A chiral heteroleptic nine-coordinate rare earth complex and its preparation method and application

Abstract

The present invention discloses a chiral heteroleptic nine-coordinate rare earth complex and its preparation method and application, belonging to the field of organic luminescent materials. This chiral rare earth complex consists of three anionic coumarin-derived diketone ligands (Coum) ‑ The chiral bis-oxazoline-derived enantiomerically pure ligands 1R,2R-2,6-bis(4-phenyl-2-oxazoline-2-yl)pyridine (1R,2R-Ph-PyBox) or 1S,2S-2,6-bis(4-phenyl-2-oxazoline-2-yl)pyridine (1S,2S-Ph-PyBox) were self-assembled with rare earth ions in alcohol solution. Thanks to the combination of the excellent photophysical properties of the Coum ligand and the strong chiral induction ability of the chiral Chiral-Ph-PyBox ligand, the two Tb 3+ The enantiomers [Tb(Coum)3(1R,2R‑Ph‑PyBox)](2)and[Tb(Coum)3(1S,2S‑Ph‑PyBox)](5) not only achieve bright and high color purity characteristic green emission (Φ PL =74%), and also obtained a strong excited state CPL activity (|g lum |=0.097‑0.103) and significantly enhanced antenna ligand center absorption behavior (ε 320nm =47820-47940M ‑1 cm ‑1 ). Complexes 2 and 5 have magnetic dipoles 5 D4→ 7 The circular polarization brightness at the F5 transition position (B CPL ) can be as high as 1132.7-1205.8M ‑1 cm ‑1 .

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials, relates to organic luminescent materials, and specifically relates to a chiral heteroleptic nine-coordinate rare earth complex and a preparation method and application thereof. Background Art

[0002] The potential applications of circularly polarized luminescence (CPL) active materials in CPL microscopy, biomolecular probes, and next-generation high signal-to-noise ratio 3D displays have attracted great interest from researchers. lum ) is insufficient and may be misleading. Therefore, a more comprehensive measure is the circular polarization brightness (B CPL )” was proposed, and the definition is B CPL =β i ×ε λ ×Φ PL ×|g lum | / 2. In addition to considering g lum and photoluminescence quantum efficiency (Φ PL ), the molar absorption coefficient (ε λ ) and the so-called specific transition branch ratio (β i ; 0≤β i ≤1) and other indicators still need attention.

[0003] Thanks to Eu 3+ Central 5 D0→ 7 F J (J=6-0) and Tb 3+ Central 5 D4→ 7 F J (J=6-0)ff transition, chiral organic Eu 3+ / Tb 3+ The complexes usually exhibit many fascinating photophysical properties, including high-color pure red or green narrow-band emission with a theoretical internal quantum efficiency of 100%, tunable molar absorption coefficients due to a controllable antenna effect sensitization mechanism, and magnetic dipole m ji Allowable and electric dipole μ ij Strong excited state circularly polarized photoactivity (|g lum |>10 -2 ). Therefore, CPL active Eu 3+ / Tb 3+ Complexes are generally considered to obtain superior B CPL As of now, many CPL active Eu 3+The complexes have been reported to exhibit high B CPL Value (103-3240M -1 cm -1 , 5 D0→ 7 F1). However, due to Tb 3+ ( 5 D4: 20500cm -1 ) and Eu 3+ ( 5 D0: 17286cm -1 ) has a large intrinsic difference in the first excited state energy level, and Tb has excellent comprehensive CPL performance. 3+ Few complexes have been reported so far.

