A room temperature phosphorescent material of phenylacetylene node-substituted pyrene derivative and a preparation method thereof

Abstract

The application discloses a room-temperature phosphorescent material of a phenylacetylene node-substituted pyrene derivative and a preparation method thereof. The pyrene is used as a substrate, and phenylacetylene is selectively substituted at a node (2 position) of the pyrene. Compared with a pyrene derivative obtained by substituting phenylacetylene at an anti-node (1 position) of the pyrene, the pyrene derivative obtained by substituting phenylacetylene at the node destroys the conjugation of the substitution site, maintains the rotation freedom between the substituent and the pyrene core, thereby enhancing the spin-orbital coupling, and enabling the room-temperature phosphorescence of the pyrene derivative. The obtained room-temperature phosphorescent material has the advantages of high luminous efficiency and long lifetime.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic room-temperature phosphorescent materials, and particularly relates to a room-temperature phosphorescent material of a phenylacetylene node-substituted pyrene derivative and a preparation method thereof. BACKGROUND

[0002] In recent years, due to the unique photophysical phenomenon of room-temperature phosphorescence and its potential application in the fields of information encryption, organic light-emitting diodes, chemical sensing, biosensors, biological imaging, etc., the design and research of room-temperature phosphorescence systems have attracted widespread attention. However, due to the presence of noble metals such as iridium and platinum, the traditional phosphorescent materials greatly increase the production cost while improving the performance of the devices, which is not conducive to their application and promotion.

[0003] Under normal circumstances, for pure organic compounds, due to some inherent shortcomings, such as thermal disturbance, intramolecular motion, collision quenching with oxygen or solvent molecules, etc., the long-lived triplet state is easily returned to the ground state through non-radiative transition; in addition, the electrons in pure organic compounds are tightly bound, which is not conducive to the conversion of the excited singlet state into the excited triplet state, so phosphorescence is usually rare in pure organic compounds. Moreover, even if pure organic compounds can have room-temperature phosphorescence characteristics, their luminescent efficiency is generally low, and they are limited to the range of photoluminescence emission, which limits their further application. SUMMARY

[0004] Based on the above technical problems, the application discloses a room-temperature phosphorescent material of a phenylacetylene node-substituted pyrene derivative and a preparation method thereof. By selecting pyrene as a substrate and selectively substituting phenylacetylene at the node (2 position) thereof, the obtained pyrene derivative breaks the conjugation at the substitution site and maintains the rotational freedom between the substituent and the pyrene core, thereby enhancing the spin-orbital coupling and enabling room-temperature phosphorescence of the pyrene derivative. The obtained room-temperature phosphorescent material has the advantages of high luminescent efficiency and long lifetime.

[0005] The room-temperature phosphorescent material of the phenylacetylene node-substituted pyrene derivative according to the application has the general structure shown in the following structural formula I:

[0006]

[0007] R is one or more, independently selected from hydrogen, an electron-donating group or an electron-withdrawing group.

[0008] Preferably, R is hydrogen, C1-6alkoxy or cyano.

[0009] Preferably, the room-temperature phosphorescent material has the structure shown in one of the following structural formulas:

[0010] 、 、 .

[0011] The application further provides a preparation method of the room-temperature phosphorescent material of the phenylacetylene node-substituted pyrene derivative.

[0012]

[0013] R is one or more, independently selected from hydrogen, an electron-donating group or an electron-withdrawing group; X is halogen.

[0014] Preferably, R is hydrogen, C1-6alkyloxy or cyano; and X is bromine.

[0015] Preferably, the preparation method specifically comprises: subjecting 2-bromopyrene shown in structural formula II and phenylacetylene shown in structural formula III to a Sonogashira coupling reaction to obtain the phenylacetylene node-substituted pyrene derivative shown in structural formula I.

[0016] Preferably, the catalyst of the Sonogashira coupling reaction comprises a palladium catalyst, a monovalent copper catalyst and an organic amine.

[0017] The palladium catalyst is at least one of Pd(PPh3)4, Pd(PPh3)2Cl2 or Pd(dppf)Cl2, the monovalent copper catalyst is at least one of CuCl, CuBr or CuI, and the organic amine is at least one of triethylamine, diethylamine or diisopropyl ethylamine.

