A nanoassembly with temperature-responsive light-harvesting capability and its preparation method and application

Abstract

The present invention provides a nanoassembly with temperature-responsive light-harvesting capability, and a preparation method and application thereof. Based on the supramolecular self-assembly of CSO molecules, the nanoassembly comprises a cyanostyrene core having both hydrophobicity and aggregation-induced emission properties, and an oligoethylene glycol chain having both hydrophilicity and temperature response. CSO can form a nanoassembly with blue fluorescence in an aqueous phase, and at the same time has a lowest critical solution temperature (LCST). When the system is heated, the fluorescence undergoes a blue shift, and the blue luminescence changes to a blue-violet luminescence. The present invention successfully prepares an artificial light-harvesting system with adjustable emission and thermal response characteristics, and shows great potential in the production of luminescent materials and the simulation of light capture in nature, and has broad application prospects.

Description

Technical Field

[0001] The invention belongs to the field of supramolecular fluorescent materials, and in particular relates to a nanoassembly with temperature-responsive light-capturing capability, a preparation method and an application thereof. Background Art

[0002] In recent years, the topic of excessive global carbon emissions has repeatedly come to the forefront. Studies have shown that erratic climate change and unpredictable climate crises are directly related to excessive carbon emissions. Carbon emissions have become a core issue restricting the sustainable development of human society today, and the environmental problems they bring are becoming increasingly severe. As a substitute for fossil fuels, solar energy has incomparable advantages. It has the absolute advantage of zero emissions from the source. At the same time, the sun is also the basis for the survival of life and the most critical link in the energy cycle in nature. In the process of photosynthesis in nature, solar energy is first absorbed by plants, then transferred to the reaction center, and finally converted into chemical energy. In the process of gradual energy transfer, the antenna pigment complexes in the leaves (complexes of chlorophyll, carotene, etc. and proteins) systematically form a set of efficient energy capture and transfer systems, which are called light-harvesting systems (Light-Harvesting System, LHS).

[0003] Another very important phenomenon of photosynthesis is that it is closely related to temperature. High temperature is one of the most sensitive physiological reaction conditions of plants. When the temperature is higher than the optimum temperature for photosynthesis, the photosynthetic rate shows a clear downward trend with rising temperature. This is because high temperature causes the passivation, denaturation and destruction of the enzymes that catalyze the dark reaction. At the same time, high temperature also causes changes and damage to the chloroplast structure. The combined effect of these factors will inevitably lead to a sharp drop in the photosynthetic rate. Therefore, introducing temperature variables in artificial light capture systems will not only help to better understand the light capture mechanism in nature, but also provide new ideas for the development of responsive artificial light capture systems. Summary of the invention

[0004] In order to improve the shortcomings of the prior art in the variable temperature artificial light capture system, the present invention provides a nanoassembly with a minimum critical solution temperature (LCST) and temperature stimulus responsive light capture capability, and its preparation method and application, which more comprehensively simulates the impact of high temperature weather on the behavior of plants capturing sunlight (high temperature in nature will inhibit the light capture behavior of plants). To achieve the above purpose, the technical solution adopted by the present invention is:

[0005] A nanoassembly with temperature-responsive light-harvesting capability, the nanoassembly is based on supramolecular self-assembly of CSO molecules in an aqueous phase, the chemical structure of CSO being as shown in Formula I:

[0006]

[0007] Preferably, the CSO has a minimum critical solution temperature in water, and the CSO body undergoes a reversible transition between a homogeneous phase and a phase separation in water as the temperature changes.

[0008] Preferably, when the concentration of CSO in water is 1.02 mM, the minimum critical solution temperature is 47.0°C.

[0009] Preferably, the fluorescence emission of CSO in water blue-shifts as the temperature increases, and red-shifts as the temperature decreases.

[0010] The present invention also provides a method for preparing the nanoassembly with temperature-responsive light-capturing capability, wherein the CSO is prepared by electrophilic addition of compound 1 and compound 2, and the preparation process is as shown in Formula II:

[0011]

[0012] CSO is then added to water, where it undergoes self-assembly driven by hydrophilic and hydrophobic forces to form a nanoassembly.

[0013] Preferably, the method for preparing CSO comprises the following steps:

[0014] Under N2 protection, compound 1 was added to a three-necked flask, dry THF was added, an ice bath was added, compound 2 was slowly added dropwise, and DMAP and triethylamine were added, and the reaction was stirred at room temperature overnight; after the reaction was completed, stirring was stopped, the organic phase was collected, dried, and dried on a rotary evaporator, and column chromatography (the eluent ratio of column chromatography was (DCM: MeOH = 20:1)), and the dried product was collected to obtain a yellow viscous liquid CSO.

