CN106431968A - Platinum complex organic light-emitting material and application thereof - Google Patents

Abstract

The invention relates to synthesis and characteristic determination of a novel Schiff base ligand and platinum complex, and belongs to the coordination chemistry field of inorganic chemistry, wherein the phosphorescence emission can be achieved effectively. According to the novel Schiff base ligand and platinum complex light-emitting material, the maximum ultraviolet absorption wavelength of the platinum complex is 487 nm, the maximum phosphorescence emission wavelength is 618 nm, and the decomposition temperature is 295 DEG C. The novel complex is convenient to synthesize, high in thermostability and not prone to decomposition under high temperature and can be prepared through a simple instrument.

Description

A kind of organic luminescent material of platinum complex and its application

technical field

The invention relates to an organic luminescent material, in particular to a yellow light luminescent material of a Schiff base platinum complex.

Background technique

The research on OLEDs began in the 1960s. In 1963, Professor Pope of New York University first discovered the electroluminescence phenomenon of organic material single crystal anthracene. In 1987, Tang of Kodak Company in the United States used ultra-thin film technology and a new device structure to make an organic electroluminescent device with low operating voltage and high luminous brightness, which fundamentally changed the research on organic electroluminescent materials. Subsequently, in 1990, Professor Burroughes and Professor Friend of the Cavendish Laboratory of the University of Cambridge in the United Kingdom used polystyrene (PPV) as a light-emitting material to make a polymer electroluminescent device, which opened up a polymer thin film electroluminescent device. device field. In 1997, Professor Forrest of Princeton University in the United States discovered the phenomenon of electrophosphorescence. The electrophosphorescent (Phosphorescent Organic Light-emitting Devices, PHOLEDs) technology reported by Professor Forrest broke through the limit of the quantum efficiency of organic electroluminescent materials below 25%. According to the spin statistics theory of quantum mechanics, the probability of forming singlet excitons and triplet excitons is 25% and 75%, respectively. Due to the spin-forbidden effect, in general, the phosphorescence emission of the triplet state is very weak and difficult to measure. However, in phosphorescent materials, due to the introduction of heavy metal atoms (Ir, Pt, Os, Au, Cu) in the complex, the coupling of spin and orbit is improved, the lifetime of phosphorescence is shortened, and the original triplet state has The characteristics of some singlet states enhance the ability of intersystem crossing, leading to the local transition from the forbidden triplet state to the ground state, so that the phosphorescence can be emitted smoothly. In principle, phosphorescent materials can use all the recombination energy of electrons and holes to emit light, and the internal quantum efficiency of the device can reach 100%, so it has attracted widespread attention.

In recent years, platinum complexes have attracted the research interests of optoelectronic scientists as phosphorescent materials. For example, our research group reported a series of Schiff base platinum complexes in "J.Mater.Chem." These complexes have bulky substituents (such as tert-butyl, triphenylamine, etc.), which can effectively reduce the platinum coordination The aggregation between the molecules or the formation of excimer dimers slows down the roll-off of the device efficiency with the current, thereby greatly improving the device efficiency.

OLEDs light-emitting materials are mainly divided into two categories: small molecular compounds and high molecular polymers. Small molecule metal complexes are easy to purify, have high luminous efficiency, good stability, and can be formed into films by vacuum evaporation. They are considered to be the most promising type of luminescent materials. Due to the unbonded lone pair of electrons on the heteroatom, the Schiff base ligand can undergo a complexation reaction with the empty orbital of the metal compound to form a stable complex. Such complexes have good luminous efficiency and thermal stability, but OLEDs using these complexes as light-emitting materials are rarely reported.

Contents of the invention

1. The purpose of the present invention is to provide a preparation method and application of a platinum complex luminescent material. The material can emit yellow light and can be used as a luminescent material in the field of photoelectric materials. The material prepared by the invention has good thermal stability and optical properties, and the preparation method adopted is simple to operate and has mild reaction conditions.