[0004] So far, the reported CPL-active Tb 3+ The vast majority of complexes are derived from isolative water-soluble or oil-soluble systems, in which only one or more single organic ligands are responsible for the three key optical indices (ε λ ,Φ PL and g lum ) quantitative optimization. Although the recent Shibasaki-Tb 3+ Magnetic dipole 5 D4→ 7 A very high B CPL Value (782-3760M -1 cm -1 However, since the three key optical indicators mentioned above are governed by different selection laws, we attempt to further improve the B of these isolative complexes by optimizing the structures of these monophenolate axial chiral ligands. CPL Another promising approach to heterogeneous construction is to use two organic ligands with clear division of labor to simultaneously bind to Tb 3+ Unfortunately, there are few reports on related research at present, which is in the absolute initial stage and mainly limited to a few cases of β-diketone-Tb 3+ Complexes and a recently reported case of monocoumarinyl Tb 3+ Complex, and the maximum circular polarization brightness B shown by the above complex CPL The value is only 11.7M -1 cm -1 . Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a chiral heteroleptic nine-coordinate rare earth complex and its preparation method and application. The synthesis method is simple, high in yield and low in cost. 3+The enantiomers can simultaneously possess strong CPL activity, high photoluminescence efficiency and good light absorption ability. 5 D4→ 7 B at the F5 jump position CPL Values ​​as high as 1132.7-1205.8M -1 cm -1 .

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A chiral heteroleptic nine-coordinate rare earth complex comprising: a chiral heteroleptic nine-coordinate Tb 3+ 、La 3+ and Gd 3+ enantiomers;

[0008] Its general structural formula includes [Ln(Coum)3(1R,2R-Ph-PyBox)](Ln=La,1;Tb,2;Gd,3) and [Ln(Coum)3(1S,2S-Ph-PyBox)](Ln=La,4;Tb,5;Gd,6).

[0009] Specifically, its structural formula is as follows:

[0010]

[0011] The present invention also protects a method for preparing the heteroleptic nine-coordinate rare earth complex as described above, comprising the following steps:

[0012] Step 1: using 4-hydroxycoumarin and acetic acid to undergo Friedel-Crafts acylation reaction in an excess of phosphorus oxychloride to obtain a coumarin-derived diketone primary ligand Coum;

[0013] Step 2: Deprotonate an equimolar amount of the ligand Coum using CH3ONa; then, add one-third of a molar amount of a rare earth chloride salt LnCl3·6H2O (Ln = La, Tb or Gd) to the above solution and stir and reflux to obtain a series of rare earth precursor complexes [Ln(Coum)3(H2O)2] (Ln = La, Tb or Gd), and the above series of precursors are recrystallized and purified;

[0014] Step 3. The [Ln(Coum)3(H2O)2] (Ln=La, Tb or Gd) purified in Step 2 was respectively mixed with an equimolar amount of 1R,2R-2,6-bis(4-phenyl-2-oxazolin-2-yl)pyridine (1R,2R-Ph-PyBox) or 1S,2S-2,6-bis(4-phenyl-2-oxazolin-2-yl)pyridine (1S,2S-Ph-PyBox) in methanol solution and refluxed for 16 hours to obtain a series of target chiral rare earth complexes [Ln(Coum)3(1R,2R-Ph-PyBox)] (Ln=La,1;Tb,2;Gd,3) and [Ln(Coum)3(1S,2S-Ph-PyBox)] (Ln=La,4;Tb,5;Gd,6), and the above complexes 1-6 were recrystallized and purified.

[0015] Preferably, the amount of phosphorus oxychloride added in step 1 is in excess relative to 4-hydroxycoumarin in terms of the amount of substance.

[0016] Furthermore, the present invention also protects a chiral heteroleptic nine-coordinate Tb as described above. 3+ Enantiomers and their applications in the light-emitting layer of high-contrast circularly polarized organic light-emitting diodes (CP-OLEDs), bioluminescent probes, or advanced anti-counterfeiting inks, chiral heteroleptic nine-coordinated Tb 3+ Enantiomers in magnetic dipoles 5 D4→ 7 B at the F5 jump position CPL Values ​​as high as 1132.7-1205.8M -1 cm -1 .

