Chiral binuclear Zn (II)-complex constructed based on chiral Salen-Schiff base ligand (R, R / S, S-L), preparation method and application of chiral binuclear Zn (II)-complex in electro-circularly polarized luminescence

Abstract

The invention relates to a chiral binuclear Zn (II)-complex constructed on the basis of a chiral Salen-Schiff base ligand (R, R / S, S-L), a preparation method of the chiral binuclear Zn (II)-complex and application of the chiral binuclear Zn (II)-complex to electro-circularly polarized luminescence, and along with the change of the configuration of the chiral Salen-Schiff base ligand, the chiral binuclear Zn (II)-complex shows different light colors in a visible light region. At room temperature, maximum emission peaks of an emission spectrum of the chiral binuclear Zn (II)-complex developed by a chiral Salen-Schiff base ligand introduced based on a methoxy (-OMe) functional group in a CH2Cl2 solution are respectively 467 nm and 462 nm, CIE coordinates are respectively (0.156, 0.192) and (0.158, 0.190), and the chiral binuclear Zn (II)-complex is located in a blue light emission region, shows a strong ground state chiral signal and a Cotton effect, and has an asymmetric factor gPL-10-4. The starting voltages of the electroluminescent devices CP-OLED-R and R-II and CP-OLED-S and S-II are both 6V, the maximum emission wavelengths of electro circularly polarized light are respectively 488 nm and 496 nm, and the CIE coordinates are respectively located in blue light regions (0.288, 0.305) and (0.283, 0.304). The maximum current efficiency of the devices CP-OLED-R and R-II is 0.90 cd / A, the maximum power efficiency of the devices CP-OLED-R and R-II is 0.47 lm / W, and the maximum external quantum efficiency of the devices CP-OLED-R and R-II is 0.43%; the maximum current efficiency of the device CP-OLED-S, S-II is 0.83 cd / A, the maximum power efficiency is 0.40 lm / W, the maximum external quantum efficiency is 0.38%, and the asymmetric factor is gEL-10 <-4 >.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic optoelectronic functional materials. It relates to a chiral metal organic photoinduced / electroinduced circularly polarized luminescent material, and specifically to a chiral binuclear Zn(II)-complex [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] constructed based on a chiral Salen-type Schiff base ligand (R,R / S,SL), a preparation method, and the application of an electroinduced circularly polarized luminescent device. Background Art

[0002] The application of chiral Salen-Schiff base-Zn(II)-complexes was mainly focused on chiral catalysis in the early stage. With the birth and development of CD spectroscopy, especially CPL spectroscopy, the interest in the chiral optoelectronic properties of chiral Salen-Schiff base-Zn(II)-complexes in the ground state and excited state has been stimulated. In recent years, 3D display CPL-OLEDs (circularly polarized-organic light-emitting diodes) have flourished. Based on chiral-Zn(II)-complexes as the main luminescent material, there are relatively few studies on electroluminescent visible light-even white light-circularly polarized organic light-emitting devices (CPL-OLEDs / CPL-WOLEDs). Tang et al. used (1R,2R)-(-)-1,2-cyclohexanediamine or (1S,2S)-(+)-1,2-cyclohexanediamine and vanillin through aldehyde amine condensation reaction and further Zn(OAc)2·2H2O coordination self-assembly to obtain chiral R,R / S,S-Salen-Zn(II)-mononuclear complexes. The photoinduced circularly polarized luminescence performance study showed that the photoinduced blue-green light had an asymmetry factor (gPL) of 10 in THF solution. -3 . Further, through the design of the chiral R,R / S,S-Salen-Zn(II)-separate film device ITO / PEDOT:PSS / TAPC / R,R / S,S-Salen-Zn(II) / TPBi / Ca / Ag structure, its electroluminescent CPL-OLED device was realized. Its shortcomings are: 1) Due to the light color interference of TAPC and TPBi auxiliary layer materials, the R,R / S,S-Salen-Zn(II)-blue-green light is compounded into yellow light; 2) Electroluminescent performance: such as 1000cd / m 2 Under this condition, the current efficiency is only 0.181cd / A and the power efficiency is only 0.074lm / W.

