CN112206724A

CN112206724A - Rare earth supermolecule gel doped with chitosan or water-soluble derivative thereof, preparation and application thereof

Info

Publication number: CN112206724A
Application number: CN202011066417.XA
Authority: CN
Inventors: 王宏; 张彬彬; 熊玉祥; 董学林; 宋洲
Original assignee: Hubei Geology Experimentation&research Institute (wuhan Mineral Resources Supervision And Testing Center Of Ministry Of Land And Resources); Huazhong University of Science and Technology
Current assignee: Hubei Geology Experimentation&research Institute (wuhan Mineral Resources Supervision And Testing Center Of Ministry Of Land And Resources); Huazhong University of Science and Technology
Priority date: 2020-09-30
Filing date: 2020-09-30
Publication date: 2021-01-12
Anticipated expiration: 2040-09-30
Also published as: CN112206724B

Abstract

The invention belongs to the field of functional rare earth fluorescent materials, and particularly relates to a rare earth supramolecular gel doped with chitosan or a water-soluble derivative thereof, and preparation and application thereof. The rare earth supermolecule gel material comprises an organic ligand, rare earth salt and bio-based macromolecular chitosan or water-soluble derivatives thereof. On one hand, the rare earth supramolecular gel material utilizes the hydrogen bond effect of a bio-based polymer and an organic ligand to increase the light absorption of the organic ligand so as to promote the energy transfer from the organic ligand to rare earth ions and further improve the luminescence property of the rare earth supramolecular gel material; on the other hand, the coordination action of the bio-based polymer and rare earth ions in rare earth salt and the hydrogen bond action of the bio-based polymer and an organic ligand are utilized to enable the bio-based polymer to be adsorbed on the surface of the rare earth supramolecular gel fiber, water molecules are far away from the rare earth ions, and the luminescence property of the rare earth supramolecular gel material is further improved.

Description

Rare earth supermolecule gel doped with chitosan or water-soluble derivative thereof, preparation and application thereof

Technical Field

The invention belongs to the field of functional rare earth fluorescent materials, and particularly relates to a rare earth supramolecular gel doped with chitosan or a water-soluble derivative thereof, and preparation and application thereof.

Background

Among the numerous luminescent gel materials, rare earth luminescent gel materials have many advantages: narrow luminous band, good fluorescence monochromaticity, large Stokes shift, long fluorescence lifetime, stimulation responsiveness and the like. Has attracted wide attention in the fields of chemical sensing, anti-counterfeiting, encryption, biological imaging, luminescent devices and the like. However, the challenge in preparing luminescent rare earth gel materials is: 1. the forbidden transition of the rare earth ions needs the sensitization of the ligand; 2. the rare earth ions are non-radiatively quenched by-OH (such as water) electron vibration coupling contained in the solvent, greatly reducing the luminous intensity and the fluorescence lifetime. In order to prepare rare earth luminescent supramolecular gels with high luminous intensity and fluorescence lifetime, ligands which can effectively sensitize and self-assemble with rare earth ions have been designed and synthesized, but this method requires complex synthesis (ACS Applied Materials)&Interfaces,2017,9(4), 3799-; angewandte Chemie-International Edition,2012,51(29), 7208-; new Journal of Chemistry,2017,41(24), 15173-15179; RSC Advances,2019,9(4), 1949-. In recent years, researchers have succeeded in preparing rare earth supramolecular luminescent gels by developing methods for small molecule-doped supramolecular gels, such as Laishram and Gorai, doped with pyrene (Chemistry select,2018,3(2),519 523) and 1-hydroxypyrene (Journal of Materials Chemistry B,2018,6(14),2143-³⁺The cholic acid gel successfully improves the Eu³⁺Luminescence of the gel. The method for doping rare earth supermolecule gel by micromolecule does not relate to multiple functionsCan synthesize the ligand and is convenient to prepare. However, these doping components are all environmentally unfriendly organic molecules.

The luminescent rare earth xerogel has wide application prospect in the fields of solid illumination, stimulus response materials, sensing and the like due to the excellent optical characteristics. In recent years, especially rare earth xerogels which can still emit light in aqueous solution have great attraction in the aspects of environmental detection, biosensing, imaging and the like. However, since rare earth luminescence is easily non-radiatively quenched by water molecules, the rare earth xerogel material capable of being applied to aqueous solutions is very limited, and therefore, the development of rare earth xerogel materials with stable luminescence in aqueous solutions is of great significance.

The wide application of various functional materials containing metal ions brings increasing concern about the pollution of the metal ions to the environment, so that the effective monitoring and identification of the metal ion concentration are very important. The technology capable of simultaneously realizing the identification of various metal ions can greatly improve the detection efficiency, so that the array sensor of various metal ions gradually replaces the single-target detection of a highly specific receptor, and becomes a powerful tool for identifying various metal ions. Some array-based sensors require synthesis of multiple sensing units to identify multiple metal ions, resulting in increased synthesis costs (Dalton Transactions,2018,47(10), 3378-. In order to solve this problem, extracting multidimensional information to distinguish and detect multiple metal ions by using multidimensional information of a single sensing unit, such as a set of multidimensional sensing devices with fluorescence, absorption signals or electric signal changes (Coordination Chemistry Reviews,2015,292, 30-55; acquisition Chemistry-International Edition,2007,46(6),893-896) becomes an effective way to solve the above problem, however, this detection mode must use different devices to detect different signals, which undoubtedly increases the complexity and time cost of experimental operation.

Disclosure of Invention

Aiming at the defects or the improvement requirements of the prior art, the invention provides a rare earth supramolecular gel doped with chitosan or water-soluble derivatives thereof, preparation and application thereof, by introducing excellent biocompatible bio-based polymer chitosan or water-soluble derivatives thereof into a rare earth supramolecular gel material system and utilizing the coordination effect of the chitosan or the water-soluble derivatives thereof and rare earth ions, and interaction force such as hydrogen bond interaction with a gel factor, namely an organic ligand, and the like, so that the luminescent property of the doped gel material is improved, and the xerogel material prepared from the gel material has better luminescent stability in aqueous solution, therefore, the technical problems that the rare earth luminescent gel material in the prior art is poor in luminescent performance, toxic micromolecule is doped, xerogel is quenched in luminescence of aqueous solution, the process of identifying various metal ions is complicated and complex and the like are solved.

In order to achieve the purpose, the invention provides a rare earth supramolecular gel material doped with chitosan or water-soluble derivatives thereof, which comprises an organic ligand, rare earth salt and a bio-based polymer, wherein the bio-based polymer is chitosan or water-soluble derivatives thereof; wherein the organic ligand is 5, 5' - (1,3, 5-triazine-2, 4, 6-trisaminonaphthalene) -tri-isophthalic acid; the rare earth ion in the rare earth salt is terbium;

under the condition of doping the bio-based polymer, the rare earth supermolecule gel material is formed by self-assembly by utilizing the coordination of the organic ligand and rare earth ions in rare earth salt, the pi-pi interaction between the organic ligand molecules, the coordination of the bio-based polymer and the rare earth ions in the rare earth salt and the hydrogen bond interaction of the bio-based polymer and the organic ligand.

On one hand, the rare earth supramolecular gel material can utilize the hydrogen bond action of the bio-based polymer and the organic ligand to increase the light absorption of the organic ligand so as to promote the energy transfer from the organic ligand to rare earth ions and further improve the luminescence property of the rare earth supramolecular gel material; on the other hand, the gel material can also make the bio-based polymer adsorbed on the surface of the rare earth supramolecular gel fiber by utilizing the coordination effect of the bio-based polymer and the rare earth ions in the rare earth salt and the hydrogen bonding effect of the bio-based polymer and the organic ligand, so that water molecules are far away from the rare earth ions, and the luminescence property of the rare earth supramolecular gel material is further improved; compared with the supermolecule gel material without the bio-based macromolecules, the rare earth supermolecule gel material has the advantages that the fluorescence intensity is improved by 9 times to the maximum, and the fluorescence life is prolonged by more than 2 times.

Preferably, the rare earth supramolecular gel material is prepared by mixing an aqueous solution of the bio-based polymer with a mixed solution of the organic ligand and a rare earth salt and heating.

Preferably, the rare earth supramolecular gel material further comprises a solvent, wherein the solvent is a mixed solvent of acetic acid and water, a mixed solvent of DMF and water or a mixed solvent of DMSO and water.

