Photochemical reaction method, photoactivated polymer, preparation method of photoactivated polymer and photopatterning method

Abstract

The invention provides a photochemical reaction method, a photoactive polymer, a preparation method of the photoactive polymer and a photopatterning method. The photochemical reaction method comprises the following steps: S1, providing a first compound; s2, the first compound is subjected to a ring flip isomerization reaction under the illumination condition, and therefore the first compound is converted into a second compound. The present invention produces and manufactures novel photoactivated luminescent materials based on small molecule systems and polymer systems, which can be used in multiple light patterning techniques.

Description

Technical Field

[0001] The present invention relates to the field of photochemistry, and in particular to a photochemical reaction method, a new photoactivated polymer, a method for preparing the photoactivated polymer, and a photopatterning method. In particular, the present invention relates to a new photochemical reaction of photoactivated patterns in a small molecule system and a polymer system, which can be used for encryption, information storage, and multiple photopatterning of photolithography. The present invention also includes a new polymerization method for in-situ generation of photoactivated polymers. Background Art

[0002] Photoactivated luminescent materials, whose luminescent properties (including fluorescence, phosphorescence, or free radical luminescence) can be controlled to "turn on" by light, show great potential in the fields of optical electronics, information storage, and bioimaging due to the visual enhancement and / or transformation of luminescence intensity and / or luminescence color. Several design principles for photoactivated luminescence can be divided into photophysical strategies (such as deoxygenation, regulation of molecular conformation, and regulation of crystal arrangement) and photochemical strategies (including photochemical reactions and photoinduced free radical generation). Since photophysical strategies are either only applicable to oxygen-sensitive systems or require complex molecular design and delicate crystal engineering, and the rarely reported luminescent free radicals are unstable and weakly luminescent, photochemical reactions involving the rapid transformation from weakly luminescent molecules to brightly luminescent molecules have become a powerful toolbox for designing photoactivated luminescent materials. However, most of the reported photochemical reactions belong to ring-opening, ring-closing, and cycloaddition reactions. Typically, the significant changes in the molecular conjugated structure in these reactions lead to significant changes in their absorption, and the apparent color also changes, making them unsuitable for information encryption. Despite great efforts to improve their luminescent properties, molecular design is still limited to different combinations and modifications of certain typical groups (such as spiropyran and diarylethenes). In addition, compared with small molecules, luminescent polymers have advantages such as excellent film-forming ability, good processability and uniform luminescent properties. However, due to the lack of diversity of photoactivated groups, the introduction of the above typical groups into polymer chains often requires complex and time-consuming monomer synthesis, which hinders their large-scale application. Therefore, it is still challenging to explore new photoactivated groups using new photochemical reactions, and the demand is huge.

[0003] It is well known that activated alkynes with electron-withdrawing substituents such as ketones, esters or amides are versatile tools in organic synthesis. In particular, acetylenedicarboxylates can form a rich variety of frameworks from simple vinyl units to complex heterocycles, aromatics and spirocycles through Michael additions, cycloadditions or multicomponent reactions. The interesting and complex frameworks they can form are extremely attractive not only to organic synthesis scientists but also to researchers in the field of luminescence. The luminescence properties of these frameworks, such as aggregation-induced emission (AIE) and cluster emission (CTE), have been studied in small molecule and polymer systems. In addition, due to the mild reaction conditions, high atom economy and excellent efficiency of constructing these frameworks, they have recently been used for triple bond polymerization. Despite the great potential of the activated alkyne reaction in constructing a variety of organic frameworks with functional substituents and the ability to extend the model reaction to triple bond polymerization, the reaction has not yet been used to prepare photoactivated materials. Summary of the invention

[0004] The present invention aims to provide a novel photochemical reaction for photopatterning, especially multiple photopatterning including encryption, information storage and photolithography. The present invention also provides novel photoactivated materials and preparation methods thereof.

[0005] Specifically, the present invention provides the following solutions.

[0006] 1. A photochemical reaction method comprising the following steps:

[0007] S1-providing a first compound comprising a unit represented by formula I; and

[0008] S2- subjecting the compound comprising the unit represented by formula I to a ring flip isomerization reaction under light conditions, thereby converting it into a second compound comprising the unit represented by formula II,

[0009]

[0010]

[0011] Wherein R is independently hydrogen, C1-C12 alkyl, halogen, C1-C12 alkoxy, C1-C12 alkylthio, C1-C12 alkylamino, C1-C12 alkyl substituted by halogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, R1 and R2 represent C1-C12 alkyl or -COO-R3, wherein R3 is C1-C12 alkyl, 1≤n≤100 and n is an integer, provided that when n is 1, the O-terminus is a C1-C12 alkyl, and when n is greater than 1, the O-terminus is a connecting bond.

[0012] Wherein, n is 1, and step S1 comprises:

[0013]

[0014] Wherein, the first compound comprising the unit represented by formula I is a photoactivated polymer represented by the following formula Poly-NS, and step S1 comprises:

[0015]

[0016] , wherein a, b, c and d are each independently an integer between 1 and 50.

[0017] Wherein, the first compound containing the unit represented by formula I is a compound represented by the following formula NS, the second compound containing the unit represented by formula II is a compound represented by the following formula NSI, and the step S2 comprises:

[0018]

[0019] The ring-flip isomerization reaction in step S2 occurs under any conditions of a solution state or a film state.

[0020] Wherein, step S1 is carried out under any one or all of the conditions selected from room temperature, without catalyst, without solvent, without heating and without irradiation.

[0021] Wherein, step S2 further comprises a photo-induced cross-linking reaction of Poly-NS.

[0022] Among them, the ring-flip isomerization reaction increased the fluorescence quantum yield from less than 2% to more than 30%.

[0023] 2. A photoactivated polymer comprising a monomer unit represented by the following formula I:

[0024]

[0025] Wherein R is independently hydrogen, C1-C12 alkyl, halogen, C1-C12 alkoxy, C1-C12 alkylthio, C1-C12 alkylamino, C1-C12 alkyl substituted by halogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, R1 and R2 represent C1-C12 alkyl or -COO-R3, wherein R3 is C1-C12 alkyl, 1≤n≤100, and n is an integer, provided that n is greater than 1, and the O-terminus is a connecting bond.