[0003] The present invention introduces functional groups (-OMe, -OH, -OPr, etc.) into chiral Salen-type Schiff bases (R, RL / S, SL), further obtains chiral binuclear Zn(II)-complexes by excessive use of Zn(OAc)2·2H2O, and uses the complexes as guest materials for the light-emitting layer to prepare CP-OLEDs devices. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a chiral dinuclear Zn(II)-complex constructed based on a chiral Salen-type Schiff base ligand (R,R / S,SL), a preparation method and an application of electroinduced circularly polarized luminescence, wherein salicylaldehyde is reacted with (1R,2R)-(-)-cyclohexanediamine or (1S,2S)-(-)-cyclohexanediamine to synthesize two asymmetric Schiff bases R,RI and S,SI respectively; then R,RI and S,SI are self-assembled with Zn(OAc)2·2H2O to obtain Zn(II)-complexes [Zn2(R,RL)(μ1-OAc)(μ2-OAc)(CH3OH)](R,R-II) and [Zn2(S,SL)(μ1-OAc)(μ2-OAc)(CH3OH)](S,S-II).

[0005] A [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type chiral Zn(II)-complex, characterized in that it has a binuclear metal-zinc(II) as the luminescent center, is formed by a chiral Schiff base ligand chelated with zinc metal, and has the following general structural formula:

[0006]

[0007] In the second aspect, a method for preparing a chiral Zn(II)-complex of [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] configuration is provided, wherein the synthesis method is as follows:

[0008]

[0009]

[0010] The synthesis steps include:

[0011] Step 1, preparation of chiral Schiff base ligand: first weigh salicylaldehyde into a round-bottom flask, add methanol to dissolve it and stir continuously, then add (1R, 2R)-(-)-1,2-cyclohexanediamine / (1S, 2S)-(-)-1,2-cyclohexanediamine dropwise at room temperature and stir at 70°C for 5 hours.

[0012] Step 2, preparation of [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type chiral Zn(II)-complex: add the chiral Schiff base ligand prepared in step 1 and Zn(OAc)2·2H2O into a flask, then add methanol and stir, heat to reflux and stir at 70°C, add a small amount of DMF after reflux for 2.5 hours (the volume ratio of DMF to the previously added methanol is 1:20), and finally reflux and stir for 24 hours.

[0013] In the above step 1, the molar ratio of salicylaldehyde to cyclohexanediamine is 2:1.

[0014] In the above step 2, the molar ratio of the chiral Schiff base ligand to Zn(OAc)2·2H2O is 1:3.

[0015] In a third aspect, the present invention provides an electro-circularly polarized light-emitting device of a [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type blue light Zn(II)-complex, wherein the light-emitting layer is doped with two [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type blue light Zn(II)-complexes (R,R-II and S,S-II) provided by the present invention, and the structural formula thereof is as follows:

[0016]

[0017] Beneficial effects of the present invention

[0018] (1) The present invention provides a novel chiral Schiff base dinuclear zinc (II) complex, and as the configuration of the chiral Salen-type Schiff base ligand changes, the chiral dinuclear Zn (II)-complex exhibits different light colors in the visible light region. This type of material has the advantages of low cost, easy synthesis, excellent photophysical properties and circular polarization activity based on the modification of the chiral Schiff base ligand.

[0019] (2) The organic electro-induced circularly polarized light-emitting device prepared by the present invention has the advantages of low starting voltage, high luminous efficiency, good environmental stability, etc., and occupies a very important position in the research field of organic electro-induced circularly polarized light-emitting. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type chiral Zn(II)-complex (R,R-II) 1 HNMR spectrum;

[0021] Figure 2 The chiral Zn(II) complex (S,S-II) of the type [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] 1HNMR spectrum;

[0022] Figure 3 The X-ray single crystal structure of the chiral Zn(II)-complexes (R,R-II and S,S-II) of the [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type is shown;

[0023] Figure 4 The emission spectra of chiral Zn(II)-complexes (R,R-II and S,S-II) of the [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type in dichloromethane are shown;