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] The present invention innovatively combines the excellent photophysical properties (strong absorption and high-efficiency sensitization properties) of coumarin-derived diketone Coum ligands and the strong chiral induction ability of chiral bisoxazoline-derived enantiopure ligands to prepare a pair of chiral heteroleptic nine-coordinated Tb 3+ Enantiomers, La 3+ Heteromorphs and Gd 3+ Heteromorphous isomers. La 3+ Enantiomers 1 and 4 are diamagnetic substances and can be used for nuclear magnetic resonance hydrogen spectrum testing of this system; Gd 3+ The low-temperature 77K spectra of enantiomers 3 and 6 can capture the triplet excited state energy level of the complex; chiral heteroleptic nine-coordinated Tb 3+On the one hand, enantiomers 2 and 5 can realize the intramolecular efficient Dexter ligand sensitized luminescence process. At the same time, the relatively compact saturated nine-coordinate molecular configuration greatly suppresses the occurrence of non-radiative transition energy loss, ensuring the high luminescence efficiency value of the complex. The design of three aromatic Coum ligands ensures that the lowest energy state absorption position of the complex (λ edge ) has a higher molar absorption coefficient value; thanks to the combination of the excellent photophysical properties of the Coum ligand and the strong chiral induction ability of the chiral Chiral-Ph-PyBox ligand, the two Tb 3+ The enantiomers [Tb(Coum)3(1R,2R-Ph-PyBox)](2)and[Tb(Coum)3(1S,2S-Ph-PyBox)](5) not only achieve bright and high color purity characteristic green emission (Φ PL =74%), and also obtained a strong excited state CPL activity (|g lum |=0.097-0.103) and significantly enhanced antenna ligand center absorption behavior (ε 320nm =47820-47940M -1 cm -1 ); finally Tb 3+ Enantiomers in magnetic dipoles 5 D4→ 7 B at the F5 jump position CPL The value can be as high as 1132.7-1205.8M -1 cm -1 Its potential applications mainly involve circularly polarized organic light-emitting diodes (CP-OLEDs / PLEDs), bioluminescent probes, and advanced anti-counterfeiting inks.

[0019] The high-color pure circularly polarized green light emitting chiral heterogeneous nine-coordinated Tb 3+ The enantiomers are low-cost, high-yield and easy to synthesize. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The synthetic route of the series of chiral rare earth complex monomers 1-6 of the present invention is as follows;

[0021] Figure 2 The ligands (Coum and 1R, 2R-Ph-PyBox) and La 3+ Liquid H NMR spectrum of complex monomer 1;

[0022] Figure 3 The ligands (Coum and 1S, 2S-Ph-PyBox) and La 3+ Liquid H NMR spectrum of complex monomer 4;

[0023] Figure 4 The ligands of the present invention (Coum, 1R, 2R-Ph-PyBox and 1S, 2S-Ph-PyBox) and their Gd 3+ Normalized UV-visible absorption spectra of enantiomers 3 and 6;

[0024] Figure 5 a is the chiral Tb of the present invention 3+ UV-visible absorption spectra of enantiomers 2 and 5; Figure 5 b is the normalized fluorescence emission spectra of 2 and 5; Figure 5 Circular dichroism spectra with c being 2 and 5; Figure 5 Circularly polarized fluorescence spectra with d of 2 and 5;

[0025] Figure 6 The chiral Tb of the present invention 3+ g of enantiomers 2 and 5 lum Relationship diagram with wavelength;

[0026] Figure 7 The chiral Tb 3+ Enantiomers 2 and 5 5 D4→ 7 Room temperature lifetime decay curve of F5 transition position;

[0027] Figure 8 The chiral Gd 3+ Low-temperature 77K spectra of enantiomers 3 and 6;

[0028] Figure 9 The chiral Tb 3+ Absolute total luminescence quantum efficiency test of enantiomer 2;

[0029] Figure 10 The chiral Tb 3+ Absolute total luminescence quantum efficiency test of enantiomer 5;

[0030] Figure 11 The chiral Tb 3+ Thermal decomposition curves of enantiomers 2 and 5. DETAILED DESCRIPTION

[0031] The specific contents of the present invention are further explained in detail below with reference to the embodiments.

