RU2321601C1 - Branched polyphenylenes and method for their preparing - Google Patents

Abstract

FIELD: organic chemistry, chemical technology, chemical industry, electronics.

SUBSTANCE: invention relates to branched polyphenylenes and a method for their synthesis. Invention concerns polyphenylenes of the following general formula:

wherein n means degree of polymerization from 5 to 20; m = 1, 2; q = 1, 2; Ar means arylene group, carboxynaphthyl group, naphthylimide, naphthyl, anthracene groups, heterocyclic group and among them pyridyl and bis-pyridyl groups. Also, invention relates to a method for synthesis of polyphenylenes of the formula given above that involves carrying out the polymerization reaction of cross-coupling in the presence of nickel or palladium complexes, and bromine- and/or boronoxy-substituted aromatic and heteroaromatic compounds wherein 1,3,5-tri-(p-bromophenyl)benzene of the formula (1): or 1,3,5-tri-(p-bromodiphenyl)benzene of the formula (2): are used a branching agent

Invention can be used in production of displays, in electrophotography, in making fixtures, photodetectors, sensors, field transistors, diode lasers and in other branches for providing luminescence in conversion of electric energy to light energy.

EFFECT: improved method of synthesis, valuable properties of compounds.

3 cl, 9 dwg, 4 ex

Description

The invention relates to the chemical and electronic industries, and in particular to branched polyphenylenes and to a process for their preparation. The invention can be used in the manufacture of displays, in electrophotography, in the manufacture of lighting sources, photodetectors, sensors, field effect transistors, diode lasers and in other areas when it is necessary to provide luminescence when converting electrical energy into light.

One of the directions in the design of displays is the use of organic materials for light emitting diodes (OLED), which are much cheaper than inorganic ones. Of particular interest are materials emitting light in the blue and violet regions, and their circle is limited by phenylene structures. These include polyphenylenes, branched star-shaped polyphenylenes, polyarylethylene, as well as branched large molecules such as phenylene dendrimers.

Crosslinked polyphenylenes of the following general formula are known.

These polyphenylenes are obtained on the basis of diethyl aromatic compounds or a mixture of diethyl aromatic and monoethynyl aromatic or aliphatic compounds in the presence of metal complexes as catalysts at temperatures up to 200 ° C (US No. 3705131, IPC 2 C08F 9/00, 1972; GB No. 13777740, IPC 2 C08F 9 / 00.1973).

The complexity and low technology of the known method is due to the synthesis of ethinyl compounds and the use of specific metal complex catalysts, the synthesis of which is also difficult. In addition, the known method does not allow to obtain light-emitting materials due to quenching of luminescence by the metal complex remaining in the polymer after isolation.

The insolubility of the polymer makes it difficult to process, in particular, it does not allow the polymer to be applied to the substrate in the form of a solution, however, in the case of obtaining the polymer directly on the substrate in a thin layer as a result of sputtering of the components and their subsequent polymerization, polymer crosslinking also contributes to quenching of luminescence.

A simpler method for producing similar structures of soluble polyphenylenes of the general formula

R

R ₁ and R ₂ are aromatic groups.

In accordance with this known method, polyphenylenes are prepared on the basis of available mono- and diacetyl aromatic compounds or their ethyl ketals in solution in the presence of acid catalysts, for example n-toluenesulfonic acid or hydrogen chloride gas, at room temperature (US No. 4064097, IPC 3 C08L 65/02, 1977; SU No. 302022, IPC 6 C08G 61 / 10.1972).

However, defective dipnon type fragments, as well as terminal acetyl or ketal groups, completely exclude the luminescence of such polymers.

The technical result of the invention is to obtain branched polyphenylenes using reactions that lead to polymer structures devoid of chemical defects quenching luminescence. The branching of the structure ensures solubility, that is, the processability of the polymer material, which is a prerequisite for its use in OLED. The polymers have effective luminescence in a wide range of the visible spectrum, including in the blue-violet region, and can be used as active layers of light-emitting diodes.

To solve this problem, polyphenylenes of the following general formula are used:

Where

n is the degree of polymerization from 5 to 20;

m is 1, 2;

q is 1, 2;

Ar is an arylene group, a carboxy naphthyl group, a naphthylimide, naphthyl, anthracene group, a heterocyclic group, including pyridyl and bipyridyl.

