An ethynyl bisphosphine ligand, its preparation, complexes and their preparation and use

Abstract

The application belongs to the technical field of mononuclear alkynyl bisphosphine halogenated Cu(I) complexes, and particularly relates to an ethynyl bisphosphine ligand and a preparation method thereof, an ethynyl π-coordination or uncoordinated complex and a preparation method and application thereof. Seven mononuclear ethynyl bisphosphine halogenated cuprous complexes are provided. Complexes 1-3 do not coordinate with cuprous in ethynyl, and complexes 4-7 are π-coordinated with cuprous in ethynyl. Complexes 4-5 emit yellow-green delayed fluorescence (λ max = 536-539 nm, τ = 0.43-21.02 μs, Φ PL = 0.08-0.30%), complexes 1-3 and 6-7 emit yellow-green to green-yellow fast fluorescence (λ max = 549-583 nm, τ = 1.7-11.0 ns, Φ PL = 0.16-3.43%). The light emission of complexes 1-7 mainly comes from metal to ligand, halogen to ligand and charge transfer within the ligand. Complex 4 exhibits a certain photocatalytic hydrogen production ability under visible light irradiation.

Description

Technical Field

[0001] This invention belongs to the technical field of mononuclear alkyne-based bisphosphine halide Cu(I) complexes, specifically relating to an acetylenoid-based bisphosphine ligand and its preparation method, acetylenoid π-coordinated or uncoordinated complexes and their preparation methods and applications. Background Technology

[0002] Cuprous complexes have attracted widespread attention due to their excellent luminescent properties, high abundance, and low cost, showing potential to replace precious metal iridium and platinum phosphorescent complexes. Since Ma Yuguang and his collaborators first reported the highly luminescent tetranuclear complex Cu4(C≡Cph)4L2 (L=1,8-bis(diphenylphosphino)-3,6-dioxooctane) as a light-emitting layer material for electroluminescent devices, the door has been opened for using cuprous complexes as OLED assembly materials.

[0003] Compared to phosphorescent (triple-state captured) materials, thermally activated delayed fluorescence (TADF, singlet-state captured) materials have a very small ΔE(S1-T1) value. Under thermal excitation, they can transition from the T1 state to the S1 state through reverse transition (RISC).

[0004] Recently, cuprous halide complexes have been applied as TADF materials in high-efficiency OLEDs. Osawa reported a tricoordinate cuprous halide complex containing a rigid bisphosphine ligand (1,2-bis(o-xylphosphino)benzene) with an EQE of 21.3%, comparable to devices assembled with iridium complexes. The rigid bisphosphine ligand can effectively suppress the Jahn-Teller effect caused by excitation of the cuprous coordination center, thereby reducing non-radiative decay.

[0005] The alkynyl ligand has a linear structure and conjugated π electrons, and can react with the copper center in an η-coupling reaction. 1 (σ bond) and η 2 (π-bond) coordination to form cuprous alkynyl complexes has attracted widespread attention due to its rich structural, luminescent, and catalytic properties. Generally, the alkynyl group is associated with more than two cuprous groups in an η-coupling manner. 1 (σ bond) and / or η 2 (π-bond) coordination forms cuprous alkynyl clusters, cuprous alkynylphosphine and imine clusters, but in binuclear, especially mononuclear, cuprous alkynylphosphine cuprous complexes, the alkynyl group and cuprous group are related by η. 2 (σ-bond) coordination has been rarely reported to date. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an acetylenic bisphosphine ligand and its preparation method, as well as acetylenic π-coordinated or uncoordinated complexes, their preparation methods, and applications. This invention introduces a rigid acetylenic group to construct an acetylenic bisphosphine ligand (L1), and introduces two or four electron-donating methoxy groups into L1 to synthesize two more acetylenic bisphosphine ligands (L2 and L3), resulting in the synthesis of seven mononuclear cuprous complexes, each with its own application.

[0007] An acetylenyl bisphosphine ligand has the following structural formula:

[0008]

[0009] in:

[0010] R1 = H, R2 = H, denoted as ligand L1;

[0011] Alternatively, R1 = OMe, R2 = H, denoted as ligand L2;

[0012] Alternatively, R1 = OMe, R2 = OMe, denoted as ligand L3.

[0013] The structure of the above ligand has a bisphosphine group that can coordinate with Cu(I), and at the same time, it has an acetylene group that can π-coordinate with Cu(I) or not coordinate with it.