[0018] Preferably, the solvent of the Sonogashira coupling reaction is at least one of tetrahydrofuran, 1,4-dioxane or N,N-dimethylformamide; the temperature of the Sonogashira coupling reaction is 70-90℃, and the time is 9-18h.

[0019] Preferably, the molar ratio of 2-bromopyrene shown in structural formula II to phenylacetylene shown in structural formula III is 1:1-1.5.

[0020] The application further provides an application of the room-temperature phosphorescent material or the room-temperature phosphorescent material prepared by the preparation method in anti-counterfeiting encryption.

[0021] In the present application, pyrene is used as a substrate, and selective phenylacetylene substitution is performed at its node (2-position). The obtained pyrene derivative has obvious room temperature phosphorescence, which directly indicates that node (2-position) and anti-node (1-position) substitution determines the photophysical properties of the molecule. Comprehensive spectral characterization reveals that anti-node substitution expands the pi conjugated system of pyrene, significantly reduces the intersystem crossing, and at the same time increases the non-radiative decay path, thereby suppressing the room temperature phosphorescence (RTP) intensity to an undetectable level; in contrast, node substitution destroys the conjugation at the substitution site, maintains the rotational freedom between the substitution group and the pyrene core, thereby enhancing the spin-orbit coupling and turning on the room temperature phosphorescence of pyrene. Ultrafast spectral measurement further confirms that due to the bonding effect of the node position, the charge transfer state retains the rotational freedom, which is beneficial to improve the phosphorescent efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Nuclear magnetic resonance spectrum of the phenylacetylene node substituted pyrene derivative described in Example 1 of the present application;

[0023] Figure 2 Nuclear magnetic resonance spectrum of the phenylacetylene node substituted pyrene derivative described in Example 1 of the present application;

[0024] Figure 3 High-resolution mass spectrum of the phenylacetylene node substituted pyrene derivative described in Example 1 of the present application;

[0025] Figure 4 UV-visible absorption spectrum and steady-state emission spectrum of the phenylacetylene node / anti-node substituted pyrene derivative described in Example 1 and Comparative Example 1 of the present application in 2-methyltetrahydrofuran (m-THF);

[0026] Figure 5 Steady-state emission spectrum of the phenylacetylene node / anti-node substituted pyrene derivative described in the present application and comparative examples in different polar solvents;

[0027] Figure 6 Delayed emission spectrum of the phenylacetylene node / anti-node substituted pyrene derivative described in the present application and comparative examples in m-THF;

[0028] Figure 7 Lifetime diagram of the two emission peaks of the phenylacetylene node substituted pyrene derivative described in the present application in m-THF;

[0029] Figure 8 Steady-state emission spectrum of the phenylacetylene node / anti-node substituted pyrene derivative described in the present application and comparative examples at room temperature and low temperature in polymethyl methacrylate (PMMA);

[0030] Figure 9The delayed emission spectrum of the phenylacetylene node / sub-node substituted pyrene derivative described in the examples and comparative examples of the present application at low temperature in PMMA;

[0031] Figure 10 The delayed emission spectrum of the phenylacetylene node substituted pyrene derivative described in the examples of the present application at room temperature in PMMA;

[0032] Figure 11 The lifetime diagram of the two emission peaks of the phenylacetylene node substituted pyrene derivative described in the examples of the present application in PMMA;

[0033] Figure 12 The room temperature phosphorescence (RTP) demonstration photos of the phenylacetylene node / sub-node substituted pyrene derivative described in the examples and comparative examples of the present application;

[0034] Figure 13 The design principle and Jablonski diagram of the phenylacetylene node / sub-node substituted pyrene derivative described in example 1 and comparative example 1 of the present application;

[0035] Figure 14 The molecular orbital wave function distribution of the phenylacetylene node / sub-node substituted pyrene derivative described in example 1 and comparative example 1 of the present application. DETAILED DESCRIPTION

[0036] Hereinafter, the technical solutions of the present application are described in detail through specific examples, but it should be made clear that these examples are used for illustration, but not to be interpreted as limiting the scope of the present application.