According to another aspect of the present invention, there is provided a method for preparing said rare earth supramolecular gel material, comprising the steps of: and mixing the water solution of the bio-based polymer with a mixed solution of an organic ligand and a rare earth salt, and obtaining the rare earth supramolecular gel material doped with the bio-based polymer under the heating condition.

Preferably, the mass volume concentration of the chitosan or the water-soluble derivative thereof in the aqueous solution of the bio-based polymer is 0.01 to 2%.

Preferably, the mass volume concentration of the chitosan or the water-soluble derivative thereof in the aqueous solution of the bio-based polymer is 0.1% to 1%.

Preferably, the water-soluble derivative of chitosan is carboxymethyl chitosan or hydroxypropyl chitosan.

Preferably, the water-soluble derivative of chitosan is carboxymethyl chitosan.

Preferably, the polymerization degree n of the chitosan or the water-soluble derivative thereof is 500-2000, and the deacetylation degree DD is more than 75%.

Preferably, the aqueous solution of chitosan is an aqueous solution of chitosan with the mass volume concentration of 0.1-5% obtained by dissolving chitosan in an aqueous solution of acetic acid.

Preferably, the water-soluble derivative of chitosan is carboxymethyl chitosan, and the substitution degree DS of the carboxymethyl chitosan is 0.1-2.

Preferably, the water-soluble derivative of chitosan is hydroxypropyl chitosan, and the substitution degree DS of the hydroxypropyl chitosan is 0.1-2.

Preferably, an organic solution of 5,5 '- (1,3, 5-triazine-2, 4, 6-triamino) -tri-isophthalic acid is mixed with a rare earth salt solution to obtain a mixed solution of an organic ligand and the rare earth salt, wherein the molar ratio of the 5, 5' - (1,3, 5-triazine-2, 4, 6-triamino) -tri-isophthalic acid to rare earth ions in the rare earth salt is 1: 0.2-1: 15;

the mass volume concentration of the organic solution of the organic ligand 5, 5' - (1,3, 5-triazine-2, 4, 6-triamino) -tri-isophthalic acid is 0.3-5%; the organic solvent in the organic solution of the 5, 5' - (1,3, 5-triazine-2, 4, 6-trimethyleneamino) -tri-isophthalic acid is DMSO or DMF, and is preferably DMSO;

the concentration of the rare earth ions in the mixed liquid of the organic ligand and the rare earth ions is 10-80 mmol/L.

Preferably, the volume ratio of the aqueous solution of the bio-based polymer to the mixed solution of the organic ligand and the rare earth ions is 9:1 to 1: 9.

Preferably, the heating temperature is 50-95 ℃; the heating time is 30-150 min.

Preferably, the heating temperature is 65-85 ℃; the heating time is 30-100 min.

According to another aspect of the present invention, there is provided a xerogel material based on said chitosan or water-soluble derivative doped rare earth supramolecular gel material.

According to another aspect of the invention, there is provided the use of said xerogel material as a rare earth supramolecular xerogel luminescent material.

According to another aspect of the invention, the application of the xerogel material is provided for preparing a fluorescence sensor for identifying a plurality of metal ions.

Preferably, it is used for preparing a fluorescent sensor or fluorescent probe for distinguishing and identifying various metal ions.

Through the technical scheme, compared with the prior art, the invention can obtain the following beneficial effects:

(1) the invention provides a rare earth supramolecular gel material doped with chitosan or water-soluble derivatives thereof, which comprises bio-based macromolecular chitosan or water-soluble derivatives thereof, an organic ligand and rare earth salt; wherein the organic ligand is 5, 5' - (1,3, 5-triazine-2, 4, 6-triamino) -tri-isophthalic acid; the rare earth ion in the rare earth salt is terbium; on one hand, the rare earth supramolecular gel material utilizes the hydrogen bond effect of chitosan or water-soluble derivatives thereof and the organic ligand to increase the light absorption of the organic ligand so as to promote the energy transfer from the organic ligand to rare earth ions and further improve the luminescence property of the rare earth supramolecular gel material; on the other hand, the coordination effect of the chitosan or the water-soluble derivative thereof and the rare earth ions in the rare earth salt and the hydrogen bonding effect of the chitosan or the water-soluble derivative thereof and the organic ligand are utilized to enable the chitosan or the water-soluble derivative thereof to be adsorbed on the surface of the rare earth supramolecular gel fiber, so that water molecules are far away from the rare earth ions, and the luminescence property of the rare earth supramolecular gel material is further improved.

(2) According to the rare earth supermolecule gel provided by the invention, chitosan or a water-soluble derivative thereof is introduced into the gel material system, and the chitosan or the water-soluble derivative thereof is an environment-friendly bio-based polymer, is non-toxic and harmless, and has good biocompatibility and biodegradability. The method has the advantages that the bio-based polymer is used as a doping component to dope the rare earth supermolecule gel, so that the method is environment-friendly and endows the original rare earth supermolecule gel with excellent functionality.

(3) The xerogel of the rare earth supermolecule gel not doped with chitosan or the water-soluble derivative thereof basically does not emit light in aqueous solution, however, the rare earth supermolecule xerogel material doped with chitosan or the water-soluble derivative thereof has stable light emission property in aqueous solution, and in a certain embodiment, H₆L/Tb³⁺The fluorescence intensity of the/CMCS supermolecule xerogel in the water solution is kept stable within 0-100 min.

(4) Compared with the rare earth supramolecular gel material which is not doped with chitosan or water-soluble derivatives thereof, the rare earth supramolecular gel material doped with chitosan or water-soluble derivatives thereof provided by the preferred embodiment of the invention not only improves the fluorescence intensity by more than 9 times, but also improves the luminescence life by more than 2 times.

(5) The rare earth doped supermolecule gel provided by the invention can be obtained only by mixing the mixed solution of the organic ligand and the rare earth ions with the aqueous solution of the chitosan or the water-soluble derivative thereof at a certain temperature, and the preparation process is simple and controllable.

(6) The light emission of the rare earth-doped supermolecule gel xerogel powder in a water environment can be controlled by pH, different response modes for different metal ions under different pH can be realized, different optical signals can be generated for different metal ions according to the difference of the response modes, namely enhancement or quenching of fluorescence intensity to different degrees, and further, the main component analysis (PCA) by means of mathematical processing can be used for distinguishing and identifying various metal ions. Therefore, the rare earth doped supermolecule xerogel provided by the invention can be used for preparing a fluorescence sensor or a fluorescence probe for identifying various metal ions, and the various metal ion sensors can extract multi-dimensional information by using a single signal source to construct multi-target metal ion identification.

Drawings

FIG. 1 is CMCS doping with H₆L/Tb³⁺SEM and appearance of xerogel.

FIG. 2 is CMCS doping with H₆L/Tb³⁺And comparing the light emission spectra of the gel under 333nm excitation light.

FIG. 3 shows different types of bio-based polymers doped with H₆L/Tb³⁺And comparing light emission spectra under 333nm excitation light.

FIG. 4 is CMCS doping with H₆L/Tb³⁺The rare earth light emission capability comparison of the gel is improved in different solvent types, wherein DMF is used as an organic solvent in the content a of figure 4, and DMSO is used as a solvent in the content b of figure 4.

FIG. 5 is CMCS doping with H₆L different rare earth ion gel for improving rare earth light emissionFor comparison, the rare earth used in the content a of fig. 5 is terbium chloride, the rare earth used in the content b of fig. 5 is europium chloride, the rare earth used in the content c of fig. 5 is dysprosium chloride, and the rare earth used in the content d of fig. 5 is samarium chloride.

FIG. 6 is a comparison of CMCS doped rare earth ion gels with different gel factors for improving rare earth light emission capability, wherein the gel factor used in content a is H₆L, content b uses Fmoc-L-tyrosine as the gelator.

FIG. 7 is CMCS doping with H₆L/Tb³⁺The fluorescence intensity curve of the supramolecular xerogel is normalized along with the change of pH.

FIG. 8 is CMCS doping with H₆L/Tb³⁺The luminous intensity of the supermolecule xerogel powder aqueous solution changes along with the standing time.

FIG. 9 is a graph of whether CMCS is doped with H₆L/Tb³⁺And (3) comparing the light emission spectrum of the gel xerogel dispersed in the aqueous solution under 333nm excitation light.