[0032] Step 1: Synthesis, purification and characterization of coumarin-derived diketone Coum ligands:

[0033] 4-Hydroxycoumarin (4-HC; 5.0 g, 30.8 mmol) was weighed and added to a round-bottom flask containing 50 mL of acetic acid and heated with stirring until completely dissolved. 6.0 mL of phosphorus oxychloride was slowly added dropwise to the mixed solution and stirred at room temperature for 0.5 h. The resulting mixture was then refluxed and stirred at 105°C for 50 min. After the reaction was completed and cooled to room temperature, the resulting mixture was poured into 100 mL of deionized water and stirred at room temperature for 1 h. The pale yellow crude product was filtered and collected, and further dissolved in methanol for natural evaporation and recrystallization at room temperature. A pale yellow needle-shaped single crystal sample was obtained after 2-3 days. The sample yield was 78%. The H NMR spectrum of the sample was tested, and the results were as follows: 1 H NMR (CDCl3, 400MHz, 298K): δ (ppm) 8.04 (m, 1H, -Ph), 7.70 (m, 1H, -Ph), 7.31 (m, 2H, -Ph), 2.78 (s, 3H, -CH3).

[0034] Step 2: Synthesis, purification and characterization of a series of rare earth precursor complexes [Ln(Coum)3(H2O)2] (Ln=La, Tb and Gd):

[0035] The coumarin-derived diketone Coum ligand (0.122 g, 0.6 mmol) and an equimolar amount of CH3ONa (0.032 g, 0.6 mmol) were dissolved in 50 mL of methanol and heated with stirring for one hour for deprotonation. Subsequently, LnCl3·6H2O (0.2 mmol; Ln = La, 0.071 g; Tb, 0.075 g; Gd, 0.074 g) was added to the obtained mixed solution system and heated under reflux with stirring for 6 hours. The obtained solution was naturally evaporated at room temperature for 1-2 weeks to obtain a series of precursor complex polycrystalline samples; the sample yield was 78-82%; the diamagnetic La 3+ The complex precursor [La(Coum)3(H2O)2] was used as a representative to test its H NMR spectrum, and the results were: 1 H NMR (CDCl3, 400MHz, 298K): δ (ppm) 8.07 (m, 3H, -Ph), 7.70 (m, 3H, -Ph), 7.32 (m, 6H, -Ph), 2.79 (s, 9H, -CH3), 1.55 (s, 4H, H2O).

[0036] Step 3: Preparation of a series of chiral rare earth complex monomers 1-6:

[0037] Purified rare earth complex precursors [Ln(Coum)3(H2O)2] (0.1 mmol; Ln = La, 0.078 g; Tb, 0.080 g; Gd, 0.080 g) were added to a round-bottom flask containing 25 mL of methanol with equimolar amounts of 1R,2R-Ph-PyBox (0.037 g, 0.1 mmol) or 1S,2S-Ph-PyBox (0.037 g, 0.1 mmol). The mixed solution was refluxed and stirred at 95°C for 16 hours. After the reaction was completed and cooled to room temperature, the colorless clear solution was naturally evaporated and diffused at room temperature for 1-2 weeks to obtain polycrystalline samples of complex monomers 1-6. The sample yield of complexes 1-6 was 67-78%; the diamagnetic La 3+ Enantiomers 1 and 4 were used as representatives to test their H NMR spectra. The results for complex 1 were: 1 H NMR (CDCl3, 400MHz, 298K): δ (ppm) 8.35 (m, 1H, -Py), 8.28 (d, 2H, -Py), 7.49 (s, 3H, -Ph) ,7.41(t,3H,-Ph),7.09(d,3H,-Ph),6.98(t,3H,-Ph),6.82(t,10H,-Ph),5.22(t,2H,-H h ),4.87(t,2H,-CH2 of-H i ),4.36(t,2H,-CH2of-H i ),2.30(s,9H,-H d ). The result of complex 4 is: 1 H NMR (CDCl3, 400MHz, 298K): δ (ppm) 8.36 (m, 1H, -Py), 8.29 (d, 2H, -Py), 7.47 (s, 3H, -Ph) ,7.38(t,3H,-Ph),7.08(d,3H,-Ph),6.97(t,3H,-Ph),6.81(t,10H,-Ph),5.22(t,2H,-H h ),4.88(t,2H,-CH2 of-H i ),4.36(t,2H,-CH2of-H i ),2.30(s,9H,-H d ).

[0038] Figure 1 The synthetic route of the chiral heteroleptic nine-coordinate rare earth complex monomers 1-6 of the present invention is shown in FIG.