[0024] Figure 5 The absorption spectra of [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type chiral Zn(II)-complexes (R,R-II and S,S-II) in dichloromethane;

[0025] Figure 6 The circular dichroism spectra of chiral Zn(II)-complexes (R,R-II and S,S-II) of the [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type in dichloromethane are shown;

[0026] Figure 7 Schematic diagram of the structure of the electroluminescent device of [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type chiral Zn(II)-complex (R,R-II and S,S-II);

[0027] Figure 8 The electroluminescence spectra of chiral Zn(II)-complexes (R,R-II and S,S-II) of the [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type are shown;

[0028] Table 1 shows the crystal data and structural refinement of the [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type chiral Zn(II)-complexes (R,R-II and S,S-II);

[0029] Table 2 shows the main bond lengths of chiral Zn(II)-complexes (R,R-II and S,S-II) of the [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type. and bond angles (°). DETAILED DESCRIPTION

[0030] Embodiment 1:

[0031] (1) Synthesis of Chiral Schiff Base Ligands R, RI and S, SI Containing R1=H, R2=CH3 Substituents

[0032] First, weigh 3-methoxysalicylaldehyde (1.216g, 8mmol) in a 50mL round-bottom flask, add 25mL methanol to dissolve it and stir continuously, then add (1R,2R)-(-)-1,2-cyclohexanediamine (0.456g, 4mmol) dropwise at room temperature, the solution quickly changes from bright yellow to brown, and the color deepens with the addition of cyclohexanediamine. After adding all the raw materials, stir at 70°C for 5h. After the reaction is completed, let the reacted solution stand at low temperature for one week, and a large amount of yellow solid precipitates. Filter and wash with a small amount of methanol to obtain 1.10g of yellow needle-shaped solid. Yield: 65.79%. Fourier transform infrared absorption spectrum, FT-IR (KBr, cm -1 ):3450(m),2927(w),2858(w),2355(w),1622(s),1463(s),1369(w),13 44(w),1273(m),1249(vs),1207(m),1188(s),1168(w),1138(w),1085(m ),1043(w),968(s),933(m),854(m),837(m),800(w),783(s),742(s),64 6(w),580(m),563(w),551(w),532(w),518(w),491(w),443(w),420(w). 1 H NMR (CDCl3, 400MHz): δ (ppm) 13.88 (s, 2H, -OH), 8.26 (s, 2H, -HC=N), 6.87 (m, 2H, -Ph), 6.80 (m, 2H, -Ph), 6. 74(t,2H,-Ph),3.88(s,6H,-OCH3),3.33(m,2H,-Ch),1.91(m,4H,-Ch),1.73(m,2H,-Ch),1.49(t,2H,-Ch).

[0033] The method for synthesizing chiral ligand S, SI is similar to that for synthesizing R, RI, except that (1R, 2R)-(-)-1,2-cyclohexanediamine is replaced by (1S, 2S)-(-)-1,2-cyclohexanediamine. The other conditions are the same. Yield: 65.79%. Fourier transform infrared absorption spectrum: FT-IR (KBr, cm -1):3452(m),2926(w),2854(w),2358(w),1622(w),1463(s),1371(w),13 44(w),1273(m),1249(vs),1207(m),1188(w),1168(w),1138(w),1085(m ),1043(w),968(s),933(m),854(m),839(m),800(w),783(s),742(s),64 8(w),580(w),563(w),553(w),530(w),518(w),491(w),443(w),418(w). 1 H NMR (CDCl3, 400MHz): δ (ppm) 13.88 (2H, s, -OH), 8.25 (2H, m, -CH = N), 6.87 (2H, m, -Ph), 6.80 (2H, m, -Ph), 6. 75(2H,t,-Ph),3.87(6H,s,-OCH3),3.34(2H,m,-Ch),1.90(2H,m,-Ch),1.74(2H,m,-Ch),1.46(2H,t,-Ch).