[0026] The photoactivated polymer is represented by the following formula Poly-NS:

[0027]

[0028] wherein a, b, c and d are each independently an integer between 1 and 50.

[0029] The photoactivated polymer has photoactivated luminescent function and / or photoinduced cross-linking property.

[0030] 3. A method for preparing a photoactivated polymer, comprising reacting an active alkyne represented by formula III with a benzothiophene represented by formula IV in the absence of solvent and at room temperature to obtain a photoactivated polymer represented by formula V:

[0031]

[0032] Wherein, R is independently hydrogen, C1-C12 alkyl, halogen, C1-C12 alkoxy, C1-C12 alkylthio, C1-C12 alkylamino, C1-C12 alkyl substituted by halogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, and a, b, c and d are each independently an integer between 1 and 50.

[0033] 4. A photopatterning method, comprising the above-mentioned photochemical reaction method.

[0034] Wherein, light patterning including encryption and fluorescence intensity gradient imaging is performed by the photochemical reaction method.

[0035] The photopatterning is performed by the photoactivated polymer, including any one of photolithography patterning and flexible patterning.

[0036] Beneficial effects of the present invention

[0037] The present invention first discovered the ring flip isomerization reaction of the first compound containing the unit represented by formula I under light conditions (e.g., the photoisomerization reaction of NS to NSI). The present invention discovered this new reaction and its mechanism and applied it to the field of photopatterning. In addition, the method for obtaining NS of the present invention does not use any solvent, and the yield is more than 40%, preferably more than 45%, and more preferably more than 48%.

[0038] The present invention also develops a new polymerization route of activated alkynes and benzothiazole. Although pyridine and benzothiazole are both heterocyclic compounds, the polymerization mechanism is very different due to the unique properties of the sulfur atom in the present invention. In addition, the properties of the obtained polymers are also very different. The polymer material prepared by the present invention is a new type of polymer material with photoactivated luminescence and photoinduced crosslinking properties. These properties are not observed in similar polymers obtained in the prior art. Therefore, the present invention can be used in new application fields, including multiple photopatterning.

[0039] The invention produces and manufactures novel light-activated luminescent materials based on small molecule systems and polymer systems, which can be used in multiple light patterning technologies, including encryption, information storage and photolithography. The novel photochemical reaction method proposed by the invention also has potential in biological imaging, optics and electronic devices.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Shown are the synthetic reaction schemes for NS, NSI and poly-NS.

[0042] Figure 2 The expression of NS in CD3CN 1 H NMR spectroscopy.

[0043] Figure 3 The expression of NS in CD3CN 13 C NMR spectroscopy.

[0044] Figure 4 Shown is the HRMS pattern of the NS molecule.

[0045] Figure 5 Shows that NSI in CDCl3 1 H NMR spectrum.

[0046] Figure 6 Shows that NSI in CDCl3 13 C NMR spectrum.

[0047] Figure 7 The HRMS spectrum of the NSI molecule is shown.

[0048] Figure 8 HPLC profiles of NS and NSI molecules are shown.

[0049] Fig. 9 . Shows the concentration of DEHD in CDCl3 1 H NMR spectrum.

[0050] Fig.10 .DEHD in CDCl3 13 C NMR spectrum.

[0051] Fig.11 Shown is the HRMS spectrum of the DEHD molecule.

[0052] Fig.12 A single crystal structure diagram of NS is shown with a probability ellipsoid at the 50% level, where white circles represent H atoms.

[0053] Fig.13 A single crystal structure diagram of NSI is shown with a probability ellipsoid at the 50% level, where white circles represent H atoms.

[0054] Fig.14 The results show that benzothiazole, DEHD, NS and poly-NS in CDCl3 1 H

[0055] NMR spectrum.

[0056] Fig.15 The absorption spectra of NS and NSI in THF solution are shown. Concentration: 10 μM.

[0057] Fig.16 The absorption spectra of NS and NSI in PMMA films are shown.

[0058] Fig.17 The photoluminescence spectra of NS and NSI in THF solution are shown. Excitation wavelength: 365 nm. Concentration: 10 μM.

[0059] Fig.18 The photoluminescence spectra of NS and NSI in PMMA films are shown. Excitation wavelength: 365 nm.

[0060] Fig.19 The photoluminescence spectra of NS and NSI in the crystalline state are shown. Excitation wavelength: 365 nm.

[0061] Fig. 20 Shown are the photoluminescence spectra of NS-PMMA (a) and NSI-PMMA (b) at room temperature and 77 K. Excitation wavelength: 365 nm.

[0062] Fig.21 The photoluminescence spectra of NS (a) and NSI (b) in solvents with different viscosities are shown. Excitation wavelength: 365 nm. Concentration: 10 μM.

[0063] Fig. 22 The time-resolved photoluminescence decay curves of NS and NSI in THF solution are shown. Excitation wavelength: 375 nm. Concentration: 10 μM.

[0064] Fig.23 The time-resolved photoluminescence decay curves of NS and NSI in PMMA film are shown. Excitation wavelength: 375 nm.

[0065] Fig.24 The time-resolved photoluminescence decay curves of NS and NSI in the crystalline state are shown. Excitation wavelength: 375 nm.

[0066] Fig.25 Shown: (a) Photochemical reactions involved in the photoactivated luminescence process, inset: Photograph showing the photoactivation process of NS-PMMA film after 10 minutes of UV irradiation; (b) Photoluminescence spectra of NS-PMMA film and NSI-PMMA film; (c) In-situ time-dependent photoluminescence spectrum and intensity diagram of NS-PMMA after 20 minutes of UV irradiation (d); (e) Quantum yield of NS-PMMA and NSI-PMMA films. Excitation wavelength: 365 nm.

