Triarylamine Compounds, Compositions and Devices

Abstract

The invention relates to a compound of Formula (I): wherein: each of R1, R2, R3, R4, R5, R6 and R7 which may be the same or different on each triarylamine unit of Formula (1) and the same or different from one triarylamine unit of Formula (1) to another is independently hydrogen or an optionally substituted substituent; n is from 5 to 20; and a and b are each independently 0, 1, 2, 3 or 4. Also claimed are compositions comprising a compound of Formula (1) and a synthetic organic polymer resin, a process for preparing a compound of Formula (1), an organic semiconducting layer prepared from the composition, and electronic devices comprising the organic semiconducting layer.

Description

PREPARATIVE EXAMPLES

Example 1

Synthesis of Cyclo-Hexa(Diphenyl-4-Methylphenylamine) (Compound (9)) via Steps A to I.

(A) Compound (1) 4-Methyltriphenylamine

To a flame-dried flask fitted with condenser, nitrogen inlet and outlet, mechanical stirrer and suba-seal was added diphenylamine (50.0 g, 295.5 mmol (1 molar equivalent)), 4-iodotoluene (128.9 g, 591.3 mmol (2 molar equivalents)) and 1,10-phenanthroline (10.7 g, 59.1 mmol (0.2 molar equivalents)). The flask and contents were thoroughly flushed with nitrogen before anhydrous o-xylene (200 ml) was added. The reaction mixture was heated to 110° C. and then copper (I) chloride (5.9 g, 59.1 mmol (0.2 molar equivalents)) and potassium hydroxide (132.6 g, 2364.0 mmol (8 molar equivalents)) were added to the reaction flask. The reaction was heated further with rapid stirring to 150° C. for 24 hours before allowing the reaction to cool to room temperature. Water and dichloromethane (DCM) were added to the solution and this was filtered though celite before extracting the product using DCM. The combined organic fractions were dried over magnesium sulphate (MgSO₄), filtered and concentrated under vacuum. Purification by column chromatography (silica gel 60; 9:1, hexane:DCM) followed by recrystallisation from methanol gave compound (1) as a white solid (46.5 g, 61%), greater than 99% pure by HPLC. ¹H NMR, 300 MHz (CDCl₃) δ 7.24-7.15 (4 H, m, H-Ar), 7.07-6.90 (10 H, m, H-Ar) and 2.29 ppm (3 H, s, Me).

(B) Compound (2) 4,4′-Dibromo-4″-methyltriphenylamine

To a flask fitted with nitrogen inlet and outlet, mechanical stirrer and suba-seal was added 4-methyltriarylamine (Compound (1)) (40.0 g, 154.4 mmol (1 molar equivalent)) and N, N-dimethylformamide (DMF) (120 ml). The resulting solution was cooled using dry ice. To the reaction mixture was added a solution of N-bromosuccinimide (NBS) (55.0 g, 308.8 mmol (2 molar equivalents)) dissolved in DMF (280 ml) over 30 minutes, once addition was complete, the dry ice bath was removed. After 1 hour the reaction was complete. The reaction solution was added to water (1 L) and the product extracted three times using hexane. The combined organic fractions were dried over MgSO₄, filtered and concentrated under vacuum. The crude product was crystallised from a mixture of methanol and acetone at 0° C. to yield compound (2) as an off white solid (59.6 g, 93%), 97% pure by HPLC. ¹H NMR, 300 MHz (CDCl₃) δ7.28 (4 H, d, J 8.88 Hz; H-Ar), 7.06 (2 H, d, J 8.22 Hz; H-Ar), 6.94 (2 H, d, J 8.22 Hz; H-Ar), 6.88 (4 H, d, J 8.88 Hz; H-Ar) and 2.29 ppm (3 H, s, Me).

