A chiral phenanthrene [9] helicene based on thiophene and its preparation method and application

Abstract

The present invention belongs to the field of chiral helicene materials, and specifically relates to a chiral phenanthrene [9] helicene based on thiophene and a preparation method and application thereof. The chiral phenanthrene [9] helicene based on thiophene of the present invention has a structural formula as shown in Formula I: Experiments have confirmed that the chiral phenanthrene [9] helicene compound based on thiophene provided by the present invention has a chiral stability of up to 300°C / 18h, and has strong phosphorescence emission and a millisecond-level phosphorescence lifetime under 77K conditions, and a long afterglow phenomenon of more than 3s, and has very excellent optical stability and good phosphorescence performance, which can provide a theoretical basis and material foundation for the development of chiral phosphorescent materials with excellent performance, and can also lay a solid foundation for the application of thiophene helicene in the field of circularly polarized luminescence (CPL) or organic light-emitting materials.

Description

Technical Field

[0001] The present invention belongs to the field of chiral helicene materials, and in particular relates to a thiophene-based chiral phenanthryl[9]helicene and a preparation method and application thereof. Background Art

[0002] Helicene is a polycyclic aromatic compound with a helical structure formed by ortho-fused aromatic rings. It is a type of non-planar structure with helical chirality and has an extremely high specific rotation (up to 5900°). Therefore, helicene and its derivatives are widely used in the fields of molecular self-assembly, circularly polarized luminescent materials, and organic electronics, and are one of the current hot topics in chemistry and materials research.

[0003] According to the different aromatic ring structural units that construct helicene, helicene can be divided into carbon helicene and heterohelicene. Among them, the helicene completely constructed by benzene rings is a carbon helicene, such as the [6] helicene compounds shown in the following structural formulas P-1 and M-1; the helicene containing heteroatoms is a heterohelicene, such as the aza[6] helicene compound shown in the following structural formula 2 and the thia[7] helicene compound shown in the structural formula 3.

[0004]

[0005] Thiophene helicene is a bright branch of helicene chemistry. In recent years, research on molecular skeleton design and synthesis has made some progress. Current research focuses on the design and synthesis of monohelicene and dihelicene compounds. The construction of a condensed ring system with a novel structure has always been one of the goals pursued by researchers in organic synthetic chemistry.

[0006] At present, the reported analogs of thiophene helicene are shown in the following compounds 4-7, among which π-expanded thiophene [9] helicene has received little attention. So far, only a very small number of thiophene hetero [9] helicenes have been reported, specifically the following compounds 6 and 7, and their synthesis process is mainly intermolecular oxidative coupling and thiolation reagent ring closure.

[0007]

[0008] However, the above-mentioned thiophene[9]helicene reported above is relatively lacking in related application research and application effects, and the synthesis process has the disadvantages of complicated steps and low yield, which limits its application in industry. Summary of the invention

[0009] The object of the present invention is to provide a chiral phenanthrene [9] helicene based on thiophene, which has excellent optical stability and good phosphorescence performance and is suitable for use in circularly polarized luminescence or organic luminescent materials.

[0010] The present invention also aims to provide a method for preparing chiral phenanthrene [9] helicene based on thiophene, which has a simple and economical synthesis process and is convenient for the preparation and application of chiral phosphorescent helicene.

[0011] The present invention also aims to provide an application of chiral phenanthrene [9] helicene based on thiophene.

[0012] In order to achieve the above-mentioned object, the chiral phenanthrene [9] helicene based on thiophene of the present invention adopts the technical scheme as follows:

[0013] A chiral phenanthrene [9] helicene based on thiophene, the structural formula of which is shown in Formula I:

[0014]

[0015] The chiral thiophene-based phenanthro[9]helicene provided by the present invention has a novel structure and good optical stability and phosphorescence performance. Performance test experiments have confirmed that the chiral stability of the compound of the present invention is 300°C / 18h, which is higher than the reported thiophene[7]helicene (199°C / 11h, the specific structure is shown in the compound 5 mentioned in the background technology section). In addition, the specific optical rotation of the compound of the present invention is [ɑ]D 25 =-3955°, which is also significantly higher than the reported thiophene[9]helicene ([ɑ]D 25 =-1170°, for the specific structure, see compound 6 mentioned in the background technology section). At the same time, the heavy atom effect produced by the sulfur atom can promote the intersystem crossing transition process from the excited singlet state to the triplet state, reduce the non-radiative transition rate, and enhance the decay process from the excited triplet state to the ground state to produce phosphorescence. When designing the compound structure, the present invention found that the compound of the present invention has strong phosphorescence emission and a millisecond-level phosphorescence lifetime under 77K, and the long afterglow phenomenon exceeds 3s.