[0067] Fig.26 The photographs of NS-PMMA film before (a) and after (b) UV irradiation under ambient light and 365 nm UV light are shown. The apparent color of NS-PMMA does not change.

[0068] Fig. 27 Energy curves showing the photochemical ring-flip isomerization.

[0069] Fig.28 Schematic diagram showing effective and ineffective intramolecular motion. Top: Overlay of optimized ground state (blue) and excited state (green) geometries of NS and NSI in the gas phase. The intramolecular vibration modes, RMSD values, and dihedral angle changes of the main ester groups are marked in the figure. Bottom: NS and NSI in S 0,min and S 1,min LUMO orbital in the 4-state (isosurface: 0.09) and optimized structure. The prominent ester group is represented by a red dashed circle.

[0070] Fig.29 The reaction mechanism of small molecule synthesis of NS and triple bond polymerization is shown.

[0071] Fig.30 (a) Alkyne polymerization for the synthesis of poly-NS. (b) Synthesis of NS, poly-NS, NSI, and poly-NS in CDCl3 after UV irradiation. 1 H NMR spectra. (c) PL spectra of poly-NS films before and after UV irradiation (top), and in situ time-dependent PL intensity of poly-NS films after 10 min of irradiation (bottom). (d) Proposed cross-linking mechanism. (e) GPC curves of poly-NS before and after UV irradiation. M was determined by GPC in THF using linear polystyrene as the calibration standard. w and M w / M n (f) DSC curves of poly-NS before and after UV irradiation. (g) Photos of poly-NS films immersed in DCM solution before and after UV irradiation.

[0072] Fig.31 The in situ photoluminescence spectrum of the poly-NS film after irradiation for 5 minutes is shown, with an excitation wavelength of 365 nm.

[0073] Fig.32 The photoactivation process of the poly-NS film is shown in the photocatalysis photograph after irradiation with 365nm ultraviolet light for 5 minutes.

[0074] Fig.33(a) Demonstration of a QR pattern with a “burn after reading” function for information encryption. (b) Fluorescence grayscale imaging. (c) Fluorescence pattern of an eye with a grayscale mask. (Top) Fluorescence intensity distribution of an eye pattern with a theoretical graph simulated by a grayscale mask. (Bottom) (d) Fluorescence pattern of a portrait. Color bars with different grayscale values ​​are marked. (e) 3D fluorescence image of a portrait pattern.

[0075] Fig.34 Shown are photos of a pattern with the HKUST logo taken on March 20, 2023 (a) and May 25, 2023 (b).

[0076] Fig.35 Shown are (a) the preparation of cross-linked patterns; (b) fluorescence images of linear patterns (left) and dot patterns (right); (c) fluorescence intensity profiles of linear patterns (left) and dot patterns (right) along the white dashed line; (d) atomic force microscope images of dot patterns and height profiles in the direction of white dashed lines; (e) three-dimensional images of the fluorescence images of dot patterns; (f) showing the poly NS used in flexible displays.

[0077] Fig.36 The images of line patterns with a width of 10 μm and a pitch of 50 μm made of NS-PMMA (a) and poly-NS (b) taken with a camera under 365 nm ultraviolet light are shown. Inset: images taken with a fluorescence microscope.

[0078] Fig.37 The confocal laser scanning microscopy (CLSM) images of poly-

[0079] Line (a) and dot-type fluorescence three-dimensional images (b) produced by NS, where the excitation wavelength is 405nm; emission filter: 450-550nm: 450-550 nanometers.

[0080] Fig.38 Shown is a SEM image of a line pattern made with poly-NS. DETAILED DESCRIPTION

[0081] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in this area or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0082] Definitions and general terms

[0083] Certain embodiments of the present invention are now described in detail, examples of which are illustrated by the accompanying structural formulas and chemical formulae. The present invention is intended to encompass all substitutions, modifications, and equivalent technical solutions, which are all included within the scope of the present invention as defined in the claims. It should be appreciated by those skilled in the art that many methods and materials similar or equivalent to those described herein can be used to practice the present invention. The present invention is in no way limited to the methods and materials described herein. In the event that one or more of the combined documents, patents, and similar materials differ from or contradict the present application (including but not limited to defined terms, term applications, described technologies, etc.), the present application shall prevail.

[0084] It should be further recognized that certain features of the present invention, which are described in multiple separate embodiments for clarity, may also be provided in combination in a single embodiment. Conversely, various features of the present invention, which are described in a single embodiment for brevity, may also be provided separately or in any suitable sub-combination.

[0085] Unless otherwise specified, all technical terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. All patents and publications related to the present invention are incorporated herein by reference in their entirety.

[0086] Unless otherwise specified or there is a clear conflict in context, the articles "a", "an", and "the" as used herein are intended to include "at least one" or "one or more". Therefore, these articles as used herein refer to one or more than one (i.e., at least one) of the objects. For example, "a component" refers to one or more components, i.e., there may be more than one component contemplated for use or use in the implementation of the described embodiment.

[0087] The term "photochemical reaction" as used herein refers to a chemical reaction caused by light, that is, a chemical reaction that occurs when a substance absorbs light energy under the irradiation of visible light or ultraviolet light, which may include chemical reactions such as combination, decomposition, oxidation, reduction, and isomerization.

[0088] The term "compound" described herein includes both small molecular compounds and high molecular compounds, ie, polymers.

[0089] The term "photo patterning" as used herein refers to producing a specific pattern or shape on a material by using a mask or other similar tools under the irradiation of visible light or ultraviolet light.

[0090] The present invention relates to a novel photochemical reaction of photoactivated patterns in a small molecule system and a polymer system, which can be used for encryption, information storage and multiple photopatterning of photolithography. The present invention also includes a novel polymerization method for in-situ generation of photoactivated polymers.

[0091] The present invention utilizes a simple and effective alkyne reaction to synthesize a novel photoactivated compound selected from a first compound comprising a unit represented by formula I:

[0092]

[0093] Wherein, R is independently hydrogen, C1-C12 alkyl, halogen, C1-C12 alkoxy, C1-C12 alkylthio, C1-C12 alkylamino, C1-C12 alkyl substituted by halogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, R1 and R2 represent C1-C12 alkyl or -COO-R3, wherein R3 is C1-C12 alkyl, 1≤n≤100 and n is an integer, provided that when n is 1, the O-terminus is a C1-C12 alkyl, and when n is greater than 1, the O-terminus is a connecting bond.