[0037] Example 1

[0038] A phenylacetylene node substituted pyrene derivative, the structural formula of which is shown as follows:

[0039]

[0040] The phenylacetylene node substituted pyrene derivative is prepared by the following method:

[0041] 2-bromopyrene (0.6 g, 2.1 mmol), bis(triphenylphosphine) palladium (II) dichloride Pd(PPh3)2Cl2(0.075 g, 0.1 mmol) and cuprous iodide (0.020, 0.1 mmol) are added into a flask, then 3 mL of a tetrahydrofuran solution containing phenylacetylene (0.25 g, 2.5 mmol) is added, followed by the addition of 7 mL of tetrahydrofuran and 10 mL of diisopropylamine, the obtained mixture is stirred at 80°C in a nitrogen atmosphere for 72 h, finally dichloromethane is added for quenching, and the product is separated and purified by column chromatography, using petroleum ether and ethyl acetate = 6:1 as the eluent, to obtain the phenylacetylene node substituted pyrene derivative (0.236 g, 36.5%), which is abbreviated as 2-H-Py.

[0042] 1 H NMR (400 MHz, Chloroform- d ) δ 8.34 (s, 2H), 8.19 (d, J = 7.6 Hz,2H), 8.11 – 7.98 (m, 5H), 7.68–7.62 (m, 2H), 7.44–7.35 (m, 3H).

[0043] Figure 1 The H NMR spectrum of the phenylacetylene node-substituted pyrene derivative described in this example is shown in the following figure: Figure 2 The 13C NMR spectrum of the phenylacetylene node-substituted pyrene derivative described in this example is shown in the following figure: Figure 3 The high-resolution mass spectrum of the phenylacetylene node-substituted pyrene derivative described in this example is shown in the following figure. The molecular structure of the phenylacetylene node-substituted pyrene derivative described in this example can be clearly determined. Figures 1-3 The H NMR spectrum of the phenylacetylene node-substituted pyrene derivative described in this example is shown in the following figure:

[0044] Example 2

[0045] A phenylacetylene node-substituted pyrene derivative, the structural formula of which is shown in the following figure:

[0046]

[0047] The phenylacetylene node-substituted pyrene derivative is prepared by the following method:

[0048] A 2-bromopyrene (0.6 g, 2.1 mmol), bis(triphenylphosphine) palladium (II) dichloride Pd(PPh3)2Cl2(0.075 g, 0.1 mmol) and cuprous iodide (0.020, 0.1 mmol) were added to a flask, and then a solution of p-methoxyphenylacetylene (0.33 g, 2.5 mmol) in 3 mL of tetrahydrofuran was added, followed by the addition of 7 mL of tetrahydrofuran and 10 mL of diisopropylamine. The resulting mixture was stirred at 80°C under a nitrogen atmosphere for 72 h, and then quenched with dichloromethane. The product was purified by column chromatography using petroleum ether and ethyl acetate = 6:1 as the eluent, to obtain the phenylacetylene node-substituted pyrene derivative (0.318 g, 44.8%), which is referred to as 2-OME-Py.

[0049] 1 H NMR (400 MHz, Chloroform- d ) δ 8.32 (d, J = 1.1 Hz, 2H), 8.18 (dd, J= 7.7, 1.2 Hz, 2H), 8.11–7.97 (m, 5H), 7.63–7.55 (m, 2H), 6.97–6.90 (m,2H), 3.86 (s, 3H).

[0050] Example 3

[0051] A phenylacetylene node-substituted pyrene derivative has the following structure:

[0052]

[0053] The phenylacetylene node-substituted pyrene derivative is prepared by the following method:

[0054] A 2-bromopyrene (0.6 g, 2.1 mmol), bis(triphenylphosphine)palladium (II) dichloride Pd(PPh3)2Cl2(0.075 g, 0.1 mmol) and cuprous iodide (0.020, 0.1 mmol) were added to a flask, followed by 3 mL of a tetrahydrofuran solution of p-cyanophenylacetylene (0.32 g, 2.5 mmol), then 7 mL of tetrahydrofuran and 10 mL of diisopropylamine, and the resulting mixture was stirred at 80°C under a nitrogen atmosphere for 72 h, and finally quenched with dichloromethane and purified by column chromatography using petroleum ether and ethyl acetate = 6:1 as the eluent to obtain the phenylacetylene node-substituted pyrene derivative (0.240 g, 34.3%), referred to as 2-CN-Py.