FIG. 10 shows CMCS doping with H₆L/Tb³⁺The effect of the supramolecular xerogel powder on the fluorescence signals of 11 metal ions, and the content a-content c in FIG. 10 are respectively the effect of 11 metal ions on H when the metal ion is 0.2mM₆L/Tb³⁺/CMCS fluorescence Signal (I)₀-I)/I₀Influence of (A), I and I₀Based on H, the luminous intensity at 546nm of metal ions added and not added respectively₆L/Tb³⁺/CMCS fluorescence Signal (I)₀-I)/I₀The heat map and PCA map of (1) were used for the identification of 11 metal ions; FIG. 10 shows contents d-f in which 11 types of metal ions are present in pairs H at a metal ion concentration of 0.01mM₆L/Tb³⁺/CMCS fluorescence Signal (I)₀-I)/I₀Based on H₆L/Tb³⁺/CMCS fluorescence Signal (I)₀-I)/I₀The heat map and PCA map of (1) were used for the identification of 11 metal ions; FIG. 10 shows the contents g-content i of 11 metal ion pairs H at a metal ion concentration of 0.002mM₆L/Tb³⁺/CMCS fluorescence Signal (I)₀-I)/I₀Based on H₆L/Tb³⁺/CMCS fluorescence Signal (I)₀-I)/I₀The thermal map and PCA map of (A) was used for the identification of 11 metal ions.

FIG. 11 is a schematic view ofCMCS doping with H₆L/Tb³⁺The ability of the supramolecular xerogel powder to distinguish mixed metal ions, content a of FIG. 11 is Fe³⁺And Fe²⁺Mixed metal ion system (total concentration 50. mu.M), content b being Fe³⁺And Cu²⁺Mixed metal ion system of (total concentration 10 μ M).

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides a rare earth supramolecular gel material doped with chitosan or water-soluble derivatives thereof, which comprises the chitosan or the water-soluble derivatives thereof, an organic ligand and rare earth salt; wherein the organic ligand (also as a gelator) is 5, 5' - (1,3, 5-triazine-2, 4, 6-trisylamino) -tri-isophthalic acid; the rare earth element in the rare earth salt is terbium.

Under the condition of doping chitosan or water-soluble derivatives thereof, the rare earth supermolecule gel material is formed by self-assembly by utilizing the coordination of the organic ligand and rare earth ions in rare earth salt, the pi-pi interaction between molecules of the organic ligand, the coordination of the chitosan or water-soluble derivatives thereof and the rare earth ions in the rare earth salt and the hydrogen bond interaction of the chitosan or water-soluble derivatives thereof and the organic ligand.

On one hand, the rare earth supramolecular gel material can utilize the hydrogen bond action of chitosan or water-soluble derivatives thereof and the organic ligand to increase the light absorption of the organic ligand so as to promote the energy transfer from the organic ligand to rare earth ions and further improve the luminescence property of the rare earth supramolecular gel material; on the other hand, the coordination effect of chitosan or the water-soluble derivative thereof and rare earth ions in the rare earth salt and the hydrogen bond effect of chitosan or the water-soluble derivative thereof and the organic ligand can be utilized to enable carboxymethyl chitosan to be adsorbed on the surface of the rare earth supramolecular gel fiber, so that water molecules are far away from the rare earth ions, and the luminescence property of the rare earth supramolecular gel material is further improved.

The rare earth supramolecular gel material provided by the invention is a rare earth supramolecular gel material doped with a bio-based macromolecule, wherein the bio-based macromolecule is chitosan or a water-soluble derivative thereof. Specifically, the chitosan/rare earth complex is prepared by mixing an aqueous solution of chitosan or a water-soluble derivative thereof with a mixed solution of the organic ligand and a rare earth salt under a heating condition. The rare earth supramolecular gel material also comprises a solvent, wherein the solvent is a mixed solvent of acetic acid and water, a mixed solvent of DMF and water or a mixed solvent of DMSO and water. For example, when the bio-based polymer is chitosan, the chitosan itself cannot be dissolved in water, and the chitosan is dissolved in an aqueous solution of acetic acid to obtain an aqueous solution of chitosan, and then the gel material is prepared. When the bio-based polymer is a water-soluble derivative thereof such as carboxymethyl chitosan or hydroxypropyl chitosan, it is directly dissolved in water to obtain an aqueous solution of the water-soluble derivative of chitosan, and then a gel material is prepared. The water-soluble derivatives of chitosan include, but are not limited to, carboxymethyl chitosan and hydroxypropyl chitosan.

The chitosan or the water-soluble derivative thereof adopted by the invention contains amino and hydroxyl, part of the water-soluble derivative of the chitosan also contains carboxyl which can be coordinately combined with rare earth ions and can form hydrogen bonds with the carboxyl and the amino of an organic ligand to interact with each other, in addition, the high-conjugated structure of the organic ligand enables the organic ligand to have good pi-pi stacking effect in the gelling process, and the carboxyl of the organic ligand and the rare earth ions can also form coordinate bonds.

Chitosan (abbreviated as CTS in the present invention) or its water-soluble derivative carboxymethyl chitosan (abbreviated as CMCS in the present invention), hydroxypropyl chitosan (abbreviated as HPCS in the present invention) and 5, 5' - (1,3, 5-triazine-2, 4, 6-trisaminol) -tri-isophthalic acid organic ligand (written as H in the present invention)₆L) has the following molecular structure:

in the experiment, it is found that,the luminous intensity of the rare earth supramolecular gel material doped with the polymer chitosan or the water-soluble derivative thereof with excellent biocompatibility is greatly enhanced compared with that of the rare earth supramolecular gel material not doped with the polymer, and the possible mechanism is as follows: the chitosan or the water-soluble derivative thereof is adsorbed on the basis of H through the interaction force of hydrogen bonds and coordination bonds among molecules₆The rare earth supermolecule gel fiber surface of L can make the aggregated gel fiber obtain dispersion, and the chitosan or its water-soluble derivative can make water molecule be "far away" from rare earth and increase H₆L light absorption to promote H₆And the energy transfer from L to the rare earth ions improves the luminescence property. Compared with the gel material which is not doped with chitosan or water-soluble derivatives thereof, the rare earth supramolecular gel material provided by the invention realizes double promotion of quantum yield and fluorescence life.

Experiments prove that the xerogel prepared by removing the solvent from the rare earth supramolecular gel doped with the bio-based polymer has stable light emission in aqueous solution, the light emission of xerogel powder in water environment can be controlled by pH, and a sensor for distinguishing and detecting 11 metal ions can be obtained by adjusting the pH value of the aqueous solution of the rare earth supramolecular gel doped with the bio-based polymer, and the sensor has good distinguishing and detecting performance on the metal ions.

The preparation method of the rare earth supramolecular gel material is characterized in that an aqueous solution of chitosan or a water-soluble derivative thereof is mixed with a mixed solution of the organic ligand and rare earth ions, and the rare earth supramolecular gel material is prepared under the heating condition. The charging sequence is not changeable, in experiments, the mixed solution of the aqueous solution of carboxymethyl chitosan and the rare earth ions is tried to be mixed firstly and then is mixed with the organic solution of the organic ligand, and the rare earth ions and CMCS are agglomerated to form white flocculent fibers, so that the supermolecule gel material cannot be obtained.

In some embodiments, the method of making comprises the steps of:

(1) dissolving chitosan or its water-soluble derivative in a solvent containing water to obtain an aqueous solution of chitosan or its water-soluble derivative;

(2) mixing an organic solution of 5, 5' - (1,3, 5-triazine-2, 4, 6-triamino) -tri-isophthalic acid with a rare earth salt solution to obtain a mixed solution of an organic ligand and rare earth ions;

(3) and (3) mixing the aqueous solution of the chitosan or the water-soluble derivative thereof in the step (1) with the mixed solution of the organic ligand and the rare earth ions in the step (2), and heating to obtain the rare earth supramolecular gel material doped with the chitosan or the water-soluble derivative thereof.

In some embodiments, the concentration of carboxymethyl chitosan in the aqueous solution of chitosan or its water-soluble derivative in step (1) is 0.01% to 2% (w/v, i.e., the mass of carboxymethyl chitosan in 100ml of the aqueous solution of carboxymethyl chitosan, g), preferably 0.1% to 1% (w/v).

The functional groups such as amino, hydroxyl and the like contained in the bio-based polymer doped in the rare earth supermolecule gel material play an important role in improving the luminous performance of the gel material. In some preferred embodiments, the water-soluble derivatives of chitosan in step (1) are carboxymethyl chitosan and hydroxypropyl chitosan, preferably carboxymethyl chitosan. The polymerization degree n of the chitosan or the water-soluble derivative thereof is 500-2000, and the deacetylation degree DD is more than 75%.