[0094] It is noteworthy that the first compound can undergo an unreported photochemical isomerization in a film (e.g., poly(methyl methacrylate), i.e., PMMA film) or in a solution to be converted into a second compound (i.e., an isomer) comprising a unit represented by formula II, wherein the ring flipping process involved is different from the type of photochemical reaction commonly discussed:

[0095]

[0096] Wherein R is independently hydrogen, C1-C12 alkyl, halogen, C1-C12 alkoxy, C1-C12 alkylthio, C1-C12 alkylamino, C1-C12 alkyl substituted by halogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, R1 and R2 represent C1-C12 alkyl or -COO-R3, wherein R3 is C1-C12 alkyl, 1≤n≤100, provided that when n is 1, the O-terminus is a C1-C12 alkyl, and when n is greater than 1, the O-terminus is a connecting bond.

[0097] The conjugated structures of these two isomers are slightly changed, resulting in similar absorption, but very different luminescence properties. The absolute photoluminescence quantum yield (QY) increases from less than 2% to more than 30%, preferably more than 34%, more preferably 34-35%, for example 34.2%.

[0098] Therefore, in a first aspect, the present invention provides a novel photochemical reaction method, comprising the following steps:

[0099] S1-providing a first compound comprising a unit represented by formula I; and

[0100] S2- subjecting the first compound comprising the unit represented by formula I to a ring flip isomerization reaction under light conditions, thereby converting the first compound comprising the unit represented by formula II,

[0101]

[0102]

[0103] Wherein R is independently hydrogen, C1-C12 alkyl, halogen, C1-C12 alkoxy, C1-C12 alkylthio, C1-C12 alkylamino, C1-C12 alkyl substituted by halogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, R1 and R2 represent C1-C12 alkyl or -COO-R3, wherein R3 is C1-C12 alkyl, 1≤n≤100 and n is an integer, provided that when n is 1, the O-terminus is a C1-C12 alkyl, and when n is greater than 1, the O-terminus is a connecting bond.

[0104] Preferably, n is 1, and step S1 comprises:

[0105]

[0106] Preferably, the first compound comprising the unit represented by formula I is a photoactivated polymer represented by the following formula Poly-NS, and step S1 comprises:

[0107]

[0108] wherein a, b, c and d are each independently an integer between 1 and 50.

[0109] Preferably, step S2 comprises:

[0110]

[0111] Preferably, the ring-flip isomerization reaction in step S2 occurs under any condition in a solution state or a film state.

[0112] Preferably, step S1 is carried out under any one or all of the conditions selected from room temperature, in the absence of catalyst, in the absence of solvent, in the absence of heating and in the absence of irradiation.

[0113] Preferably, step S2 further comprises subjecting Poly-NS to a light-induced cross-linking reaction.

[0114] Although not limited to specific theoretical limitations, effective and ineffective intramolecular motion can be proposed to explain the significant difference in their luminescent properties. In addition, a new type of photoactivated polymer (poly-NS) was successfully fabricated by in situ generation of this new pattern based on a one-pot polymerization reaction of activated alkynes, which has the properties of both photoluminescence and photoinduced cross-linking. The QY value of the photoactivated molecules in the film state after photoactivation was greatly improved from 1.9% to 34.2%, realizing two-dimensional code (QR) pattern and fluorescent grayscale imaging, which can be used for encryption and storage of complex information.

[0115] Due to the unique light-induced cross-linking properties of the photoactivated polymer (poly-NS), high-resolution (over 500 dpi) photolithographic patterns can be obtained. The present invention synthesizes new photoactivated compounds in small molecules and macromolecules through acetylenic reactions / acetylenic polymerization reactions, thus opening up new possibilities for the design and application of new photoactivated luminescent materials.

[0116] Therefore, in a second aspect, the present invention provides a photoactivated polymer comprising a monomer unit represented by the following formula I:

[0117]

[0118] Wherein, R is independently hydrogen, C1-C12 alkyl, halogen, C1-C12 alkoxy, C1-C12 alkylthio, C1-C12 alkylamino, C1-C12 alkyl substituted by halogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, R1 and R2 represent C1-C12 alkyl or -COO-R3, wherein R3 is C1-C12 alkyl, 1≤n≤100 and n is an integer, provided that n is greater than 1, and the O-terminus is a connecting bond.

[0119] Preferably, the photoactivated polymer is represented by the following formula Poly-NS:

[0120]

[0121] wherein a, b, c and d are each independently an integer between 1 and 50.

[0122] Preferably, the photoactivated polymer has a photoactivated luminescent function and / or a photoinduced cross-linking property.

[0123] In a third aspect, the present invention also provides a method for preparing a photoactivated polymer, comprising reacting an active alkyne represented by formula III with a benzothiophene represented by formula IV in the absence of solvent and at room temperature to obtain a photoactivated polymer represented by formula V:

[0124]

[0125] Wherein, R is independently hydrogen, C1-C12 alkyl, halogen, C1-C12 alkoxy, C1-C12 alkylthio, C1-C12 alkylamino, C1-C12 alkyl substituted by halogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, and a, b, c and d are each independently an integer between 1 and 50.

[0126] In a fourth aspect, the present invention provides a photopatterning method, comprising utilizing the above-mentioned photochemical reaction method.

[0127] Preferably, light patterning including encryption and fluorescence intensity gradient imaging is performed by the photochemical reaction method.

[0128] Alternatively, photopatterning is performed by the above-mentioned photoactivated polymer, including any one of photolithographic patterning and flexible patterning.

[0129] Although not limited by theory, it is believed that the photoactivation process and photochemical reaction of the present invention is due to the photochemical isomerization process of the first compound, which involves a ring flip process and then a hydrogen migration step. Density functional theory (DFT) calculations illustrate the reaction pathway ( Fig. 27 ).