[0014] Specifically, the synthetic route for the above-mentioned ethynyl bisphosphine ligand is as follows:

[0015]

[0016] This invention also provides a mononuclear cuprous halide bisphosphine acetylene complex, the structural formula of which is as follows:

[0017]

[0018] in:

[0019] R1 = H, R2 = H, X = I, denoted as coordination compound 1;

[0020] Alternatively, R1 = H, R2 = H, X = Br, denoted as complex 2;

[0021] Alternatively, R1 = H, R2 = H, X = Cl, denoted as coordination compound 3.

[0022] In the aforementioned complexes, the bisphosphine group in the ligand coordinates with Cu(I), while the acetylene group does not coordinate with Cu(I). This invention also provides an acetylene π-coordinated mononuclear cuprous halide bisphosphine complex, the structural formula of which is as follows:

[0023]

[0024] in:

[0025] R1 = OMe, R2 = H, X = I, denoted as complex 4;

[0026] Alternatively, R1 = OMe, R2 = H, X = Br, denoted as complex 5;

[0027] Alternatively, R1 = OMe, R2 = H, X = Cl, denoted as complex 6;

[0028] Alternatively, R1 = OMe, R2 = OMe, X = I, denoted as coordination compound 7.

[0029] In each of the above complexes, the bisphosphine group in the ligand coordinates with Cu(I), and the acetylene group coordinates with Cu(I).

[0030] Specifically, the reaction takes place at room temperature.

[0031] The present invention also provides a method for preparing the above-mentioned complexes, which are obtained by coordination of acetylenic bisphosphine ligands with cuprous halide.

[0032] The specific synthetic route is as follows:

[0033]

[0034] The present invention also provides applications of the above-mentioned complexes 1 to 3 as green-yellow fast fluorescent materials.

[0035] The present invention also provides applications of the above-mentioned complex 4 or 5, specifically:

[0036] R1 = OMe, R2 = H, X = I, and complex 4 serves as a yellow-green delayed fluorescence material;

[0037] Alternatively, R1 = OMe, R2 = H, X = B, and r complex 5 can be used as a yellow-green delayed fluorescence material.

[0038] The present invention also provides applications of the above-mentioned complex 6 or 7, specifically:

[0039] R1 = OMe, R2 = H, X = Cl, and complex 6 is used as a green-yellow fast fluorescent material;

[0040] Alternatively, R1 = OMe, R2 = OMe, X = I, and complex 7 can be used as a green-yellow fast fluorescent material.

[0041] The present invention also provides another application of the above-mentioned complexes 4, where R1 = OMe, R2 = H, and X = I, and complexes 4 are used as photocatalytic hydrogen production materials.

[0042] In general, this invention provides seven mononuclear acetylenic bisphosphine halide cuprous complexes, CuX(L1), CuX(L2), and CuX(L3) [L1 = (2-PPh2-C6H4)2(C≡C), X = I(1), B(2), Cl(3); L2 = (4,5-OMe-2-PPh2-C6H2)C≡C(2-PPh2-C6H4), X = I(4), Br(5), Cl(6); L3 = (4,5-OMe-2-PPh2-C6H2)2(C≡C), X = I(7)]. In complexes 1-3, the acetylenic group is not coordinated with the cuprous group, while in complexes 4-7, the acetylenic group is π-coordinated with the cuprous group. Complexes 4-5 exhibit yellow-green delayed fluorescence (λ). max =536-539nm,τ=0.43-21.02μs,Φ PL =0.08-0.30%), complexes 1-3 and 6-7 exhibit rapid yellow-green to greenish-yellow fluorescence (λ). max =549-583nm,τ=1.7-11.0ns,Φ PL = 0.16-3.43%. The luminescence of complexes 1-7 mainly originates from metal-to-ligand, halogen-to-ligand, and charge transitions within ligands. Complex 4 exhibits a certain photocatalytic hydrogen production capability under visible light irradiation. Attached Figure Description

[0043] Figure 1 This is the ORTEP diagram of coordination compounds 1-7.

[0044] Figure 2 The absorption spectra of (a) ligands L1-L3; (b) L1 and complexes 1-3; (c) L2 and complexes 4-6 and (d) L3 and complex 7 in CH2Cl2 at rt.

[0045] Figure 3 It refers to the shape of the HOMO and LUMO orbital electron clouds after optimizing the S0 configuration in complexes 1-7.

[0046] Figure 4 The emission spectra of complexes 1-7 at room temperature (a, λex = 455 nm for 1, 426 nm for 2, 455 nm for 3, 365 nm for 4-7) and at low temperature (77 K) in solid state (b, λex = 271 nm for 1, 344 nm for 2, 435 nm for 3, 365 nm for 4).

