Substituted benzonaphthathiophene compounds for organic electronics

Abstract

The present invention provides compounds of formulae (1) (2) wherein R.sup.1 and R.sup.2 are C.sub.1-30alkyl, C.sub.2-3O-alkenyl, C.sub.2-30-alkynyl, C.sub.5-7-cycloalkyl, C.sub.6-14-aryl or 5 to 14 membered heteroaryl, wherein C.sub.1-30-alkyl, C.sub.2-3O-alkenyl and C.sub.2-3O-alkynyl can be substituted with one or more substituents selected from the group consisting of halogen, phenyl, O—C.sub.1-20-alkyl, O—C.sub.2-20-alkenyl and O—C.sub.2-2O-alkynyl, and wherein C.sub.5-7-cycloalkyl, C.sub.6-14-aryl and 5 to 14 membered heteroaryl can be substituted with one or more substituents selected from the group consisting of halogen, C.sub.1-20alkyl, C.sub.2-2O-alkenyl, C.sub.2-2O-alkynyl, O—C.sub.1-20-alkyl, O—C.sub.2-2o-alkenyl and O—C.sub.2-2o-alkynyl, R.sup.a, R.sup.b, R.sup.c and R.sup.d are independently and at each occurrence selected from the group consisting of C.sub.1-30alkyl, C.sub.2-30-alkenyl, C.sub.2-30-alkynyl, C.sub.6-14-aryl and 5 to 14 membered heteroaryl, wherein C.sub.1-30-alkyl, C.sub.2-3o-alkenyl and C.sub.2-3o-alkynyl can be substituted with one or more substituents selected from the group consisting of halogen, phenyl, O—C.sub.1-20-alkyl, O—C.sub.2-20-alkenyl and O—C.sub.2-20-alkynyl, and wherein C.sub.5-7-cycloalkyl, C.sub.6-14-aryl and 5 to 14 membered heteroaryl can be substituted with one or more substituents selected from the group consisting of halogen, C.sub.1-20alkyl, C.sub.2-2o-alkenyl, C.sub.2-20-alkynyl, O—C.sub.1-20-alkyl, O—C.sub.2-20-alkenyl and O—C.sub.2-2o-alkynyl, n and o are independently 0, 1, 2, 3, 4 or 5, and m and p are independently 0, 1, 2 or 3, and to electronic device comprising the compounds of formulae 1 or 2. ##STR00001##

Claims

1. Compounds of formulae ##STR00033## wherein R.sup.1 and R.sup.2 are C.sub.6-14 alkyl or ##STR00034## wherein R.sup.3 is H or C.sub.1-20 alkyl.

2. Compounds of claim 1, wherein R.sup.1 and R.sup.2 are C.sub.6-14 alkyl.

3. Compounds of claim 2 which are of formulae ##STR00035##

4. An electronic device comprising the compounds of claim 1.

5. The electronic device of claim 4, wherein the electronic device is an organic field effect transistor (OFET).

6. The method of forming a semiconducting layer comprising performing a solution deposition or thermal evaporation in vacuo of the compounds of claim 1.

Description

(1) FIG. 1 shows the drain current I.sub.D [A] in relation to the drain-source voltage V.sub.DS [V] (output curve) for the bottom-gate top-contact organic field effect transistor comprising compound 1a as semiconducting material at a gate-source voltage V.sub.GS of −11 V (first and top curve), −10.5 V (second curve), −10 V (third curve) and −9.5 V (fourth and bottom curve).

(2) FIG. 2 shows the drain current I.sub.D [A] in relation to the gate-source voltage V.sub.GS [V] (transfer curve) for the bottom-gate top-contact organic field effect transistor comprising compound 1a as semiconducting material at a drain-source voltage V.sub.DS of −5 V.

(3) FIG. 3 shows the drain current I.sub.D [A] in relation to the drain-source voltage V.sub.DS [V] (output curve) for the bottom-gate, top-contact organic field effect transistor comprising compound 2a as semiconducting material at a gate-source voltage V.sub.GS of −10 V (first and top curve).