[0015] Preferably, the synthesis method of compound 1 is: starting from p-methoxyphenylacetonitrile, firstly a condensation reaction is performed to generate a cyanostyrene mother core, then demethylation is performed, and then condensation is performed with benzoyl chloride derived from a triethylene glycol group.

[0016] Preferably, the concentration of CSO in water is greater than 205 μM.

[0017] The present invention also provides application of the nanoassembly with temperature-responsive light-capturing capability in simulating temperature-responsive photosynthesis.

[0018] Preferably, an aqueous solution of CSO is prepared, and the hydrophobic dye sulfonyl rhodamine 101 is loaded by ultrasonic method, CSO is used as donor D, sulfonyl rhodamine 101 is used as acceptor A, and the donor-acceptor molar ratio D / A is 300:1 to 750:1.

[0019] The above technical solution has the following advantages or beneficial effects:

[0020] 1. The CSO molecule contains a hydrophobic core and a temperature-responsive hydrophilic end (polyethylene glycol ether chain). It is an amphiphilic molecule. This design kills two birds with one stone. It can not only self-assemble in the water phase, but also respond to temperature by LCST.

[0021] 2. CSO molecules exist in different aggregation forms in water during the heating / cooling transition, thus having thermoresponsive fluorescence. As the temperature gradually increases, CSO shows an obvious blue shift, which can be used for temperature visualization;

[0022] 3. The present invention has developed a supramolecular artificial light harvesting system that responds to temperature stimulation, which further simulates the effect of temperature on photosynthesis, i.e., high temperature in nature leads to inhibition of light harvesting;

[0023] 4. The temperature stimulus responsive light capture system constructed by CSO can achieve objective control of the light capture process by artificially regulating the ambient temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the present invention, in which:

[0025] Figure 1 is the NMR hydrogen of compound CSO ( 1 H NMR) spectrum.

[0026] Figure 2 This is the high-resolution mass spectrum of compound CSO.

[0027] Figure 3 It is a schematic diagram of the technical solution of the self-assembly behavior and light harvesting system of the present invention.

[0028] Figure 4 The temperature response diagram of the system measured by the transmittance experiment, (a) is the turbidity point measurement diagram, and (b) is the temperature response cycle diagram.

[0029] Figure 5 This is the fluorescence spectrum change diagram of CSO thermal response.

[0030] Figure 6 This is the fluorescence spectrum of energy transfer after acceptor loading. DETAILED DESCRIPTION

[0031] The disclosure below provides many different embodiments or examples to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0032] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments are all conventional methods in the art unless otherwise specified.

[0033] The present invention provides a supramolecular light harvesting system with LCST behavior and temperature stimulus responsiveness. The nanoassembly is based on supramolecular self-assembly of CSO in an aqueous phase. The chemical structural formula I of CSO is as follows:

[0034]

[0035] The present invention also provides a method for preparing the nanoassembly, as shown in Formula II, CSO is prepared by electrophilic substitution of Compound 1 and Compound 2:

[0036]

[0037] The first characteristic of CSO is that it is an amphiphilic molecule, containing an oligoethylene glycol ether chain as a hydrophilic end and a cyanostyrene part as a hydrophobic core. Above the critical aggregation concentration (CAC, the value of which is 205 μM as determined by the transmittance experiment), CSO will be driven by the hydrophilic and hydrophobic forces in the aqueous phase to form spherical nanoassemblies. The self-assembly behavior and light-harvesting system are shown in the attached Figure 3 shown.

[0038] The second characteristic of CSO is that it contains a large number of oligoethylene glycol groups. At low temperatures, the O atoms in its groups form a hydrogen bond network with water, thus forming a uniform phase; as the temperature rises, the hydrogen bonds are destroyed, the two phases separate, and the solution becomes turbid. c Generally, it is the lowest temperature at which the solution changes from clear to turbid when the temperature rises, also known as the lower critical solution temperature (LCST). When the concentration of CSO is 1.02mM, its turbidity point is 47.0℃. Therefore, CSO has temperature stimulus responsiveness. Figure 4 The temperature rise and fall cycle response of the CSO nanoassembly is demonstrated. When the temperature is higher than the turbidity point, the CSO nanoassembly in the aqueous phase undergoes phase separation from a homogeneous phase, and the solution changes from clear to turbid. When the temperature is lower than the turbidity point, the solution becomes clear again.

[0039] The third characteristic of CSO is that it will exist in different aggregate forms in water during the heating / cooling transition, such as Figure 3 As shown, it exhibits thermoresponsive fluorescence. When the solution is at 30°C, the CSO molecules self-assemble into ordered nanospheres in which the CS parts are tightly stacked, which greatly enhances the restriction of the intramolecular motion effect, resulting in a strong emission solution with a maximum peak at 450nm, showing blue fluorescence. As the temperature increases from 30°C to 60°C, the fluorescence intensity of CSO gradually decreases at 450nm, while a new peak appears at 387nm and gradually increases. At the same time, the fluorescence color changes from blue to blue-purple. This is because the phase change of the oligoethylene glycol chain upon heating changes the self-assembly behavior of CSO, resulting in blue-shifted fluorescence, see Appendix Figure 5 .