[0047] Figure 5 In the image, (a) is the CIE diagram, and (b) is a photograph of the room temperature powder state of complexes 1-7 (365 nm under UV light).

[0048] Figure 6 It refers to the shape of the HOMO and LUMO orbital electron clouds after optimizing the S1 configuration in complexes 1-7.

[0049] Figure 7 The curves and fitting curves show the temperature-dependent decay lifetime of complex 4.

[0050] Figure 8 These are the TGA curves for complexes 1-7.

[0051] Figure 9 This is a graph showing the photocatalytic H2 production performance of complex 4. The photocatalytic hydrogen production experiment was conducted under simulated sunlight in 15% triethanolamine, 20% methanol, and pure water, with complex 4 as the photocatalyst and 1% Pt as the cocatalyst.

[0052] Figure 10 This describes the photocatalytic hydrogen production performance of complex 4 in different sacrificial reagents. Detailed Implementation

[0053] The principles and features of the present invention are described below. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0054] Instruments and reagents

[0055] Reagents: All reagents were commercially available and of analytical grade. THF solvent was used after being soaked in sodium wire for 24 hours to remove water. 3,4-Dibromofuran was synthesized according to previously reported literature.

[0056] Instrumentation: Infrared spectroscopy was performed using a Perkin Elmet BX FI-IR Fourier transform infrared spectrometer (KBr pellet). 1 H, 13 C and 31 P NMR spectroscopy was performed using a Varian 400MHz NMR spectrometer with deuterium band reagent field locking and reference. Chemical shifts were measured in ppm. H NMR spectroscopy used SiMe4 as the standard, and phosphorus NMR spectroscopy used 85% H3PO4 as the standard. High-resolution mass spectrometry was performed using an HRMS-ESI mass spectrometer. The single-crystal structure of the complex was determined using a Bruker APEX DUO diffractometer. UV-Vis spectroscopy was performed using a Unicam Heλiosα spectrometer, and photoluminescence spectroscopy was performed using an FLS980 steady-state and time-resolved fluorescence spectrometer. Solid-state quantum efficiency was determined using a Hamamatsu system with an integrating sphere. Thermogravimetric analysis was performed using a Perkin-Elmer DiamondTG / DTA thermal analyzer.

[0057] Ligand synthesis

[0058] The ligands (L1-L3) are synthesized according to the following method:

[0059] Under a nitrogen atmosphere and at a low temperature of -90°C, a 2.5 mol / L hexane solution of n-butyllithium was added dropwise (11.12 mL, 27.79 mmol) to 50 mL of a THF solution of 1,2-bis(2-bromophenyl)acetylene (B1), 1-bromo-2-(2-(2-bromo-4,5-dimethoxyphenyl)acetylene (B3). After the addition was complete, the solution was stirred continuously at the same low temperature of -90°C for 50 minutes. Then, 29.05 mmol of dichlorophosphine reagent was added dropwise, and the solution was maintained at -90°C for 2.5 hours. The reaction system was then slowly restored to room temperature. The reaction mixture was extracted with ethyl acetate, and the organic phase was dried over anhydrous sodium sulfate. The solvent was removed by vacuum distillation to obtain a white crude product, which was purified by column chromatography to obtain a white solid.

[0060] L1 (Yield: 4.21g, 61.0%) 1 H NMR (500MHz, CDCl3), δ=7.35~7.28(m, 20H), 7.20~7.08(m, 6H), 6.76~6.72(m, 2H). 13 C NMR (100MHz, CDCl3), δ =140.16,140.04,136.59,136.47,133.97,132.56,132.24,128.69,128.51,128.47,128.18,128.09,127.98,127.68,95.12. 31 P NMR (160MHz, CDCl3), δ = 9.07.Anal.Calcd for C 38 H 28 P2:C,83.50;H,5.16,found:C,83.52;H,5.15. HRMS(ESI):m / z calcd for[C 38 H 28 P2] + ,546.1666,found:546.1638.