[0016] Therefore, the chiral thiophene-based phenanthro[9]helicene compound provided by the present invention has excellent optical stability and good phosphorescence performance, which can provide a theoretical basis and material foundation for the development of chiral phosphorescent materials with excellent performance, and can also lay a solid foundation for the application of thiophene helicene in the field of circularly polarized luminescence (CPL) or organic light-emitting materials.

[0017] The method for preparing the chiral phenanthrene [9] helicene based on thiophene of the present invention comprises the following steps:

[0018] (1) reacting the raw material 2,5-bis(trimethylsilyl)-dithieno[2,3-b:3',2'-d]thiophene with N-bromosuccinimide in a solvent, and then purifying to obtain an intermediate compound a, named 2-(trimethylsilyl)-5-bromo-dithieno[2,3-b:3',2'-d]thiophene;

[0019] (2) The intermediate compound a, the metal alkyl compound and the inert solvent are mixed and reacted at -70 to -80°C, and then N,N-dimethylformamide is added and the reaction is continued at -70 to -80°C. After the reaction, the mixture is placed at 20 to 35°C and purified to obtain the intermediate compound b, which is named 5-(trimethylsilyl)-2-aldehyde-dithieno[2,3-b:3',2'-d]thiophene;

[0020] (3) mixing 1,4-di((triphenylphosphine bromide)methyl)benzene, a metal alkyl compound and an inert solvent, reacting at -70 to -80°C, then adding the intermediate compound b to the system after the reaction to carry out a Wittig reaction, and purifying after the reaction to obtain an intermediate compound c, named 1,4-di(2-(5-(trimethylsilyl)-dithieno[2,3-b:3',2'-d]thiophene-2)vinyl)benzene;

[0021] (4) The intermediate compound c, iodine and an inert solvent are mixed, subjected to a photochemical reaction, and then purified to obtain the thiophene-based chiral phenanthro[9]helicene of formula I.

[0022] The present invention provides a method for preparing a chiral thiophene-based phenanthro[9]helicene. The method comprises the following steps: firstly brominating a raw material 2,5-di(trimethylsilyl)-dithieno[2,3-b:3',2'-d]thiophene with N-bromosuccinimide (NBS) to obtain an intermediate compound a; then subjecting the intermediate compound a to bromine-lithium exchange and N,N-dimethylformamide (DMF) formaldehyde reaction to obtain an intermediate compound b; further subjecting the intermediate compound b to an intermolecular Wittig reaction to obtain an intermediate compound c; and finally subjecting the intermediate compound c to a photochemical oxidation ring closure to obtain the thiophene-based chiral phenanthro[9]helicene shown in formula I.

[0023] The present invention adopts a simple, economical and efficient photochemical method to synthesize a chiral phenanthrene [9] helicene compound based on thiophene. The obtained compound has a relatively high optical stability and good phosphorescent property, and is suitable for the preparation and application of chiral luminescent phosphorescent materials.

[0024] Furthermore, in step (1), the solvent is a mixture of chloroform and acetic acid; in step (2), step (3) and step (4), the inert solvent is one or more of anhydrous ether, anhydrous tetrahydrofuran and anhydrous toluene.

[0025] Preferably, in step (2) and step (3), the metal alkyl compound is n-butyllithium.

[0026] In order to take into account the yield of intermediates and products and the efficiency of the reaction, preferably, in step (1), the reaction temperature is 0-5°C and the reaction time is 1.5-2.5h; in step (2), the reaction time at -70--80°C is 1-3h, and the reaction time at -70--80°C is 0.5-1.5h; the storage time at 20-35°C is 8-10h; in step (3), the reaction time at -70--80°C is 1-3h; the Wittig reaction temperature is -70--80°C and the reaction time is 0.5-1.5h; in step (4), the photochemical reaction is carried out using a medium-pressure mercury lamp, and the photochemical reaction time is 15-25h.