(4) FIG. 4 shows the drain current I.sub.D [A] in relation to the gate-source voltage V.sub.GS [V] (transfer curve) for the bottom-gate top-contact organic field effect transistor comprising compound 2a as semiconducting material at a drain-source voltage V.sub.DS of −5 V.

(5) FIG. 5 shows the drain current I.sub.D [A] in relation to the drain-source voltage V.sub.DS [V] (output curve) for the bottom-gate, top-contact organic field effect transistor comprising compound 2b as semiconducting material at a gate-source voltage VGS of −10 V (first and top curve), −9.5 V (second curve) and −9 V (third and bottom curve).

(6) FIG. 6 shows the drain current I.sub.D [A] in relation to the gate-source voltage V.sub.GS [V] (transfer curve) for the bottom-gate top-contact organic field effect transistor comprising compound 2b as semiconducting material at a drain-source voltage VDS of −5 V.

EXAMPLES

Example 1

(7) Preparation of Compound 3

(8) ##STR00027##

(9) Preparation of Compound 9

(10) To a solution of benzothiophene (10) (10 g, 75 mmol) and AcOH (75 mL) in CHCl.sub.3 (75 mL) at 0° C. was added NBS (16.6 g, 93 mmol) portion-wise over a period of 15 mins. The reaction mixture was allowed to stir at room temperature overnight. After 15.5 hours, the reaction mixture was diluted with CHCl.sub.3. The organic layer was washed with Na.sub.2S.sub.2O.sub.3 (×1), Na.sub.2CO.sub.3 (x1), water (×1) and dried over Na.sub.2SO.sub.4. The crude material was purified through flash column chromatography (100% hexane) to yield compound 9 as pale yellow oil (12.86 g, 81%) after solvent removal. .sup.1H NMR (400 MHz, CDCl.sub.3) δ7.85 (m, 2H), 7.45 (m, 3H).

(11) Preparation of Compound 8

(12) To a solution of compound 9 (9.6 g, 45 mmol) in anhydrous Et.sub.2O (150 mL) at −78° C. was added n-BuLi (21.6 mL, 54 mmol) drop-wise. The reaction mixture was allowed to stir at −78° C. for 2 hours. After 2 hours, p-anisaldehyde (5.5 mL, 45 mmol) was then added drop-wise to the reaction mixture at −78° C. The reaction mixture was allowed to warm to room temperature gradually and stir overnight. After overnight stirring at room temperature, the reaction mixture was quenched with NH.sub.4Cl. The organic layer was extracted with Et.sub.2O (×3). The organic extract was washed with water (×2), brine (×1) and dried over Na.sub.2SO.sub.4. The crude compound 8 was obtained as a pale yellow oil and was used for the next step without further purification.

(13) Preparation of Compound 7

(14) To a suspension of LiAlH.sub.4 (1.9 g, 50 mmol) and AlCl.sub.3 (6.7 g, 50 mmol) in anhydrous Et.sub.2O (140 mL) at room temperature was added compound 8 (12.9 g, 48 mmol) in ether (20 mL) drop-wise. The reaction mixture was heated at 40° C. After 1.5 hours, the reaction mixture was cooled to room temperature. The reaction was then cooled to 0° C. by an ice bath and quenched by the addition of water drop-wise. The reaction mixture was then poured into 50% H.sub.2SO.sub.4 solution.

(15) The organic layer was extracted with Et.sub.2O (×3). The organic extract was washed with water (×2), brine (×1) and dried over Na.sub.2SO.sub.4. The crude material was purified by column chromatography (50:50 DCM/Hexane) to yield compound 7 as white solid (7.77 g, 64%). .sup.1H NMR (400 MHz, CD.sub.2Cl.sub.2) δ7.87 (m, 1H), 7.70 (m, 2H), 7.33 (m, 2H), 7.19 (m, 2H), 6.82 (m, 2H), 4.14 (s, 2H), 3.77 (s, 3H).