[0055] 1 H NMR (400 MHz, Chloroform- d ) δ 8.34 (s, 2H), 8.20 (d, J = 7.6 Hz,2H), 8.11 (d, J = 9.0 Hz, 2H), 8.07–8.01 (m, 3H), 7.73–7.65 (m, 4H).

[0056] Comparative Example 1

[0057] A phenylacetylene anti-node-substituted pyrene derivative has the following structure:

[0058]

[0059] The phenylacetylene anti-node-substituted pyrene derivative is prepared by the following method:

[0060] To a flask was added 1-bromopyrene (0.6 g, 2.1 mmol), Pd(PPh3)2Cl2(0.075 g, 0.1 mmol) and copper iodide (0.020, 0.1 mmol), followed by 3 mL of tetrahydrofuran solution of phenylacetylene (0.25 g, 2.5 mmol), then 7 mL of tetrahydrofuran and 10 mL of diisopropylamine, the resulting mixture was stirred at 80 °C under nitrogen atmosphere for 72 h, finally quenched by dichloromethane, purified by column chromatography, eluent was petroleum ether and ethyl acetate = 6:1, to obtain the phenylacetylene anti-node substituted pyrene derivative (0.496 g, 76.8%), abbreviated as 1-H-Py.

[0061] 1 H NMR (400 MHz, Chloroform- d ) δ 8.67 (d, J = 9.1 Hz, 1H), 8.26 - 8.17 (m, 4H), 8.15 - 8.08 (m, 2H), 8.07 - 8.00 (m, 2H), 7.75 - 7.70 (m, 2H), 7.47 - 7.37 (m, 3H).

[0062] Comparative Example 2

[0063] A phenylacetylene anti-node substituted pyrene derivative, the structural formula is as follows:

[0064]

[0065] The phenylacetylene anti-node substituted pyrene derivative is prepared by the following method:

[0066] To a flask was added 1-bromopyrene (0.6 g, 2.1 mmol), Pd(PPh3)2Cl2(0.075 g, 0.1 mmol) and copper iodide (0.020, 0.1 mmol), followed by 3 mL of tetrahydrofuran solution of p-methoxyphenylacetylene (0.33 g, 2.5 mmol), then 7 mL of tetrahydrofuran and 10 mL of diisopropylamine, the resulting mixture was stirred at 80 °C under nitrogen atmosphere for 72 h, finally quenched by dichloromethane, purified by column chromatography, eluent was petroleum ether and ethyl acetate = 6:1, to obtain the phenylacetylene anti-node substituted pyrene derivative (0.606 g, 85.4%), abbreviated as 1-OME-Py.

[0067] 1 H NMR (400 MHz, Chloroform- d ) δ 8.66 (d,J = 9.1 Hz, 1H), 8.25–8.15(m, 4H), 8.14–7.99 (m, 4H), 7.69–7.63 (m, 2H), 7.00–6.93 (m, 2H), 3.87 (s,3H).

[0068] Comparative Example 3

[0069] A phenylacetylene anti-node substituted pyrene derivative, the structural formula of which is as shown below:

[0070]

[0071] The phenylacetylene anti-node substituted pyrene derivative is prepared by the following method:

[0072] A flask was charged with 1-bromopyrene (0.6 g, 2.1 mmol), bis(triphenylphosphine)palladium (II) dichloride Pd(PPh3)2Cl2(0.075 g, 0.1 mmol) and cuprous iodide (0.020, 0.1 mmol), and then a solution of p-cyanophenylacetylene (0.32 g, 2.5 mmol) in 3 mL of tetrahydrofuran was added, followed by 7 mL of tetrahydrofuran and 10 mL of diisopropylamine. The mixture was stirred at 80°C under a nitrogen atmosphere for 72 h, and then quenched with dichloromethane. The product was purified by column chromatography using petroleum ether and ethyl acetate = 6:1 as the eluent to obtain the phenylacetylene anti-node substituted pyrene derivative (0439 g, 62.8%), which is referred to as 1-CN-Py.