[0130] In addition, for the first compound (NS) and the second compound (NSI), their HOMO is mainly located in the heterocyclic skeleton and only exhibits slight vibrations upon excitation. Their RMSD based on the tricyclic skeleton (ignoring the ester group coordinates) is very similar (NS is 0.0649A and NSI is 0.0651A), indicating that the changes in the backbone conformation are also negligible, which is also confirmed by the low temperature and viscosity experiments ( Figure 20-21 ). In contrast, their LUMO spans multiple ester groups of the diene ring and exhibits significant vibrations when excited ( Fig.28 The intramolecular vibrations of multiple ester groups (denoted as EG1-4) can be divided into two categories: twisting and rocking. For the first compound, EG2 and EG3 exhibit twisting motions, while EG1 and EG4 exhibit rocking motions, which are opposite to NSI. Therefore, we investigated how the different motions of these flexible ester groups consume the excitation energy in different ways. First, the LUMOs of the first compound (NS) and the second compound (NSI) in the ground and excited states are located only on one or two ester groups with an equivalent of 0.09 ( Fig.28 , bottom), so it is called a "protruding ester group". 0,min In the first compound (NS), the LUMO is completely distributed on EG1. EG1 will swing when excited, and the dihedral angle α1 changes very little, which is 6.4°. The change from 167.57° to 173.97° is too small to change the conjugated structure. 1,minIn the S state, the electron density on EG1 is almost the same, making its motion "ineffective". In contrast, EG2 undergoes a twisting motion, and the dihedral angle α2 changes significantly by 30.83°. Since α2 changes from -78.52° to -47.69°, the twisting motion provides a structure that is more favorable for the conjugation of the carbonyl group in EG2 and the olefin group in the ring. Therefore, unlike EG1, EG2 in S 0,min There is no electron density distribution in the S state, but 1,min A distinct electron density distribution appears in the S1 state. After excitation, the torsional motion of EG2 greatly changes the electron distribution of LUMO, making it an "effective intramolecular motion (EIM)". The situation of the protruding ester group EG3 in the second compound (NSI) is similar to that of EG1 in the first compound (NS). Along with the swinging motion of EG3, a slight change in α3 does not effectively change the conjugated structure and LUMO distribution of the second compound (NSI). Due to the EIM effect of EG2 in the first compound (NS), it exhibits more obvious CT characteristics in the S1 state and dissipates more excitation energy, which is consistent with the experimental results. In contrast, the protruding ester group only exhibits ineffective intramolecular motion (IIM) in the second compound, showing more LE characteristics and dissipating less energy. Therefore, the effective twisting of the protruding ester group in the first compound (NS) changes the electron density distribution in its LUMO, so that the S0-S1 transition has more obvious CT characteristics and more non-radiative channels, resulting in a smaller energy gap and weaker emission in the first compound (NS). The concepts of EIM and IIM clarify the relationship between specific motion modes and energy dissipation in the excited state.

[0131] The mechanism of photoactivated polymers is as follows Fig.29 As predicted, poly-NS exhibited obvious photoactivation. Within 90 seconds, the emission peak shifted from 575 nm to 530 nm, and the intensity continued to rise within 5 minutes ( Fig.30 c, Fig.31 ), the emission color changes significantly from orange-yellow to yellow-green, and the intensity increases significantly ( Fig.32 ). The poly-NS was measured before and after UV irradiation. 1 H NMR spectra were obtained and compared with those of NS and NSI small molecules. As expected, after UV irradiation, the NS characteristic peak at 8.42 ppm disappeared, while another NSI characteristic peak at 6.40 ppm appeared, indicating that the NS motif in the polymer chain underwent cycloisomerization, leading to a photoactivation phenomenon similar to that of poly-NS ( Fig.30 b) The faster conversion rate of poly-NS indicates that these polymer chains provide a more flexible environment for the ring-flipping process than PMMA.

[0132] All patents, patent applications, provisional applications, and publications referenced or cited herein are hereby incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.

[0133] Example

[0134] The following are examples of methods for implementing the present application. These examples should not be construed as limiting. Unless otherwise specified, all percentages are weight percentages, and all solvent mixing ratios are volume ratios.

[0135] Synthesis of the photoactive molecule 4aH-benzo[4,5]thiazolo[3,2-a]pyridine-2,3,4,4a-tetracarboxylic acid tetramethyl ester (NS), its ring-flip isomer 1H-benzo[4,5]thiazolo[3,2-a]pyridine-1,2,3,4-tetracarboxylic acid tetramethyl ester (NSI) and photoactive polymer (poly-NS) Figure 1 ).

[0136] Synthesis of NS: Mix dimethyl acetylenedicarboxylate (DMAD) (2.0 mmol, 250 uL) and benzothiazole (1.0 mmol, 100 uL) and stir overnight under nitrogen at room temperature. After the reaction is completed, DCM is added and evaporated in vacuo to remove unreacted DMAD. The crude product is purified by silica gel column chromatography using EA / n-hexane (v / v=1:2) as eluent. Recrystallization from DCM / EtOH gives compound NS as yellow needle crystals with a yield of 48% (0.2 g).

[0137] Synthesis of NSI: NS (0.05 mmol, 20 mg) was dissolved in DCM / chloroform (10 mL, v / v = 9 / 1). The solution was stirred overnight under irradiation at a wavelength of 365 nm. After removing the solvent in vacuo, the crude product was purified by two thin layer chromatography (TLC) with EA / n-hexane (v / v = 1:3). Recrystallization from DCM / EtOH gave compound NSI as yellow block crystals with a yield of 33% (7 mg).