In some embodiments, the aqueous solution of chitosan in step (1) is an aqueous solution of chitosan with a mass volume concentration of 0.1% to 5% obtained by dissolving chitosan in a mixed solvent of acetic acid and water. When the water-soluble derivative of chitosan is carboxymethyl chitosan, the preferred degree of substitution DS is 0.1 to 2. When the water-soluble derivative of chitosan is hydroxypropyl chitosan, the preferred substitution degree DS is 0.1-2.

In some embodiments, the molar ratio of the 5, 5' - (1,3, 5-triazine-2, 4, 6-trisylamino) -tri-isophthalic acid to the rare earth ions in the rare earth salt in step (2) is from 1:0.2 to 1: 15; preferably 1: 0.5-1: 10; the mass volume concentration of the organic solution of the organic ligand 5, 5' - (1,3, 5-triazine-2, 4, 6-triimido) -tri-isophthalic acid is 0.3-5% (w/v); the final concentration of the rare earth ions in the mixed solution of the organic ligand and the rare earth ions is 10-80 mmol/L.

In some embodiments, the volume ratio of the aqueous solution of chitosan or its water-soluble derivative in step (3) to the mixed solution of organic ligand and rare earth ions is 9: 1-1: 9. The heating temperature in the step (3) is 50-95 ℃; the heating time is 30-150 min; preferably, the heating temperature is 65-85 ℃; the heating time is 30-100 min.

The invention also provides a xerogel material based on the rare earth supermolecular gel material doped with the chitosan or the water-soluble derivative thereof. The xerogel material is obtained by removing the solvent in the rare earth supermolecule gel material; wherein the solvent is a mixed solvent of DMSO and water, a mixed solvent of DMF and water, a mixed solvent of DMSO, water and acetic acid, or a mixed solvent of DMF, water and acetic acid.

In some embodiments, the solvent in the prepared rare earth supramolecular gel material doped with chitosan or water-soluble derivatives thereof is replaced by solvent water, and then the xerogel material is obtained by freeze drying. In some of these examples, solvent displacement was performed using soxhlet extraction.

The invention also provides application of the xerogel material as a rare earth supermolecule xerogel luminescent material. The xerogel material can also be used for preparing a fluorescent sensor or a fluorescent probe for distinguishing and identifying various metal ions. The xerogel powder prepared from the doped rare earth supermolecule gel provided by the invention can identify various metal ions in a water environment with high specificity.

In a preferred embodiment of the invention, chitosan or a water-soluble derivative thereof is first dissolved in a solvent comprising water, and then H is added₆Mixing the organic solution of L and the solution of rare earth ion salt according to a certain proportion and concentration, and then mixing the aqueous solution of chitosan or the water-soluble derivatives thereof with H₆And mixing the L with the mixed solution of the rare earth ions, and further heating to obtain the rare earth-doped supermolecule gel luminescent material. The heating here serves to promote the formation of coordination, pi-pi and hydrogen bonding weak interaction forces. The preferable organic solvent is DMSO or DMF, the preferable doped polymer is chitosan or water-soluble derivatives thereof, and the prepared doped rare earth supramolecular gel material has the best performance. Experiment ofOther bio-based polymers, such as cellulose, have been tried, but the prepared gel material has poor luminescence under the same conditions. From this, it is presumed that chitosan or a water-soluble derivative thereof, H₆The L and the rare earth ions have specific interaction, so that the L and the rare earth ions become an integral body which can be divided to jointly play a role of improving the fluorescence intensity of the L and the rare earth ions, and the mutual cooperation of the L and the rare earth ions can improve the luminescence property of the doped gel and keep the state of the gel.

Rare earth ions other than terbium, such as europium chloride (Eu), dysprosium chloride (Dy), and samarium chloride (Sm), were also tried in the experiments of the present invention, but it was found that the fluorescence intensity did not change before and after doping chitosan or its water-soluble derivative for europium chloride and dysprosium chloride, and that the gel fluorescence intensity did not increase or decrease for samarium chloride after doping chitosan or its water-soluble derivative. In the gel system of the invention, different types of rare earth ions before and after doping with chitosan or water-soluble derivatives thereof have completely different performances, probably because other rare earth ions and ligand H₆The energy level of L is not matched, H cannot be caused₆The energy of L is transferred to other rare earth ions, and even though the chitosan or the water-soluble derivative thereof can exclude the water molecules coordinated around the rare earth ions, the chitosan or the water-soluble derivative thereof cannot protect the luminescence without the source of energy transfer.

The bio-based polymer chitosan or the water-soluble derivative thereof doped rare earth supramolecular gel luminescent material provided by the invention is not only environment-friendly, but also endows the original rare earth supramolecular gel with excellent functionality. The preparation process is simple and controllable, and the obtained rare earth-doped supermolecule gel realizes double promotion of quantum yield and fluorescence life. And the doped rare earth supermolecule gel xerogel powder has stable light emission in water environment and can be used for constructing multi-target metal ion identification.

The rare earth supermolecule gel system comprises a doping component, an organic ligand and rare earth ions, and is formed by being driven by the coordination interaction of the organic ligand and the doping component and the rare earth ions depending on the pi-pi interaction and the hydrogen bond interaction of the organic ligand and the hydrogen bond interaction of the doping component and the organic ligand. The formed gel has the characteristic light emission of rare earth, good fluorescence monochromaticity, high quantum yield and long fluorescence life. The invention has the advantages that: the doped component is a bio-based polymer, so that the rare earth doped supermolecule gel is environment-friendly, and the quantum yield and the fluorescence life are improved; the doped rare earth supermolecule xerogel has stable light emission in aqueous solution and can be used as a sensor for identifying various metal ions in aqueous phase.

The following are examples:

example 1

A rare earth supramolecular gel material with luminescence stability is prepared by the following specific steps: 6mg of CMCS (n 1000; DS 1; DD 80%) are dissolved in 0.5mL of H₂O,7.4mg H₆L was dissolved in 0.5mL of DMSO, 5. mu.L of a 2.4mol/L aqueous solution of terbium chloride was added thereto and mixed by shaking sufficiently, and then the above CMCS-containing aqueous solution and H were added₆And (3) vortex mixing the L and a DMSO solution of terbium chloride, placing the mixture into an oven at 85 ℃ and standing the mixture for 100min to form a milky gel, namely the rare earth-doped supermolecule gel, as shown in figure 1.

Compared with the gel material of undoped CMCS, the rare earth-doped supermolecular gel has the advantages that the luminous intensity is increased by 9 times, and the fluorescence life is prolonged by 2.4 times; and the rare earth doped supermolecule gel material is frozen and dried to remove the solvent, so that a xerogel powder material is obtained, and the material still has stable luminescence in water.

Example 2

1mg of CMCS (n 600; DS 1.2; DD 90%) was dissolved in 0.4mL of H₂O,8mg H₆L was dissolved in 0.6mL of DMSO, and then 15. mu.L of a 2.4mol/L aqueous solution of terbium chloride was added thereto and mixed well with shaking, and then the above CMCS-containing aqueous solution and H were added₆And (3) vortex mixing the L and a DMSO solution of terbium chloride, placing the mixture into an oven at 85 ℃ and standing the mixture for 90min to form a milky white gel, namely the rare earth doped supermolecule gel.

Compared with the gel material of undoped CMCS, the rare earth-doped supermolecular gel has the advantages that the luminous intensity is increased by 1.2 times, and the fluorescence life is prolonged by more than 1.1 times; and the rare earth doped supermolecule gel material is frozen and dried to remove the solvent, so that a xerogel powder material is obtained, and the material still has stable luminescence in water.

Example 3

2mg of CMCS (n 1500; DS 0.8; DD 95%) was dissolved in 0.4mL of H₂O,10mg H₆L was dissolved in 0.6mL of DMSO, 10. mu.L of a 2.4mol/L aqueous solution of terbium chloride was added thereto and mixed well with shaking, and the above aqueous solution containing CMCS and H were added₆And (3) vortex mixing the L and a DMSO solution of terbium chloride, placing the mixture into a 65 ℃ oven, and standing for 50min to form a milky white gel, namely the rare earth doped supermolecule gel.

Compared with the gel material of undoped CMCS, the rare earth-doped supermolecular gel has the advantages that the luminous intensity is increased by 2.3 times, and the fluorescence life is prolonged by more than 1.5 times; and the rare earth doped supermolecule gel material is frozen and dried to remove the solvent, so that a xerogel powder material is obtained, and the material still has stable luminescence in water.