[0061] L2 (Yield: 4.93g, 64.3%) 1 H NMR (400MHz, CDCl3), δ=7.36~7.27(m, 20H), 7.22~7.10(m, 3H), 6.72~6.70(m, 1H), 6.545(d, J=4Hz, 1H), 6.23(d, J=4Hz,1H),3.78(s,3H),3.49(s,3H).13 13C NMR (100 MHz, CDCl3), δ = 149.15, 148.91, 137.21, 134.16, 133.96, 133.91, 133.71, 133.17, 128.67, 128.61, 128.51, 128.44, 128.38, 128.12, 127.97, 95.51, 93.47, 56.05, 55.45. 31 31P NMR (160 MHz, CDCl3), δ = 8.54 (d, J = 1.6 Hz, 1P), 9.33 (d, J = 3.2 Hz, 1P). Anal. Calcd for C 40 H 32 O2P2: C, 79.20; H, 5.32, found: C, 79.21; H, 5.31. HRMS (m / z): calcd for [C 40 H 32 O2P2] + , 606.1878, found: 606.1859.

[0062] L3 (Yield: 5.73 g, 68.1%): 1 1H NMR (400 MHz, CDCl3), δ = 7.36 ~ 7.27 (m, 20H), 6.58 (d, J = 4 Hz, 2H), 6.19 (d, J = 4 Hz, 2H), 3.78 (s, 6H, OMe), 3.49 (s, 6H, OMe). 13 13C NMR (100 MHz, CDCl3), δ = 148.96, 148.88, 137.13, 133.89, 133.69, 128.57, 128.41, 128.34, 121.08, 120.78, 115.06, 114.82, 114.77, 93.76, 55.99, 55.39. 31 31P NMR (160 MHz, CDCl3), δ = 8.79 (s). Anal. Calcd for C 42 H 36 O4P2: C, 75.67; H, 5.44, found: C, 75.68; H, 5.42. HRMS (m / z): calcd for [C 42 H 36 O4P2] + , 666.2089, found: 666.2074.

[0063] Synthesis of Complexes 1 - 7

[0064] At room temperature, cuprous halide (0.66 mmol) was added to 30 mL of dichloromethane solution containing ligands (L1-L3) (0.66 mmol). The mixture was stirred in the dark for 4 hours, filtered, and the filtrate was collected and evaporated to dryness to obtain a white solid powder. The powder was then recrystallized from dichloromethane and methanol or ethyl acetate to obtain colorless crystals 1 and 5, and the remainder were yellow crystals.

[0065] Complex 1 (Yield: 0.38 g, 78.0%). 1 H NMR (500MHz, CDCl3), δ= 7.81-7.76(m,2H), 7.48-7.42(m,12H), 7.38-7.30(m,7H), 7.24-7.21(m,5H), 7.18-7.14(m,2H). 31 P NMR(160MHz,CDCl3),δ=-7.56(s).Anal.Calcd for C 38 H 28 CuIP2:C,61.93;H,3.83,found:C,61.95;H,3.82.HRMS(m / z):calcd for [C 38 H 28 P2Cu] + ,609.0962,found:609.0962.

[0066] Complex 2 (Yield: 0.37 g, 80.4%). 1 H NMR (500MHz, CDCl3), δ= 7.76-7.70(m,1H),7.65-7.60(m,1H),7.50-7.40(m,11H),7.35-7.28(m,7H), 7.24-7.19(m,6H),7.15~7.11(m,2H). 31 P NMR (160MHz, CDCl3), δ = -7.62 (s).Anal.Calcd for C 38 H 28 CuBrP2:C,66.14;H,4.09,found:C,66.12;H,4.07. HRMS(m / z):calcd for[C 38 H 28 P2Cu] + ,609.0962,found:609.0965.

[0067] Complex 3 (Yield: 0.35 g, 82.3%). 11H NMR (400 MHz, CDCl3), δ = 7.77 (d, J = 4 Hz, 2H), 7.47 - 7.40 (m, 11H), 7.35 - 7.28 (m, 7H), 7.25 - 7.21 (m, 6H), 7.15 - 7.11 (m, 2H). 31 31P NMR (160 MHz, CDCl3), δ = -7.85 (s). Anal. Calcd for C 38 H 28 CuClP2: C, 70.70; H, 4.37, found: C, 70.72; H, 4.38. HRMS (m / z): calcd for [C 38 H 28 P2Cu] + , 609.0962, found: 609.0928.

[0068] Complex 4 (Yield: 0.45 g, 85.3%). 1 1H NMR (400 MHz, CDCl3), δ = 7.83 - 7.72 (m, 1H), 7.53 - 7.46 (m, 4H), 7.45 - 7.27 (m, 13H), 7.25~7.18 (m, 6H), 7.15 - 7.10 (m, 1H), 6.54 (t, J = 4 Hz, 1H), 3.93 (s, 3H), 3.59 (s, 3H). 31 31P NMR (160 MHz, CDCl3), δ = 7.​​​​​​​​​​​​​​​​31P NMR (160 MHz, CDCl3), δ = 7.74 (s). Anal. Calcd for C 40 H 32 CuBrO2P2: C, 64.05; H, 4.30, found: C, 60.06; H, 4.32. HRMS (m / z): calcd for [C 40 H 32 CuO2P2] + , 669.1174, found: 669.1158.