[0027] Further preferably, in step (2), the molar ratio of the intermediate compound a, the metal alkyl compound and N,N-dimethylformamide is 2.28:0.84:1.6.

[0028] Preferably, in step (3), the molar ratio of 1,4-di((triphenylphosphine bromide)methyl)benzene, the metal alkyl compound and the intermediate compound b is 0.13:0.33:0.29.

[0029] Preferably, in step (4), the molar ratio of the intermediate compound c to the iodine element is 0.047:0.28.

[0030] The application of the thiophene-based chiral phenanthrene [9] helicene of the present invention is specifically the application of the thiophene-based chiral phenanthrene [9] helicene as a chiral phosphorescent material in circularly polarized luminescence or organic luminescence.

[0031] The chiral thiophene-based phenanthro[9]helicene provided by the present invention has excellent optical stability and good phosphorescence performance, and has good application prospects in the field of circularly polarized luminescence or organic luminescence. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The hydrogen nuclear magnetic resonance spectrum (500 MHz, CDCl) of the intermediate compound b prepared in Example 2 of the present invention is shown in FIG. 3 );

[0033] Figure 2 The carbon NMR spectrum (125 MHz, CDCl) of the intermediate compound b prepared in Example 2 of the present invention 3 );

[0034] Figure 3 This is a high-resolution mass spectrum of the intermediate compound b prepared in Example 2 of the present invention;

[0035] Figure 4 This is the infrared spectrum of the intermediate compound b prepared in Example 2 of the present invention;

[0036] Figure 5 The hydrogen nuclear magnetic resonance spectrum (400 MHz, CDCl) of the intermediate compound c prepared in Example 2 of the present invention is shown in FIG. 3 );

[0037] Figure 6 This is a high-resolution mass spectrum of the intermediate compound c prepared in Example 2 of the present invention;

[0038] Figure 7 This is the infrared spectrum of the intermediate compound c prepared in Example 2 of the present invention;

[0039] Figure 8 The hydrogen nuclear magnetic resonance spectrum (400 MHz, CDCl) of the target compound [9]BH-1 prepared in Example 2 of the present invention is shown in FIG. 3 );

[0040] Fig. 9 The carbon NMR spectrum (100 MHz, CDCl) of the target compound [9]BH-1 prepared in Example 2 of the present invention is 3 );

[0041] Fig.10 This is a high-resolution mass spectrum of the target compound [9]BH-1 prepared in Example 2 of the present invention;

[0042] Fig.11 This is the infrared spectrum of the target compound [9]BH-1 prepared in Example 2 of the present invention;

[0043] Fig.12 The UV-visible absorption spectrum, fluorescence spectrum and phosphorescence spectrum of the target compound [9]BH-1 prepared in Example 2 of the present invention;

[0044] Fig.13 This is the phosphorescence lifetime diagram of the target compound [9]BH-1 prepared in Example 2 of the present invention;

[0045] Fig.14 This is a long afterglow phenomenon diagram of the target compound [9]BH-1 prepared in Example 2 of the present invention;

[0046] Fig.15 This is a circular dichroism analysis result diagram of the target compound [9]BH-1 prepared in Example 2 of the present invention; wherein, Fig.15 (a) is the circular dichroism diagram of compound [9]BH-1; Fig.15 (b) is the absorption asymmetry factor diagram of the circular dichroism of compound [9]BH-1;

[0047] Fig.16This is a diagram showing the chiral stability analysis results of the target compound [9]BH-1 prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto. The raw materials used in the following examples are conventional materials in the art unless otherwise specified.