Example 4

6mg of CMCS (n 500; DS 1.8; DD 85%) was dissolved in 0.6mL of H₂O,8mg H₆L was dissolved in 0.4mL of DMSO, 5. mu.L of a 2.4mol/L aqueous solution of terbium chloride was added thereto and mixed by shaking sufficiently, and then the above CMCS-containing aqueous solution and H were added₆And (3) vortex mixing the L and a DMSO solution of terbium chloride, placing the mixture into an oven at 85 ℃ and standing the mixture for 30min to form a milky white gel, namely the rare earth doped supermolecule gel.

Compared with the gel material of undoped CMCS, the rare earth-doped supermolecular gel has the advantages that the luminous intensity is increased by 4.4 times, and the fluorescence life is prolonged by more than 1.5 times; and the rare earth doped supermolecule gel material is frozen and dried to remove the solvent, so that a xerogel powder material is obtained, and the material still has stable luminescence in water.

Example 5

3mg of CMCS (n 800; DS 1.4; DD 92%) was dissolved in 0.4mL of H₂O,12mg H₆L was dissolved in 0.6mL of DMSO, 25. mu.L of a 2.4mol/L aqueous solution of terbium chloride was added thereto and mixed by shaking sufficiently, and then the above CMCS-containing aqueous solution and H were added₆L and a DMSO solution of terbium chloride are mixed in a vortex mode, then placed in a 75 ℃ oven and kept stand for 60min to form a milky white gel, namely the rare earth-doped ultra-separation material(ii) a subgel.

Compared with the gel material of undoped CMCS, the rare earth-doped supermolecular gel has the advantages that the luminous intensity is increased by 2.9 times, and the fluorescence life is prolonged by more than 1.6 times; and the rare earth doped supermolecule gel material is frozen and dried to remove the solvent, so that a xerogel powder material is obtained, and the material still has stable luminescence in water.

Example 6

5mg of CMCS (n 1200; DS 0.5; DD 90%) are dissolved in 0.5mL of H₂O,12mg H₆L was dissolved in 0.5mL of DMSO, 25. mu.L of a 2.4mol/L aqueous solution of terbium chloride was added thereto and mixed by shaking sufficiently, and then the above CMCS-containing aqueous solution and H were added₆And (3) vortex mixing the L and a DMSO solution of terbium chloride, placing the mixture into a 75 ℃ oven, and standing for 60min to form a milky white gel, namely the rare earth-doped supermolecule gel.

Compared with the gel material of undoped CMCS, the rare earth-doped supermolecular gel has the advantages that the luminous intensity is increased by 6.9 times, and the fluorescence life is prolonged by more than 1.8 times; and the rare earth doped supermolecule gel material is frozen and dried to remove the solvent, so that a xerogel powder material is obtained, and the material still has stable luminescence in water.

Example 7

0.2mg of CMCS (n 500; DS 0.8; DD 95%) was dissolved in 0.8mL of H₂O,7.4mg H₆L was dissolved in 0.2mL of DMSO, 5. mu.L of a 2.4mol/L aqueous solution of terbium chloride was added thereto and mixed by shaking sufficiently, and then the above CMCS-containing aqueous solution and H were added₆And (3) vortex mixing the L and a DMSO solution of terbium chloride, placing the mixture into a 75 ℃ oven, and standing the mixture for 70min to form a milky white gel, namely the rare earth doped supermolecule gel.

Compared with the gel material of undoped CMCS, the rare earth-doped supermolecular gel has the advantages that the luminous intensity is increased by 0.9 times, and the fluorescence life is prolonged by more than 1.1 times; and the rare earth doped supermolecule gel material is frozen and dried to remove the solvent, so that a xerogel powder material is obtained, and the material still has stable luminescence in water.

Example 8

6mg of CMCS (n 1000; DS 1; DD 80%) are dissolved in 0.5mL of H₂O,7.4mg H₆L was dissolved in 0.5mL DMSO and inoculatedAdding 5 mu L of 2.4mol/L aqueous solution of terbium nitrate, sufficiently shaking and mixing, and then mixing the aqueous solution containing CMCS and H₆And (3) vortex mixing the L and a DMSO solution of terbium nitrate, placing the mixture into an oven at 85 ℃ and standing for 100min to form a milky white gel, namely the rare earth doped supermolecule gel.

Compared with the gel material of undoped CMCS, the rare earth-doped supermolecular gel has the advantages that the luminous intensity is increased by 4.4 times, and the fluorescence life is prolonged by more than 1.7 times; and the rare earth doped supermolecule gel material is frozen and dried to remove the solvent, so that a xerogel powder material is obtained, and the material still has stable luminescence in water.

Example 9

6mg of CTS (n 1000; DS 1; DD 80%) was dissolved in 0.5mL of 0.1% aqueous acetic acid, 7.4mg of H₆L was dissolved in 0.5mL of DMSO, 5. mu.L of a 2.4mol/L aqueous solution of terbium chloride was added thereto and mixed well with shaking, and then the above aqueous solution containing CTS and H were added₆And (3) vortex mixing the L and a DMSO solution of terbium chloride, placing the mixture into an oven at 85 ℃ and standing for 100min to form a milky white gel, namely the rare earth doped supermolecule gel.

Compared with the gel material without CTS, the rare earth-doped supermolecule gel has the advantages that the luminous intensity is increased by 4.9 times, and the fluorescence life is prolonged by more than 1.9 times; and the rare earth doped supermolecule gel material is frozen and dried to remove the solvent, so that a xerogel powder material is obtained, and the material still has stable luminescence in water.

Likewise, in H₆The concentration of the L organic solution is 0.4-2% (w/v), the organic solvent is DMSO or DMF, the rare earth salt is terbium chloride, terbium nitrate or terbium sulfate, the polymerization degree n of the chitosan or the water-soluble derivative thereof is 500-2000, the substitution degree DS of the water-soluble derivative of the chitosan is 0-2, and the deacetylation degree DD is>75％，H₆The concentration of rare earth ions in the mixed solution obtained by mixing the organic solution L and the rare earth salt is within the range of 12-60 mmol/L, other groups of experiments are carried out, the rare earth doped supermolecule gel can be obtained, and the experiments prove that the fluorescence intensity of the gel is higher than that of the gel prepared when the chitosan or the water-soluble derivative thereof is not doped. And the prepared rare earth doped supermolecule gel material is subjected to freeze drying to remove the solvent to obtain xerogelThe powder material still has stable luminescence in water.

Comparative example 1

The emission spectra of rare earth ions in CMCS doped supramolecular gels were compared to undoped protosupramolecular gels.

(I) test materials

Material 1: h provided by the embodiment₆L/Tb³⁺CMCS doped rare earth supermolecule gel, with DMSO and H as solvent₂O, the total volume is 1mL, the rare earth ion is terbium chloride, the concentration of CMCS (n is 1000; DS is 1; DD is 80%) is 0.6% (w/v), the final concentration of terbium ion is 12mmol/L, H₆L was prepared as described in example 1, with a final concentration of 0.74% (w/v).

Material 2: h used in this example₆Mixed solution of L and terbium ions, and the solvent is DMSO and H₂O, the total volume is 1mL, the rare earth ion is terbium chloride, the final concentration of the terbium ion is 12mmol/L, H₆L was prepared as described in example 1, with a final concentration of 0.74% (w/v).

(II) experimental method: the above two materials in a sealed quartz cuvette were tested for fluorescence by fluorescence spectrometer and the results are shown in fig. 2 and table 1.

After being tested by a fluorescence spectrometer, the terbium ion is in H₆The fluorescence emission spectra in the supramolecular gel formed by L compared to that in solution are shown in fig. 2. As can be seen from fig. 2, the luminescence intensity of the rare earth ions in the doped supramolecular gel of the present invention is increased by 9 times compared to that in the original supramolecular gel. As shown in table 2, the quantum yield of the rare earth ions in the doped supramolecular gel of the present invention is also improved by 9 times compared to the original supramolecular gel, and the luminescence lifetime is increased from 0.58ms to 1.21 ms.

TABLE 1 doping of rare earth ions before and after CMCS doping supramolecular gel H in this example₆L/Tb³⁺/CMCS and Prosupramolecular gel H₆L/Tb³⁺Quantum yield of (2) compared to fluorescence lifetime

Comparative example 2

Comparison of luminous performance of different kinds of bio-based polymer doped rare earth supermolecule gel and original supermolecule gel state retaining capability

(I) test materials

Material 2: h provided by the embodiment₆L/Tb³⁺the/C-doped rare earth supermolecule gel (in the invention, C is cellulose), and the solvent is DMSO and H₂O, the total volume is 1mL, the rare earth ion is terbium chloride, the concentration of C is 0.6% (w/v), the final concentration of terbium ion is 12mmol/L, H₆L was prepared as described in example 1, with a final concentration of 0.74% (w/v).