(C) Compound (3)—Triarylamine diboronic ester

To a flame-dried flask fitted with condenser, nitrogen inlet and outlet, mechanical stirrer and suba-seal was added 4,4′-dibromo-4″-methyltriphenylamine (Compound (2)) (15.0 g, 36.0 mmol (1 molar equivalent)) and the flask flushed with nitrogen for 15 minutes. Anhydrous tetrahydrofuran (THF) (60 ml) was added and the solution cooled to −78° C. using an acetone/dry ice cold bath. N-Butyl lithium(n-BuLi) 2.5 molar (in hexanes) (34.6 ml, 86.4 mmol (2.4 molar equivalents)) was added drop-wise over 30 minutes, and the resulting solution stirred at −78° C. for 1 hour. 2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (19.1 ml, 93.6 mmol (2.6 molar equivalents)) was added and the resulting solution allowed to warm up to room temperature with stirring over night. Water was added to the reaction flask and the product extracted with DCM. The combined organic extracts were dried over magnesium sulphate (MgSO₄), filtered and concentrated under vacuum to give the crude product. Purification by column chromatography (silica gel 60; 9:1, hexane:EtOAc) followed by recrystallisation from methanol gave the title compound as a white solid (12.9 g, 70%), 95% pure by HPLC. ¹H NMR, 300 MHz (CDCl₃) δ 7.66 (4 H, d, J 8.55 Hz; H-Ar), 7.11-6.97 (8 H, m, H-Ar), 2.23 (3 H, s, Me) and 1.33 ppm (24 H, s, boronic ester).

(D) Compound (4) 4-Methyldiphenylamine

To a flame-dried flask fitted with condenser, nitrogen inlet and outlet, mechanical stirrer and suba-seal was added bromobenzene (26.8 ml, 254.4 mmol (1 molar equivalent)), p-toluidine (30.0 g, 279.8 mmol (1.1 molar equivalents)), racemic-2,2′bis(diphenylphosphino)-1,1′binaphthyl (rac-BINAP) (1.2 g, 1.9 mmol (0.0075 molar equivalents)), tris-(dibenzylidineacetone)dipalladium(0) (Pd₂(dba)₃) (0.6 g, 0.6 mmol (0.0025 molar equivalents)) and sodium tert-butoxide (NaO^tBu) (34.2 g, 356.2 mmol (1.4 molar equivalents)) the flask and contents were then flushed with nitrogen for 15 minutes. Anhydrous toluene (500 ml) was added to the reaction flask and the mixture stirred at 110° C. for 4 hours. On cooling, the reaction mixture was filtered through celite and the toluene solution washed with water, dried over magnesium sulphate (MgSO₄), filtered and concentrated under vacuum. Purification by column chromatography (silica gel 60; 9:1, hexane:DCM) followed by recrystallisation from hexane gave compound (4) as a white solid (32.7 g, 70%). 94% pure by HPLC. ¹H NMR, 300 MHz (CDCl₃) δ 7.29-7.17 (1 H, m, H-Ar), 7.07 (2 H, d, J 8.12 Hz; H-Ar), 7.04-6.97 (4 H, m, H-Ar), 6.88 (1 H, t, J 7.35 Hz; H-Ar), 5.60 (1 H, s, NH) and 2.30 ppm (3 H, s, Me).

(E) Compound (5) 4-Bromo-4′-methyldiphenylamine

To a flask fitted with nitrogen inlet and outlet, mechanical stirrer and suba-seal was added 4-methyldiphenylamine (Compound (4)) (30.0 g, 163.7 mmol (1 molar equivalent)) and DMF (75 ml). The resulting solution was cooled using dry ice. To the reaction mixture was added a solution of N-bromosuccinimide (NBS) (29.1 g, 163.7 mmol (1 molar equivalent)) dissolved in DMF (75 ml) over 30 minutes. The cold bath was then removed and the reaction allowed to warm to room temperature. After 1 hour the reaction was complete. The reaction solution was added to water (500 ml) and the product extracted three times with hexane. The combined organic fractions were dried over magnesium sulphate (MgSO₄), filtered and concentrated under vacuum. Purification by column chromatography (silica gel 60; 9:1, hexane:DCM) followed by recrystallisation from hexane gave compound (5) as an off white solid (31.8 g, 74%). 96% pure by HPLC. ¹H NMR, 300 MHz (CDCl₃) δ 7.30 (2 H, d, J 8.88 Hz; H-Ar), 7.08 (2 H, d, J 8.00 Hz; H-Ar), 6.96 (2 H, d, J 8.44 Hz; H-Ar), 6.84 (2 H, d, J 8.88 Hz; H-Ar), 5.56 (1 H, s, NH) and 2.30 ppm (3 H, s, Me).