[0138] Polymerization: All polymerization reactions were carried out in air. Benzothiazole (109 μL, 1.0 mmol) and 4,4'-diethyl O'1,O1-(hexane-1,6-diyl) bis(but-2-ynedioic acid) ester (DEHD) (168 μL, 0.50 mmol) were added to a 5 mL volumetric flask equipped with a magnetic stirring bar. After stirring for 24 hours, 2 mL of DCM was added to dissolve the viscous mixture. After precipitation in n-hexane and ether twice, respectively, a brown polymer Poly-NS was obtained by filtration and vacuum drying with a yield of 78% (0.2 g). The structural formula is as follows Figure 1As shown, wherein a, b, c and d are each independently an integer between 1 and 50, and a+b+c+d=70. w :28,800;M w / M n : 1.45 (GPC, polystyrene calibration).

[0139] The chemical structures and purities of NS and NSI were verified by nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS), X-ray single crystal analysis, and high-performance liquid chromatography (HPLC). Figure 1-13 To determine the structure of poly-NS, the monomer, model compound NS and poly-NS were compared. 1 H NMR spectroscopy ( Fig.14 ). As shown in Table 2, the polymerization conditions were optimized.

[0140] Table 1: Crystallographic data of single crystals of NS and NSI

[0141]

[0142] a R1=Σ||F o |-|F c || / Σ|F o |.

[0143] b wR2=[Σw(F o 2 -F c 2 ) 2 / Σw(F o 2 ) 2 ] 1 / 2 .

[0144] Table 2 Optimization of polymerization conditions a

[0145]

[0146] a The reaction was carried out in air at room temperature without catalyst or solvent.

[0147] b Measured by GPC in THF using linear PS as calibration standard.

[0148] c Dichloromethane was used as the solvent. [Benzothiazole] = 1.0M.

[0149] Photophysical properties

[0150] The photophysical properties of NS and NSI in solution, film and crystal states were measured, including absorption spectra, photoluminescence (PL) spectra and time-resolved PL decay curves ( Figure 15-24 and Table 3-4).

[0151] Table 3: Photophysical parameters of NS and NSI

[0152]

[0153] a k F =Φ F / τ F

[0154] b k nr =(1-Φ P ) / τ F

[0155] Table 4: Photophysical parameters of NS-PMMA and MSI-PMMA

[0156]

[0157] a k F =Φ F / τ F

[0158] b k nr =(1-Φ P ) / τ F

[0159] Photoactivation processes and photochemical reactions

[0160] Photochemical reactions such as Fig.25 The PL spectra of NS and NSI-PMMA were measured, and the results showed that the emission peaks of NS and NSI were located at 550 nm and 510 nm, corresponding to yellow and green fluorescence, respectively ( Fig.25 b). To verify whether the photoactivation phenomenon is caused by the conversion of NS to NSI, the PL spectrum over time was taken in situ. Under irradiation at 365 nm, it can be observed that the emission peak gradually blue-shifts from 550 nm to 510 nm within 1 minute, which is consistent with the fluorescence of NS-PMMA and NSI-PMMA, respectively. The intensity at 510 nm continued to rise within 15 minutes and then remained almost unchanged, indicating that the conversion was complete ( Fig.25 c, 25d). QY increased 18 times, from 1.9% (almost dim) to 34.2% ( Fig.25 e). It is worth noting that its appearance color remains unchanged ( Fig.26), which highlights the potential of this compound molecule in fluorescent anti-counterfeiting and encryption. To clarify the photochemical isomerization mechanism, a ring flip process followed by a hydrogen migration step was proposed. Density functional theory (DFT) calculations illustrate the reaction pathway ( Fig. 27 ).

[0161] Photophysical mechanism of different luminescence properties between NS and NSI

[0162] The photophysical experimental results of NS and NSI in PMMA films show that there are more non-radiative channels in NS to consume the excitation energy ( Fig.16 , Fig.18 , Fig.23 and Table 4). However, the S 0,min With S 1,min The RMSD values ​​between the states are very close ( Fig.28 ). This suggests that they have similar intramolecular motions to dissipate the excitation energy, and that NS has smaller structural changes after excitation, which contradicts the experimental results we discussed above. Therefore, the relationship between their intramolecular motions and excited-state energy dissipation needs to be further investigated. For NS and NSI, their HOMOs are mainly located in the heterocyclic skeleton and only exhibit slight vibrations upon excitation. Their RMSDs based on the tricyclic skeleton (ignoring the ester group coordinates) are very similar (0.0649A for NS and 0.0651A for NSI), suggesting that the changes in the backbone conformation are equally insignificant, which is also confirmed by low temperature and viscosity experiments ( Figure 20-21 ). In contrast, their LUMO spans the four ester groups of the diene ring and exhibits significant vibrations when excited ( Fig.28 The intramolecular vibrations of the four ester groups (denoted as EG1-4) can be divided into two categories: twisting and rocking. For NS, EG2 and EG3 exhibit twisting motions, while EG1 and EG4 exhibit rocking motions, which are opposite to NSI. Therefore, we are curious about how the different motions of these four flexible ester groups consume the excitation energy in different ways. First, the LUMOs of NS and NSI in the ground and excited states are located on only one or two ester groups with an equivalent of 0.09 ( Fig.28 , bottom), so it is called a "protruding ester group". 0,minIn the NS state, the LUMO is completely distributed on EG1, which undergoes a rocking motion upon excitation, and the dihedral angle α1 changes very little, to 6.4°. The change from 167.57° to 173.97° is too small to change the conjugated structure, so in the S1,min state, the electron density on EG1 is almost the same, making its motion "invalid". In contrast, EG2 undergoes a twisting motion, and the dihedral angle α2 changes drastically by 30.83°. Since α2 shifts from -78.52° to -47.69°, the twisting motion provides a structure that is more favorable for the conjugation of the carbonyl group in EG2 and the olefin group in the ring. Therefore, unlike EG1, EG2 is not as good in the S1,min state as EG1. 0,min There is no electron density distribution in the S state, but 1,min A distinct electron density distribution appears in the state. After excitation, the torsional motion of EG2 greatly changes the electron distribution of LUMO, making it an "effective intramolecular motion (EIM)". The situation of the protruding ester group EG3 in NSI is similar to that of EG1 in NS. Along with the swinging motion of EG3, a slight change in α3 does not effectively change the conjugated structure and LUMO distribution of NSI. Due to the EIM effect of EG2 in NS, it exhibits more obvious CT characteristics in the S1 state and dissipates more excitation energy, which is consistent with the experimental results. In contrast, the protruding ester group only exhibits ineffective intramolecular motion (IIM) in NSI, showing more LE characteristics and dissipating less energy. Therefore, the effective twisting of the protruding ester group in NS changes the electron density distribution in its LUMO, so that the S0-S1 transition has more obvious CT characteristics and more non-radiative channels, resulting in a smaller energy gap and weaker emission in NS. The concepts of EIM and IIM clarify the relationship between specific motion modes and energy dissipation in the excited state.