Material 3: h used in this example₆Mixed solution of L and terbium ions, and the solvent is DMSO and H₂O, the total volume is 1mL, the rare earth ion is terbium chloride, the final concentration of the terbium ion is 12mmol/L, H₆L was prepared as described in example 1, with a final concentration of 0.74% (w/v).

(II) experimental method: the three gels prepared in the sealed quartz cuvette were tested for fluorescence by a fluorescence spectrometer and observed for the condition that each doped component retained the original gel state, and the results are shown in fig. 3.

After the test of the fluorescence spectrometer, each doped gel and H₆The fluorescence emission spectra of the supramolecular gel of L/Tb are shown in comparison in FIG. 3. As can be seen from FIG. 3, CMCS promotes Tb³⁺The best luminous effect, C (representing cellulose) has the worst luminous performance, and Tb is improved³⁺There is substantially no enhancement in luminescence (the peak at 470nm in this curve is the enhanced ligand light).

Example 10

Comparison of organic solvent types on CMCS (China Mobile communication System) for improving rare earth supramolecular gel luminescence property

(I) test materials

Material 3: h provided by the embodiment₆L/Tb³⁺CMCS doped rare earth supermolecule gel, with DMF and H as solvent₂O, the total volume is 1mL, the rare earth ion is terbium chloride, the concentration of CMCS (n is 1000; DS is 1; DD is 80%) is 0.6% (w/v), the final concentration of terbium ion is 12mmol/L, H₆L was prepared as described in example 1, with a final concentration of 0.74% (w/v).

Material 4: h used in this example₆Mixed solution of L and terbium ion, and solvents of DMF and H₂O, the total volume is 1mL, the rare earth ion is terbium chloride, the final concentration of the terbium ion is 12mmol/L, H₆L was prepared as described in example 1, with a final concentration of 0.74% (w/v).

(II) experimental method: the four gels prepared in the sealed quartz cuvette were tested for fluorescence by a fluorescence spectrometer and observed for the condition that each doped component retained the original gel state, and the results are shown in fig. 4.

After the test of the fluorescence spectrometer, each doped gel and H₆The fluorescence emission spectra of the supramolecular gel of L/Tb is shown in comparison in FIG. 4. Wherein, the content b in fig. 4 is the comparison of the fluorescence emission spectra of the supramolecular gel prepared by the

materials

1 and 2 by using DMSO as an organic solvent, and the content a in fig. 4 is the comparison of the fluorescence emission spectra of the supramolecular gel prepared by the

materials

3 and 4 by using DMF as a solvent. ByFIG. 4 shows that CMCS is performed in the presence of DMF and H as solvents₂Lifting Tb in O³⁺Luminescence intensity was 1.5 fold, CMCS in solvents DMSO and H₂Lifting Tb in O³⁺The intensity of luminescence is 9 times, so that DMSO or DMF can be selected as the organic solvent in the doped gel, and DMSO is preferred.

Comparative example 3

Influence of rare earth ion type on CMCS (China Mobile communication System) doped supramolecular gel luminescence property

The preparation method of the gel is the same as that of the example 1, other conditions are completely the same, only the types of the rare earth ions are changed, and whether the gel is formed by different rare earth ions or not is observed and compared. The results are shown in FIG. 5, in which the rare earth used in the content a of FIG. 5 is terbium (Tb) chloride, the rare earth used in the content b of FIG. 5 is europium (Eu) chloride, the rare earth used in the content c of FIG. 5 is dysprosium (Dy) chloride, and the rare earth used in the content d of FIG. 5 is samarium (Sm) chloride.

Experimental results show that the CMCS has the best effect of improving the luminous performance of the supramolecular gel when only the rare earth ion is terbium chloride. Possible reasons are other rare earth ions and ligand H₆The energy level of L is not matched, H cannot be caused₆The energy of L is transferred to other rare earth ions, and even though CMCS can exclude the water molecules coordinated around these rare earth ions, without a source of energy transfer, CMCS cannot protect luminescence.

Comparative example 4

Influence of gel factor type on CMCS (China Mobile communication System) doped supramolecular gel luminescence property and doped supramolecular gel state

(I) test materials

Material 1: h provided by the embodiment₆L/Tb³⁺CMCS doped rare earth supermolecule gel, with DMSO and H as solvent₂O, the total volume is 1mL, the rare earth ion is terbium chloride, the concentration of CMCS (n is 1000; DS is 1; DD is 80%) is 0.6% (w/v); the final concentration of terbium ion is 12mmol/L, H₆L was prepared as described in example 1, with a final concentration of 0.74% (w/v).

Material 3: Fmoc-Tyr-OH/Tb provided in this example³⁺CMCS doped rare earth supramolecular gel (in the embodiment, Fmoc-Tyr-OH is Fmoc-L-tyrosine), and solvents of methanol and H₂O, terbium chloride as a rare earth ion, 0.6% (w/v) as a CMCS (n 1000; DS 1; DD 80%), 5mmol/L as a terbium ion, 0.8% (w/v) as a Fmoc-Tyr-OH, and 1:1 as a molar ratio of NaOH to Fmoc-Tyr-OH in a total volume of 1mL (volume ratio of 1:4), followed by mixing all the components, vortexing, and standing.

Material 4: Fmoc-Tyr-OH/Tb provided in this example³⁺Rare earth supermolecule gel, methanol and H as solvent₂O, the total volume is 1mL (volume ratio is 1:4), the rare earth ion is terbium chloride, the final concentration of terbium ion is 5mmol/L, the final concentration of Fmoc-Tyr-OH is 0.8% (w/v), the molar ratio of NaOH to Fmoc-Tyr-OH is 1:1, all the components are mixed, vortexed and mixed evenly, and the mixture is kept stand. The structural formula of Fmoc-Tyr-OH is as follows:

(II) experimental method: the four gels prepared in sealed quartz cuvettes were tested for fluorescence by fluorescence spectroscopy and the results are shown in FIG. 6.

The fluorescence emission spectra of each doped gel and the original supramolecular gel after the fluorescence spectrometer test are shown in figure 6, and the gel factor used in the content a is H₆L, content b uses Fmoc-L-tyrosine as the gelator. As can be seen from FIG. 6, only the gelator is H₆And in the case of L, the CMCS has the best effect of improving the luminous performance of the supermolecule gel.

Example 11

The light emission characteristic of the rare earth doped supermolecule xerogel is disclosed.

(I) test materials

6mg of CMCS dissolved in 0.5mL of H₂O,7.4mg H₆L was dissolved in 0.5mL DMSO, followed by addition of 5. mu.L of a 2.4mol/L aqueous solution of terbium chloride and vigorous shakingMixing, and adding H to the above aqueous solution containing CMCS (n 1000; DS 1; DD 80%)₆And (3) vortex mixing the L and a DMSO solution of terbium chloride, placing the mixture into an oven at 85 ℃ and standing for 100min to form a milky white gel, namely the rare earth-doped supramolecular gel of the embodiment. The solvent DMSO/H in the rare earth-doped supermolecule gel is extracted by Soxhlet extraction₂Replacing the O with solvent water, and then freeze-drying to obtain the xerogel material corresponding to the rare earth-doped supermolecular gel.

(II) experimental method: the xerogels are respectively dispersed in buffer solutions (Tris-HCl buffer solution, 10mM) with different pH values, the change of the luminous intensity of the doped supermolecule xerogel powder aqueous solution along with the pH value is measured by a fluorescence spectrometer, and the dosage of the xerogels is 20 mg/L. The fluorescence intensity curves normalized at different pH's are shown in FIG. 7. The fluorescence emission intensity of the doped rare earth supramolecular xerogel dispersed in aqueous phase of buffer (Tris-HCl buffer, 10mM) at pH 7.4 and pH 6.2 was changed with time, and the results are shown in fig. 8.

The luminescence of the rare earth supramolecular xerogel in the range of pH 3.5-9.8 is tested by adopting a fluorescence spectrometer, as can be seen from FIG. 7, the luminescence of the doped rare earth supramolecular xerogel can be adjusted by pH, which is beneficial to extracting multidimensional information from a single signal source to construct a multi-target metal ion recognition sensor, and in the embodiment, the doped supramolecular xerogel is selected as a sensing array in an aqueous solution with the buffer pH 7.4 and the buffer pH 6.2.