(16) Preparation of Compound 6

(17) To a solution of compound 7 (5.8 g, 23 mmol) in THF (31 mL) at −78° C. was added n-BuLi (11.0 mL, 27 mmol) drop-wise. The reaction mixture was allowed to stir at −78° C. for 1 hour. After 1 h, DMF (3.5 mL, 46 mmol) was then added drop-wise to the reaction mixture. The reaction mixture was allowed to warm to room temperature and stir overnight. After 18 hours, the reaction mixture was quenched with NH.sub.4Cl. The organic layer was extracted with Et.sub.2O (×3). The organic extract was washed with water (×3), brine (×1) and dried over Na.sub.2SO.sub.4. The crude solid was filtered and washed with hexane followed by MeOH. The crude material was purified by column chromatography (10:90 EA/Hexane) to yield compound 6 as yellow solid (6.44 g, 61%). .sup.1H NMR (400 MHz, d.sub.4-TCE) δ10.31 (s, 1 H), 7.88 (m, 2H), 7.52 (m, 1H), 7.41 (m, 1H), 7.13 (m, 2H), 6.82 (m, 2H), 4.57 (s, 2H), 3.77 (s, 3H).

(18) Preparation of Compound 5

(19) Polyphosphoric acid (50 g) was weighed into a one-neck round bottom flask using a syringe. Compound 6 (4.0 g, 14 mmol) was then added into the flask in one portion. The reaction mixture was heated at 50° C. After 2 hours, the heating was discontinued. Ice water was poured into the reaction mixture. The organic layer was extracted with EA (×3). The organic extract was washed with water (×2), NaHCO.sub.3 (×1) and dried over Na.sub.2SO.sub.4. The crude material was purified by flash column chromatography (50:50 DCM/Hexane) to yield compound 5 as a pale yellow solid (0.67 g, 18%). .sup.1H NMR (400 MHz, d.sub.4-TCE) δ8.55 (s, 1 H), 8.25 (m, 2H), 7.95 (m, 1H), 7.85 (m, 1 H), 7.50 (m, 2H), 7.20 (m, 2H), 3.97 (s, 3H).

(20) Preparation of Compound 4

(21) To 4-methoxy-naphtha[2,3-b]benzo[d]thiophene (0.6 g, 2 mmol) in anhydrous DCM (12 mL) at room temperature was added BBr.sub.3 (3.7 mL, 4 mmol) drop-wise slowly. The reaction mixture was stirred at room temperature overnight. After 24 hours, the reaction mixture was diluted with water and NaHCO.sub.3. The organic layer was extracted with EA (×3). The organic extract was washed with water (×2), brine (×1) and dried over Na.sub.2SO.sub.4. The crude material (0.57 g, 95%) as a pale yellow solid was used for the next step without further purification. .sup.1H NMR (400 MHz, d.sub.4-TCE) δ8.56 (s, 1 H), 8.23 (m, 1H), 8.14 (m, 1H), 7.98 (m, 1H), 7.83 (m, 1H), 7.50 (m, 2H), 7.20 (s, 1H), 7.17 (s, 1H).

(22) Preparation of Compound 3

(23) To compound 4 (0.57 g, 2 mmol) in anhydrous DCM (23 mL) was added pyridine (0.38 mL, 5 mmol) slowly. The reaction mixture was cooled to 0° C. and triflic anhydride (0.47 mL, 3 mmol) was added drop-wise. The reaction mixture was then warmed to room temperature. After 1 hour, the reaction mixture was quenched with 10% HCl. The organic layer was extracted with EA (×3). The organic extract was washed with 10% HCl (×1), water (×2), brine (x1) and dried over Na.sub.2SO.sub.4. Crude compound 3 was purified with flash column chromatography (20:80 EA/Hexane) to give compound 3 as a pale yellow solid (0.79 g, 96%). .sup.1H NMR (400 MHz, d.sub.4-TCE) δ8.69 (s, 1 H), 8.37 (s, 1H), 8.31 (d, 1H, J=1.6 Hz), 8.15 (d, 1H, J=9.2 Hz), 7.89 (d, 1H, J=2.0 Hz), 7.83 (s, 1 H), 7.56 (m, 2H), 7.42 (d, 1H, J=9.2 Hz).