(F) Compound (6)—tert-butoxycarbonyl(Boc) protected 4-bromo-4′-methyldiphenylamine

To a flame-dried flask fitted with condenser, nitrogen inlet and outlet, mechanical stirrer and suba-seal was added 4-bromo-4′-methyldiphenylamine (Compound (5)) (3.5 g, 13.4 mmol (1 molar equivalent)), 4-dimethylaminopyridine (DMAP) (0.7 g, 5.4 mmol (0.4 molar equivalents)) and di-^tbutyl dicarbonate (8.7 g, 40.1 mmol (3 molar equivalents)). The flask contents were then flushed with nitrogen for 30 minutes before anhydrous THF (15 ml) was added. The reaction solution was heated with stirring at 70° C. for 3 hours. The reaction mixture was concentrated under vacuum and the crude material purified by column chromatography (silica gel 60; 8:2, hexane:DCM) followed by recrystallisation from methanol, yielding compound (6) as a white solid (2.4 g, 50%), greater than 99% pure by HPLC. ¹H NMR, 300 MHz (CDCl₃) δ 7.39 (2 H, d, J 8.88 Hz; H-Ar), 7.15-7.01 (4 H, m, H-Ar), 2.33 (3 H, s, Me) and 1.44 (9 H, s, Boc).

(G) Compound (7) - Di-tert-butoxycarbonyl(boc) protected triarylamine trimer

To a flask fitted with condenser, nitrogen inlet and outlet, mechanical stirrer and suba-seal was added compound (3) (10.0 g, 19.6 mmol (1 molar equivalent)), tert-butoxycarbonyl(Boc) protected 4-bromo-4′-methyldiphenylamine (Compound (6)) (17.7 g, 48.9 mmol (2.5 molar equivalents)) and toluene (60 ml). The resulting solution was degassed with nitrogen for 15 minutes and then tetrakis(triphenylphosphine)palladium(0) (Pd(PPh₃)₄) (1.4 g, 1.2 mmol (6 mol %)) was added. To this solution was added degassed 2 M aqueous sodium carbonate (Na₂CO₃) (60 ml) and the reaction mixture rapidly stirred at 110° C. for 24 hours. On cooling, the reaction mixture was diluted with water and the crude product extracted with DCM three times. The combined organic fractions were dried over MgSO₄, filtered and concentrated under vacuum. Purification by column chromatography (silica gel 60; 8:2, hexane:EtOAc) gave compound (7) as a cream/yellow solid (10.3 g, 64%), 91% pure by HPLC. ¹H NMR, 300 MHz (CDCl₃) δ 7.45 (8 H, dd, J 8.55, 6.69 Hz; H-Ar), 7.23 (4 H, m, H-Ar), 7.16-7.04 (16 H, m, H-Ar), 2.33 (9 H, s, H-Me) and 1.46 ppm (18 H, s, H-Boc).

(H) Compound (8)—Di-NH triarylamine trimer

To a flask fitted with nitrogen inlet and outlet, mechanical stirrer and suba-seal was added di-boc protected triarylamine trimer (Compound (7)) (10.3 g, 12.6 mmol) and DCM (20 ml). To this solution, trifluoroacetic acid (TFA) (20 ml) was added and reaction mixture stirred for 1.5 hours. The TFA was neutralised with sodium carbonate (Na₂CO₃) solution and the product extracted with DCM. The combined organic fractions were dried over MgSO₄, filtered and concentrated under vacuum. Purification by column chromatography (silica gel 60; 1:1, hexane:ethyl acetate) followed by a hot methanol wash yielded compound (8) as a yellow/brown solid (6.8 g, 86%), greater than 98% pure by HPLC. ¹H NMR, 300 MHz (D₆ DMSO) δ 8.14 (2 H, s, NH), 7.50 (8 H, m, H-Ar), 7.18-6.95 (20 H, m, H-Ar), 2.28 (3 H, s, H-Me) and 2.23 ppm (6 H, s, H-Me).