FIG. 8 is terbium ion-induced H₆And the change of the fluorescence intensity of the L/Tb supermolecule metal gel xerogel in the aqueous solution along with the time is a fluorescence intensity graph. As can be seen in FIG. 8, H₆L/Tb³⁺The fluorescence intensity of the/CMCS supermolecule xerogel in the water solution is kept stable within 0-100 min, which shows that the light emission of the gel has water stability and is beneficial to the construction of the sensor.

Comparative example 5

The fluorescence intensity of the corresponding rare earth ions before and after CMCS doping in the doped supermolecule xerogel is compared with that of the aqueous solution in the undoped original supermolecule xerogel.

(I) test materials

Material 1: h provided by the embodiment₆L/Tb³⁺CMCS doped rare earth supermolecule gel, with DMSO and H as solvent₂O, the total volume is 1mL, the rare earth ion is terbium chloride, the concentration of CMCS (n is 100; DS is 1; DD is 80%) is 0.6% (w/v), the final concentration of terbium ion is 12mmol/L, H₆L was prepared as described in example 1, with a final concentration of 0.74% (w/v). The solvent DMSO/H in the rare earth-doped supermolecule gel is extracted by Soxhlet extraction₂Replacing the O with solvent water, and then freeze-drying to obtain the xerogel material corresponding to the rare earth-doped supermolecular gel.

Material 2: h used in this example₆Mixed solution of L and terbium ions, and the solvent is DMSO and H₂O, the total volume is 1mL, the rare earth ion is terbium chloride, the final concentration of the terbium ion is 12mmol/L, H₆L was prepared as described in example 1, with a final concentration of 0.74% (w/v). The solvent DMSO/H in the rare earth-doped supermolecule gel is extracted by Soxhlet extraction₂Replacing the O with solvent water, and then freeze-drying to obtain the xerogel material corresponding to the rare earth-doped supermolecular gel.

(II) experimental method: the two types of dry gels were dispersed in distilled water (both at 20mg/L) and tested for fluorescence by fluorescence spectrometer, the results are shown in FIG. 9.

The emission spectra of the two xerogels in water after fluorescence spectroscopy are shown in fig. 9. As can be seen from fig. 9, the luminescence intensity of the rare earth ions in the doped supramolecular xerogel of the present invention is improved by 27 times compared with that of the original supramolecular xerogel. The original supramolecular xerogel hardly luminesces in aqueous solution.

Example 12

The supramolecular gel luminescent material of the embodiment identifies and verifies various metal ions.

(I) test materials

The material of this embodiment is doped with H₆L/Tb³⁺CMCS supramolecular gel with DMSO and H as solvent₂O, the total volume is 1mL, the rare earth ion is terbium chloride, and the final concentration of the terbium ion is 12mmol/L, and the preparation method is as described in example 1. The rare earth doped supermolecule xerogel is prepared by placing the solvent doped with the supermolecule gel in waterReplacing, and freeze-drying.

(II) experimental method:

respectively reacting H with₆L/Tb³⁺the/CMCS supramolecular xerogel 4mg was dispersed in 100mL aqueous phase of pH 7.4 and pH 6.2 buffer (Tris-HCl buffer, 10mM) to make H₆L/Tb³⁺The concentration of the/CMCS probe mother liquor is 40mg/L, 0.5mL of the probe mother liquor with the pH value of 7.4 is transferred and placed in 12 cuvettes respectively, and Zn is added respectively²⁺、Ag⁺、Mg²⁺、Al³⁺、Ca²⁺、Na⁺、K⁺、Ba² ⁺、Fe³⁺、Co²⁺、Cu²⁺Adding a certain volume of buffer water solution with pH value of 7.4 to supplement the volume of the buffer water solution to 1mL after 11 metal ions are added and no metal ion is added; transferring 0.5mL of the mother solution with the pH value of 6.2 probe into 12 cuvettes respectively, and adding Zn into the mother solution²⁺、Ag⁺、Mg²⁺、Al³⁺、Ca²⁺、Na⁺、K⁺、Ba²⁺、Fe³⁺、Co²⁺、Cu²⁺And adding a certain volume of buffer water solution with the pH value of 6.2 to make up the volume of the buffer water solution to 1mL after waiting for 11 metal ions and without adding any metal ions. The final concentration of metal ions in this example was 0.2 mM. Measuring the luminous intensity (I) of metal ion solution added under 333nm exciting light wavelength and the H without any substance to be measured by a fluorescence spectrometer₆L/Tb³⁺Luminescence intensity (I) of/CMCS Probe (20mg/L)₀) The results are shown in FIG. 10. As can be seen from FIG. 10, content a, different metal ion pairs H₆L/Tb³⁺the/CMCS sensor has different response modes. Such as Fe³⁺、Co²⁺、Cu²⁺Quenching light emission, and Zn²⁺、Ag⁺Then enhanced light emission, Mg²⁺、Al³⁺、Ca²⁺、Ba²⁺Fluorescence is enhanced at pH 6.2 and quenched to varying degrees at pH 7.4, while Na⁺、K⁺The two metal ions also exhibit different degrees of quenched luminescence.

From the heat map of FIG. 10, content b, each metal ion pair H can be more effectively distinguished₆L/Tb³⁺of/CMCSA response mode. Next, by analyzing the experimental results using PCA technique, we performed 2-dimensional fingerprint with the first principal component PC1 (95.651%) and the second principal component PC2 (4.349%) as abscissa and ordinate, respectively, as shown in FIG. 10, content c, 11 separate clusters corresponding to 11 metal ions, indicating that the metal ions can be well separated, so H is₆L/Tb³⁺the/CMCS xerogel can be used as a sensor for distinguishing 11 metal ions.

Respectively reacting H with₆L/Tb³⁺the/CMCS supramolecular xerogel 4mg was dispersed in 100mL aqueous phase of pH 7.4 and pH 6.2 buffer (Tris-HCl buffer, 10mM) to make H₆L/Tb³⁺The concentration of the/CMCS probe mother liquor is 40mg/L, 0.5mL of the probe mother liquor with the pH value of 7.4 is transferred and placed in 12 cuvettes respectively, and Zn is added respectively²⁺、Ag⁺、Mg²⁺、Al³⁺、Ca²⁺、Na⁺、K⁺、Ba² ⁺、Fe³⁺、Co²⁺、Cu²⁺Adding a certain volume of buffer water solution with pH value of 7.4 to supplement the volume of the buffer water solution to 1mL after 11 metal ions are added and no metal ion is added; transferring 0.5mL of the mother solution with the pH value of 6.2 probe into 12 cuvettes respectively, and adding Zn into the mother solution²⁺、Ag⁺、Mg²⁺、Al³⁺、Ca²⁺、Na⁺、K⁺、Ba²⁺、Fe³⁺、Co²⁺、Cu²⁺And adding a certain volume of buffer water solution with the pH value of 6.2 to make up the volume of the buffer water solution to 1mL after waiting for 11 metal ions and without adding any metal ions. The final concentration of metal ions in this example was 0.01 mM. Measuring the luminous intensity (I) of metal ion solution added under 333nm exciting light wavelength and the H without any substance to be measured by a fluorescence spectrometer₆L/Tb³⁺Luminescence intensity (I) of/CMCS Probe (20mg/L)₀) The results are shown in FIG. 10. As can be seen from FIG. 10, item d, different metal ion pairs H₆L/Tb³⁺the/CMCS sensor has different response modes.

Each metal ion pair H can be more effectively distinguished from the heat map of FIG. 10, content e₆L/Tb³⁺Response mode of/CMCS. Next, analysis was performed by using PCA techniqueAs a result of the experiment, we performed 2-dimensional fingerprint images of the first principal component PC1 (91.043%) and the second principal component PC2 (8.957%) as abscissa and ordinate, respectively, as shown in FIG. 10, content f, 11 separate clusters corresponding to 11 metal ions, which indicates that the metal ions can be well separated, so H is₆L/Tb³⁺the/CMCS xerogel can be used as a sensor for distinguishing 11 metal ions.