[0070] Complex 6 (Yield: 0.41 g, 87.8%). 1 1H NMR (400 MHz, CDCl3), δ = 7.79 (d, J = 8 Hz, 1H), 7.52 - 7.45 (m, 5H), 7.43 - 7.28 (m, 12H), 7.25 - 7.18 (m, 6H), 7.12 - 7.08 (m, 1H), 6.53 (t, J = 4 Hz, 1H), 3.93 (s, 3H), 3.58 (s, 3H). 31 31P NMR (160 MHz, CDCl3), δ = 7.92 (s). Anal. Calcd for C 40 H 32 CuClO2P2: C, 68.09; H, 4.57, found: C, 68.11; H, 4.56. HRMS (m / z): calcd for [C 40 H 32 CuO2P2] + , 669.1174, found: 669.1163.

[0071] Complex 7 (Yield: 0.48 g, 85.0%). 1 1H NMR (400 MHz, CDCl3), δ = 7.48 - 7.44 (m, 8H), 7.33 (t, J = 4 Hz, 4H), 7.24 (t, J = 4 Hz, 10H), 6.53 (t, J = 4 Hz, 2H), 3.91 (s, 6H), 3.58 (s, 6H). 31 31P NMR (160 MHz, CDCl3), δ = 7.74 (s). HRMS (m / z): calcd for [C 42 H 36 CuO4P2] + , 729.1385, found: 729.1361.

[0072] Synthesis and Characterization

[0073] The synthetic routes for ligands L1-L3 and complexes 1-7 are as follows:

[0074]

[0075] First, B1-B3 reacted with n-butyllithium at a molar ratio of 1:2 in anhydrous THF solution at -90°C under a nitrogen atmosphere, followed by further reaction with diphenylphosphine chloride to yield ligands L1-L3 in yields of 61.0-68.1%. Ligands L1-L3 reacted with CuX at a molar ratio of 1:1 in CH2Cl2 to give cuprous halide complexes 1-7 in yields of 78.0-87.8%. These complexes were stable in air and soluble in common organic solvents such as acetonitrile and chloroform. The structures of the complexes were confirmed by nuclear magnetic resonance, high-resolution mass spectrometry, and single-crystal X-ray diffraction.

[0076] Table 1. Crystal data for complexes 1-7.

[0077]

[0078]

[0079]

[0080]

[0081]

[0082] Table 2. Partial bond lengths of coordination compounds 1-7 Bond angle (°)

[0083]

[0084] Table 3. Dihedral angles between the Cu-XP plane and the plane of the benzene ring attached to the acetylene group in complexes 1-7

[0085]