The method for producing polyphenylenes of the above general formula consists in carrying out a polymer-forming cross-coupling reaction of bromine-substituted aromatic or heteroaromatic compounds or a reaction of bromine-substituted and boroxo-or pinacolborate-substituted aromatic or heteroaromatic compounds in the presence of nickel or palladium complexes, in which 1 starting and simultaneously branching monomers are used 3,5-tri (n-bromophenyl) benzene or 1,3,5-tri (n-bromodiphenyl) benzene.

The materials were studied in terms of optical properties, primarily luminescence. It was determined that these substances have effective fluorescence in the blue region of the spectrum at 370-410 nm and also have high relative quantum fluorescence yields in the range from 50 to 94%. Preliminary studies have shown significant electroluminescence of polymer films in this spectral range.

The possibility of carrying out the invention is confirmed by the following synthesis examples.

Example 1. Obtaining a polymer from 1,3,5-tri (n-bromophenyl) benzene (monomer 1) with a Ni (0) catalyst (m = 1; q = 2) in accordance with the reaction proceeding according to the following scheme.

Where

[Ni⁰]NiCl₂+Zn+Ph₃P+bipy.

[Ni ⁰ ] NiCl ₂ + Zn + Ph ₃ P + bipy.

The synthesis of a branching monomer, 1,3,5-tri (n-bromophenyl) benzene (1), is preliminarily carried out.

At room temperature, 60 g (0.3 mol) of n-bromoacetophenone, 60 ml (0.36 mol) of orthoformate ether and 50 ml of benzene were charged into a 500 ml flask, and HCI gas was passed through this solution for three hours. After one hour, the solution turns brown-red and a precipitate forms.

The resulting precipitate was filtered off, washed with acetone until the pink precipitate turned white, and dried in vacuo. The yield was 29% (2.6 g).

Dimethylformamide (DMF) is distilled under argon in the presence of calcium hydride. T _bale DMF = 153 ° C. Anhydrous NiCl ₂ (0.026 g, 0.0002 mol), Ph ₃ P (0.112 g, 0.0004 mol), bipyridyl (0.032 g, 0.0002 mol), 4-bromobenzene (0.67 g, 4.25 mol ) and 1,3,5-tri (n-bromophenyl) benzene (1) (2.3 g, 0.0043 mol) are placed in a Schlenk tube filled with argon. The tube is evacuated and filled with argon (5 times). Then dry DMF (1 ml) was added to it.

The reaction mixture is quickly heated to 90 ° C and then stirred at this temperature for 6 hours. In the first 10 minutes, the reaction mass becomes red-brown, which indicates the formation of a catalytic complex. The final solution was precipitated in methanol, the precipitate was collected, washed with HCI solution, water, methanol and dried in a vacuum desiccator at room temperature for 10 hours. The yield is 76% (1.7 g).

Example 2. Obtaining a polymer from 1,3,5-tri (n-bromodiphenyl) benzene (monomer 2) and phenylenediboric acid with a Pd (0) catalyst in accordance with the reaction proceeding according to the following scheme.

где Ar - в соответствии с примером 1,

where Ar is in accordance with example 1,

[Pd] = Pd (PPh ₃ ) ₄ ; PdCl ₂ + Ph ₃ P; PdCl ₂ (Ph ₃ P) ₂ + Ph ₃ P; Pd (Ac) ₂ + Ph ₃ P.

Pre-carry out the synthesis of the monomer - 1,3,5-tri (n-bromodiphenyl) benzene (2).

At room temperature, 10 g (0.036 mol) of bromoacetophenone, 21.5 ml (0.13 mol) of orthoformate ether and 25 ml of benzene were charged into a 200 ml flask, and gaseous HCl was passed through this solution for three hours. After one hour, the solution turns brown-red and precipitates.

The resulting precipitate was filtered off, washed with acetone until the pink precipitate turned white, and dried in vacuo. The yield was 42% (3.9 g).

Distilled solvents immediately before synthesis in argon.