[0049] The method for preparing the chiral phenanthrene [9] helicene based on thiophene of the present invention comprises the following steps:

[0050] (1) reacting the raw material 2,5-bis(trimethylsilyl)-dithieno[2,3-b:3',2'-d]thiophene with N-bromosuccinimide in a solvent, and then purifying to obtain an intermediate compound a, named 2-(trimethylsilyl)-5-bromo-dithieno[2,3-b:3',2'-d]thiophene;

[0051] (2) The intermediate compound a, the metal alkyl compound and the inert solvent are mixed and reacted at -70 to -80°C, and then N,N-dimethylformamide is added and the reaction is continued at -70 to -80°C. After the reaction, the mixture is placed at 20 to 35°C and purified to obtain the intermediate compound b, which is named 5-(trimethylsilyl)-2-aldehyde-dithieno[2,3-b:3',2'-d]thiophene;

[0052] (3) mixing 1,4-di((triphenylphosphine bromide)methyl)benzene, a metal alkyl compound and an inert solvent, reacting at -70 to -80°C, then adding the intermediate compound b to the system after the reaction to carry out a Wittig reaction, and purifying after the reaction to obtain an intermediate compound c, named 1,4-di(2-(5-(trimethylsilyl)-dithieno[2,3-b:3',2'-d]thiophene-2)vinyl)benzene;

[0053] (4) The intermediate compound c, iodine and an inert solvent are mixed, subjected to a photochemical reaction, and then purified to obtain the thiophene-based chiral phenanthro[9]helicene of formula I.

[0054] In the following examples, the specific synthetic route used in the preparation of chiral phenanthrene [9] helicene based on thiophene is as follows:

[0055]

[0056] Among them, the raw material 2,5-bis(trimethylsilyl)-dithieno[2,3-b:3',2'-d]thiophene is denoted as bb-DTT, and N-bromosuccinimide is denoted as NBS; intermediate compound a, intermediate compound b, and intermediate compound c correspond to compounds a, b, and c in the synthesis route, respectively.

[0057] The synthesis process of the raw material 2,5-bis(trimethylsilyl)-dithieno[2,3-b:3',2'-d]thiophene (bb-DTT) was carried out according to the literature (Yangguang Wang, Zhihua Wang, Dongfeng Zhao, Zhen Wang, Yangxiang Cheng, Hua Wang. Efficient synthesis of trimethylsilyl-substituted dithieno[2,3-b:3',2'-d]thiophene, tetra[2,3-thienylene]and hexa[2,3-thienylene]from substituted[3,3']bithiophenyl. Synlett., 2007, 15, 2390–2394).

[0058] Example 1

[0059] The chiral phenanthrene [9] helicene based on thiophene in this embodiment has a structural formula as shown in Formula I:

[0060]

[0061] Example 2

[0062] This example is used to prepare the chiral phenanthrene [9] helicene based on thiophene in Example 1. The specific preparation process is as follows:

[0063] 1. Preparation of 2-(trimethylsilyl)-5-bromo-dithieno[2,3-b:3',2'-d]thiophene (intermediate compound a)

[0064] The raw material 2,5-bis(trimethylsilyl)-dithieno[2,3-b:3',2'-d]thiophene (bb-DTT, 0.50 g, 1.47 mmol) was dissolved in 20 mL of chloroform, and then N-bromosuccinimide (0.31 g, 1.76 mmol, 1.2 equiv) dissolved in a mixed solvent of chloroform / acetic acid (volume ratio 8 / 1, 34 mL) was added dropwise, and the mixture was reacted at 0°C for 2 h. The reaction solution was transferred to a 250 mL separatory funnel, extracted with chloroform (3×15 mL), and the organic phases were combined. The organic phase was washed with water (50 mL), saturated sodium bicarbonate solution (50 mL), and water (50 mL), dried over anhydrous magnesium sulfate, filtered, and the solvent was removed and precipitated with chloroform and methanol (chloroform was added until just dissolved, and methanol was added dropwise until solid appeared) to obtain a light yellow solid (0.46 g, yield 89%), and the intermediate compound a was obtained, named 2-(trimethylsilyl)-5-bromo-dithieno[2,3-b:3',2'-d]thiophene.

[0065] 2. Preparation of 5-(trimethylsilyl)-2-aldehyde-dithieno[2,3-b:3',2'-d]thiophene (intermediate compound b)