[0086] The single-crystal structures of complexes 1-3 show that the mononuclear copper (I) center forms a planar tricoordinate configuration with one halogen and two phosphorus atoms, with a sum of angles of 359.91-359.96°. The introduction of the acetylenic group into 2,2'-di(diphenylphosphine) results in an unusual mononuclear tricoordinate structure. This is because 2,2'-di(diphenylphosphine) forms a halogen-bridged dinuclear cuprous complex, possibly due to the steric hindrance of the acetylenic group leading to instability of the Cu2X2 structural unit. In the structures of complexes 4-7, the mononuclear cuprous center coordinates with one halogen, two phosphorus atoms, and an acetylenic group coordinated in a π-coordinate mode (e.g., ...). Figure 1As shown in Tables 1 and 2, it is shown that the introduction of the electron-donating methoxy group is beneficial to the coordination of the ethynyl group with copper(I). In complexes 4 - 7, the sum of the angles centered on copper(I) is 406.12 - 409.71°, and for the halogen, the two P atoms and the copper(I) center are almost in the same plane, with the sum of the angles being 357.86 - 359.18°. As the radius of the halogen increases, the bond length of Cu - X increases (1 > 2 > 3 and 4 > 5 > 6). For the same halogen, the bond length order of Cu - X is 4 > 1, 5 > 2, and 6 > 3, indicating that the Cu - X bond in 1 - 3 has a stronger coordination ability than that in 4 - 6. The bond lengths of Cu - X (2.2370(6) - 2.5421(4) ) and Cu - P (2.2311(8) - 2.2558(5) ) in 1 - 3 are smaller than those in the binuclear halogen-bridged complexes of 2,2'-bis(diphenylphosphino)biphenyl (Cu - X: 2.3757(9) - 2.7229(11) Cu - P: 2.2598(10) - 2.292(3) ), which indicates that the introduction of the ethynyl group enhances the coordination ability of the tricoordinate copper(I) halide complexes. The introduction of the electron-rich ethynyl group can increase the conjugation of the whole molecule and the electron density of the P atom, making it easier for the P atom to coordinate with copper(I). In complexes 4 - 7, the distance between copper(I) and the triple-bond carbon is 2.515(2) - 2.619(2) within the range of the Cu - C bond lengths of the copper(I) alkynyl cluster compounds in the prior art (1.986(5) - 2.632(4) ). The bond length order of C≡C in 1 - 6 is 1 > 2 > 3, 4 > 5 > 6, which is opposite to the electronegativity order of the halogens (I < Br < Cl). The C - C≡C bond angles in 1 - 3 are 172.4(3) - 178.2(2)°, similar to those in complexes 4 - 7 (172.4(3) - 176.6(3)°), close to linear, and very different from the C - C≡C bond angle (160.7(4)°) of the ethynyl group connected to copper(I) by a σ bond in the prior art, far deviating from linearity. The dihedral angles between the Cu - X - P plane and the benzene ring plane connected to the ethynyl group in complexes 1 - 7 are shown in Table 3. The dihedral angles in complexes 4 and 5 (72.33 - 75.43°) are smaller than those in 1 - 3 and 6 - 7 (80.85 - 84.38°), and the latter are close to the perpendicular angle.

[0087] Photophysics and theoretical calculations

[0088] Figure 2These are the UV absorption spectra of complexes 1-7 and their ligands L1-L3 in CH2Cl2 solution at room temperature. Ligands L1-L3 exhibit strong absorption peaks in the 273-280 nm range, with two broad peaks at 308-333 nm and 330-345 nm, attributed to the π-π* and n-π* transitions of ethynylphenylphosphine. Compared to the maximum absorption peak (272 nm) of 2,2'-bis(diphenylphosphine biphenyl), the absorption band of L1 is red-shifted by 1 nm, while L2 and L3 are red-shifted by 4-7 nm compared to L1, indicating that the introduction of the ethynyl group and two or four methoxy groups increases the overall conjugation of the molecule. Complexes 1-3 exhibit strong absorption at 273-278 nm, a broad peak at 317-319 nm, and a tail band at 390-420 nm. Complexes 4-6 show strong absorption at 254-258 nm, two broad peaks at 310-315 nm and 331-333 nm, and a tail band at 387-415 nm, with a weak absorption tail band appearing at 330-360 nm. Complex 7 shows strong absorption at 280 nm, two broad peaks at 327 and 347 nm, and a tail band (381-400 nm). TDDFT calculations indicate that this weak absorption tail band can be attributed to charge transitions from copper to ligands, halogens to ligands, and charge transitions within the ligand (e.g., ...). Figure 3 (As shown). In contrast to complexes 1-3, two or four electron-donating methoxy groups can raise the LUMO level, which leads to a blue shift in the absorption tail bands of 4-7.

[0089] Table 4. Photophysical data of complexes 1-7 in powder form.

[0090]

[0091] a Maximum emission peak wavelength. * indicates that the emission peak is a shoulder peak or a weak peak.

[0092] b Average luminous lifetime.

[0093] c Absolute quantum efficiency.

[0094] d TDDFT calculations yielded the energy (S1 and T1 energy levels, and the energy difference between S1 and T1) from adiabatic excitation.

[0095] e The emission wavelength obtained by TDDFT optimization of the S1 configuration