The Schlenk tube, purged with dry argon, was charged with the starting products in a stream of argon: 0.5 g (0.003 mol) of phenyl diboric acid, 0.9 g (0.001656 mol) of 1,3,5-tri (n-bromophenyl) benzene and 0.375 g (0.00135 mol) of 4-bromo-1,8-naphthalic anhydride, DMF and the catalyst tetra-cystriphenylphosphine palladium, 25 mg of tetrabutylammonium chloride were added, and heated to complete dissolution of the starting materials.

With weak heating, dissolution occurred, and with increasing temperature, the mass turned bright orange. The reaction mass was heated to 80 ° C and stirred at this temperature for 2 hours.

The solution was precipitated into methanol and the precipitate formed was filtered. The precipitate was washed with a solution of HCl, water, methanol and dried in a vacuum desiccator at room temperature for 10 hours. The yield was 65% (0.7 g).

Example 3. Obtaining a polymer from 1,3-di (n-boroxyphenyl), 5- (n-bromophenyl) benzene (monomer 3) with a Pd (0) catalyst in accordance with the reaction proceeding according to the following scheme.

Ar - in accordance with example 1,

[Pd] = Pd (PPh ₃ ) ₄ ; PdCl ₂ + Ph ₃ P; PdCl ₂ (Ph ₃ P) ₂ + Ph ₃ P; Pd (Ac) ₂ + Ph ₃ P.

Preliminarily, 1,3-di (n-boroxyphenyl), 5- (n-bromophenyl) benzene (monomer 3) are obtained.

To a solution of 3 g (0.0055 mol) of monomer 1 (1,3,5-tri (n-bromophenyl) benzene) in THF (100 ml) at a temperature of -78 ° C, 6.64 ml of 2.5 M are added with stirring a solution of n-butyllithium in hexane for 30 minutes The reaction mass is stirred for 6 hours at the same temperature, and then 4.1 ml (53 mmol) of trimethyl borate are added. The mixture was warmed to room temperature, diluted with chloroform, washed with water and dried. Then the mixture is separated on a chromatographic column with silica gel - eluent - chloroform. The yield is 42%. Next, 1,3-di (n-boroxyphenyl), 5- (n-bromophenyl) benzene (monomer 3) (1.8 g, 0.0043 mol) are placed in a Schlenk tube filled with argon. The tube is evacuated and filled with argon (5 times). Then dry DMF (1 ml) was added to it, the catalyst was tetra-tas-triphenylphosphine palladium, 25 mg of tetrabutylammonium chloride. The reaction mixture is quickly heated to 90 ° C and then stirred at this temperature for 1 hour. Then bromobenzene (0.67 g, 0.0043 mol) is added to the tube and heated at the same temperature for 5 hours.

The final solution was precipitated in methanol, the precipitate was collected, washed with HCl solution, water, methanol and dried in a vacuum desiccator at room temperature for 10 hours. The yield is 95% (1.7 g).

Example 4. Obtaining a polymer from monomer 1 and 1,3,5-tri (n-phenyl pinacolborate) benzene (monomer 4) with a Pd (0) catalyst in accordance with the reaction proceeding according to the following scheme.

Ar - in accordance with example 1,

[Pd] -Pd (PPh ₃ ) ₄ ; PdCl ₂ + Ph ₃ P; PdCl ₂ (Ph ₃ P) ₂ + Ph ₃ P; Pd (Ac) ₂ + Ph ₃ P.

Preliminarily, 1,3,5-tri (n-phenyl pinacolborate) benzene is prepared (monomer 4). 2. Dissolve 1,3,5-tri (n-bromophenyl) benzene (0.5 g, 0.9208 mmol) in distilled tetrahydrofuran (15 ml). 3. Add the catalyst - [1,1'-bis (diphenylphosphino) -ferrocene] dichloropalladium (2) complex with dichloromethane (1/1) (0.1 mol%). Add 4,4,5,5-tetramethyl-1,3,2-dioxaboralan (2.7624 mmol, 1 M, 3.3 ml (taking into account a 20% excess). The solution instantly turns dark cherry. Then add the base ( triethylamine - 9 mmol, 1.3 ml). Vigorous gas evolution occurs. We produce heating to 80 ° C for 4 hours. The precipitate formed is precipitated in methanol, and then filtered on a membrane filter.