[0066] Add the intermediate compound a (0.90 g, 2.28 mmol) to a 100 mL dry Schlenk bottle, and then vacuum dry the entire system for 0.5 h; use argon as an inert protective gas, add 100 mL of anhydrous ether along the wall of the Schlenk bottle, and adjust the temperature to -78 ° C after the raw material is completely dissolved. Slowly add n-BuLi (2.35 M n-BuLi in n-hexane solution, take 0.36 mL, 0.84 mmol, 1.05 equiv) to the system under argon protection, stir continuously, react at -78 ° C for 2 h, and the solution is a yellow transparent liquid; then add DMF (0.12 mL, 1.60 mmol, 2.0 equiv) to the system and react for 1 h; after the reaction, turn off the cryostat and naturally warm to room temperature overnight. Add a few drops of water to quench the reaction under low temperature conditions, first spin out the ether solvent, and use CH 2 Cl 2 Dissolve the swirled solid, extract the solution with a 250 mL separatory funnel, and use (3 × 50 mL) H 2 The organic phase was washed with (3×15 mL) CH 2 Cl 2 The aqueous phase was extracted; the organic phase was collected and then washed with anhydrous MgSO 4After drying, filtering and removing the organic solvent under reduced pressure, the crude product was purified by column chromatography (eluent: petroleum ether / dichloromethane) (v / v=2 / 1) to give a yellow solid (189.8 mg, yield 80%), which is the intermediate compound b, named 5-(trimethylsilyl)-2-aldehyde-dithieno[2,3-b:3',2'-d]thiophene.

[0067] The nuclear magnetic resonance hydrogen spectrum, nuclear magnetic resonance carbon spectrum, high-resolution mass spectrum and infrared spectrum of the intermediate compound b are shown in order: Figures 1 to 4 As shown. Figures 1 to 4 It can be concluded that the structural characterization result of the intermediate compound b is: Mp: 171-172°C. 1 HNMR (500MHz, CDCl 3 )δ9.93(s,1H),8.00(s,1H),7.50(s,1H),0.39(s,9H). 13 C NMR (125 MHz, CDCl 3 )δ182.75,149.46,146.01,144.84,140.26,137.80,127.67,124.82,-0.12.HRMS(AP-MALDI-Positive)m / z[M+H] + Calculate for C 12 H 13 OS 3 Si 296.9893; found 296.9892.IR(KBr)3087,2951,1664,1232,944,843cm -1 .

[0068] 3. Preparation of 1,4-bis(2-(5-(trimethylsilyl)-dithieno[2,3-b:3',2'-d]thiophene-2)vinyl)benzene (intermediate compound c)

[0069] The weighed compound 1,4-di((triphenylphosphinobromide)methyl)benzene (103 mg, 13 mmol, 1.0 equiv) was added to a 250 mL dry Schlenk bottle, and then the entire system was vacuum dried for 0.5 h; argon was used as an inert protective gas, and 80 mL of anhydrous THF was added along the wall of the Schlenk bottle. After the raw material was completely dissolved, the temperature was adjusted to -78 ° C. n-BuLi (2.35 M hexane solution, 0.14 mL, 0.33 mmol, 2.5 equiv) was slowly added to the system under argon protection at -78 ° C and stirred for 2 h.

[0070] Weigh the intermediate compound b (85 mg, 0.29 mmol, 2.2 equiv) and add it to a dry 50 mL Schlenk bottle and vacuum dry it for 30 min. During this period, replace the argon three times. Under the protection of argon, add 10 mL of inert organic solvent anhydrous THF solvent along the wall of the Schlenk bottle to completely dissolve it. Add the THF solution of the intermediate compound b dropwise to the 250 mL Schlenk bottle after the above reaction, stir well, react at -78 ° C for 1 h, turn off the cryostat, and naturally warm to room temperature overnight. Add a few drops of water to quench the reaction under low temperature conditions, spin out the THF solvent first, and use CH 2 Cl 2 Dissolve the swirled solid, extract the solution with a 250 mL separatory funnel, and add (3 × 50 mL) H 2 The organic phase was washed with (3×15 mL) CH 2 Cl 2 The aqueous phase was extracted; the organic phase was collected and then washed with anhydrous MgSO 4 After drying, filtering and removing the organic solvent under reduced pressure, the crude product was purified by column chromatography (eluent: petroleum ether / dichloromethane) (v / v=2 / 1) to give a yellow solid (51.7 mg, yield 60%), which is the intermediate compound c, named 1,4-bis(2-(5-(trimethylsilyl)-dithieno[2,3-b:3',2'-d]thiophene-2)vinyl)benzene.