Example 2

(24) Preparation of Compound 1a

(25) ##STR00028##

(26) To compound 3 (0.8 g, 2 mmol) and Ni(dppp)Cl.sub.2 (55 mg, 0.10 mmol) in anhydrous THF (4 mL) at room temperature was added C.sub.8H.sub.17MgBr (2.4 mL, 2 mmol) drop-wise. The reaction mixture was heated at 80° C. After 5.5 h, the reaction mixture was quenched with water. The organic layer was extracted with DCM (×3) and dried over Na.sub.2SO.sub.4. The crude material was purified with flash column chromatography (10:90 DCM/Hexane) to give compound 1a as a white solid (0.35 g, 49%). M.p. 120° C.; .sup.1H NMR (400 MHz, d.sub.4-TCE) δ8.59 (s, 1 H), 8.26 (m, 2H), 7.98 (m, 1H), 7.84 (m, 1H), 7.69 (s, 1H), 7.50 (m, 2H), 7.40 (m, 1H), 2.81 (m, 2H), 1.76-1.67 (m, 6H), 1.41-1.1.30 (m, 6H), 0.90 (m, 3H).

Example 3

(27) Preparation of Compound 11

(28) ##STR00029##

(29) Preparation of Compound 13

(30) To a suspension of AlCl.sub.3 (9.4 g, 70 mmol) in anhydrous DCM (213 mL) at room temperature was added phthalic anhydride (3.5 g, 24 mmol) in one portion. The suspension was allowed to stir at room temperature for 15 mins. The suspension was then cooled to 0° C. and compound 14 (5.0 g, 24 mmol) in DCM (10 mL) was added drop-wise. The reaction mixture was stirred overnight at room temperature. After 15.5 h, the reaction mixture was poured into ice water and acidified with 10% HCl. The suspension was filtered through celite, washing with DCM. The filtrate was concentrated to obtain the precipitate. The crude solid was then recrystallized with toluene to yield compound 13 as a pale yellow solid (4.2 g, 50%). .sup.1H NMR (400 MHz, DMSO) δ8.39 (s, 1 H), 7.99 (m, 1H), 7.89 (m, 1H), 7.75 (m, 2H), 7.57 (m, 1H), 7.23 (m, 1H), 7.15 (m, 1H).

(31) Preparation of Compound 12

(32) To compound 13 (4.2 g, 12 mmol) and PCl.sub.5 (4.9 g, 23 mmol) in anhydrous 1,2-dichlorobenzene (117 mL) at room temperature was added AlCl.sub.3 (3.1 g, 23 mmol) portion-wise. The reaction mixture was heated at 140° C. After 4.5 hours, the heating was discontinued. The reaction mixture was diluted with DCM and poured onto ice. The mixture was filtered through celite, washing with DCM. The filtered mixture was extracted with DCM (×3) and dried over Na.sub.2SO.sub.4. The crude mixture was then distilled to remove excess 1,2-dichlorobenzene and later purified by flash column chromatography (80:20 DCM/Hexane) to yield compound 12 as a dark green solid (3.11 g, 78%). .sup.1H NMR (400 MHz, CDCl.sub.3) δ8.78 (m, 1 H), 8.26 (m, 2H), 8.12 (s, 1H), 7.77 (m, 2H), 7.72 (m, 1H).

(33) Preparation of Compound 11

(34) To compound 12 (2.5 g, 7 mmol) in AcOH (72 mL) at room temperature was added HI (7.1 mL, 54 mmol) and H.sub.3PO.sub.2 (1.6 mL, 14 mmol) drop-wise. The reaction mixture was heated at 150° C. overnight. After 26 hours, heating was discontinued and the reaction mixture was poured onto 1% NaHSO.sub.3 solution (500 mL). The precipitate was collected by vacuum filtration. The crude solid was purified by column chromatography (40:60 DCM/Hexane) to give compound 11 as a pale yellow solid (0.62 g, 27%). .sup.1H NMR (400 MHz, d.sub.4-TCE) δ8.62 (s, 1 H), 8.31 (s, 1H), 8.15 (d, 1H, J=8.4 Hz), 8.06 (d, 1H, J=7.6 Hz), 8.00 (s, 1H), 7.93 (d, 1H, J=7.6 Hz), 7.64 (d, 1H, J=8.4 Hz), 7.57 (m, 2H).