[0163] Photoactivation of polymers

[0164] The polymerization mechanism is as follows Fig.29 As predicted, poly-NS exhibited obvious photoactivation. Within 90 seconds, the emission peak shifted from 575 nm to 530 nm, and the intensity continued to rise within 5 minutes ( Fig.30 c, Fig.31 ), the emission color changes significantly from orange-yellow to yellow-green, and the intensity increases significantly ( Fig.32 ). The poly-NS was measured before and after UV irradiation. 1 H-NMR spectra were obtained and compared with those of NS and NSI small molecules. As expected, after UV irradiation, the NS characteristic peak at 8.42 ppm disappeared, while another NSI characteristic peak at 6.40 ppm appeared, indicating that the NS motif in the polymer chain underwent ring-flip isomerization, leading to a photoactivation phenomenon similar to that of poly-NS ( Fig.30b) The faster conversion rate of poly-NS indicates that these polymer chains provide a more flexible environment for the ring-flipping process than PMMA.

[0165] In addition, after UV irradiation, the solubility of poly-NS in DCM was significantly different ( Fig.30 g), which indicates a possible cross-linking process. Note that DCM is the solvent used to make the poly-NS thin film on the silicon wafer substrate by spin coating. Before UV irradiation, when the bottom of the silicon wafer was immersed in DCM, the poly-NS dissolved in the solution, and the solution emitted a faint yellow light. However, after UV irradiation, the polymer did not dissolve in dichloromethane, and it remained attached to the silicon wafer even when immersed in the dichloromethane solution. Fig.30 d proposed a plausible mechanism for the observed cross-linking process. The NS groups in the polymer chain first undergo a ring-opening process similar to the reaction of small molecules. While in the ring-closing process, the thiol anion may attack the pyridine core on the other chain, and hydrogen migration occurs at the same time, leading to the cross-linking process. To confirm the formation of the cross-linked product, gel permeation chromatography (GPC) was measured after filtering out the insoluble part. A significant increase in molecular weight from 13,700 to 33,000 and an increase in PDI from 1.61 to 4.09 ( Fig.30 e). The differential scanning calorimetry (DSC) curve also showed that the Tg of poly-NS increased from 46.0°C to 56.5°C after UV irradiation, indicating that a harder network was formed during the cross-linking process ( Fig.30 f).

[0166] Multiple light patterning

[0167] All films were prepared by spin coating on silicon wafers. The silicon wafers were ultrasonically cleaned in acetone and ethanol for 30 min respectively before use. The typical steps for preparing the films are as follows.

[0168] NS (2 mg) and PMMA (200 mg) were dissolved in dichloroethane (10 mL). Then, 800 uL of the prepared solution was dropped on a silicon wafer (1.5 cm x 1.5 cm) to completely cover the surface. After irradiation with a handheld UV lamp under a mask for 60 seconds, the pattern was written on the NS-PMMA film. Using 2 mL of solution and a lower rotation speed (2000 rpm) for 120 seconds, a large grayscale light pattern (4 cm x 4 cm) was obtained.

[0169] The method of making cross-linked photopatterns with poly-NS is similar. Poly-NS (200 mg) was dissolved in DCM (10 ml). 800 uL of the solution was used to cover the entire surface of the silicon wafer, and then spin-coated at 4000 rpm for 60 seconds to obtain a poly-NS film, which was then irradiated with 365 nm ultraviolet light for 60 seconds under a mask to form a fluorescent pattern. The fluorescent pattern was then washed with DCM to reveal the cross-linked pattern.

[0170] All photos were taken by camera or mobile phone. ImageJ software was used to convert grayscale mask images or fluorescence images into grayscale or fluorescence intensity distribution maps and three-dimensional maps.

[0171] like Fig.33 As shown in Figure a, the QR code pattern is written on the NS-PMMA film after irradiating with ultraviolet light for 1 minute under a mask with a QR code pattern. After removing the mask, the QR code can only be read under ultraviolet light, while the information is hidden under ambient light. To improve confidentiality, the QR code can be erased by further exposing the film to ultraviolet light for 5 minutes, thus realizing the "read and burn" function.

[0172] Considering the photoactivated properties of NS-PMMA, its fluorescence intensity increases with the increase of ultraviolet intensity, and a fluorescence pattern with variable intensity between "1" and "0" can be realized. The different darkness of the grayscale mask can control the transmittance of ultraviolet light, thereby adjusting the intensity of ultraviolet light to form a monochrome image with variable fluorescence intensity ( Fig.33 b). Fluorescence intensity can be extracted by computer processing and projected into RGB color bars for better visualization. This approach was used to create patterned images of the eye ( Fig.33 c). The extracted fluorescence intensity distribution map was compared with the theoretical map simulated by grayscale mask, and the results showed that the two were highly consistent. It is worth noting that high QY is the key to achieve detailed fluorescence grayscale imaging. More complex information can be stored, such as detailed portraits ( Fig.33 d) High-resolution monochrome images can show rich details, such as tree branches, clothing folds, sunsets, and lake reflections. Fig.33 The 2D pattern in Figure 1 is converted into a 3D graph, and it can be found that each pixel contains a grayscale value between 0 and 255. Due to the large variation in QY (from 1.9% to 34.2%), 256 possible grayscale values ​​are provided, which greatly expands the information storage capacity of the binary pattern. Since NSI is a more stable form, the light pattern can be stored for a longer time (compared to the usual light switching pattern (which usually disappears after 28 days) Fig.34 ). This feature provides better durability and greater potential for practical applications.