In the Slap test tube, purged with dry argon, the starting products were loaded in a stream of argon: 0.21 g (0.003 mol) of monomer 4, 0.9 g (0.001656 mol) of 1,3,5-tri (n-bromophenyl) benzene and 0.375 g (0.00135 mol) of 4-bromo-1,8-naphthalic anhydride, DMF and a tetra-cystriphenylphosphine palladium catalyst, 25 mg of tetrabutylammonium chloride were added, and heated to complete dissolution of the starting materials.

With weak heating, dissolution occurred, and with increasing temperature, the mass turned bright orange. The reaction mass was heated to 80 ° C and stirred at this temperature for 2 hours.

The solution was precipitated into methanol and the precipitate formed was filtered. The precipitate was washed with HCl, water, methanol and dried in a vacuum desiccator at room temperature for 10 hours. The yield was 60% (0.56 g).

The structure of the obtained polymers was confirmed using model compounds. As model compounds, 1,3,5-triphenylbenzene (3), 1,3,5-tri (diphenylyl) benzene (4) and tridecaphenyl (5) were studied. Both the starting and model compounds were obtained by cyclotrimerization of the corresponding monoacetyl aromatic compounds in the presence of triethyl orthoformate and an acid catalyst (gaseous HCl) according to the scheme:

Figure 1 shows the 13C NMR spectrum (and 1H) for compound 3 - 1,3,5-triphenylbenzene with signal assignment.

Figure 2 shows the PMR spectrum for compound 5 - tridecaphenyl with signal assignment.

Figure 3 presents the x-ray diffraction analysis of compound 4.

Figure 4 shows the mass spectrum of compound 1.

Figure 5 shows the PMR spectrum of 1,3,5-tri (4-pinacolborate-yl-phenyl) benzene.

Figure 6 presents the NMR13C spectrum of 1,3,5-tri (4-pinacolborate-yl-phenyl) benzene.

7 shows the IR spectrum of a polymer with carboxy-naphthyl groups.

On Fig shows the PMR spectrum of branched polyphenylene.

Figure 9 presents the NMR13C spectrum of polyphenylene.

The NMR spectra of compound 3 were studied, which made it possible to attribute the signals of the main aromatic structure in polymers. Figure 1 shows the ¹³ NMR spectra of 1,3,5-triphenylbenzene (3); a) ¹³ C - { ¹ H} -spectrum); b) the spin-spin interaction of ¹³ C- ¹ H is not compensated. The signal positions of monosubstituted benzene rings are in good agreement with the positions given in the catalogs for biphenyl. Two signals - “a” and “f” should be attributed to the quaternary and tertiary carbon atoms of the 1,3,5-trisubstituted benzene ring, respectively. This is confirmed by the ¹³ C-NMR spectrum 3, in which the spin-spin interaction of ¹³ C- ¹ H is not suppressed: the signal of tertiary carbon atoms ("f") with the spin-spin coupling constants 1J ( ¹³ C- ¹ H) ≈157 Hz and 3J (13C-1Н) ≈6.2 Hz and the signal of the Quaternary carbon atom ("a") per triplet with the constant 2J (13C-1Н) ≈3.4 Hz.

Figure 2 presents the PMR spectrum of tridecaphenyl (5) with reference signals. The position of the signals and the ratio of integrated intensities unambiguously confirm the structure of this compound.

The structure of compound 4 is confirmed by the data of x-ray diffraction analysis, presented in figure 3.

The bond lengths of the central benzene ring of molecule 4 (1.395 (3) Å (Fig. 3) correspond to the standard length of the aromatic bond (1.394 (5) Å). However, in the p-phenylene fragments the C-C bonds are already slightly shortened. The bond lengths CPh- CPhs are 1.480 Å for 4. These values are similar in length or slightly shorter than the same bonds in 1,3,5-triphenylbenzene (3) (1,487 Å).

It is noted that the bond lengths in the terminal phenyl groups, as well as the bond lengths between the terminal core and the previous core, are somewhat shorter than the standard values, probably due to the thermal motion of the molecule. The benzene rings in molecule 4 are planar. Triphenylbenzene fragment in accordance with its 32-symmetry has the conformation of the propeller. In general, for molecule 4, most bond lengths and angles are close to their low molecular weight counterparts, i.e. geometric parameters do not change with increasing size of the molecule.