Example 4

(35) Preparation of Compound 2a

(36) ##STR00030##

(37) To compound 11 (375 mg, 1.2 mmol) and Ni(dppp)Cl.sub.2 (32.4 mg, 0.1 mmol) in anhydrous THF (2.4 mL) at room temperature was added C.sub.6H.sub.13MgBr (1.8 mL, 1.8 mmol) drop-wise. The reaction mixture was heated at 80° C. overnight. After 18 h, the reaction mixture was quenched with water. The organic layer was extracted with DCM (×3). The organic extract was washed with brine (×1) and dried over Na.sub.2SO.sub.4. The crude material was purified by column chromatography (10:90 DCM/Hexane) to give compound 2a as a white solid (0.28 g, 73%). M.p. 100° C.; .sup.1H NMR (400 MHz, d.sub.4-TCE) δ8.58 (s, 1 H), 8.29 (s, 1H), 8.18 (s, 1H), 8.05 (m, 1H), 7.91 (m, 1H), 7.66 (s, 1H), 7.53 (m, 2H), 7.33 (m, 1H), 2.77 (m, 2H), 1.73-1.60 (m, 4H), 1.41-1.1.27 (m, 4H), 0.90 (m, 3H).

Example 5

(38) Preparation of compound 2b

(39) ##STR00031##

(40) Preparation of compound 20

(41) To 2-hexylthiophene (1.00 g, 6.0 mmol) in anhydrous THF (14 mL) at −78° C. was added n-BuLi (4.1 mL, 1.6M in hexane) drop-wise. The reaction mixture was gradually warmed to room temperature for 1.5 hour. After 1.5 hour, the reaction mixture was cooled down to −78° C. and Me.sub.3SnCl (1.53 g, 7.7 mmol) in THF (2 mL) was added drop-wise. The reaction mixture was warmed to room temperature and stirred overnight. After 22 hours, the reaction mixture was quenched with NH.sub.4Cl. The organic layer was extracted three times with Et.sub.2O. The organic extract was washed with two times with water, once with brine and dried over Na.sub.2SO.sub.4. The crude material was purified by kugelrohr distillation (150° C. @3 mm Hg) to give compound 20 as a pale yellow oil (0.67 g, 34%). .sup.1H NMR (400 MHz, CDCl.sub.3) δ7.01 (s, 1 H), 6.90 (s, 1 H), 2.86 (m, 2H), 1.68 (m, 2H), 1.36-1.30 (m, 6H), 0.90 (m, 3H), 0.34 (m, 9H).

(42) Preparation of Compound 2b

(43) To compound 11 (0.53 g, 1.7 mmol) and compound 20 (0.67 g, 2 mmol) in a reaction flask was added anhydrous DMF (28 mL) at room temperature. Pd(PPh.sub.3).sub.4 (195 mg, 0.17 mmol) was then added to the reaction mixture under N.sub.2 atmosphere in one portion. The reaction mixture was heated at 90° C. for 18 h. The reaction mixture was quenched with water. The organic layer was extracted with DCM (×2). The organic extract was washed with brine and dried over Na.sub.2SO.sub.4. The crude material was purified by column chromatography (5:95 DCM/Hexane) to give compound 2b as a white solid (0.23 g, 33%). .sup.1H NMR (400 MHz, d.sub.4-TCE) δ8.48 (s, 1 H), 8.26 (s, 1H), 8.15 (s, 1H), 8.05 (m, 1H), 7.96 (m, 1H), 7.66 (s, 1H), 7.55 (m, 2H), 7.36 (m, 1H), 7.22 (m, 1 H), 6.78 (m, 1 H), 2.88 (m, 2H), 1.72-1.69 (m, 2H), 1.44-1.30 (m, 6H), 0.90 (m, 3H).