[0040] The present invention also provides the use of the temperature stimulus responsive fluorescent nanoassembly in photosynthesis simulating temperature response. An aqueous solution of CSO is prepared, and the hydrophobic dye sulforhodamine 101 (SR101) is loaded by ultrasonic method; CSO is used as a donor (D), and SR101 is used as an acceptor (A), and the molar ratio D / A of the donor and the acceptor is 300:1 to 750:1.

[0041] Example 1

[0042] (1) Synthesis of CSO: Under N2 protection, compound 1 was added to a 100 mL three-necked flask, dry THF was added, ice bath was added, compound 2 was slowly added dropwise, DMAP and triethylamine were added, and the reaction was stirred at room temperature overnight. After the reaction was completed, stirring was stopped. The organic phase was collected, dried, and dried by rotary evaporation. Column chromatography was performed, and the dried product was collected to obtain yellow viscous liquid CSO. The H NMR spectrum of CSO is shown in the attached figure. Figure 1 As shown in the attached high resolution mass spectra Figure 2 As shown, [M+NH4] + =1435.7032.

[0043] (2) CSO molecules self-assemble in distilled water driven by hydrophilic and hydrophobic forces. The transmittance experiment determined that the critical aggregation concentration of CSO was 205 μM, above which CSO assembled into nanoparticles.

[0044] (3) CSO molecules have temperature-responsive polyethylene glycol ether chains. A 1.02 mM aqueous solution of CSO was prepared and the cloud point temperature T under this condition was determined by a transmittance experiment. c is 47.0℃, see attached Figure 4 The temperature response in this step is reversible and can be cycled 2 to 50 times.

[0045] (4) When the CSO solution is at 30°C, the CSO molecules self-assemble into ordered nanospheres, in which the CS parts are tightly packed, the intramolecular motion is restricted, and there is strong emission at 450nm, showing blue fluorescence. As the temperature increases from 30°C to 60°C, the fluorescence intensity of CSO gradually decreases at 450nm, while a new peak appears at 387nm and gradually increases. At the same time, the fluorescence color changes from blue to blue-purple. See Appendix Figure 5 .

[0046] (5) A 0.25 mM aqueous solution of CSO was prepared, and the hydrophobic dye sulfonyl rhodamine SR101 was loaded by ultrasound. The CSO group was used as the energy donor (D) and SR101 was used as the energy acceptor (A). A donor-acceptor solution with a donor-acceptor molar ratio of D / A = 300:1 was prepared.

[0047] Energy transfer efficiency calculation:

[0048] The fluorescence spectra of CSO and SR101@CSO were measured under 355 nm excitation;

[0049] Energy transfer efficiency (Φ ET ) is calculated by equation S1:

[0050] Φ ET =1-I DA / I D (eq.S1)

[0051] Among them I DA and I D are the fluorescence intensities of SR101@CSO (donor and acceptor) and CSO (donor) at 450 nm when excited at 355 nm, respectively, where [CSO] = 2.5 × 10-4 mol / L, [SR101] = 8.3 × 10 -7 mol / L. Substituting the data into formula S1, we get D / A = 1:300. The energy transfer efficiency of energy transfer is 20.6%. Figure 6 .

[0052] In this embodiment, the ultrasonic instrument used is an ultrasonic cleaning machine commonly used in laboratories, and the frequency is 40 kHz.

[0053] Example 2

[0054] Steps (1) to (4) are the same as those in Example 1, and the same CSO as in Example 1 is prepared.

[0055] In this embodiment, in step (5), the supramolecular polymer formed by the compound CSO is used as the energy donor, and the fluorescent dye SR101 is used as the acceptor. The preparation method is as follows:

[0056] A 0.25 mM aqueous solution of CSO was prepared, and SR101 was loaded by ultrasound to prepare a donor-acceptor solution with a D / A ratio of 400:1. Ultrasonication was performed for 10 min with shaking during the process. The fluorescence spectrum and fluorescence intensity of the sample were measured by a fluorescence spectrophotometer. The calculation method of Example 1 was used to obtain Φ ET It is 16.1%.

[0057] Embodiment 3:

[0058] Steps (1) to (4) are the same as those in Example 1, and the same CSO as in Example 1 is prepared.