[0071] The nuclear magnetic resonance hydrogen spectrum, high-resolution mass spectrum, and infrared spectrum of the intermediate compound c are shown in order: Figures 5 to 7 As shown. Figures 5 to 7 It can be seen that the structural characterization results of the intermediate compound c are: Mp:>300℃. 1 H NMR (400 MHz, CDCl 3)(for a mixture of cis and trans isomers of 7a) δ7.49(d,J=8.8Hz),7.44(d,J=6.0Hz),7.39(t,J=7.0Hz),7.32(d,J=6.4Hz),7.28(d,J=2.4Hz),6.93(d,J=10.8H z), 6.89 (d, J = 10.4Hz), 6.75 (t, J = 12.0Hz), 6.64 (d, J = 12.0Hz), 6.59 (d, J = 12.0Hz), 0.38 (s), 0.36 (s), 0.33 (s); the ratio of integral areas of the peaks are 1:1:0.6:0.6:0.6:0.3:0.3:0.5:0.3:0.3:4:1.5:1.5.HRMS(AP-MALDI-FT)m / z[M] + Calculate for C 32 H 30 S 6 Si 2 662.0210; found 662.0215.IR(KBr)3019,2955,1254,948,836cm -1 .

[0072] 4. Preparation of Thiophene-Based Chiral Phenanthrene [9] Helicene (Compound [9] BH-1) Represented by Formula I

[0073] Weigh the intermediate compound c (31 mg, 0.047 mmol) and (71.2 mg, 0.28 mmol, 6.0 equiv) iodine into a 20 mL quartz tube, add 10 mL of anhydrous toluene, an inert organic solvent, seal the tube mouth with a rubber stopper, and insert a thick needle to remove oxygen for 15 min. Set up the photochemical experimental device, turn on the power of the medium-pressure mercury lamp, place the quartz tube about 7 cm away from the light source, and start irradiation. Photochemical reaction for 20 hours, turn off the instrument. Transfer the reaction solution to a 100 mL round-bottom flask, remove the organic solvent under reduced pressure, dissolve it with 15 mL of chloroform, transfer it to a 60 mL separatory funnel, add 10 mL of saturated sodium thiosulfate solution to separate the liquids. The aqueous phase is extracted with 3×5 mL of chloroform, and the combined organic phases are washed with 50 mL of water, saturated sodium bicarbonate solution, and water, respectively. An appropriate amount of anhydrous magnesium sulfate powder was added to the organic phase to dry it, filtered, and the organic solvent was removed by vortexing under reduced pressure to obtain a crude product, which was purified by column chromatography (petroleum ether / dichloromethane) (v / v = 2 / 1) to obtain a yellow solid (7.7 mg, 25%), which is the thiophene-based chiral phenanthro[9]helicene of formula I, recorded as compound [9]BH-1.

[0074] The H NMR spectrum, C NMR spectrum, high-resolution mass spectrum, and infrared spectrum of compound [9]BH-1 are shown in the following order: Figures 8 to 11 As shown. Figures 8 to 11 It can be seen that the structural characterization results of compound [9]BH-1 are: Mp:>300℃. 1 HNMR (400MHz, CDCl 3 )δ8.12(d,J=10.8Hz,2H),8.04(s,2H),8.03(d,J=11.2Hz,2H),5.36(s,2H),0.23(s,18H). 13 C NMR (100 MHz, CDCl 3 )δ142.04,141.55,141.34,141.31,140.22,134.79,130.88,129.63,126.11,125.31,123.81,123.39,121.37,-0.07.HRMS(MALDI-Positive)m / z[M + ]calcd for C 32 H 26 S 6 Si 2 657.9897; found 657.9892.IR(KBr)3053,2956,1257,961,833cm -1 .

[0075] Test Example 1: UV-visible light, fluorescence, and phosphorescence analysis

[0076] The chiral thiophene-based phenanthro[9]helicene compound [9]BH-1 prepared in Example 2 was analyzed by UV-visible absorption spectrum, fluorescence spectrum and phosphorescence spectrum. The test conditions were: UV-visible-near infrared spectrophotometer (PELambda 950), (RT, C = 1×10 -5 M, DCM), fluorescence spectrometer (FLS980) (RT, C = 1 × 10 -5 M, DCM, excitation wavelength 350 nm), phosphorescence spectrometer (Edinburgh FLS980), (77 K, C = 1 × 10 -5 M, 2-MTHF, excitation wavelength 350nm). The results are as follows Fig.12 shown.