[0039] LnCl3·6H2O (Ln=La, Tb or Gd) and three deprotonated (Coum) -The ligands were self-assembled in a methanol solution at a molar ratio of 1:3 to obtain a series of precursor complexes [Ln(Coum)3(H2O)2] (Ln = La, Tb, and Gd). Furthermore, a second chiral N^N^N-ligand, 1R,2R-Ph-PyBox or 1S,2S-Ph-PyBox, was introduced to fill the unsaturated coordination site of [Ln(Coum)3(H2O)2]. Two series of chiral complex monomers, [Ln(Coum)3(1R,2R-Ph-PyBox)] (Ln = La, 1; Tb, 2; Gd, 3) and [Ln(Coum)3(1S,2S-Ph-PyBox)] (Ln = La, 4; Tb, 5; Gd, 6), were successfully synthesized.

[0040] Figure 2 and Figure 3 They are the representative diamagnetic La 3+ 400 MHz for enantiomers 1 and 4 1 H NMR spectrum, prepared with deuterated chloroform.

[0041] Compared with the main ligand Coum (δ = 8.04-2.78 ppm) and the chiral auxiliary ligand Chiral-Ph-PyBox (δ = 8.34-4.41 ppm), the coordinated (Coum) in complexes 1 and 4 - The proton signal spectrum peak range of the chiral Chiral-Ph-PyBox is significantly broadened (δ=8.36-2.30ppm), accompanied by a moderate upfield shift. - The hydrogen proton integration ratio with a chiral ligand (1R,2R-Ph-PyBox or 1S,2S-Ph-PyBox) is consistent with the expected complex formula [Ln(Coum)3(Chiral-Ph-PyBox)]. It is worth noting that complexes 1 and 4 show almost identical hydrogen proton integration ratios in the range of δ = 5.50-2.00 ppm and δ = 8.50-8.00 ppm. 1 H NMR distribution pattern. However, Ph-PyBox and (Coum) - There are obvious differences in the proton peak distribution on the benzene ring of the ligand, which indicates that the chiral enantiomeric ligand 1R,2R-Ph-PyBox or 1S,2S-Ph-PyBox successfully coordinated with the rare earth precursor [La(Coum)3(H2O)2] and obtained complexes 1 and 4 with different spatial configurations.

[0042] Figure 4 Coum, 1R, 2R-Ph-PyBox and 1S, 2S-Ph-PyBox and Gd 3+ Room temperature normalized ultraviolet-visible absorption (UV-vis) spectra of enantiomers 3 and 6; Figure 5 a is the UV-vis spectra of complexes 2 and 5; Figure 5 b is the normalized fluorescence emission (PL) spectra of complexes 2 and 5; Figure 5 c is the circular dichroism (CD) spectra of complexes 2 and 5; Figure 5 d is the circularly polarized fluorescence emission (CPL) spectra of complexes 2 and 5; Figure 6 The luminescence asymmetry of complexes 2 and 5 is g lum The relationship between the value and wavelength. The above spectrum test concentration is 1×10 -5 M, the solvent was chromatographically pure CH2Cl2.

[0043] Tb 3+ / Gd 3+ The enantiomers exhibit very similar UV-visible absorption behavior, indicating the inherent ligand-centered nature of the electronic transition. 3+ The absorption bands of the enantiomers at 225, 303 and 320 nm (see Figure 5 a) Singlet n-π states attributable to the Coum ligand center * andπ-π * The lower energy state absorption peak (λ abs = 303 and 320 nm) showed similar molar absorption coefficients (ε 320nm =47820-47940M -1 cm -1 ;See Table 1). Further, through the UV-vis edge absorption band (λ edge =350nm) can be further estimated that Tb 3+ The singlet excited state energy level of the enantiomer ( 1 π-π * ;28571cm -1 ) and the optical HOMO-LUMO energy gap value (E g opt =3.54eV).