[0059] In this embodiment, in step (5), the supramolecular polymer formed by the compound CSO is used as the energy donor, and the fluorescent dye SR101 is used as the acceptor. The preparation method is as follows:

[0060] A 0.25 mM aqueous solution of CSO was prepared, and SR101 was loaded by ultrasound to prepare a donor-acceptor solution with a D / A ratio of 500:1. Ultrasonication was performed for 10 min with shaking during the process. The fluorescence spectrum and fluorescence intensity of the sample were measured by a fluorescence spectrophotometer. The calculation method in Example 1 was used to obtain Φ ET It is 11.6%.

[0061] Embodiment 4:

[0062] Steps (1) to (4) are the same as those in Example 1, and the same CSO as in Example 1 is prepared.

[0063] In this embodiment, in step (5), the supramolecular polymer formed by the compound CSO is used as the energy donor, and the fluorescent dye SR101 is used as the acceptor. The preparation method is as follows:

[0064] A 0.25 mM aqueous solution of CSO was prepared, and SR101 was loaded by ultrasound to prepare a donor-acceptor solution with a D / A ratio of 750:1. Ultrasonication was performed for 10 min with shaking during the process. The fluorescence spectrum and fluorescence intensity of the sample were measured by a fluorescence spectrophotometer. The calculation method in Example 1 was used to obtain Φ ET It is 8.6%.

[0065] The ratios of the donor and acceptor solutions in Examples 1 to 4 were 300:1, 400:1, 500:1, and 750:1, respectively. The fluorescence spectra of these solutions are shown in the attached figure. Figure 6 The artificial light harvesting system is based on the self-assembly of the following CSO molecules:

[0066] By ultrasonic loading SR101, when SR101 is encapsulated in the confined space of the nanoparticles, the distance between the donor and the acceptor is close enough, creating conditions for the occurrence of fluorescence resonance energy transfer (FRET). By studying the light capture performance of the system, it was found that there is a good overlap between the absorption spectrum of SR101 and the fluorescence spectrum of CSO. Under the condition of the donor-acceptor ratio (D / A=1:300), the energy transfer efficiency (Φ ET ) can reach about 20.6%. However, in a high temperature environment of 60°C, due to the blue shift of the fluorescence spectrum of CSO as a donor, the overlap with the absorption spectrum of SR101 is greatly reduced, and the energy transfer is greatly reduced.

[0067] Those skilled in the art will readily appreciate other embodiments of the invention after considering the specification and practicing the invention herein. The invention is intended to cover any variations, uses or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art of the invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the claims.

[0068] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A nanoassembly having temperature-responsive light-harvesting capability, characterized in that: The nanoassembly is based on the supramolecular self-assembly of CSO molecules in an aqueous phase, and the chemical structure of the CSO is as shown in Formula I:

2. The nanoassembly having temperature-responsive light-harvesting capability according to claim 1, characterized in that: The CSO has a minimum critical solution temperature in water, and the CSO undergoes a reversible transition between a homogeneous phase and a phase separation in water depending on the temperature.

3. The nanoassembly having temperature-responsive light-harvesting capability according to claim 2, characterized in that: When the concentration of CSO in water is 1.02 mM, the lower critical solution temperature is 47.0°C.

4. The nanoassembly having temperature-responsive light-harvesting capability according to claim 1, characterized in that: The fluorescence emission of the CSO in water blue-shifts as the temperature increases, and red-shifts as the temperature decreases.

5. The method for preparing a nanoassembly having temperature-responsive light-harvesting capability according to claim 1, characterized in that: The CSO is prepared from compound 1 and compound 2, and the preparation process is as shown in Formula II: Then the CSO is added into water, and self-assembled to form the nano-assembly through the hydrophilic-hydrophobic interaction.

6. The method for preparing a nanoassembly having temperature-responsive light-harvesting capability according to claim 5, characterized in that: The preparation method of the CSO comprises the following steps: Under N2 protection, the compound 1 was added to a three-necked flask, dry THF was added, an ice bath was added, the compound 2 was slowly added dropwise, and DMAP and triethylamine were added, and the reaction was stirred at room temperature overnight; after the reaction was completed, the stirring was stopped, the organic phase was collected, dried, and dried by a rotary evaporator, column chromatography was performed, and the dried product was collected to obtain a yellow viscous liquid CSO.

7. The method for preparing a nanoassembly having temperature-responsive light-harvesting capability according to claim 5, characterized in that: The concentration of the CSO in water is greater than 205 μM.

8. Use of the nanoassembly with temperature-responsive light-harvesting capability according to claim 1 in simulating temperature-responsive photosynthesis.

9. The use according to claim 8, characterized in that: The aqueous solution of the CSO is prepared, and the hydrophobic dye sulfonyl rhodamine 101 is loaded by ultrasonic method. The CSO is used as a donor D, and the sulfonyl rhodamine 101 is used as an acceptor A. The molar ratio of the donor to the acceptor D / A is 300:1 to 750:1.

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