[0073] 1 H NMR (400 MHz, Chloroform- d ) δ 8.58 (d, J = 9.1 Hz, 1H), 8.27–8.17(m, 4H), 8.15–8.09 (m, 2H), 8.07–8.01 (m, 2H), 7.77–7.63 (m, 4H).

[0074] The phenylacetylene node / anti-node substituted pyrene derivatives of Example 1 and Comparative Example 1 were dissolved in m-THF and subjected to spectral testing at room temperature, and the results are shown in Figure 4 Figure 4 The UV-visible light absorption spectrum and the steady-state emission spectrum (λex=350 nm, c=1×10 -5 mol / L) of the phenylacetylene node / anti-node substituted pyrene derivatives of Example 1 and Comparative Example 1 in m-THF are shown in

[0075] Figure 4 ​​It can be seen that the absorption spectrum of 2-H-Py is blue-shifted compared to 1-H-Py; the UV-Vis spectrum of 1-H-Py shows an additional absorption band near 375 nm, while that of 2-H-Py is not, that is, the substitution of the anti-node (1-position) disrupts the original high symmetry of the pyrene ring, thereby allowing new electronic transitions; the steady-state emission spectrum shows that both 1-H-Py and 2-H-Py exhibit two main emission vibration peaks at 391 nm and 411 nm.

[0076] To investigate the existence of intramolecular charge transfer (ICT) states, the phenylacetylene node / anti-node substituted pyrene derivatives described in the examples and comparative examples were dissolved in solvents of different polarities (m-THF, DMF, DMSO), and spectroscopic measurements were performed at room temperature. The results are as follows: Figure 5 As shown, Figure 5 The steady-state emission spectra of the phenylacetylene nodal / anti-nodal substituted pyrene derivatives described in the examples and comparative examples in different polar solvents (λex = 350 nm, c = 1 × 10⁻⁶). -5 mol / L).

[0077] Depend on Figure 5 It is evident that increasing solvent polarity leads to a redshift of approximately 10 nm in the emission peak of 2-H-Py (from 391 nm to 401 nm), resulting in the disappearance of its fine vibrational structure. In contrast, 1-H-Py exhibits only a slight redshift (from 391 nm to 395 nm and from 411 nm to 416 nm), preserving its vibrational structure. In m-THF, with the introduction of substituents, the emission peaks of the 1- and 2-position derivatives gradually redshift, with the cyano-substituted compounds showing the most significant shifts (30 nm for 1-CN-Py and 26 nm for 2-CN-Py).

[0078] The phenylacetylene node / anti-node substituted pyrene derivatives described in the examples and comparative examples were dissolved in m-THF (c=1×10⁻⁶). - 5 (mol / L), and spectroscopic measurements were performed at 77 K. The results are as follows: Figure 6 As shown, Figure 6 The images show the delayed emission spectra (λex = 298 nm, delay time = 5 ms) of the phenylacetylene node / anti-node substituted pyrene derivatives described in the examples and comparative examples in m-THF. The insets are photographs taken under UV light irradiation and after the UV lamp was turned off.

[0079] Depend on Figure 6It is known that, although the anti-node (1 -position) and node (2-position) substituted pyrene derivatives show some similarities in the steady-state luminescence, their phosphorescence behavior is significantly different: all three node-type 2-substituted derivatives show a clear red phosphorescence emission at low temperature (77 K) in m-THF solution, characterized by two main emission vibrational peaks at 587 nm and 648 nm.