Respectively reacting H with₆L/Tb³⁺the/CMCS supramolecular xerogel 4mg was dispersed in 100mL aqueous phase of pH 7.4 and pH 6.2 buffer (Tris-HCl buffer, 10mM) to make H₆L/Tb³⁺The concentration of the/CMCS probe mother liquor is 40mg/L, 0.5mL of the probe mother liquor with the pH value of 7.4 is transferred and placed in 12 cuvettes respectively, and Zn is added respectively²⁺、Ag⁺、Mg²⁺、Al³⁺、Ca²⁺、Na⁺、K⁺、Ba² ⁺、Fe³⁺、Co²⁺、Cu²⁺Adding a certain volume of buffer water solution with pH value of 7.4 to supplement the volume of the buffer water solution to 1mL after 11 metal ions are added and no metal ion is added; transferring 0.5mL of the mother solution with the pH value of 6.2 probe into 12 cuvettes respectively, and adding Zn into the mother solution²⁺、Ag⁺、Mg²⁺、Al³⁺、Ca²⁺、Na⁺、K⁺、Ba²⁺、Fe³⁺、Co²⁺、Cu²⁺And adding a certain volume of buffer water solution with the pH value of 6.2 to make up the volume of the buffer water solution to 1mL after waiting for 11 metal ions and without adding any metal ions. The final concentration of metal ions in this example was 0.002 mM. Measuring the luminous intensity (I) of metal ion solution added under 333nm exciting light wavelength and the H without any substance to be measured by a fluorescence spectrometer₆L/Tb³⁺Luminescence intensity (I) of/CMCS Probe (20mg/L)₀) The results are shown in FIG. 10. As can be seen from FIG. 10, content g, the different metal ion pairs H₆L/Tb³⁺the/CMCS sensor has different response modes.

It is more effective to distinguish each metal ion pair H from the heat map of FIG. 10₆L/Tb³⁺Response mode of/CMCS. Next, by analyzing the experimental results using the PCA technique, we analyzed the first principal component PC1 (76.670%)And the second principal component PC2 (23.330%) as abscissa and ordinate respectively for 2-dimensional fingerprint, as shown in FIG. 10, content i, 11 separation clusters corresponding to 11 metal ions, show that the metal ions can be well separated, therefore H₆L/Tb³⁺the/CMCS xerogel can be used as a sensor for distinguishing 11 metal ions.

Example 13

The supermolecular gel luminescent material of the embodiment identifies and verifies mixed metal ions

(I) test materials

The material of this embodiment is doped with H₆L/Tb³⁺CMCS supramolecular gel with DMSO and H as solvent₂O, the total volume is 1mL, the rare earth ion is terbium chloride, and the final concentration of the terbium ion is 12mmol/L, and the preparation method is as described in example 1. The doped rare earth supermolecule xerogel is obtained by replacing the solvent of the doped supermolecule gel with water and then freezing and drying.

(II) experimental method: respectively reacting H with₆L/Tb³⁺the/CMCS supramolecular xerogel 4mg was dispersed in 100mL aqueous phase of pH 7.4 and pH 6.2 buffer (Tris-HCl buffer, 10mM) to make H₆L/Tb³⁺The concentration of the/CMCS probe mother liquor is 40mg/L, 0.5mL of the probe mother liquor with the pH value of 7.4 is transferred and respectively placed in 7 cuvettes, and Fe with different valence states and different molar ratios and the total concentration of 50 mu M are respectively added³⁺And Fe²⁺Mixing metal ions and adding no metal ions, and continuously adding a certain volume of buffer water solution with the pH value of 7.4 to make up the volume to 1 mL; transferring 0.5mL of the above mother solution with pH 6.2 probe into 7 cuvettes, respectively, and adding Fe with different valence states and different molar ratios to total concentration of 50 μ M³⁺And Fe²⁺Mixing metal ions and adding a certain volume of buffer water solution with pH value of 6.2 to make up the volume to 1 mL. As in FIG. 11, Contents a, use H₆L/Tb³⁺CMCS tests it on Fe³⁺And Fe²⁺The results show that these mixtures and pure Fe³⁺And Fe²⁺Clearly separated in the PCA plot.

Respectively reacting H with₆L/Tb³⁺4mg of/CMCS supramolecular xerogel dispersed inAqueous phase 100mL of pH 7.4 and pH 6.2 buffer (Tris-HCl buffer, 10mM) was prepared as H₆L/Tb³⁺The concentration of the probe mother liquor/CMCS is 40mg/L, 0.5mL of the probe mother liquor with the pH value of 7.4 is transferred and respectively placed in 7 cuvettes, and Fe with the total concentration of 10 MuM and different molar ratios is respectively added³⁺And Cu² ⁺Mixing metal ions and adding no metal ions, and continuously adding a certain volume of buffer water solution with the pH value of 7.4 to make up the volume to 1 mL; 0.5mL of the above mother solution with pH 6.2 probe was transferred to 7 cuvettes, and Fe was added to the cuvettes at a total concentration of 10. mu.M in different molar ratios³⁺And Cu²⁺Mixing metal ions and adding a certain volume of buffer water solution with pH value of 6.2 to make up the volume to 1 mL. As in FIG. 11, Contents b, use H₆L/Tb³⁺CMCS tests it on Fe³⁺And Cu²⁺And mixtures thereof, which indicate these mixtures as well as pure Fe³⁺And Cu²⁺Clearly separated in the PCA plot.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. The rare earth supramolecular gel material doped with chitosan or water-soluble derivatives thereof is characterized by comprising an organic ligand, rare earth salt and a bio-based polymer, wherein the bio-based polymer is chitosan or water-soluble derivatives thereof; wherein the organic ligand is 5, 5' - (1,3, 5-triazine-2, 4, 6-trisaminonaphthalene) -tri-isophthalic acid; the rare earth ion in the rare earth salt is terbium;

under the condition of doping the bio-based polymer, self-assembling to form the rare earth supramolecular gel material by utilizing the coordination of the organic ligand and rare earth ions in rare earth salt, the pi-pi interaction between the organic ligand molecules, the coordination of the bio-based polymer and the rare earth ions in the rare earth salt and the hydrogen bonding of the bio-based polymer and the organic ligand;

on one hand, the rare earth supramolecular gel material can utilize the hydrogen bond action of the bio-based polymer and the organic ligand to increase the light absorption of the organic ligand so as to promote the energy transfer from the organic ligand to rare earth ions and further improve the luminescence property of the rare earth supramolecular gel material; on the other hand, the gel material can also make the bio-based polymer adsorbed on the surface of the rare earth supramolecular gel fiber by utilizing the coordination effect of the bio-based polymer and the rare earth ions in the rare earth salt and the hydrogen bonding effect of the bio-based polymer and the organic ligand, so that water molecules are far away from the rare earth ions, and the luminescence property of the rare earth supramolecular gel material is further improved.

2. The rare earth supramolecular gel material as claimed in claim 1, further comprising a solvent, wherein the solvent is a mixed solvent of acetic acid and water, a mixed solvent of DMF and water, or a mixed solvent of DMSO and water.

3. A method for the preparation of rare earth supramolecular gel materials as claimed in claim 1 or 2, characterized by comprising the following steps: and mixing the water solution of the bio-based polymer with a mixed solution of an organic ligand and a rare earth salt, and obtaining the rare earth supramolecular gel material doped with the bio-based polymer under the heating condition.

4. The method according to claim 3, wherein the aqueous solution of the bio-based polymer has a mass volume concentration of the chitosan or the water-soluble derivative thereof of 0.01% to 2%.

5. A process according to claim 3, wherein the water-soluble derivative of chitosan is carboxymethyl chitosan or hydroxypropyl chitosan, preferably carboxymethyl chitosan.

6. The method according to claim 3, wherein the degree of polymerization n of the chitosan or the water-soluble derivative thereof is 500 to 2000 and the degree of deacetylation DD > 75%.

7. The method according to claim 3, wherein an organic solution of 5,5 ', 5 "- (1,3, 5-triazine-2, 4, 6-trisylamino) -tri-isophthalic acid is mixed with a rare earth salt solution to obtain a mixed solution of an organic ligand and a rare earth salt, wherein the molar ratio of the 5, 5', 5" - (1,3, 5-triazine-2, 4, 6-trisylamino) -tri-isophthalic acid to rare earth ions in the rare earth salt is 1:0.2 to 1: 15;

the mass volume concentration of the organic solution of the 5, 5' - (1,3, 5-triazine-2, 4, 6-triimido) -tri-isophthalic acid is 0.3 to 5 percent; the organic solvent in the organic solution of the 5, 5' - (1,3, 5-triazine-2, 4, 6-triamino) -tri-isophthalic acid is DMSO or DMF;

8. A xerogel material based on a rare earth supramolecular gel material doped with chitosan or water-soluble derivatives thereof as claimed in claim 1 or 2.

9. Use of the xerogel material according to claim 8 as a rare earth supramolecular xerogel luminescent material.

10. Use of the xerogel material of claim 8 to prepare a fluorescence sensor for the identification of a plurality of metal ions.