Thus, a comparison of X-ray diffraction analysis data for cyclotrimers 3 and 4 showed that the central 1,3,5-triphenylbenzene ring of these compounds is rather planar with respect to neighboring benzene rings, and the structure of the branches is loose and allows inclusion molecules to be introduced.

Thus, the presence of a 1,3,5-trisubstituted nucleus in cyclotrimers was proved by various methods, and signals were assigned in the NMR spectra, which allowed the signals to be attributed to the polymer spectra and to prove their structure.

One of the starting compounds for the synthesis of polyphenylenes was 1,3,5-tri (p-bromophenyl) benzene (1).

The mass spectrum of compound 1 is shown in Fig.4.

Figures 5 and 6 show NMR spectra ( ¹ H and ¹³ C, respectively) that completely confirm the structure of the starting compound for Suzuki reactions - 1,3,5-tri (4-pinacolborate-yl-phenyl) benzene synthesized from compound 1 , its interaction with bis-pinacolborate according to Suzuki. The data of elemental analysis for boron are fully consistent with the calculated data.

Polyphenylenes were characterized by elemental analysis. To control the content of the bromine end groups, bromine analysis was performed. The bromine content was from 5 to 25%. The latter value corresponded to the polymer, which was obtained only on the basis of tri - and monofunctional monomer. Lower bromine values were obtained by blocking the end groups with an additional portion of the monofunctional compound. In polymers with naphthylimide, pyridyl and bipyridyl groups, the nitrogen content was determined. For example, in a polymer with a naphthylimide group, it was 5.8% (calculated at 6.2%).

The polymer with carboxy-naphthyl groups was investigated by IR spectroscopy (Fig.6).

7 shows the IR spectrum of a polymer with carboxy-naphthyl groups.

Oscillations are observed in the spectrum at a wavelength of 830, 1500 and 1600 cm ^-1 , which corresponds to a substituted benzene ring. Also present are bands at 1730-1770 cm ^-1 characterizing the anhydride group.

The NMR spectra of a number of polymers were recorded. The most characteristic are shown in Figs. 8 and 9.

In the PMR spectrum ( ¹ N), a doublet of doublets at 7.14-7-25 ppm. can be attributed to the p-substitution of benzene rings. Singlet at 7.72 ppm refers to a 1,3,5-substituted benzene ring. More information can be extracted from the ¹³ C NMR spectrum (FIG. 6).

Signals at 131.94 ppm, as well as at 128.5-129.0 ppm. can be attributed to carbon atoms of the benzene ring. Signals at 141.32 and 125.01 ppm refer to a substituted and unsubstituted carbon atom of the benzene ring, respectively.

The molecular weights of the polymers were measured.

The weight average molecular weights Mw, determined by GPC with a polystyrene standard, ranged from 1039 to 1650 with a polydispersity coefficient of 1.6 and 1.3, respectively. It is likely that for such branched polymers, only the polydispersity values are reliable, while the absolute values of molecular weights can differ very much from the true values due to the use of polystyrene standards that are not suitable for these polymers. The determination of molecular weight for polymers by sedimentation in an ultracentrifuge gave Mw from 5330 to 8500.

Claims (2)

1. Polyphenylenes of the general formula

where n is the degree of polymerization from 5 to 20; m is 1, 2; q is 1, 2; Ar is an arylene group, a carboxy naphthyl group, a naphthylimide, naphthyl, anthracene group, a heterocyclic group, including pyridyl and bipyridyl. 2. The method for producing polyphenylenes according to claim 1 includes carrying out a polymer-forming cross-coupling reaction of bromine-substituted aromatic or heteroaromatic compounds or a reaction of bromine-substituted and boroxo-or pinacolborate-substituted aromatic or heteroaromatic compounds in the presence of nickel or palladium complexes, in which the starting and simultaneously branching monomers are used 1,3,5-tri (n-bromophenyl) benzene or 1,3,5-tri (n-bromodiphenyl) benzene.

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