(I) Compound (9)—Cyclo-hexa(diphenyl-4-methylphenylamine)

To a flame-dried flask fitted with condenser, nitrogen inlet and outlet, mechanical stirrer, dropping funnel and suba-seal was charged di-NH triarylamine trimer (compound (8)) (2.9 g, 4.9 mmol (0.5 molar equivalents)), 4, 4′-diiodobiphenyl (3.7 g, 9.2 mmol (0.98 molar equivalents)), copper powder 200 mesh (2.4 g, 37.5 mmol (4 molar equivalents)), potassium carbonate (10.6 g, 76.8 mmol (8 molar equivalents)) and 18-crown-6 (0.3 g, 0.9 mmol (0.1 molar equivalents)). The dropping funnel was charged with di-NH triarylamine trimer (compound (8)) (2.9 g, 4.9 mmol (0.5 molar equivalents)). The reaction vessel was flushed with nitrogen for 15 minutes. o-Dichlorobenzene (250 ml) was then charged to the flask and a further o-dichlorobenzene (250 ml) charged to the dropping funnel. The contents of the reaction flask was heated at 180° C. with rapid stirring for 4 hours before the contents of the dropping funnel were added over 1 hour. The resulting mixture was stirred at 180° C. for 14 days. On cooling, the reaction mixture was filtered through celite to remove any insoluble materials, the solution was then concentrated under vacuum, and a dark brown glassy solid resulted. Soxhlet extraction of this solid with acetone removed most of the low molecular weight impurities. The remaining material was dissolved in a minimum amount of refluxing tetrahydrofuran (THF) and allowed to cool to room temperature, during which time a solid precipitated out, which was analysed by HPLC and found to be 70% pure. Purification by column chromatography (silica gel 60; 1:1, toluene:hexane) gave a yellow solid, which by HPLC was 95% pure. Repeated recrystallisations from THF gave compound (9) as white/yellow needles (0.15 g, 2%), greater than 99% pure by HPLC. ¹H NMR, 500 MHz (D₈ THF) δ 7.51 (24 H, d, J 8.43 Hz; H-Ar), 7.15-7.06 (m, 48 H, H-Ar) and 2.34 ppm (18 H, s, Me); ¹³C NMR, 125 MHz (D₈ THF) δ 148.0, 146.0, 135.8, 133.7, 130.7, 128.0, 125.7, 124.7 and 20.9 ppm; m/z (DEI) 152 (50%), 771 (100%); Cyclic voltammetry versus ferrocene, −5.17 eV (reversible) and −5.82 eV (irreversible).

Example 2

Alternatively, cyclo-hexa(diphenyl-4-methylphenylamine) (Compound (9)) can be prepared from steps A to H as described in example (1) above followed by steps J to M as described below.

(J) Compound (10) 4-Bromo-4′-(Trimethylsilyl)biphenyl

To a solution of 1-bromo-4-iodobenzene (14.14 g, 50 mmol), 4-(trimethylsilyl)phenyl boronic acid (9.71 g, 50 mmol) and Pd(PPh₃)₄ (2.31 g, 2.0 mmol) in degassed 1,4-dioxane (100 ml) was added a solution of potassium carbonate (16.6 g, 120 mmol) in degassed water (50 ml). The mixture was refluxed under a nitrogen atmosphere until the reaction was complete (according to HPLC analysis).

The reaction mixture was then washed with distilled water and brine and then dried over MgSO₄ before being filtered through a silica plug. The crude product was purified by flash column chromatography (silica gel 60; 9:1, hexane:dichloromethane) followed by recrystallisation from methanol to yield a colourless crystalline solid (12.01 g, 78.7%) greater than 99% pure by HPLC. ¹H NMR, 300 MHz (CDCl₃) δ 7.42-7.27 (4 H, AA′BB′, H-Ar), 7.36 (4 H, m, H-Ar) and 0.15 ppm (9 H, s, Si-Me).

