (s), 1463 (s), 1460 (s), 1452 (m), 1438 (w), 1400 (w), 1354 (w), 1332 (w), 1296 (w), 1244 (s), 1190 (w), 1165 (w), 1141 (w), 1103 (w), 1020 (w), 869 (w), 839 (w), 802 (m), 765 (w), 746 (w), 721 (w), 692 (w).

1H NMR (THF-d8 , 600 MHz): δ = 6.00–7.75 (m, 12 H), 3.78–3.98 (m, 4 H), 1.83–1.87 (br, 1 H), 1.29–1.62 (m, 46 H), 0.78–1.00 (m, 9 H).

13C NMR (THF-d8 , 150 MHz): δ = 160.1 (Cquat), 156.5 (Cquat), 145.7 (Cquat), 145.3 (Cquat), 141.3 (Cquat), 137.1 (Cquat), 133.0 (Cquat), 132.9 (Cquat), 131.2 (CH), 129.4 (CH), 129.3 (CH), 129.2 (CH), 125.8 (Cquat), 125.0 (CH), 124.2 (CH), 116.9 (CH), 116.6 (CH), 116.4 (CH), 115.5 (CH), 101.4 (Cquat), 84.5 (Cquat), 72.0 (CH), 48.2 (CH2), 39.4 (CH), 32.6 (CH2), 32.6 (CH2), 31.2 (CH2), 30.9 (CH3), 30.8 (CH2), 30.5 (CH2), 28.1 (CH2), 27.7 (CH2), 27.5 (CH2), 23.8 (CH2), 23.7 (CH2), 20.8 (CH2), 14.7 (CH3), 14.5 (CH3), 14.3 (CH3).

MS (MALDI): m/z = 1327.681 ([pinB-PT-(DTT-PT)]+), 1453.764 ([pinB-PT-(DTT-PT)-Bpin]+), 2247.143 ([pinB-PT-(DTT-PT)2]+), 2372.227 ([pinB-PT-(DTT-PT)2-Bpin]+), 3165.621 ([pinB-PT-(DTT-PT)3]+), 3291.700 ([pinB-PT-(DTT-PT)3-Bpin]+), 4087.500 ([pinB-PT-(DTT-PT)4]+), 4213.300 ([pinB-PT-(DTT-PT)4-Bpin]+).


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Die Autoren geben an, dass kein Interessenkonflikt besteht.

Acknowledgment

The authors are very grateful to Ms. Stephanie Scheelen (group of Prof. L. Hartmann, HHU Düsseldorf) for gel permeation chromatography measurements and Dr. Alexa Schmitz (group of Prof. C. Janiak, HHU Düsseldorf) for thermogravimetric analyses of compounds 4.

Supporting Information

Supporting Information for this article is available online at https://doi.org/10.1055/a-1528-6301.


Supporting Information

  • References

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    • 3c Bronstein H, Nielsen CB, Schroeder BC, McCulloch I. Nat. Rev. Chem. 2020; 4: 66
    • 3d Bhosale ME, Chae S, Kim JM, Choi J.-Y. J. Mater. Chem. A 2018; 6: 19885
    • 3e Bujak P, Kulszewicz-Bajer I, Zagorska M, Maurel V, Wielgus I, Pron A. Chem. Soc. Rev. 2013; 42: 8895
    • 3f Dong H, Zhu H, Meng Q, Gong X, Hu W. Chem. Soc. Rev. 2012; 41: 1754
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    • 13b Müller TJ. J, Franz AW, ,Barkschat (née Krämer) C. S. Sailer M, Meerholz K, Müller D, Colsmann A, Lemmer U. Macromol. Symp. 2010; 287: 1
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Publikationsverlauf

Eingereicht: 22. April 2021

Angenommen: 17. Mai 2021

Publikationsdatum:
14. Juni 2021 (online)