[0080] Figure 7 Lifetime plots of the two emission peaks of the phenylacetylene node-substituted pyrene derivatives described in the examples in m-THF are shown in the insets, which are photographs taken under UV light irradiation and after the UV lamp was turned off, respectively. Figure 7 It is known that the lifetime of 2-H-Py is = 0.54 s; after substitution of the para-position of the alkynyl moiety with a methoxy and a cyano group, both the phosphorescence brightness and the duration were increased compared to 2-H-Py, specifically, the lifetime of the 587 nm emission peak was increased to 0.69 s (2-OME-Py) and 0.74 s (2-CN-Py), respectively; 2-CN-Py with the strongest electron-withdrawing cyano group showed the brightest phosphorescence and the longest lifetime in m-THF solution at 77 K, which is attributed to the enhanced ICT character that promotes intersystem crossing (ISC) and stabilizes the triplet state through a highly distorted donor-acceptor geometry; in contrast, no phosphorescence emission was observed for the three 1 -position substituted derivatives in glassy solution at 77 K, indicating a low ISC efficiency and a very significant non-radiative decay.

[0081] The phenylacetylene node / anti-node substituted pyrene derivatives described in the examples and comparative examples were doped into PMMA at a mass fraction of 0.5%, and the spectral tests were carried out at room temperature and 77 K, and the results are shown in Figure 8 , Figure 8 The steady-state emission spectra (λex= 350 nm) of the phenylacetylene node / anti-node substituted pyrene derivatives described in the examples and comparative examples in PMMA are shown in

[0082] From the above results, it can be seen that the 2-H-Py derivative shows a clear red phosphorescence emission at low temperature (77 K) in m-THF solution, characterized by two main emission vibrational peaks at 587 nm and 648 nm, which is attributed to the enhanced ICT character that promotes intersystem crossing (ISC) and stabilizes the triplet state through a highly distorted donor-acceptor geometry; in contrast, no phosphorescence emission was observed for the three 1 -position substituted derivatives in glassy solution at 77 K, indicating a low ISC efficiency and a very significant non-radiative decay. Figure 8It can be seen that at room temperature (left), the steady-state emission of all anti-node (1-position) substituted pyrene derivatives in PMMA films exhibits a significant red shift with increasing substituent polarity, while node (2-position) substituted pyrene derivatives show a slight blue shift and loss of fine spectral structure; for example, when the phenyl group is substituted with a cyano group at the 1-position, the maximum emission value shifts from 418 nm to 457 nm, a red shift of 39 nm, while the spectrum broadens and the vibrational electronic structure disappears; for the 2-position substituted pyrene derivatives in PMMA, 2-H-Py retains three vibrational peaks (the main peaks are located at 427 nm and 44 nm). The emission peak position did not follow the same redshift trend as in m-THF solution (7 nm); this observation can be explained by the rigid color change effect; in polar solvents such as m-THF, the fluorescence state of pyrene can be stabilized by nearby dielectric groups such as OMePh- and CNPh-, while in rigid media such as PMMA, the transition is vertical (no dielectric stabilization), and the substitution of nodal positions by more polar groups will increase the curvature of the wavefunction at position 2 to a greater extent; the overall effect is that the substitution of OMePh- and CNPh- increases the emission state, thus causing a blue shift. At 77 K (right), the steady-state emission spectrum of 1-H-Py shows a more pronounced fine structure, with its peaks redshifted at 417 nm, 426 nm, and 454 nm. The spectra of the nodal (2-position) pyrene derivatives are more complex: 2-H-Py exhibits three main vibrational peaks at 424 nm, 446 nm, and 465 nm, similar to its room-temperature spectrum; while 2-OME-Py shows a new shoulder peak at 408 nm, and the emission wavelength of 2-CN-Py is close to 435 nm. Notably, in the longer wavelength region, the 2-position pyrene derivatives exhibit a broad emission band between 550 nm and 680 nm.

[0083] The phenylacetylene node / anti-node substituted pyrene derivatives described in the examples and comparative examples were doped into PMMA at a mass fraction of 0.5%, and spectroscopic measurements were performed at 77 K. The results are as follows: Figure 10 As shown, Figure 10 The delayed emission spectra of the phenylacetylene node / anti-node substituted pyrene derivatives in PMMA for the examples and comparative examples are shown (λex = 298 nm, delay time = 5 ms).

[0084] Depend on Figure 9 It can be seen that in PMMA films, the anti-node (1-position) pyrene derivative again exhibits an undetectable level of phosphorescence emission; in contrast, the RTP spectrum of the node (2-position) pyrene derivative remains essentially unchanged, consistent with the spectrum observed in m-THF solution.