(K) Compound (11)

To a solution of compound (8) (1.70 g, 2.74 mmol), 4-bromo-4′-(trimethylsilyl)biphenyl (1.67 g, 5.48 mmol) and sodium t-butoxide (1.58 g, 16.43 mmol) in dry degassed toluene (30 ml) was added a solution of tris(dibenzylidineacetone) dipalladium(O) (Pd₂(dba)₃) (50.1 mg, 0.055 mmol) and 2-(dicyclohexylphosphino)biphenyl (115.7 mg, 0.33 mmol) in dry degassed toluene (5 ml). The mixture was stirred and heated to 100° C. and the progress of the reaction monitored by HPLC. Once the reaction was complete the mixture was cooled to ambient temperature and diluted with toluene (50 ml). The resultant solution was then filtered and the solvent removed in vacuo to yield the crude product, which was then purified by column chromatography (silica gel 60; 95:5, hexane:ethylacetate) followed by recrystallisation from methanol to yield an olive coloured solid (2.66 g, 90.7%) greater than 96% pure by HPLC. ¹H NMR, 300 MHz (CDCl₃) δ 7.65-7.05 (44 H, m, H-Ar), 2.30 (9 H, s, CH₃) and 0.25 ppm (18 H, s, Si-Me).

(L) Compound (12)

To a stirred solution of (Compound 11) (2.50 g, 2.34 mmol) in dry dichloromethane (16 ml) was added a solution of iodine monochloride (1.14 g, 7.01 mmol) in dry dichloromethane (16 ml) dropwise over a period of 30 minutes at −10° C. The resulting mixture was stirred at this temperature until HPLC analysis indicated that the reaction was complete before a saturated solution of sodium meta bisulphate (Na₂S₂O₅) (17 ml) was added. The organic and aqueous layers were separated and the aqueous layer extracted with dichloromethane (2×50 ml). The combined organic phase was dried (MgSO₄), filtered and concentrated in vacuo. The crude product was purified by flash column chromatography (SiO₂; hexane:ethylacetate, 70:30 (consistency)) followed by recrystallisation from methanol and hexane to yield a tan coloured solid (2.29 g, 86.9%) greater than 95% pure by HPLC. ¹H NMR, 300 MHz (CDCl₃) δ 7.65-7.05 (44 H, m, H-Ar) and 2.30 ppm (9 H, s, CH₃).

(M) Compound (9)—Cyclohexa(diphenyl-4-methylphenylamine)

To a solution of Compound (12) (261 mg, 0.221 mmol), Compound (8) (138 mg, 0.221 mmol) and sodium t-butoxide (127.8 mg, 1.33 mmol) in dry degassed o-xylene (6.0 ml) was added a solution of Pd₂(dba)₃ (2.0 mg, 0.0022 mmol) and 2-(dicyclohexylphosphino)biphenyl (4.6 mg, 0.0132 mmol) in dry degassed o-xylene (1 ml). The mixture was stirred and heated to 100° C. and the progress of the reaction monitored by HPLC.

Complete conversion of reactants to the desired product was achieved after 24 hours (as verified by HPLC analysis) and the reaction mixture was cooled to 70° C., diluted with toluene (50 ml) and filtered whilst hot through a bed of celite. The celite layer was subsequently washed further with hot toluene (200 ml). The solvent was removed in vacuo to yield the crude product which was purified by column chromatography (silica gel 60; 50:50; hexane:toluene) and recrystallised from tetrahydrofuran to yield the product as a colourless crystalline solid (150 mg, 44%) greater than 99% pure by HPLC. ¹H NMR, 300 MHz (CDCl₃) δ 7.40 (24 H, m, H-tolyl), 7.10 (48 H, m, H-Ar), 2.35 (18 H, s, CH₃).

Example 3

Alternatively, compounds (13) and (14) are prepared in analogy to the methods described in example (1) above.

Determination of the Field Effect Mobility

The field effect mobility of the materials was tested using the techniques described by Holland et al, J. Appl. Phys. Vol.75, p.7954 (1994).

In the following examples a test field effect transistor (FET) was manufactured by using a PEN poly(ethylene-2,6-naphthalene dicarboxylate) substrate upon which were patterned Pt/Pd source and drain electrodes by standard techniques, for example, shadow masking. A semiconductor formulation was made using a cyclic triarylamine compound for example compound (9) blended with an inert binder resin (poly(alpha-methyl styrene)(p-αMS) Aldrich catalogue number 19,184-1.