Example 5

(44) Preparation of bottom-gate top-contact organic field effect transistors (OFETs) comprising compounds 1a, 2a, respectively, 2b, as semiconducting material

(45) 30 nm Al.sub.2O.sub.3 coated, highly doped silicon wafers were thoroughly cleaned with 2-propanol and after a short oxygen plasma treatment functionalized with decylphosphonic acid (when compound 1a was used as semiconducting material, respectively octadecylphosphonic acid (when compounds 2a or 2b were used as semiconducting material) from solution in 2-propanol. The highly-doped silicon is used as substrate and gate electrode, the decylphosphonic acid, respectively octadecylphosphonic acid treated Al.sub.2O.sub.3 acts as the gate dielectric. The organic semiconducting material 1a, 2a, respectively, 2b was thermally evaporated in high vacuum (<10.sup.−5 mbar) while the substrate was held at 40° C. (when compound 1a was used as semiconducting material), respectively at 30° C. (when compounds 2a or 2b were used as semiconducting material). A 50 nm-thick of Au layer for source and drain electrodes was deposited through a shadow mask to give top contact OFET devices. The channel width (W) was 500 μm and channel length (L) was 100 μm.

(46) The output curves and the transfer curves of the organic field effect transistors were determined in ambient air and in the dark using a B1500 Agilent parameter analyzer.

(47) FIG. 1 shows the drain current I.sub.D [A] in relation to the drain-source voltage V.sub.DS [V] (output curve) for the bottom-gate top-contact organic field effect transistor comprising compound 1a as semiconducting material at a gate-source voltage V.sub.GS of −11 V (first and top curve), −10.5 V (second curve), −10 V (third curve) and −9.5 V (fourth and bottom curve).

(48) FIG. 2 shows the drain current I.sub.D [A] in relation to the gate-source voltage V.sub.GS [V] (transfer curve) for the bottom-gate top-contact organic field effect transistor comprising compound 1a as semiconducting material at a drain-source voltage V.sub.DS of −5 V.

(49) FIG. 3 shows the drain current I.sub.D [A] in relation to the drain-source voltage V.sub.DS [V] (output curve) for the bottom-gate, top-contact organic field effect transistor comprising compound 2a as semiconducting material at a gate-source voltage V.sub.GS of −10 V (first and top curve).

(50) FIG. 4 shows the drain current I.sub.D [A] in relation to the gate-source voltage V.sub.GS [V] (transfer curve) for the bottom-gate top-contact organic field effect transistor comprising compound 2a as semiconducting material at a drain-source voltage V.sub.DS of −5 V.

(51) FIG. 5 shows the drain current I.sub.D [A] in relation to the drain-source voltage V.sub.DS [V] (output curve) for the bottom-gate, top-contact organic field effect transistor comprising compound 2b as semiconducting material at a gate-source voltage V.sub.GS of −10 V (first and top curve), −9.5 V (second curve) and −9 V (third and bottom curve).

(52) FIG. 6 shows the drain current I.sub.D [A] in relation to the gate-source voltage V.sub.GS [V] (transfer curve) for the bottom-gate top-contact organic field effect transistor comprising compound 2b as semiconducting material at a drain-source voltage V.sub.DS of −5 V.

(53) The compounds 1a, 2a and 2b show typical behavior of p-type semiconducting materials.

(54) The charge-carrier mobility (μ) was extracted in the saturation regime from the slope of (I.sub.D).sup.1/2 versus V.sub.GS using the equation
μ={2L/(W×C.sub.i)}×(dI.sub.D.sup.1/2/dV.sub.GS.sup.1/2).sup.2
wherein L denotes the channel length; W denotes the channel width; C.sub.i denotes the capacitance per unit area of the gate dielectric; I.sub.D denotes the drain source current and V.sub.GS denotes the gate-source voltage.

(55) The threshold voltage (V.sub.th) was extracted from the intersection of the linear extrapolation of the I.sub.D.sup.1/2 versus V.sub.GS plot with the V.sub.GS axis.

(56) The average values of the threshold voltage V.sub.th, the charge carrier mobility μ, and the I.sub.ON/I.sub.OFF ratios are given in table 1.