© 2021. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

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  • References

  • 2 Rasmussen SC. ChemPlusChem 2020; 85: 1412
    • 3a Fratini S, Nikolka M, Salleo A, Schweicher G, Sirringhaus H. Nat. Mater. 2020; 19: 491
    • 3b Wang C, Zhang X, Hu W. Chem. Soc. Rev. 2020; 49: 653
    • 3c Bronstein H, Nielsen CB, Schroeder BC, McCulloch I. Nat. Rev. Chem. 2020; 4: 66
    • 3d Bhosale ME, Chae S, Kim JM, Choi J.-Y. J. Mater. Chem. A 2018; 6: 19885
    • 3e Bujak P, Kulszewicz-Bajer I, Zagorska M, Maurel V, Wielgus I, Pron A. Chem. Soc. Rev. 2013; 42: 8895
    • 3f Dong H, Zhu H, Meng Q, Gong X, Hu W. Chem. Soc. Rev. 2012; 41: 1754
    • 4a Jayakumar J, Chou H.-H. ChemCatChem 2020; 12: 689
    • 4b Dai C, Liu B. Energy Environ. Sci. 2020; 13: 24
    • 5a Li J, Pu K. Chem. Soc. Rev. 2019; 48: 38
    • 5b Nezakati T, Seifalian A, Tan A, Seifalian AM. Chem. Rev. 2018; 118: 6766
    • 6a Mazzio KA, Luscombe CK. Chem. Soc. Rev. 2015; 44: 78
    • 6b Facchetti A. Chem. Mater. 2011; 23: 733
    • 6c Cheng Y.-J, Yang S.-H, Hsu C.-S. Chem. Rev. 2009; 109: 5868
  • 7 Ying L, Huang F, Bazan GC. Nat. Commun. 2017; 8: 14047
  • 8 Wang J, Liu K, Ma L, Zhan X. Chem. Rev. 2016; 116: 14675
  • 9 Cinar ME, Ozturk T. Chem. Rev. 2015; 115: 3036
  • 10 Aitken RA, Aitken KM. 1,4-Thiazines and their Benzo Derivatives. In: Comprehensive Heterocyclic Chemistry III. Katritzky AR, Ramsden AC, Scriven EF. .. V, Taylor RJ. .. K. Elsevier; Amsterdam: 2008: 607
  • 11 Pereţeanu IS, Müller TJ. J. Org. Biomol. Chem. 2013; 11: 5127
    • 12a Park Y, Kim B, Lee C, Hyun A, Jang S, Lee J.-H, Gal Y.-S, Kim TH, Kim K.-S, Park J. J. Phys. Chem. C 2011; 115: 4843
    • 12b Salunke JK, Wong FL, Feron K, Manzhos S, Lo MF, Shinde D, Patil A, Lee CS, Roy VA. L, Sonar P, Wadgaonkar PP. J. Mater. Chem. C 2016; 4: 1009
    • 12c Qu B, Chen Z, Liu Y, Cao H, Xu S, Cao S, Lan Z, Wang Z, Gong Q. J. Phys. D: Appl. Phys. 2006; 39: 2680
    • 12d Zhu Y, Champion RD, Jenekhe SA. Macromolecules 2006; 39: 8712
    • 13a Urselmann D, Deilhof K, Mayer B, Müller TJ. J. Beilstein J. Org. Chem. 2016; 12: 2055
    • 13b Müller TJ. J, Franz AW, ,Barkschat (née Krämer) C. S. Sailer M, Meerholz K, Müller D, Colsmann A, Lemmer U. Macromol. Symp. 2010; 287: 1
    • 13c Sailer M, Franz AW, Müller TJ. J. Chem. Eur J. 2008; 14: 2602
  • 14 May L, Müller TJ. J. Chem. Eur J. 2020; 26: 12111
  • 15 May L, Müller TJ. J. Molecules 2020; 25: 2180
    • 16a Dostert C, Müller TJ. J. Org. Chem. Front. 2015; 2: 481
    • 16b Dostert C, Czajkowski D, Müller TJ. J. Synlett 2014; 25: 371
  • 17 Nau J, Schneeweis AP. W, Müller TJ. J. Mater. Chem. Front. 2020; 4: 621
  • 18 Mori S, Barth HG. Size Exclusion Chromatography. Springer Science & Business Media; Berlin: 2013
  • 19 Netopilík M, Kratochvíl P. Polymer 2003; 44: 3431
  • 20 Meyer T, Ogermann D, Pankrath A, Kleinermanns K, Müller TJ. J. J. Org. Chem. 2012; 77: 3704
  • 21 Brutting W, Rieß W. Phys. J. 2008; 7: 33
  • 22 Krämer CS, Zimmermann TJ, Sailer M, Müller TJ. J. Synthesis 2002; 1163
  • 23 Heiskanen JP, Vivo P, Saari NM, Hukka TI, Kastinen T, Kaunisto K, Lemmetyinen HJ, Hormi OE. O. J. Org. Chem. 2016; 81: 1535
  • 24 Han FS, Higuchi M, Kurth DG. Org. Lett. 2007; 9: 559
  • 25 Zanello P. In Ferrocenes. A. Togni, A.; Hayashi, T. VCH; Weinheim: 1995: 317

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Scheme 1 Synthesis of syn,syn-dithienothiazine starting materials 1 and 2.
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Scheme 2 Suzuki polymerization synthesis of dithienothiazine copolymers 4.
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Scheme 3 Negishi polymerization synthesis of dithienothiazine copolymers 4.
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Figure 1 Representative GPC traces of copolymers 4a (left) and 4h (right) (eluent THF, flow rate 1 mL/min, T = 293 K).
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Figure 2 Cyclic voltammograms of dithienothiazine copolymers 4e (left) and 4h (right) (recorded in CH2Cl2, T = 293 K, 0.1 m electrolyte [ n Bu4N][PF6]; v = 100 mV/s; Pt working electrode, Ag/AgCl reference electrode and Pt counter electrode).
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Figure 3 Solutions of selected dithienothiazine copolymers 4 (recorded in CH2Cl2, T = 293 K, c(4) = 10−6 M, under daylight (top) and under the handheld UV lamp, λ exc = 365 nm).
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Figure 4 Normalized absorption (solid lines) and emission (dashed lines) spectra of copolymers 4a (red lines), 4e (magenta lines), and 4h (yellow lines) (absorption spectra recorded in CH2Cl2, T = 293 K, c(4) = 10−5 m; emission spectra recorded in CH2Cl2, T = 293 K, c(4) = 10−5 m, λ exc = 470 nm).
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