[0044] Under the strongest photoexcitation at 350-351 nm, chiral Tb 3+ Both enantiomers 2 and 5 exhibited four major narrow-band emission peaks with high signal-to-noise ratio (see Figure 5 b), the emission peak positions are 490, 543, 587 and 622 nm, respectively, which are attributed to Tb 3+ The first excited state of the ion 5 D4 energy level to lower energy level 7 F J The magnetic dipole 5 D4→ 7The F5 transition emission dominates the entire emission spectrum and the full width at half maximum (FWHM) of the emission peak is only 8 nm, resulting in two abnormally high 5 D4→ 7 F5 transition branch proportional coefficient (β i =66%; see Table 1). The final complexes 2 and 5 both showed bright, highly pure characteristic green emission, with CIE chromaticity coordinates of x=0.312-0.314, y=0.607-0.605.

[0045] like Figure 5 As shown in c, the CD spectra of complexes 2 and 5 show two perfect split mirror symmetry curves. - π-π of the ligand * Two strong Cotton absorption peaks were observed within the electronic transition range (complex 2: (-)-308 and (-)-334 nm; complex 5: (+)-307 and (+)-334 nm), indicating that the chiral signal on the bisoxazoline moiety was successfully transferred to (Coum) through intramolecular interactions. - Chromophore. Two Tb 3+ CPL spectra of the enantiomers (see Figure 5 d) In 5 D4→ 7 F J (J=6-3) transition range shows a pair of multiple positive and negative signal distribution patterns with high-resolution Stark energy levels, which are basically consistent with the corresponding PL emission wavelengths. 5 D4→ 7 The maximum g is obtained at the F5 transition position PL The values ​​are +0.097 and -0.103 respectively (see Figure 6 ), the CPL activity value observed here is slightly lower than that of chiral PyBox-Ln reported in the literature. 3+ Interestingly, although the electric dipole 5 D4→ 7 The CPL signal intensity at the F3 transition is weak, but the 610 nm wavelength under this transition shows an unusually high asymmetric luminescence activity value (|g lum |=0.171-0.202), which is inconsistent with the transition rule described by Richardson. Finally, the relatively strong CPL activity combined with the other two enhanced optical indicators (Φ PL =74%;ε 320nm =47820-47940M -1 cm -1 ) produced two very superior B CPL Value (1132.7-1205.8M -1cm -1 ; 5 D4→ 7 F5).

[0046] Table 1. Photophysical properties of complexes 2 and 5 and their B CPL value

[0047]

[0048] Figure 7 For complexes 2 and 5 5 D4→ 7 The room temperature lifetime decay curve of the F5 transition position, Figure 8 For Gd 3+ 77K spectra of enantiomers 3 and 6; Figure 9 This is the absolute total luminous efficiency test of complex 2; Figure 10 This is the absolute total luminous efficiency test of complex 5. The above spectral test concentration is 1×10 -5 M, the solvent was chromatographically pure CH2Cl2.

[0049] like Figure 7 As shown, complexes 2 and 5 5 D4→ 7 The F5 transition emission decay curve shows a single exponential decay distribution, indicating that complex 2 or 5 exists as a single diastereoisomer in solution. At the same time, the similar μs-level lifetimes of the two complexes (complex 2: 808μs; complex 5: 805μs) further confirm the inherent properties of the complex phosphorescence emission. The triplet excited state energy level of the complex was calculated from the 77K spectrum data. 3 π-π * 23255cm respectively -1 and 23364cm -1 The energy difference between the singlet excited state and the triplet excited state ( 1 π-π * - 3 π-π * ) are 5316cm -1 and 5207cm -1 , all greater than 5000cm -1 According to Reinhouldt's empirical rule, effective intersystem crossing (ISC) can occur within the molecules of complexes 2 and 5. Further calculation of the triplet energy level of the complex and the rare earth ion Tb 3+ of 5 D4(20500cm -1 ) energy level difference, the difference is 2755cm -1 and 2864cm -1 , all fall within the optimal sensitization Tb mentioned in Latva rule3+ Energy level range (2500~4500cm -1 Absolutely allowed ISC process and unidirectional complete ligand-Tb 3+ ( 3 π-π * → 5 D4) Energy transfer (LMET) combined with the two Tb 3+ Enantiomers in CH2Cl2 solution (1.0×10 -5 mol / L) in the absolute total luminescence quantum efficiency is as high as 74% (see Figure 9 and Figure 10 ), is the heterogametic type of all reported Tb 3+ The efficiency of the complex is 1.35 times the highest value.