The invention provides a platinum complex luminescent material, the structural formula of which is:

2. The platinum complex luminescent material provided by the invention comprises the following synthesis steps:

1) Preparation of ligand HL by condensation of aniline and 3,5-di-tert-butyl salicylaldehyde

2) Reaction of Schiff base ligand HL and K ₂ PtCl ₄ to synthesize platinum complex Pt2L

3. The Schiff base platinum complex luminescent material containing tert-butyl group provided by the present invention has the following photophysical properties:

1) The maximum ultraviolet absorption and fluorescence emission wavelengths in chloroform are 487nm and 618nm respectively;

2) The thermal decomposition temperature is 295°C;

3) With the saturated Ag/Ag+ electrode as the reference electrode, the redox (CV) curve of the material was tested, and the obtained initial oxidation potential was +0.78V, which was calculated by the empirical formula [HOMO=-(Eox+4.71)]eV The energy level of the highest occupied orbital (HOMO) of the material is -5.49eV, and the energy level of the lowest empty orbital (LUMO) is calculated by the formula [LUMO=HOMO+Eg] to be -3.12eV, where the energy band gap [Eg=1240/ λmax], the Ag/Ag ⁺ electrode potential is 4.71V.

4. The luminescent material of the present invention can be applied in the preparation of organic photoelectric displays.

5. The Schiff base platinum complex luminescent material obtained in the present invention is a yellow light material, which has good thermal stability and photophysical properties. The material can be used as a photoelectric material in the display field. The adopted preparation method has simple reaction operation and mild conditions.

Description of drawings

Fig. 1 is a phosphorescence emission diagram of Pt2L of the present invention.

Fig. 2 is an ultraviolet-visible absorption diagram of Pt2L of the present invention.

Fig. 3 is the thermogravimetric analysis diagram of Pt2L of the present invention.

Fig. 4 is a cyclic voltammogram of Pt2L of the present invention.

detailed description

Implementation column 1

1) Take aniline (307mg, 3.27mmol) and 3,5-di-tert-butyl salicylaldehyde (756mg, 3.23mmol), place in a 50ml round bottom flask, add 15ml of dehydrated ethanol, magnetically stir, at 75 degrees Celsius Reflux for about 6 hours, cool in a refrigerator until a large amount of orange-yellow solid precipitates, and filter under reduced pressure. Wash with 95% ethanol for 2-3 times and dry in a drying oven. The product is an orange-yellow powder, weighing 0.504 g, and the yield is 50.3%. ¹ HMMR(CDCl ₃ 400MHZ)δ13.69(s, 1H, OH), 8.64(s, 1H, HC=N), 7.47-7.38(m, 4H, Ar-H), 7.28(d, J=7.5Hz , 2H, Ar-H), 7.22 (d, J=2.4Hz, 1H, Ar-H), 1.48 (s, 9H, CH ₃ ), 1.33 (s, 9H, CH ₃ ).IR: 3427, 3180, 2860, 2555, 2483, 2328, 1614, 1575, 1361, 1247, 1170, 972, 866, 759. C ₂₁ H ₂₇ NO (309.4452): calcd. C 81.51, H 8.79, N4.53; found C 81.66, H 8.64, N4.54.