(57) TABLE-US-00001 TABLE 1 Compound V.sub.th [V] μ [cm.sup.2/Vs] I.sub.on/off 1a −8.5 0.39 8 × 10.sup.5 2a −8.6 0.01 6 × 10.sup.4 2b −8.7 0.22 2 × 10.sup.5

Comparative Example 1

(58) Preparation of Compound 15

(59) ##STR00032##

(60) Preparation of Compound 18

(61) To a suspension of AlCl.sub.3 (3.75 g, 28 mmol) in anhydrous DCM (108 mL) at room temperature was added phthalic anhydride (2.09 g, 14 mmol) in one portion. The suspension was allowed to stir at room temperature for 15 mins. The suspension was then cooled to 0° C. and 5-bromo-benzo[b]thiophene (3.0 g, 14 mmol) in DCM (10 mL) was added dropwise. The reaction mixture was stirred overnight for 4 h at room temperature. The reaction mixture was poured into ice water and quenched with 10% aqueous sodium carbonate. The organic phase was washed twice with water, treated with 10% solution of hydrochloric acid, washed twice with water, brine and dried over magnesium sulfate. The orange solid obtained after solvent evaporation was recrystallized from toluene to yield compound 18 as a yellow solid (1.83 g, 36%). .sup.1H NMR (400 MHz, CDCl.sub.3) δ7.92 (s, 2H), 7.67 (d, 2H), 7.45 (m, 4H).

(62) Preparation of Compound 17

(63) To 2-(5-bromobenzo[b]thiophene-2-carbonyl)benzoic acid (1.33 g, 3.7 mmol) and PCl.sub.5 (1.53 g, 7.4 mmol) in 1,2-dichlorobenzene (37 mL) at room temperature was added AlCl.sub.3 (1.0 g, 7.4 mmol) portion-wise. The reaction mixture was then heated at 140° C. After 4.5 hours, the heating was stopped. The reaction mixture was diluted with DCM and poured onto ice. The mixture was filtered through celite, washing with DCM. The filtered mixture was extracted with DCM (×3) and dried over Na.sub.2SO.sub.4. The crude mixture was then distilled to remove excess 1,2-dichlorobenzene and later purified by flash column chromatography (50:50 DCM/Hexane) to yield compound 17 as a yellow solid (1.09 g, 86%). .sup.1H NMR (400 MHz, CDCl.sub.3) δ9.12 (d, 1 H), 8.30-8.24 (m, 2H), 7.85-7.69 (m, 3H), 7.67 (d, 1H).

(64) Preparation of Compound 16

(65) To 2-bromo-6,11-dione-naphta[2,3-b]benzo[d]thiophene (0.47 g, 1.4 mmol) in AcOH (14 mL) at room temperature was added HI (1.4 mL, 10 mmol) and H.sub.3PO.sub.2 (0.3 mL, 2.7 mmol) dropwise. The reaction mixture was heated at 150° C. overnight. After 24 hours, heating was discontinued and the reaction mixture was poured onto 1% NaHSO.sub.3 solution (500 mL). The precipitate was collected by vacuum filtration. The crude solid was purified by column chromatography (17:83 DCM/Hexane) to give compound 16 as a white solid (0.17 g, 37%). .sup.1H NMR (400 MHz, CDCl.sub.3) δ8.60 (s, 1 H), 8.40 (d, 1H), 8.29 (s, 1H), 8.03 (d, 1H), 7.92 (d, 1H), 7.69 (d, 1H), 7.60-7.51 (m, 3H).

(66) Preparation of Compound 15

(67) To 2-bromo-naphtha[2,3-b]benzo[d]thiophene (0.17 g, 0.5 mmol) and Ni(dppp)Cl.sub.2 (15 mg, 0.03 mmol) in anhydrous THF (3 mL) at room temperature was added C.sub.6H.sub.13MgBr (1.0 mL, 0.8 mmol) dropwise. The reaction mixture was stirred at room temperature overnight. The reaction mixture was quenched with water. The organic layer was extracted with ethyl acetate (×2). The organic extract was washed with water (×1) and then brine (×1) and dried over Na.sub.2SO.sub.4. The crude material was purified by column chromatography (10:90 DCM/Hexane) to give compound 15 as a yellow oil (0.04 g, 23%). 8.61 (s, 1H), 8.26 (s, 1H), 8.08 (s, 1H), 8.03 (d, 1H), 7.81 (d, 1H), 7.72 (d, 1H), 7.50 (m, 2H), 7.32 (d, 1H), 2.80 (m, 2H), 1.73 (m, 2H), 1.35 (m, 6H), 0.90 (m, 3H).

(68) It was not possible to fabricate an organic field effect transistor using compound 15 as semiconducting material, because compound 15 is liquid at room temperature and no solid film could be obtained.