[0034]

[0035] (2) Synthesis of chiral Zn(II) complexes R, R-II and S, S-II

[0036] Chiral Zn(II)-complex R,R-II: Add R,RI (38.2mg, 0.1mmol) and Zn(OAc)2·2H2O (65.8mg, 0.3mmol) to a flask, then add 10mL methanol and stir. It cannot be completely dissolved and the solution is light yellow. Heat under reflux and stir at 70℃. The Schiff base gradually dissolves completely and the solution is light yellow. After reflux for 2.5h, 0.5mL DMF is added and the solution is still yellow. After heating and stirring for 14h, the solution is orange. The solvent is naturally evaporated at room temperature to cultivate crystals. After standing for one week, bright yellow granular crystals are produced. Yellow granular crystals: 0.416g, yield: 78.78%. Fourier transform infrared absorption spectrum: FT-IR (KBr, cm -1):3321(w),3057(w),2928(w),2859(w),1630(s),1570(s),1438(s),1415( s),1394(s),1351(w),1304(m),1284(m),1242(s),1217(s),1174(w),1106 (w),1082(s),1047(m),1014(m),968(s),918(w),879(w),853(m),782(w), 744(vs),662(s),618(s),586(m),552(s),510(m),469(m),441(s),413(s). 1 HNMR (400MHz, DMSO-d6): δ(ppm)8.33(2H,s,-CH=N),6.80(4H,m,-Ph),6.38(2H,m,-Ph),4.12(1H,- OH),3.71(6H,s,-OCH3),3.21(2H,m,-Ch),3.17(3H,d,-CH3),2.45(6H,d,-OAc),1.80(8H,d,-Ch).

[0037] Chiral Zn(II)-complex S, S-II: The synthesis method of chiral Zn(II)-complex S, S-II is similar to that of chiral Zn(II)-complex R, R-II, except that the chiral ligands R, RI are replaced by S, SI. Yellow granular crystals: 0.428g, yield: 81.06%. Fourier transform infrared absorption spectrum: FT-IR (KBr, cm -1 ):3321(w),3057(w),2928(w),2859(w),1630(s),1570(s),1438(s),1415( s),1394(s),1351(w),1304(m),1284(m),1242(s),1217(s),1174(w),1106 (w),1082(s),1047(m),1014(m),968(s),918(w),879(w),853(m),782(w), 744(vs),662(s),618(s),586(m),552(s),510(m),469(m),441(s),413(s). 1H NMR (400MHz, DMSO-d6): δ(ppm)8.33(2H,s,-CH=N),6.82(4H,m,-Ph),6.43(2H,m,-Ph),4.12(1H,m, -OH),3.72(6H,s,-OCH3),3.23(2H,s,-Ch),3.17(3H,d,-CH3),2.47(6H,d,-OAc),1.80(8H,d,-Ch).

[0038]

[0039] (3) Analysis of the photophysical properties of chiral Zn(II) complexes R, R-II and S, S-II

[0040] At room temperature, the chiral Zn(II)-complexes R,R-II and S,S-II -5 The UV absorption peaks of the M dichloromethane solution are 235, 277, 359 nm and 235, 278 and 356 nm, respectively. The maximum emission peaks are located at 467 and 462 nm, respectively. The corresponding CIE coordinates are (0.156, 0.192) and (0.158, 0.190), respectively, located in the blue light emission region. The circular dichroism results show that at 10 -5 The results of the experiment showed that both R, R-II and S, S-II have strong ground state chiral signals in dichloromethane solution, i.e., there are multiple Cotton peaks on the upper and lower sides of the x-axis and the curves are mirror-symmetric about the upper and lower sides of the x-axis: the Cotton peaks of the chiral Zn(II)-complexes R and R-II are (-)-296, (+)-342 and (-)-380nm, respectively; the Cotton peaks of the chiral Zn(II)-complexes S and S-II are (+)-295, (-)-343 and (+)-380nm, respectively. The circularly polarized spectra show that the asymmetry factor |g PL |~10 -4 .