[0096] like Figure 4 As shown, complexes 1-3 exhibit a greenish-yellow luminescence (λ) in their room-temperature powder state. max =572-583nm, Φ PL = 0.0284-0.0343), complexes 4-7 emit yellowish-green to yellow light (λ).max =536-572nm, Φ PL = 0.0008-0.003). Comparing the luminescence of existing diphosphine halide cuprous complexes and complexes 4-7, complexes 1-3 were found to have additional strong and broad emission bands (753 nm for 1, 694 nm for 2, 685 nm for 3), possibly due to the introduction of the acetylene group without coordination with the cuprous group. The chromaticity coordinates of complexes 1-7 are (0.465, 0.503), (0.445, 0.488), (0.466, 0.504), (0.410, 0.552), (0.371, 0.463), (0.470, 0.495), and (0.430, 0.538), respectively. Figure 5 Compared to complexes 1 and 2, the emission peaks of complexes 4 and 5 showed a blue shift of 41-47 nm, attributed to the introduction of two electron-donating methoxy groups, which raised the LUMO energy level. Based on TDDFT calculations, the emission wavelengths of complexes 1-7 were close to experimental values. The luminescence of complexes 1-7 mainly originated from the LUMO→HOMO transition. The HOMO electrons are mainly distributed on Cu, X, and two P atoms, while the LUMO electrons are mainly distributed on acetylene and the two benzene rings attached to it (e.g., ...). Figure 6 (As shown). Therefore, the luminescence of complexes 1-7 mainly originates from MLCT, XLCT, and ILCT.

[0097] like Figure 4 As shown, the maximum emission wavelength of complexes 1-7 at 77 K is 498-552 nm. Compared to 298 K, the emission wavelength is blue-shifted, which is due to the suppression of energy release caused by vibration and rotation in the excited state at low temperature. At room temperature, the lifetimes of complexes 1-3 and 6-7 are 1.7–11.0 ns, indicating that complexes 1-3 and 6-7 emit fast fluorescence at room temperature, while the lifetimes of complexes 4 and 5 are 0.43–21.02 μs, indicating delayed fluorescence. The room temperature lifetimes of 4 and 5 are 1–3 orders of magnitude shorter than the lifetimes at 77 K (743–1677 μs), indicating the existence of different emission and thermal activation processes through interconversion. The ΔE of complexes 4-5 was calculated using TDDFT. adiThe ΔE(S1-T1) is 0.0867-0.1766 eV, much smaller than that of complexes 6-7 (0.2028-0.3040 eV). Therefore, complexes 4 and 5 exhibit thermally activated delayed fluorescence. Furthermore, the dihedral angle (72.33-75.43°) between the Cu-XP plane and the plane of the benzene ring attached to the ethynyl group in complexes 4-5 is smaller than that in complexes 1-3 and 6-7 (80.85-84.38°). Generally, ΔE(S1-T1) depends on the exchange integrals of S1 and T1, or the exchange integrals of HOMO and LUMO. The smaller the overlap between HOMO and LUMO, the smaller the mixing of S1 and T1, and the smaller the value of ΔE(S1-T1). The calculated radiative rate constant k of complexes 4-5 is... r It is 1.43-1.86×10 2 s -1 It is 2-3 orders of magnitude smaller than existing bisphosphine halide cuprous complexes.

[0098] To confirm the existence of TADF, complex 4 was selected as a representative, and its decay lifetime at different temperatures (77K-298K) was tested. The following equation (1) illustrates the relationship between lifetime and temperature, assuming that S1 and T1 are in thermal equilibrium:

[0099]

[0100] (K B Boltzmann constant; T: absolute temperature; τ(S1): lifetime of state S1; τ(T1): lifetime of state T1; ΔE ST The energy level difference between S1 and T1 is used to fit the lifetimes to the curves, resulting in lifetimes of S1 (0.2708 μs) and T1 (740.2 μs). This yields ΔE. ST (0.0741 eV). Therefore, the lifetime τ = 21.02 μs at 298 K represents delayed fluorescence. The fitted (T1) is 740.2 μs, close to the actual measured lifetime value of 743 μs at 77 K, and the fitted ΔE ST The value (0.0741 eV) is also close to the calculated value (0.0867 eV) (Figure 7, Table 3). Complex 4 mainly emits phosphorescence at 77 K. As the temperature increases, phosphorescence emission (T1) decreases, while TADF increases.

[0101] The optimized S0, S1, and T1 configurations of coordination compounds 1-7 were obtained through TDDFT calculations, as shown below. Figure 6As shown, in the S1 configuration, compared to complexes 1-3, the P-Cu-C≡ and ≡C-Cu-C≡ bond angles and Cu-C≡ bond lengths in complexes 4-7 undergo significant changes, leading to a larger Jahn-Teller effect in the excited state, and thus resulting in lower luminescence efficiency in complexes 4-7. Since there is no coordinate bond between the alkynyl group and cuprous oxide in 1-3, the Cu-C≡ bond length changes in the S0 and S1 configurations (…). for 1, for2, for 3) less than 4-7 ( for 4, for 5, for 6, (for 7). Compared with existing 2,2'-bis(diphenylphosphino)biphenyl-bridged halogen binuclear cuprous complexes (Φ<0.01%), complexes 1-3 exhibit higher quantum efficiency because the tricoordinate configuration reduces the Jahn-Teller effect.