[0085] The phenylacetylene nodally substituted pyrene derivative described in the examples was doped into PMMA at a mass fraction of 0.5%, and spectroscopic measurements were performed at room temperature. The results are as follows: Figure 10As shown, Figure 10 The delayed emission spectrum (λex = 298 nm, delay time = 5 ms) of the phenylacetylene nodally substituted pyrene derivative described in the examples is shown in PMMA. The insets are photographs taken under UV irradiation and after the UV lamp is turned off.

[0086] Depend on Figure 10 It is known that all three 2-substituted pyrene derivatives (2-H-Py, 2-OME-Py, 2-CN-Py) exhibit significant phosphorescence behavior at room temperature and 77 K; multiple vibrational peaks were observed at approximately 587 nm, 648 nm and 710 nm, with the peak at 587 nm being the most significant; the introduction of electron-withdrawing substituents enhances the room temperature phosphorescence (RTP) phenomenon, with 2-CN-Py exhibiting the most significant RTP.

[0087] Figure 11 This is a lifetime plot of the two emission peaks of the phenylacetylene nodally substituted pyrene derivative described in the examples in PMMA. Figure 11 It can be seen that 2-CN-Py has the longest lifetime in PMMA at 77 K and room temperature, while 2-OME-Py has the shortest lifetime (0.29s and 74.70ms, respectively).

[0088] The phenylacetylene node / anti-node substituted pyrene derivatives described in Example 1 and Comparative Example 1 were dissolved in DCM and then doped into polymethyl methacrylate (PMMA) at a mass fraction of 1%. The resulting image was then coated on filter paper with the number "1958" (the founding year of the University of Science and Technology of China) and irradiated under 365 nm ultraviolet light. Figure 12 As shown. Figure 12 This is a room-temperature phosphorescent (RTP) encryption demonstration image (λex = 365 nm) of the phenylacetylene node / anti-node substituted pyrene derivatives described in the examples and comparative examples. Figure 12 It is known that the phenylacetylene nodally substituted pyrene derivative described in the examples emits blue fluorescence under 365 nm ultraviolet light, and produces obvious red afterglow after the ultraviolet light is removed.

[0089] Regarding the differences in room-temperature phosphorescence properties of the phenylacetylene node / non-node substituted pyrene derivatives described in the above embodiments and comparative examples, the inventors offer the following explanation based on molecular orbital (MO) theory:

[0090] For those skilled in the art, introducing electron-donating or electron-withdrawing groups at the antinode position (i.e., the position where the orbital wavefunction amplitude is maximum) of an aromatic molecule can extend the π-conjugation length, which typically leads to an increase in the transition dipole moment (TDM) of the substituted compound, according to the following formula:

[0091]

[0092] where i = initial and f = final, is the transition dipole moment (vector), is the operator is the expectation value between the initial and final states, and are the wave functions of the initial and final states, is the electric dipole operator, is the volume element in space.

[0093] According to this equation, as the effective conjugation is enhanced, or the average r is increased, and the symmetry of the wave function is reduced, the transition dipole moment (TDM) of the molecule is expected to increase sharply; when the core structure is highly symmetrical, this effect is particularly pronounced, because the anti-node substitution breaks the symmetry during the electronic transition, resulting in an increase in TDM by several orders of magnitude; therefore, the influence of anti-node substitution is twofold:

[0094] (1) The increase in TDM inevitably reduces the intersystem crossing (ISC) efficiency;

[0095] (2) The extended π-conjugation promotes the increase in the molecular motion freedom.

[0096] The combined effect is expected to result in a decrease in room-temperature phosphorescence (RTP) efficiency; on the contrary, substitution at the node position will minimize the perturbation to the aromatic core electronic structure, which means that the ground-state electronic conjugation can be ignored, and therefore the rotational freedom of the substituent group at room temperature is also small; in this case, when the substituent and the core exhibit a certain degree of charge transfer characteristics, the RTP will be enhanced, because this will mix the spin multiplicity of the singlet and triplet states.