2) Take the dried Schiff base ligand (209mg, 0.67mmol) and place it in a 50ml round bottom flask, add 5ml of DMF to dissolve it, then add dry sodium hydroxide (28mg, 0.70mmol); at the same time, weigh K2PtCl4 (148mg, 0.36mmol), and heated to dissolve with 3mlDMSO and then added to the reaction flask. After reacting in an oxygen-free and water-free environment for 24 hours, it was found by TLC that the raw materials basically disappeared and new products were formed, so the reaction was stopped. After the device is completely cooled, build a vacuum distillation device on the original flask, distill out the solvents DMF and DMSO, stop heating, after the device cools down, add 30ml of chloroform to dissolve the solid in the bottle, wash it with a separatory funnel about 5 times, and use it every time 50ml deionized water for washing. The organic solvent in the lower layer after washing was evaporated to dryness with a rotary evaporator. Finally, the impurity and product were separated by a chromatographic column, recrystallized and centrifuged, and then dried to obtain 105 mg of a red crystal product with a yield of 38.6%. ¹ HMMR(CDCl ₃ 400MHZ)δ8.20(s, 2H, HC=N), 7.63(d, J=2.5Hz, 4H, Ar-H), 7.56(d, J=2.4Hz, 8H, Ar-H ), 7.10(d, J=2.5Hz, 1H, Ar-H), 7.01(d, J=2.5Hz, 1H, Ar-H), 1.26(d, J=18.1Hz, 36H, CH ₃ ).IR : 2956, 2904, 2868, 2079, 1614, 1577, 1523, 1458, 1431, 1359, 1255, 1172, 803, 701. HRMS (MALDI-TOF, positive mode, DCTB): m/z=811.3695[M] ⁺ (C ₄₂ H ₅₂ N ₂ O ₂ Pt: calcd.811.3675, Δ _m =2.49ppm).C ₄₂ H ₅₂ N ₂ O ₂ Pt (811.9585): calcd.C 62.13, H 6.46, N3.45; found C 62.20 , H 6.41, N 3.40.

Implementation column 2

Accurately weigh 10 mg Schiff base platinum complex and dissolve it in chloroform to obtain a 1.0×10 ^-5 M solution. Accurately pipette 3.0 ml of the above solution and add it to a cuvette, then measure it on a FLS980 fluorescence instrument. Both the slit and emission slit width are 10nm, and the excitation wavelength is 487nm. The ultraviolet absorption spectrum was measured on a Shimadzu UV-2450 UV/Vis ultraviolet-visible absorption instrument. The tests were performed at room temperature and outside atmospheric pressure. The normalized results of the emission and absorption test spectra are shown in Figure 1 and Figure 2. It can be known from Fig. 2 that the maximum ultraviolet absorption wavelength is 48nm, and the maximum phosphorescence emission wavelength is 618nm.

Implementation column 3

Under the protection of nitrogen, the thermogravimetric analysis (TGA) of the material was carried out with TA Instruments SDTQ600 instrument, and the decomposition temperature was 295° C., and the heating rate was 10° C./min. The measurement results are shown in Figure 3.

Implementation column 4

Accurately weigh 10 mg Schiff base platinum complex and dissolve in chloroform to prepare a 1.0×10 ^-4 M solution. Accurately take 4.0ml of the solution and add it to a 10.0ml beaker, test the cyclic voltammetry curve of the compound in the AUTOLAB three-electrode system, the reference electrode is a saturated calomel electrode, and the supporting electrolyte is 0.1mol/l tetrabutylammonium hexafluorophosphate , the scanning speed at room temperature is 50mv/s, and the measurement results are shown in Figure 4.

The specific embodiments described in the present invention are only to illustrate the spirit of the present invention. Those skilled in the art to which the present invention belongs can make various modifications or supplements to the described specific embodiments or adopt similar methods to replace them, but they will not deviate from the spirit of the present invention or go beyond the definition of the appended claims range.

Claims (5)

1. A platinum complex yellow light luminescent material, characterized in that the structural formula is: 2. The preparation method of platinum complex yellow light luminescent material as claimed in claim 1, is characterized in that, comprises the steps: 1) Prepare the Schiff base ligand HL by condensation of aniline and 3,5-di-tert-butyl salicylaldehyde; 2) Reaction of Schiff base ligand HL and K ₂ PtCl ₄ to synthesize platinum complex Pt2L. 3. according to the preparation method of the organic luminescent material of a kind of platinum complex according to claim 2, it is characterized in that: the part described in step 1) is Schiff base ligand, uses aniline and 3,5-di-tert-butyl Salicylaldehyde is prepared in a molar ratio of 1-1.25:1. 4. The organic luminescent material of a platinum complex according to claim 2, characterized in that: the complex described in step 2) is a Schiff base platinum complex, using a Schiff base ligand and K ₂ PtCl ₄ Prepared with a molar ratio of 2:1-1.25. 5. The application of the yellow luminescent material according to claim 1, characterized in that: the luminescent material can be applied in organic photoelectric displays.