[0102] thermal properties

[0103] The initial decomposition temperatures of complexes 1-7 under nitrogen atmosphere were determined by thermogravimetric analysis (TGA). The initial decomposition temperatures of complexes 1-3 were 368-379℃, and those of complexes 4-7 were 242-270℃. Figure 8 As shown in the figure, they exhibit good thermal stability. Complex 4-7 decomposes more readily than 1-3, attributed to the longer Cu-X and Cu-P bond lengths in complex 4-7. Complex 1-3 loses approximately 53-69% of its weight between 476 and 486 °C, complex 4-6 loses 53-57% of its weight between 487 and 499 °C, and complex 7 loses 53% of its weight at 522 °C, corresponding to the loss of halogens and ligands L1-L3.

[0104] Photocatalytic properties

[0105] Using complex 4 as a photocatalyst, experiments were conducted on the photocatalytic production of H2. Methanol and triethanolamine served as sacrificial electron donors, acting as electron sources in the water reduction half-reaction. Figure 9 As shown, when 15% triethanolamine or 20% methanol is used as the sacrificial reagent, the hydrogen production rates of complex 4 are 74.4 and 372.0 μmol h⁻¹, respectively. -1 g -1 However, without the sacrificial reagent, only trace amounts of hydrogen were observed in pure water with complex 4. The total hydrogen production over 3 hours using methanol and triethanolamine was 222 μmol g, respectively. -1 and 1115 μmol g -1 ( Figure 10This indicates that complex 4 exhibits photocatalytic hydrogen production activity under simulated sunlight irradiation.

[0106] This invention discloses for the first time seven mononuclear alkynyl phosphine halide cuprous complexes, their molecular structures, and applications. The introduction of the acetylenic group into 2,2'-bis(diphenylphosphino)biphenyl results in an unusual three-coordinate structure, providing a novel method for synthesizing three-coordinate cuprous halides. The introduction of the electron-donating methoxy group facilitates the π-coordinate of acetylenic group based on cuprous halides. This π-coordinate mode is commonly found in polynuclear cuprous alkynyl bisphosphine clusters and rarely in mononuclear alkynyl bisphosphine cuprous complexes. The smaller dihedral angle between the Cu-XP plane and the acetylenic group-connected benzene ring plane in complexes 4 and 5 leads to less overlap between the HOMO and LUMO and a smaller ΔE(S1-T1) value, resulting in delayed fluorescence emission in complexes 4 and 5. Complexes 1-3 exhibit higher luminescence efficiency than 4-7, attributed to the three-coordinate planar configuration of cuprous halides in complexes 1-3. This reduces the Jahn-Teller effect after excitation. Furthermore, complex 4 exhibits catalytic hydrogen production capability under visible light irradiation. Alkyne-phosphine halide cuprous complexes, as a class of abundant and low-cost luminescent materials and potential photosensitizers and photocatalytic hydrogen production agents, have great potential applications.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A mononuclear cuprous halide bisphosphine ethyne complex characterized by, The structural formula is as follows: Wherein: R1=H, R2=H, X=Br; Or, R1=H, R2=H, X=Cl.

2. An ethyne π-coordinated mononuclear copper halide bisphosphine complex characterized by, The structural formula is as follows: Wherein: R1=OMe, R2=H, X=I; Or, R1=OMe, R2=H, X=Br; Or, R1=OMe, R2=H, X=Cl; Or, R1=OMe, R2=OMe, X=I.

3. A process for the preparation of a complex according to claim 1 or 2, characterized in that, Comprise the following steps: Obtained by corresponding acetylene group bisphosphine ligand and corresponding cuprous halide coordination.

4. Use of a complex according to claim 1, characterized in that: As a green yellow fast fluorescent material.

5. The application of the complex according to claim 2, characterized in that: R1=OMe, R2=H, X=I, the complex is used as a yellow-green delayed fluorescent material Or, R1=OMe, R2=H, X=Br, the complex is used as a yellow-green delayed fluorescent material.

6. The application of the complex according to claim 2, characterized in that: R1=OMe, R2=H, X=Cl, the complex is used as a green yellow fast fluorescent material; Or, R1=OMe, R2=OMe, X=I, the complex is used as a green yellow fast fluorescent material.

7. Use of a complex according to claim 2, characterized in that: R1=OMe, R2=H, X=I, the complex is used as a photocatalytic hydrogen production material.

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