[0097] As shown in Figure 13 , orbital phase analysis reveals how the substitution position (1 -substitution vs. 2-substitution) on pyrene affects the exciton spin state. When a substituent is introduced at the 1 -position, the fluorescence decay rate increases significantly, accompanied by a non-radiative decay competition of the triplet exciton; in contrast, substitution at the node (i.e., the 2-position) reverses the slow fluorescence decay induced by the symmetry of pyrene, and the π-electronic system of the substituent can promote an “intermolecular-like” charge transfer (CT) state within the molecule; this CT state with rotational freedom can greatly enhance the spin-orbit coupling (SOC), thereby enhancing the room-temperature phosphorescence (RTP).

[0098] As described above, the benzenethynyl substituted pyrene derivatives of the present application have lower yields in the palladium-catalyzed Sonogashira coupling reaction as the electron-withdrawing ability of the substituents increases, and the anti-node substituted pyrene derivatives have higher yields than their node substituted isomers. However, there is a large difference in yield between the C-C coupling reactions at the node and the anti-node; in the Sonogashira reaction, the key step involves the nucleophilic attack of the acetylide anion (highest occupied molecular orbital (HOMO) of the alkyne) on the electrophilic carbon (characterized by its lowest unoccupied molecular orbital (LUMO)) of the aryl halide.

[0099] As shown in Figure 14 , the bromination position on the pyrene core in the substrate (i.e. the site where the coupling reaction occurs) exhibits different frontier orbital properties; when the coupling reaction occurs at the anti-node, the overlap between the acetylide HOMO and the pyrene LUMO is maximized; this efficient orbital interaction lowers the activation energy of the reaction, thus increasing the yield; when the reaction occurs at the node position of the LUMO, the orbital wavefunction amplitude near the carbon is essentially zero, and there is no overlap between the acetylide HOMO and the pyrene LUMO; the reaction can proceed through a higher LUMO (e.g. LUMO+1), in which case the overlap is optimal; however, this pathway requires additional energy, and is less stable due to the rapid relaxation from LUMO+1 to LUMO, and as a result, the yield is much lower, as observed.

[0100] The above only describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes to the technical solutions and the inventive concept of the present application within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A room-temperature phosphorescent material of a phenylacetylene node-substituted pyrene derivative, characterized in that, Its structural formula is shown in one of the following: , .

2. The room-temperature phosphorescent material of the phenylacetylene nodally substituted pyrene derivative according to claim 1, characterized in that, The synthesis route of the room-temperature phosphorescent material is shown below: R is a methoxy or cyano group; X is a halogen.

3. The room-temperature phosphorescent material of the phenylacetylene nodally substituted pyrene derivative according to claim 2, characterized in that, The specific preparation method of the room temperature phosphorescent material includes: The 2-bromopyrene shown in structural formula II and the phenylacetylene shown in structural formula III were subjected to a Sonogashira coupling reaction to obtain the nodally substituted pyrene derivative of phenylacetylene shown in structural formula I.

4. The room-temperature phosphorescent material of the phenylacetylene nodally substituted pyrene derivative according to claim 3, characterized in that, The catalysts for the Sonogashira coupling reaction include palladium catalysts, monovalent copper catalysts, and organic amines; The palladium catalyst is at least one of Pd(PPh3)4, Pd(PPh3)2Cl2 or Pd(dppf)Cl2, the monovalent copper catalyst is at least one of CuCl, CuBr or CuI, and the organic amine is at least one of triethylamine, diethylamine or diisopropylethylamine.

5. The room-temperature phosphorescent material of the phenylacetylene node-substituted pyrene derivative according to claim 3, characterized in that, The solvent for the Sonogashira coupling reaction is at least one of tetrahydrofuran, 1,4-dioxane, or N,N-dimethylformamide; the Sonogashira coupling reaction is carried out at a temperature of 70-90°C for 9-18 hours.

6. The method for preparing the room-temperature phosphorescent material of the phenylacetylene nodally substituted pyrene derivative according to claim 3, characterized in that, The molar ratio of 2-bromopyrene shown in structural formula II to phenylacetylene shown in structural formula III is 1:1-1.

5.

7. The application of a room-temperature phosphorescent material of a phenylacetylene node-substituted pyrene derivative as described in any one of claims 1-6 in anti-counterfeiting encryption.

Images