[0173] Since poly-NS has unique photoactivated cross-linking properties, it can be used in photolithography to produce a variety of patterns ( Fig.35 a). First, a poly-NS film was fabricated on a silicon wafer by spin coating, and then exposed to ultraviolet light to form a fluorescent pattern ( Fig.36Given the cross-linked nature of the irradiated area, patterns can be quickly formed simply by washing with conventional organic solvents such as dichloromethane. Linear patterns with a width of 10 microns and a pitch of 50 microns, as well as dot patterns with a diameter of 10 microns and a pitch of 40 microns, can be successfully achieved, equivalent to a high resolution of more than 500 dpi ( Fig.35 b), comparable to the most advanced commercial OLED displays (mobile phones: 300-500dpi, computers: 200-300dpi). Fig.35 c shows the fluorescence profile in the direction of the white dashed line with high contrast. Fig.35 The atomic force microscopy (AFM) image and height profile in d show that the dot pattern has a thickness of about 300 nm, while the 3D image of the fluorescence image shows the uniform intensity of the pattern ( Fig.35 e, Figure 37-38 ). In addition, poly-NS has excellent processing properties and can be used in flexible displays. For example, a piece of filter paper is immersed in a poly-NS / DCM solution and then irradiated with ultraviolet light to write "Together we shine, united we soar". This information can only be read under ultraviolet light. The filter paper can be bent in half, showing excellent flexibility ( Fig.35 f).

[0174] in conclusion

[0175] As shown in the above examples, the present invention provides new photoactive materials and photoactive polymers and new unique photochemical reactions that can be used for multiple photopatterning, including encryption, information storage and lithography. The photoactive materials of the present invention can also be used in flexible display technology.

[0176] It is understood that, under the spirit of the present invention, within the scope of protection defined by the attached claims, those skilled in the art may make many other changes to the details, materials, steps and arrangements described herein for explaining the characteristics of the subject matter. It should also be understood that the embodiments described herein are for illustrative purposes and are not meant to limit the scope of the subject matter, which is defined by the attached claims.

Claims

1. A photochemical reaction method, characterized in that The following steps are involved: S1-providing a first compound comprising a unit represented by formula I; as well as S2- subjecting the compound comprising the unit represented by formula I to a ring flip isomerization reaction under light conditions, thereby converting it into a second compound comprising the unit represented by formula II, Wherein, R is independently hydrogen, C1-C12 alkyl, halogen, C1-C12 alkoxy, C1-C12 alkylthio, C1-C12 alkylamino, C1-C12 alkyl substituted by halogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, R1 and R2 represent C1-C12 alkyl or -COO-R3, wherein R3 is C1-C12 alkyl, 1≤n≤100 and n is an integer, provided that when n is 1, the O-terminus is a C1-C12 alkyl, and when n is greater than 1, the O-terminus is a connecting bond.

2. The photochemical reaction method according to claim 1, characterized in that n is 1, and step S1 comprises:

3. The photochemical reaction method according to claim 1, characterized in that The first compound including the unit represented by Formula I is a photoactivated polymer represented by the following formula Poly-NS, and step S1 comprises: wherein a, b, c and d are each independently an integer between 1 and 50.

4. The photochemical reaction method according to claim 1, characterized in that The first compound containing the unit represented by formula I is a compound represented by the following formula NS, the second compound containing the unit represented by formula II is a compound represented by the following formula NSI, and the step S2 comprises:

5. The photochemical reaction method according to any one of claims 1 to 4, characterized in that The ring-flip isomerization reaction in step S2 occurs under any conditions in a solution state or a film state.

6. The photochemical reaction method according to claim 3, characterized in that Step S1 is carried out under any one or all of the conditions selected from room temperature, in the absence of catalyst, in the absence of solvent, in the absence of heating and in the absence of radiation.

7. The photochemical reaction method according to claim 3, characterized in that Step S2 also includes causing a photo-induced cross-linking reaction of the Poly-NS.

8. The photochemical reaction method according to any one of claims 1 to 8, characterized in that The ring-flip isomerization reaction increased the fluorescence quantum yield from less than 2% to more than 30%.

9. A photoactivated polymer, characterized in that It comprises a monomer unit represented by the following formula I: Wherein, R is independently hydrogen, C1-C12 alkyl, halogen, C1-C12 alkoxy, C1-C12 alkylthio, C1-C12 alkylamino, C1-C12 alkyl substituted by halogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, R1 and R2 represent C1-C12 alkyl or -COO-R3, wherein R3 is C1-C12 alkyl, 1≤n≤100, and n is an integer, provided that n is greater than 1, and the O-terminus is a connecting bond.

10. The photoactivated polymer according to claim 9, characterized in that It is represented by the following formula Poly-NS: wherein a, b, c and d are each independently an integer between 1 and 50.

11. The light activated polymer according to claim 9 or 10, characterized in that The photoactivated polymer has a photoactivated luminescent function and / or a photoinduced cross-linking property.

12. A method for preparing a photoactivated polymer, characterized in that The method comprises reacting an active alkyne represented by formula III with a benzothiophene represented by formula IV in the absence of solvent and at room temperature to obtain a photoactivated polymer represented by formula V: Wherein, R is independently hydrogen, C1-C12 alkyl, halogen, C1-C12 alkoxy, C1-C12 alkylthio, C1-C12 alkylamino, C1-C12 alkyl substituted by halogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, and a, b, c and d are each independently an integer between 1 and 50.

13. A method for light patterning, characterized in that A photochemical reaction method comprising any one of claims 1 to 8.

14. The light patterning method according to claim 13, characterized in that Photopatterning including encryption and fluorescence intensity gradient imaging is performed by the photochemical reaction method.

15. The light patterning method according to claim 13, characterized in that The photopatterning performed by the photoactivated polymer of claim 3 includes any one of photolithographic patterning and flexible patterning.

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