[0050] Figure 11 Graphs showing the thermal decomposition curves of complexes 2 and 5 of the present invention are shown. Complexes 2 and 5 of the present invention were tested by heating at a rate of 10° C. / min in a nitrogen atmosphere.

[0051] Depend on Figure 11 It can be seen that the decomposition temperatures corresponding to 5% mass loss of complexes 2 and 5 are both higher than 290°C, indicating that both complexes have good thermal stability and are fully capable of being used as light-emitting layer materials for circularly polarized organic electroluminescent devices.

[0052] The chiral heteroleptic nine-coordinated Tb of the present invention 3+ The enantiomer perfectly combines the strong light absorption ability and high efficiency sensitization properties of the coumarin-derived diketone Coum ligand, and the strong chiral induction ability of the chiral bisoxazoline-derived enantiopure ligand to achieve high B CPL The circularly polarized green light emission coefficient is high; it can be used as the light-emitting layer material of the next generation of high signal-to-noise ratio, true backlight CP-OLED devices; the charming high-color pure circularly polarized green light emission also makes it have potential application value in the fields of biological fluorescent probes and advanced anti-counterfeiting inks.

[0053] The present invention is not limited to the specific technical solutions described in the above embodiments, and all technical solutions using equivalent replacement forms are within the protection scope required by the present invention.

Claims

1. A chiral heteroleptic nine-coordinate rare earth complex, characterized in that: include: Chiral heteroleptic nine-coordinate Tb 3+ 、La 3+ and Gd 3+ enantiomers; Its general structural formula includes [Ln(Coum)3(1R,2R-Ph-PyBox)], Ln=La,1;Tb,2;Gd,3 and [Ln(Coum)3(1S,2S-Ph-PyBox)], Ln=La,4;Tb,5;Gd,6; The structural formula is as follows:

2. The chiral heteroleptic nine-coordinate rare earth complex according to claim 1, characterized in that: Chiral heteroleptic nine-coordinate Tb 3+ Enantiomers in magnetic dipoles 5 D4→ 7 B at the F5 jump position CPL Values ​​as high as 1132.7-1205.8M -1 cm -1 .

3. A method for preparing the chiral heteroleptic nine-coordinate rare earth complex according to claim 1 or 2, characterized in that: The following steps are involved: Step 1: using 4-hydroxycoumarin and acetic acid to undergo Friedel-Crafts acylation reaction in an excess of phosphorus oxychloride to obtain a coumarin-derived diketone primary ligand Coum; Step 2: Deprotonate an equimolar amount of the ligand Coum using CH3ONa; then, add one-third of a molar amount of a rare earth chloride salt LnCl3·6H2O, Ln=La, Tb or Gd to the above solution and stir and reflux to obtain a series of rare earth precursor complexes [Ln(Coum)3(H2O)2], Ln=La, Tb or Gd, and the above series of precursors are recrystallized and purified; Step 3. The [Ln(Coum)3(H2O)2], Ln=La, Tb or Gd purified in step 2 was respectively refluxed with an equimolar amount of 1R,2R-2,6-bis(4-phenyl-2-oxazolin-2-yl)pyridine (1R,2R-Ph-PyBox) or 1S,2S-2,6-bis(4-phenyl-2-oxazolin-2-yl)pyridine (1S,2S-Ph-PyBox) in methanol solution for 16 hours to obtain a series of target chiral rare earth complexes [Ln(Coum)3(1R,2R-Ph-PyBox)], Ln=La,1; Tb,2; Gd,3 and [Ln(Coum)3(1S,2S-Ph-PyBox)], Ln=La,4; Tb,5; Gd,6, and the above complexes 1-6 were recrystallized and purified.

4. The method for preparing a chiral heteroleptic nine-coordinate rare earth complex according to claim 3, wherein: In the step 1, the amount of phosphorus oxychloride added is in excess relative to 4-hydroxycoumarin in terms of the amount of substance.

5. A chiral heteroleptic nine-coordinated Tb in the chiral heteroleptic nine-coordinated rare earth complex according to claim 1 or 2 3+ Application of enantiomers as luminescent materials.

Images