[0077] Depend on Fig.12 It can be seen that the UV-visible absorption of compound [9]BH-1 (solid line, 1×10 -5 M, DCM) has a maximum absorption peak at 332 nm, and the fluorescence spectrum (dotted line, 1×10 -5The maximum emission peaks of M, DCM are at 412 nm and 434 nm, and the phosphorescence spectrum (dashed line, 1×10 -5 The emission peaks of M, 77K, 2-MTHF, excitation wavelength 350nm are 514nm and 555nm.

[0078] The phosphorescence lifetime and afterglow phenomenon of [9]BH-1 were further analyzed in the frozen state (77K). The results are as follows: Fig.13 , Fig.14 shown.

[0079] Depend on Fig.13 It can be seen that compound [9]BH-1 has a millisecond-level phosphorescence lifetime (267ms) in the frozen state (77K). With the introduction of sulfur atoms in the molecular skeleton, the heavy atom effect is aggravated, the intersystem crossing (ISC) transition is enhanced, and the phosphorescence emission is enhanced, which is consistent with the trend of the heavy atom effect enhancement.

[0080] Depend on Fig.14 It can be seen that the long afterglow phenomenon of the compound [9]BH-1 helicene molecule in the frozen state (77K) exceeds 3s, indicating that the compound has excellent phosphorescent properties.

[0081] Experimental Example 2 Circular Dichroism Analysis

[0082] The thiophene-based chiral phenanthro[9]helicene compound BH[9]-1 prepared in Example 2 was subjected to circular dichroism analysis. The test conditions were: circular dichroism spectrometer (420SF) (4.54×10 -5 M, DCM) (+)-[9]BH-1 and (-)-[9]BH-1 (4.45×10 -5 M, DCM). The circular dichroism diagram of the compound and the absorption asymmetry factor diagram of the circular dichroism are shown in Fig.15 (a) and 15(b).

[0083] Depend on Fig.15 (a) The circular dichroism results of compound [9]BH-1 show that (+)-[9]BH-1 (dashed line, 4.54×10 -5 M, DCM) and (-)-[9]BH-1 (solid line, 4.45×10 -5 M, DCM), and the optically active isomers of BH[9]-1 were obtained by chiral separation. The circular dichroism spectrum showed that the two optically active isomers were in a perfect mirror-image relationship.

[0084] Depend on Fig.15 (b) The absorption asymmetry factor diagram of compound [9]BH-1 shows that (+)-[9]BH-1 (dashed line, 4.54×10 -5 M, DCM) and (-)-[9]BH-1 (solid line, 4.45×10-5 M, DCM), according to the absorption asymmetry factor formula g abs =2×(ε L -ε R ) / (ε L +ε R ), the calculated absorption asymmetry factor can reach 1.6×10 -3 , indicating that compound [9]BH-1 has good chiral optical properties.

[0085] Experimental Example 3 Chiral Stability and Specific Rotation Analysis

[0086] The specific rotation of the chiral thiophene-based phenanthro[9]helicene compound BH[9]-1 (0.3 mg / mL) prepared in Example 2 was analyzed using a fully automatic polarimeter Digipol-P910. The results showed that the specific rotation of the compound of the present invention was [ɑ]D 25 =-3955°, significantly higher than the reported thiophene[9]helicene ([ɑ]D 25 =-1170°, the specific structure of thiophene[9]helicene can be found in compound 6 mentioned in the background technology section).

[0087] Furthermore, the chiral stability of the target compound [9]BH-1 prepared in Example 2 of the present invention was analyzed. The results are as follows: Fig.16 shown.

[0088] Depend on Fig.16 It can be seen that the optically active form (+)-[9]BH-1 of the target compound [9]BH-1 prepared in Example 2 of the present invention was heated in a high-temperature oven at 300°C / 18h and analyzed by high performance liquid chromatography (HPLC) and did not undergo racemization, indicating that compound [9]BH-1 has high chiral stability. The chiral stability data of thiophene [7] helicene (the specific structure of which is shown in the compound 5 mentioned in the background technology section) reported in existing literature is 199°C / 11h. This shows that the compound of the present invention has better chiral stability.