The semiconductor formulation was dissolved one part into 99 parts of toluene, and spin coated onto the substrate at 1000 rpm for 20 seconds to yield a thin film of less than 100 nm. To ensure complete drying the sample was placed in an oven for 20 minutes at 100° C. A solution of an insulator material for example TOPAS™8007 (dielectric constant=2.2-2.3) was then spin coated onto the semiconductor giving a thickness typically in the range of 0.5 to 1 μm. The sample was placed once more in an oven at 100° C. to evaporate solvent from the insulator. A gold gate contact was defined over the device channel area by evaporation through a shadow mask. To determine the capacitance of the insulator layer a number of devices were prepared which consisted of a non-patterned Pt/Pd base layer, an insulator layer prepared in the same way as that on the FET device, and a top electrode of known geometry. The capacitance was measured using a hand-held multimeter, connected to the metal either side of the insulator. Other defining parameters of the transistor are the length of the drain and source electrodes facing each other (W=30 mm) and their distance from each other (L=130 μm).

The voltages applied to the transistor are relative to the potential of the source electrode. In the case of a p-type gate material, when a negative potential is applied to the gate, positive charge carriers (holes) are accumulated in the semiconductor on the other side of the gate insulator. (For an n channel FET, positive voltages are applied). This is called the accumulation mode. The capacitance/area of the gate dielectric C_i determines the amount of the charge thus induced. When a negative potential V_DS is applied to the drain, the accumulated carriers yield a source-drain current I_DS which depends primarily on the density of accumulated carriers and, importantly, their mobility in the source-drain channel. Geometric factors such as the drain and source electrode configuration, size and distance also affect the current. Typically a range of gate and drain voltages are scanned during the study of the device. The source-drain current is described by Equation 1:

$\begin{array}{cc}{I}_{\mathrm{DS}}=\frac{\mu {\mathrm{WC}}_i}{L}\left(\left(V_G-V_0\right)V_{\mathrm{DS}}-\frac{V_{\mathrm{DS}}^2}{2}\right)+I_{\Omega }& \mathrm{Equation}1\end{array}$

where;

V₀ is an offset voltage, and I_Ω is an ohmic current independent of the gate voltage and is due to the finite conductivity of the material. The other parameters have been described above.

For the electrical measurements the transistor sample was mounted in a sample holder. Microprobe connections were made to the gate, drain and source electrodes using Karl Suss PH100 miniature probe-heads. These were linked to a Hewlett-Packard 4155B parameter analyser. The drain voltage was set to −5 V and the gate voltage was scanned from +20 to −60V in 1 V steps. In accumulation, when |V_G|>|V_DS| the source-drain current varies linearly with V_G. Thus the field effect mobility μ, can be calculated from the gradient (S) of I_DS versus V_G given by Equation 2.

$\begin{array}{cc}S=\frac{\mu {\mathrm{WC}}_iV_{\mathrm{DS}}}{L}& \mathrm{Equation}2\end{array}$

All field effect mobilities quoted below were calculated using this regime (unless stated otherwise). Where the field effect mobility varied with gate voltage, the value was taken as the highest level reached in the regime where |V_G|>|_DS| in accumulation mode. The results show the charge mobility obtained when the cyclic triarylamine compounds of the present invention were tested in combination with up to 50% by weight of resin.

In accordance with the present invention, an FET device prepared with a 50:50 percent by weight composition of compound 9 with resin poly α-methyl styrene, gave a mobility μ=3.26×10^-4cm²V^-1s^-1.

Use Example 1

For this purpose compound (9) is dissolved with poly α-methyl styrene at 0.5% solids in toluene. The solution is spin coated onto masked Pt/Pd patterned source/drain electrodes. A 5% solution of Topas 8007 in methyl cyclohexane was used as the gate insulator. Compound (9), gave a mobility, μ=3.26×10^-4cm²V^-1s^-1. Average I_On/Off=3600.

Use Example 2

For this purpose compound (13) is dissolved with poly α-methyl styrene at 1% solids in toluene. The solution is spin coated onto masked Pt/Pd patterned source/drain electrodes. Cytop was used as the gate insulator. Compound (13), gave a mobility, μ=2.5×10^-4cm²V^-1s^-1. Average I_On/Off=18,500.

Use Example 3

For this purpose compound (9) is dissolved with compound (14) (1:1 by weight) at 0.5% solids in toluene. The resulting solution is then spin coated upon masked Pt/Pd patterned source/drain electrodes. Topas is used as the gate insulator. Compound (9) gives an average mobility, μ of 2.9×10^-3 cm²/Vs. Average I_On/Off=18,100.