[0041] (4) Fabrication of organic electroluminescent circularly polarized light-emitting devices

[0042] The chiral Zn(II)-complex prepared in step (2) is used as the electroluminescent material to prepare an electroluminescent circularly polarized light-emitting device. The devices CP-OLEDs-R, R-II and CP-OLEDs-S, S-II are developed by vacuum evaporation. The device structure is ITO / MoO3 (5nm) / TAPC (40nm) / mCP: 5wt% Zn-Complex R, R-II / S, S-II (20nm) / TPBI (40nm) / LiF (1nm) / Al (100nm). Indium tin oxide (ITO) with a sheet resistance of 20Ω was used as the anode of CP-OLEDs. Its surface was cleaned with deionized water, acetone, trichloroethylene and isopropyl alcohol, and each sheet was sonicated with an ultrasonic bath. TAPC is 4-[1-[4-[di(4-methylphenyl)amino]phenyl]cyclohexyl]-N-(3-methylphenyl)-N-(4-methylphenyl)aniline, which plays a hole transport role, and TPBI is 1,3,5-tri(1-phenyl-1H-benzimidazol-2-yl)benzene, which is used as an electron transport layer. The maximum emission wavelengths of the electroluminescence of the devices CP-OLEDs-R, R-II and CP-OLEDs-S, S-II are located at 488nm and 496nm, respectively. When the driving voltage is 6V, the devices CP-OLEDs-R, R-II and CP-OLEDs-S, S-II begin to light up. When the voltage reaches 17.5V, the luminous brightness of the devices CP-OLEDs-R, R-II and CP-OLEDs-S, S-II reaches the maximum, which is 99.81cd / cm 2 and 102.27cd / cm 2 The maximum current efficiency of the device CP-OLED-R, R-II is 0.90cd / A, the maximum power efficiency is 0.47lm / W and the maximum external quantum efficiency is 0.43%; the maximum current efficiency of the device CP-OLED-S, S-II is 0.83cd / A, the maximum power efficiency is 0.40lm / W and the maximum external quantum efficiency is 0.38%, and the asymmetry factor |g EL |~10 -4 .

[0043] Table 1 shows the crystal data and structure refinement of [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type chiral Zn(II)-complexes (R,R-II and S,S-II)

[0044]

[0045] Table 2 shows the main bond lengths of chiral Zn(II)-complexes (R,R-II and S,S-II) of the [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type. and bond angle (°)

[0046]

Claims

1. A chiral Zn(II)-complex based on the [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] configuration, characterized in that: It has the following general structural formula:

2. A method according to claim 1 based on [Zn2(R,R / S,SL)(μ A chiral Zn(II)-complex of [μ1-OAc)(μ2-OAc)] configuration, characterized in that The preparation method thereof, wherein the synthesis method is as follows:

3. The method for synthesizing a chiral Zn(II)-complex of [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] configuration according to claim 2, characterized in that: The preparation method comprises the following steps: Step 1, preparation of chiral Salen-type Schiff base ligand: first weigh salicylaldehyde in a round-bottom flask, add methanol to dissolve it and stir continuously, then add (1R, 2R)-(-)-1,2-cyclohexanediamine / (1S, 2S)-(-)-1,2-cyclohexanediamine dropwise at room temperature, and stir at 70° C. for 5 h; Step 2, preparation of [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type chiral Zn(II)-complex: add the chiral Salen-type Schiff base ligand prepared in step 1 and Zn(OAc)2·2H2O into a flask, then add methanol and stir, heat to reflux and stir at 70°C, add a small amount of DMF after reflux for 2.5 hours (the volume ratio of DMF to the previously added methanol is 1:20), and finally reflux and stir for 24 hours.

4. The method for preparing a chiral Zn(II)-complex of the configuration [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] according to claim 3, characterized in that: The molar ratio of salicylaldehyde to cyclohexanediamine in step 1 is 2:

1.

5. The method for preparing a chiral Zn(II)-complex of the configuration [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] according to claim 3, characterized in that: In the step 2, the molar ratio of the chiral Salen-type Schiff base ligand to Zn(OAc)2·2H2O is 1:

3.

6. A chiral Zn(II)-complex of [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] configuration is applied to an electro-circularly polarized light-emitting device, wherein the light-emitting layer is doped with two [Zn2(R,R / S,SL)(μ1-OAc)(μ2-OAc)] type blue light-emitting Zn(II)-complexes (R,R-II and S,S-II), and the structural formula thereof is as follows:

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