[0089] In summary, the chiral thiophene-based phenanthro[9]helicene compound provided by the present invention has excellent optical stability and good phosphorescent properties, which can provide a theoretical basis and material foundation for the development of chiral phosphorescent materials with excellent performance, and can also lay a solid foundation for the application of thiophene helicene in the field of circularly polarized luminescence (CPL) or organic light-emitting materials.

Claims

1. A chiral thiophene-based phenanthro[9]helicene, characterized in that: The structural formula is shown in Formula I:

2. The method for preparing chiral phenanthrene [9] helicene based on thiophene according to claim 1, characterized in that: The following steps are involved: (1) reacting the raw material 2,5-bis(trimethylsilyl)-dithieno[2,3-b:3',2'-d]thiophene with N-bromosuccinimide in a solvent, and then purifying to obtain an intermediate compound a, named 2-(trimethylsilyl)-5-bromo-dithieno[2,3-b:3',2'-d]thiophene; (2) The intermediate compound a, the metal alkyl compound and the inert solvent are mixed and reacted at -70 to -80°C, and then N,N-dimethylformamide is added and the reaction is continued at -70 to -80°C. After the reaction, the mixture is placed at 20 to 35°C and purified to obtain the intermediate compound b, which is named 5-(trimethylsilyl)-2-aldehyde-dithieno[2,3-b:3',2'-d]thiophene; (3) mixing 1,4-di((triphenylphosphine bromide)methyl)benzene, a metal alkyl compound and an inert solvent, reacting at -70 to -80°C, then adding the intermediate compound b to the system after the reaction to carry out a Wittig reaction, and purifying after the reaction to obtain an intermediate compound c, named 1,4-di(2-(5-(trimethylsilyl)-dithieno[2,3-b:3',2'-d]thiophene-2)vinyl)benzene; (4) The intermediate compound c, iodine and an inert solvent are mixed, subjected to a photochemical reaction, and then purified to obtain the thiophene-based chiral phenanthro[9]helicene of formula I.

3. The method for preparing chiral phenanthrene [9] helicene based on thiophene according to claim 2, characterized in that: In step (1), the solvent is a mixture of chloroform and acetic acid; in step (2), step (3) and step (4), the inert solvent is one or more of anhydrous ether, anhydrous tetrahydrofuran and anhydrous toluene.

4. The method for preparing chiral phenanthrene [9] helicene based on thiophene according to claim 2, characterized in that: In step (2) and step (3), the metal alkyl compound is n-butyllithium.

5. The method for preparing chiral phenanthrene [9] helicene based on thiophene according to claim 2, characterized in that: In step (1), the reaction temperature is 0 to 5°C and the reaction time is 1.5 to 2.5 hours; in step (2), the reaction time at -70 to -80°C is 1 to 3 hours, and the reaction time at -70 to -80°C is 0.5 to 1.5 hours; the storage time at 20 to 35°C is 8 to 10 hours; in step (3), the reaction time at -70 to -80°C is 1 to 3 hours; the Wittig reaction temperature is -70 to -80°C and the reaction time is 0.5 to 1.5 hours; in step (4), the photochemical reaction is carried out using a medium-pressure mercury lamp, and the photochemical reaction time is 15 to 25 hours.

6. The method for preparing chiral phenanthrene [9] helicene based on thiophene according to any one of claims 2 to 5, characterized in that: In step (2), the molar ratio of the intermediate compound a, the metal alkyl compound and N,N-dimethylformamide is 2.28:0.84:1.

6.

7. The method for preparing chiral phenanthrene [9] helicene based on thiophene according to any one of claims 2 to 5, characterized in that: In step (3), the molar ratio of 1,4-di((triphenylphosphine bromide)methyl)benzene, the metal alkyl compound, and the intermediate compound b is 0.13:0.33:0.

29.

8. The method for preparing chiral phenanthrene [9] helicene based on thiophene according to any one of claims 2 to 5, characterized in that: In step (4), the molar ratio of the intermediate compound c to the iodine element is 0.047:0.

28.

9. The use of the chiral phenanthrene [9] helicene based on thiophene according to claim 1, characterized in that: The chiral thiophene-based phenanthro[9]helicene is used as a chiral phosphorescent material in circularly polarized luminescence or organic luminescence.

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