Claims

1. A compound of Formula (1):

2. A compound according to claim 1 wherein each of R1, R2, R3, R4 and R5 independently comprises hydrogen or a substituent selected from the group comprising an optionally substituted C1-C40 carbyl or hydrocarbyl group; an optionally substituted C1-C40 alkoxy group; an optionally substituted C6-C40 aryloxy group; an optionally substituted C7-C40 alkylaryloxy group; an optionally substituted C2-C40 alkoxycarbonyl group; an optionally substituted C7-C40 aryloxycarbonyl group; a cyano group (—CN); a carbamoyl group (—C(═O)NH2); a haloformyl group (—C(═O)—X, wherein X represents a halogen atom); a formyl group (—C(═O)—H); an isocyano group; an isocyanate group; a thiocyanate group; a thioisocyanate group; an optionally substituted amino group; a hydroxy group; a nitro group; a CF3 group; a halo group; an optionally substituted silyl group; and each of R6 and R7 is independently selected from the group comprising H, CH3, F, CN or CF3.

3. A compound according to claim 1 wherein: n is 6 to 15.

4. A compound according to claim 1 wherein R1, R2, R3, R4 and R5 are each independently a saturated, linear or branched acyclic group.

5. A compound according to claim 5 wherein the saturated, linear or branched acyclic group comprises an optionally substituted C1-40 alkyl group, more preferably an optionally substituted C1-20 alkyl group, most preferably an optionally substituted C1-12 alkyl group.

6. A compound according to claim 1 wherein: R6 and R7 are each independently H or —CH3.

7. A compound according to claim 1 wherein n=6.

8. A compound according to claim 1 which comprises a field effect mobility μ of more than 10-4cm2V-1s-1, more preferably more than 10-4cm2V-1 s-1.

9. A composition comprising: (i) a cyclic triarylamine compound of Formula (1) according to claim 1; and(ii) a synthetic organic polymer resin, wherein the resin may be a semiconductor.

10. A composition according to claim 9 comprising between 10 and 90 weight % of cyclic triarylamine compound and 90 to 10 weight % of synthetic organic polymer resin.

11. A composition according to claim 9 in the form of fibres, films or sheets.

12. A composition according to claim 9 wherein the synthetic organic polymer resin has a permittivity at 1000 Hz of no higher than 3.3 and greater than 1.7.

13. A composition according to claim 9 wherein the synthetic organic polymer resin preferably has a number average molecular weight (Mn) of between 1×103 and 1×106, more preferably at least 3000, most preferably at least 5000.

14. A composition according to claim 9 wherein the synthetic organic polymer resin comprises a copolymer.

15. A composition according to claim 9 which further comprises one or more of the following:

16. A composition according to claim 9, which further comprises one or more solvents.

17. A composition according to claim 9 wherein the proportions of resin to cyclic triarylamine compound comprises 1:99 to 99:1, more preferably 20:1 to 1:20 and most preferably 2:1 to 1:2.

18. Use of the composition as claimed in claim 9 in an electronic device.

19. Use of the composition as claimed in claim 9 in an electrophotographic apparatus.

20. An organic semiconducting layer for use in an electronic device comprising the composition as claimed in claim 9.

21. A layer as claimed in claim 20 wherein the layer is deposited on a part of an electronic device by solution coating.

22. A layer as claimed in claim 20 comprising a charge mobility μ of greater than 10-4cm2V-1s-1.

23. A layer as claimed in claim 20 wherein the layer is prepared by

24. A layer as claimed in claim 20 wherein the layer is deposited on a part of an electronic device by one of the following coating or printing techniques:

25. A layer as claimed in claim 20 wherein the layer is used as a semiconducting layer in one of the following electronic devices: field effect transistor (FET), organic light emitting diode (OLED), photodetector, chemical detector, photovoltaic cell capacitor sensor, logic circuit, display, or memory device.

26. A FET, OLED, photodetector, chemical detector, photovoltaic cell capacitor sensor, logic circuit, display, or memory device comprising a compound, composition or layer as claimed in claim 1.

27. A process for preparing a compound as claimed in claim 1 comprising the steps of:

28. A process as claimed in claim 27 wherein step (ix) is replaced by the following steps: