Method for preparing rare earth nanocrystals based on oleylamine surfactant in non-polar solvent and application thereof in fingerprint development

Abstract

The application discloses a method for preparing rare earth nanocrystals in non-polar solvents by using an oleylamine surfactant and application of the method to fingerprint development, and belongs to the technical field of rare earth luminescent materials.

Description

Technical Field

[0001] This invention belongs to the field of rare earth luminescent materials technology, specifically relating to a method for preparing rare earth nanocrystals based on oleylamine surfactants in nonpolar solvents and its application in fingerprint development. Background Technology

[0002] The luminescence properties of rare earth ions stem from the unique transition mechanism of their 4f electron layer. Compared to other luminescent centers, their narrow-band emission, long fluorescence lifetime, and rich energy level structure endow them with a high degree of tunability in emission wavelength and efficiency, making rare earth functional materials irreplaceable in the optoelectronic field. Among the many rare earth functional material systems, rare earth organic complexes have attracted much attention due to their unique "antenna effect."

[0003] However, the practical application of rare earth complexes still faces two major bottlenecks. First, the nonradiative energy loss caused by ligand vibrational coupling remains a persistent challenge. Although some rigid aromatic ring structures can partially suppress luminescence quenching caused by high-frequency CH / OH vibrations, such modifications often come at the cost of sacrificing material processing performance. Second, the structural designability of traditional complexes is severely limited. Existing high-luminescence systems mostly rely on rigid coordination modes between specific anionic and neutral ligands. While this "sandwich" type coordination structure can effectively shield against solvent molecule interference, it greatly restricts the material's potential for self-assembly, thin film processing, or the construction of hierarchical structures. Summary of the Invention

[0004] To improve the above-mentioned technical problems, the present invention provides a method for preparing rare earth nanocrystals based on oleylamine surfactants in a non-polar solvent, comprising the following steps: dissolving a rare earth complex in a non-polar solvent, adding an oleylamine surfactant and stirring to obtain the rare earth nanocrystals;

[0005] The selected rare earth complex has the following structure:

[0006]

[0007] Where n is selected from 0, 1, 2, 3, 4, 5 or 6;

[0008] Q is selected from alkali metals, such as Li, Na, K, and Cs;

[0009] R1 and R2 may be the same or different, and are independently selected from each other without substitution or arbitrarily selected by one, two or more Rs. 11 The following groups are substituted: C 1-6 Alkyl, C 6-14 Aryl, 5-14 quinone heteroaryl; each R 11 They are the same or different, and are independently selected from halogens and C. 6-14Aryl, 5-14 heteroaryl, (C 6-14 (aryl)2-N-;

[0010] M is selected from lanthanide rare earth elements, such as lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium; europium is preferred.

[0011] Lg1 is selected from neutral ligands that can form two coordinations with M;

[0012] Lg2 is selected from neutral ligands that can form tricoordinates with M;

[0013] The nonpolar solvent is selected from at least one of n-hexane, cyclohexane, or petroleum ether;

[0014] The oleylamines indicate that the surfactant is selected from C. 6-20 alkenyl-NH2, C 6-20 alkenyl-NH(C) 1-6 Alkyl), C 6-20 alkenyl-N(C) 1-6 Alkyl)2, C 6-20 alkenyl-NH-C 1-6 Alkyl-NH2, for example C 10-18 alkenyl-NH2, C 10-18 alkenyl-NH(C) 1-6 Alkyl), C 10-18 alkenyl-N(C) 1-6 Alkyl)2, C 10-18 alkenyl-NH-C 1-6 Alkyl-NH2, such as oleylamine, linoleylamine, N,N-dimethyl-9-octadeceneamine, N-9-octadecene-1,3-propanediamine; oleylamine is preferred.

[0015] According to an embodiment of the present invention, when the neutral ligand has two coordinating atoms, wherein the coordinating atom is N, and n = 0, 3 or 4; the selected rare earth complex is an eight-coordinating complex;

[0016] When n = 0, it is a neutral rare earth complex;

[0017] When n=3, it is a ternary rare earth complex;

[0018] When n=4, it is an anionic rare earth complex;

[0019] When the neutral ligand has three coordinating atoms, the coordinating atoms are N or O; where n = 0, 1, 2, 3;

[0020] When n=0, it is a neutral rare earth complex and is nine-coordinated;

[0021] When n=1, the number of neutral ligands is 2, which is an octet;

[0022] When n=2, the number of neutral ligands is 1, which is an octet;

[0023] When n=3, the number of neutral ligands is 1, which is nine-coordinate.

[0024] According to an embodiment of the present invention, R1 and R2 may be the same or different, and are independently selected from C. 1-6 Alkyl, Halogenated C 1-6 Alkyl, C 6-10 Aryl, C 13-14 Aryl, 5-6 member heteroaryl, 9-14 member heteroaryl, (C 6-10 Aryl)2-NC 6-10 Aryl, C 6-10 Aryl-C 6-10 Aryl, Halogenated C 6-10 Aryl, 9-14 heteroaryl-C 6-10 Aryl;

[0025] According to embodiments of the present invention, R1 and R2 may be the same or different, and are independently selected from methyl, tert-butyl, trifluoromethyl, phenyl, thiophene, pentafluoroethyl, pyridyl, naphthyl, fluorenyl, carbazole, diphenylaminophenyl, biphenyl, bromophenyl, and carbazoleylphenyl.

[0026] According to an embodiment of the present invention, The β-diketone anionic ligand shown in Formula A The form after coordination with M; the definitions of R1 and R2 are as described above.

[0027] According to an embodiment of the present invention, the β-diketone anionic ligand represented by formula A is selected from:

[0028]

[0029] According to an embodiment of the present invention, the neutral ligand is selected from nitrogen-containing or oxygen-containing ligands, for example selected from:

[0030]

[0031] According to an embodiment of the present invention, the selected rare earth complex is selected from octagonal or ninagonal complexes formed by rare earth metal M with the anionic ligand and / or the neutral ligand.

[0032] According to an embodiment of the present invention, the rare earth complex is selected from:

[0033]

[0034] According to an embodiment of the present invention, the weight ratio of the rare earth complex to the volume ratio of the nonpolar solvent is selected from 1 mg:(1-100) mL, for example 1 mg:(2-50) mL, such as 1 mg:5 mL, 1 mg:6 mL, 1 mg:10 mL, 1 mg:20 mL, 1 mg:30 mL, 1 mg:40 mL.

[0035] According to an embodiment of the present invention, the weight ratio of the rare earth complex to the volume ratio of the oleylamine surfactant is selected from 1 mg:(1-200) μL, for example 1 mg:(5-100) μL, such as 1 mg:10 μL, 1 mg:20 μL, 1 mg:30 μL, 1 mg:40 μL, 1 mg:50 μL, 1 mg:60 μL, 1 mg:68 μL, 1 mg:70 μL, 1 mg:80 μL, 1 mg:90 μL.

[0036] According to an embodiment of the present invention, the stirring speed is 200-800 r / min.

[0037] According to an embodiment of the present invention, the stirring time is 3 to 12 hours, for example, 6 hours.

[0038] The present invention also provides rare earth nanocrystals prepared by the method described above.

[0039] The present invention also provides the application of the rare earth nanocrystals in fingerprint development.

[0040] The present invention also provides a method for fingerprint development, wherein a solution of the rare earth nanocrystals is sprayed onto a carrier containing the fingerprint to be detected, and the fingerprint is observed under an ultraviolet light.

[0041] According to an embodiment of the present invention, the wavelength of the ultraviolet lamp is 365nm.

[0042] Beneficial effects

[0043] 1. Compared with general rare earth complex solutions, the rare earth nanocrystals prepared by this invention have enhanced luminescence intensity, significantly improved luminescence lifetime, and significantly improved photoluminescence quantum efficiency.

[0044] 2. The rare earth nanocrystals prepared by this invention are dispersed in solutions of hexane, cyclohexane, and petroleum ether, which are originally insoluble, thus expanding the range of applicable solvents to a certain extent.

[0045] 3. The developer prepared using the rare-earth nanocrystals of this invention can develop fingerprints. Under ultraviolet light, relatively obvious patterns can be observed. Attached Figure Description

[0046] Figure 1The images show the luminescence states of the n-hexane-NaEu(dbm)4 rare earth nanocrystal solution (left) of Example 1 and the dichloromethane solution (right) of Comparative Example 1 under ultraviolet light.

[0047] Figure 2 The emission spectra are those of the n-hexane-NaEu(dbm)4 rare earth nanocrystal solution of Example 1 and the dichloromethane solution of Comparative Example 1.

[0048] Figure 3 The lifetime spectra of the n-hexane-NaEu(dbm)4 rare earth nanocrystal solution of Example 1 and the dichloromethane solution of Comparative Example 1 are shown.

[0049] Figure 4 The emission spectrum of the cyclohexane-NaEu(dbm)4 rare earth nanocrystal solution in Example 2 is shown.

[0050] Figure 5 The lifetime spectrum of the cyclohexane-NaEu(dbm)4 rare earth nanocrystal solution in Example 2 is shown.

[0051] Figure 6 The emission spectrum of the petroleum ether-NaEu(dbm)4 rare earth nanocrystal solution in Example 3 is shown.

[0052] Figure 7 The lifetime spectrum of the petroleum ether-NaEu(dbm)4 rare earth nanocrystal solution in Example 3 is shown.

[0053] Figure 8 The emission spectrum of the cyclohexane-Eu(tfaa)3TPTZ rare earth nanocrystal solution in Example 4 is shown.

[0054] Figure 9 The lifetime spectrum of the cyclohexane-Eu(tfaa)3TPTZ rare earth nanocrystal solution in Example 4 is shown.

[0055] Figure 10 The images show the luminescence states of the cyclohexane-Eu(tfba)3TPTZ rare earth nanocrystal solution (left) of Example 5 and the ethyl acetate solution (right) of Comparative Example 2 under fluorescent lamp, ultraviolet lamp and green laser irradiation, respectively.

[0056] Figure 11 The emission spectrum of the cyclohexane-Eu(tfba)3TPTZ rare earth nanocrystal solution in Example 5 is shown.

[0057] Figure 12 The lifetime spectrum of the cyclohexane-Eu(tfba)3TPTZ rare earth nanocrystal solution in Example 5 is shown.

[0058] Figure 13 The emission spectrum of the cyclohexane-Eu(TTA)3TPTZ rare earth nanocrystal solution in Example 6 is shown.

[0059] Figure 14 The lifetime spectrum of the cyclohexane-Eu(TTA)3TPTZ rare earth nanocrystal solution in Example 6 is shown.

[0060] Figure 15 The emission spectrum of the cyclohexane-Eu(dbm)3TPTZ rare earth nanocrystal solution in Example 7 is shown.

[0061] Figure 16 The lifetime spectrum of the cyclohexane-Eu(dbm)3TPTZ rare earth nanocrystal solution in Example 7 is shown.

[0062] Figure 17 The emission spectra are those of the n-hexane-Eu(dbm)3bipy rare earth nanocrystal solution of Example 8 and the dichloromethane solution of Comparative Example 3.

[0063] Figure 18 The lifetime spectrum of the n-hexane-Eu(dbm)3bipy rare earth nanocrystal solution in Example 8 is shown.

[0064] Figure 19 The emission spectrum of the n-hexane-Eu(dbm)3tbbipy rare earth nanocrystal solution in Example 9 is shown.

[0065] Figure 20 The lifetime spectrum of the n-hexane-Eu(dbm)3tbbipy rare earth nanocrystal solution in Example 9 is shown.

[0066] Figure 21 The emission spectra are those of the n-hexane-Eu(dbm)3dmbipy rare earth nanocrystal solution of Example 10 and the dichloromethane solution of Comparative Example 4.

[0067] Figure 22 The lifetime spectra of the n-hexane-Eu(dbm)3dmbipy rare earth nanocrystal solution of Example 10 and the dichloromethane solution of Comparative Example 4 are shown.

[0068] Figure 23 The emission spectra are those of the n-hexane-Eu(dbm)3PBO rare earth nanocrystal solution of Example 11 and the dichloromethane solution of Comparative Example 5.

[0069] Figure 24 The lifetime spectra of the n-hexane-Eu(dbm)3PBO rare earth nanocrystal solution of Example 11 and the dichloromethane solution of Comparative Example 5 are shown.

[0070] Figure 25 The emission spectra are those of the n-hexane-Eu(dbm)3phen rare earth nanocrystal solution of Example 12 and the dichloromethane solution of Comparative Example 5.

[0071] Figure 26The lifetime spectra of the n-hexane-Eu(dbm)3phen rare earth nanocrystal solution of Example 12 and the dichloromethane solution of Comparative Example 5 are shown.

[0072] Figure 27 The image shows a fingerprint under ultraviolet light irradiation, obtained by using the cyclohexane-NaEu(dbm)4 rare earth nanocrystal solution from Example 2 as a fingerprint developer.

[0073] Figure 28 The image shows a fingerprint under ultraviolet light irradiation, obtained by using the n-hexane-NaEu(dbm)4 rare earth nanocrystal solution from Example 1 as a fingerprint developer.

[0074] Figure 29 The fingerprint is shown under ultraviolet light irradiation using the petroleum ether-NaEu(dbm)4 rare earth nanocrystal solution of Example 3 as a fingerprint developer.

[0075] Terminology Definitions and Explanations

[0076] Unless otherwise stated, the definitions of groups and terms recorded in this application specification and claims, including definitions as examples, exemplary definitions, preferred definitions, definitions recorded in tables, and definitions of specific compounds in the examples, can be arbitrarily combined and combined with each other. Such combinations and combinations of group definitions and compound structures should be understood as being within the scope of this application specification and / or claims.

[0077] Unless otherwise stated, the numerical ranges described in this specification and claims are equivalent to describing at least each specific integer value therein. For example, the numerical range "1-20" is equivalent to describing each integer value in the numerical range "1-10", namely 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and each integer value in the numerical range "11-20", namely 11, 12, 13, 14, 15, 16, 17, 18, 19, 20.

[0078] It should be understood that in the description of 1, 2 or more, "more" should refer to an integer greater than 2, such as an integer greater than or equal to 3, such as 3, 4, 5, 6, 7, 8, 9 or 10.

[0079] The term "halogen" refers to fluorine, chlorine, bromine, and iodine.

[0080] The term "alkyl" should be understood to refer to a straight-chain or branched saturated hydrocarbon group having 1 to 20 carbon atoms, such as C 1-6 Alkyl group. "C" 1-6"Alkyl" means a straight-chain or branched alkyl group having 1, 2, 3, 4, 5, or 6 carbon atoms. The alkyl group is, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl, 1,2-dimethylbutyl, etc., or their isomers.

[0081] The term "alkenyl" should be understood to preferably refer to a linear or branched hydrocarbon group containing one or more double bonds and having 2 to 20 carbon atoms, such as C. 6-20 alkenyl or C 10-18 Alkenyl. "C" 10-18 "Alkenyl" should be understood to preferably represent a linear or branched hydrocarbon group containing one or more double bonds and having 10, 11, 12, 13, 14, 15, 16, 17 or 18 carbon atoms, for example, having 12, 13, 14, 15 or 16 carbon atoms (i.e., C...). 12-16 (Alkenyl). It should be understood that when the alkenyl group contains more than one double bond, the double bonds may be separable or conjugated. The alkenyl group is, for example, vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl.

[0082] Term "C" 6-14 "Aryl" should preferably be understood to represent an aromatic or partially aromatic monocyclic, bicyclic (such as fused ring, bridged ring, spiro ring), or tricyclic hydrocarbon ring having 6, 7, 8, 9, 10, 11, 12, 13, or 14 carbon atoms. It can be a monoaromatic ring or a polyaromatic ring fused together, preferably "C". 6-10 Aryl", C 13-14 "Aryl". It can be a ring with 6 carbon atoms ("C6 aryl"), such as phenyl; or biphenyl, or a ring with 9 carbon atoms ("C9 aryl"), such as indenyl or indenyl, or a ring with 10 carbon atoms ("C9 aryl"). 10 Aryl groups, such as tetrahydronaphthyl, dihydronaphthyl, or naphthyl, or rings with 13 carbon atoms (“C”). 13 Aryl groups, such as fluorene groups, or rings with 14 carbon atoms (“C”). 14 Aryl), for example, anthracene. When the C 6-20 When the aryl group is substituted, it can be monosubstituted or polysubstituted. Furthermore, there are no restrictions on the substitution site; for example, it can be ortho, para, or meta substituted.

[0083] The term "5-14-membered heteroaryl" should be understood to include monocyclic, bicyclic (e.g., fused, bridged, spirocyclic), or tricyclic aromatic ring systems having 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14 ring atoms and containing 1-5 heteroatoms independently selected from N, O, and S, such as "5-6-membered heteroaryl" and "9-14-membered heteroaryl". It may contain 5, 6, 9, or 10 carbon atoms and contain 1-5, preferably 1-3, heteroatoms independently selected from N, O, and S, and in each case may be benzo-fused. "Heteroaryl" also refers to a group in which the heteroaryl ring is fused with one or more aryl, alicyclic, or heterocyclic rings, wherein the root or point of the connection is on the heteroaryl ring. Non-limiting examples of the term "heteroaryl" include, for example, pyridyl, pyrazinyl, furanyl, thiopheneyl, pyrimidinyl, isoxazolyl, isothiazolyl, oxazolyl, thiazolyl, pyrazolyl, furazolyl, pyrroleyl, pyrazolyl, triazolyl, tetrazolyl, 1,2,4-thiadiazolyl, pyridazinyl, isoindolyl, indolyl, indazoleyl, quinolinyl, and isoquinolinyl. When the 5-14-membered heteroaryl group is linked to other groups to form the compounds of the present invention, the carbon atom of the 5-14-membered heteroaryl ring may be linked to other groups, or the heteroatom of the 5-14-membered heteroaryl ring may be linked to other groups. When the 5-14-membered heteroaryl group is substituted, it may be monosubstituted or polysubstituted. Furthermore, there are no limitations on the substitution site; for example, the hydrogen atom linked to the carbon atom on the heteroaryl ring may be substituted, or the hydrogen atom linked to the heteroatom on the heteroaryl ring may be substituted.

[0084] The term "spirocycle" refers to a ring system in which two rings share a single ring atom.

[0085] The term "fused ring" refers to a ring system in which two rings share two cyclic atoms.

[0086] The term "bridged ring" refers to a ring system in which two rings share three or more cyclic atoms. Detailed Implementation

[0087] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0088] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0089] Example 1: Preparation of rare earth nanocrystals:

[0090] At room temperature, 5 mL of n-hexane (a nonpolar solvent) was injected into a sample vial containing 0.5 mg NaEu(dbm)4, and 34 μL of oleylamine was added and stirred for 6 h to obtain a n-hexane-NaEu(dbm)4 rare earth nanocrystal solution.

[0091] The rare earth complex is NaEu(dbm). 4， Its structural formula is as follows:

[0092]

[0093] Comparative Example 1

[0094] NaEu(dbm)4 was dissolved in dichloromethane to prepare a dichloromethane solution of NaEu(dbm)4 with the same concentration and volume as in Example 1.

[0095] The rare earth nanocrystal solution of Example 1 and the dichloromethane solution of Comparative Example 1 both exhibited bright fluorescence under ultraviolet light. Figure 1 In the emission spectrum, the luminescence intensity of rare-earth nanocrystals is an order of magnitude higher than that of dichloromethane solution. Figure 2 Regarding luminescence lifetime ( Figure 3 In terms of lifetime, the rare earth nanocrystal solution exhibits a lifetime 2.19 times longer than the dichloromethane solution (472.9 μs for n-hexane and 215.6 μs for dichloromethane). Simultaneously, the photoluminescence quantum efficiency was measured. Due to the long alkyl chain encapsulation of oleylamine, energy loss from high-energy vibrations in the external environment was avoided, resulting in a quantum efficiency of 16.3% for the nanocrystal, approximately 15 times that of the dichloromethane solution (1.09%).

[0096] Example 2

[0097] The only difference between this embodiment and Example 1 is that the nonpolar solvent was replaced with cyclohexane, resulting in a cyclohexane-NaEu(dbm)4 rare earth nanocrystal solution.

[0098] The luminescence lifetime of the rare-earth nanocrystal solution was measured to be 447.6 μs, and the photoluminescence efficiency was 14.1%. (See attached image.) Figure 4 and Figure 5 Compared to dichloromethane solution, the lifetime was extended by more than 200 µs, and the luminous efficiency was increased by 13 times.

[0099] Example 3

[0100] The only difference between this embodiment and Example 1 is that the non-polar solvent was replaced with petroleum ether, resulting in a petroleum ether-NaEu(dbm)4 rare earth nanocrystal solution.

[0101] The luminescence lifetime of the rare-earth nanocrystal solution was measured to be 475.1 μs, and the photoluminescence efficiency was 14.1%. (See attached image.) Figure 6 and Figure 7Compared to dichloromethane solution, the lifetime was extended by 260 µs and the luminous efficiency was increased by 15.5 times.

[0102] Example 4

[0103] The only difference between this embodiment and Example 2 is that the rare earth complex was replaced with Eu(tfaa)3TPTZ, resulting in a cyclohexane-Eu(tfaa)3TPTZ rare earth nanocrystal solution. The structural formula of Eu(tfaa)3TPTZ is as follows:

[0104]

[0105] Photoluminescence lifetime of nanocrystalline solution: 559 μs; Photoluminescence quantum efficiency: 7.3%, see [link to relevant documentation]. Figure 8 and Figure 9 .

[0106] Example 5

[0107] The only difference between this embodiment and Example 2 is that the rare earth complex was replaced with Eu(tfba)3TPTZ, resulting in a cyclohexane-Eu(tfba)3TPTZ rare earth nanocrystal solution. The structural formula of Eu(tfba)3TPTZ is as follows:

[0108]

[0109] Photoluminescence lifetime of nanocrystalline solution: 610 μs; Photoluminescence quantum efficiency: 17.3%, see [link to relevant documentation]. Figure 11 and Figure 12 .

[0110] Comparative Example 2

[0111] Eu(tfba)3TPTZ was dissolved in ethyl acetate to prepare an ethyl acetate solution of Eu(tfba)3TPTZ with the same concentration and volume as in Example 5.

[0112] The states of the cyclohexane rare earth nanocrystal solution (left) of Example 5 and the ethyl acetate solution (right) of Comparative Example 2 under fluorescent lamp, ultraviolet lamp, and green laser pointer irradiation are shown in the figure. Figure 10 Under fluorescent light, both are clear and transparent liquids; under ultraviolet light, both exhibit a distinct europium characteristic red; under green laser illumination, rare earth nanocrystals show a clear Tyndall effect, while the effect in the solution is somewhat dimmer.

[0113] Example 6

[0114] The only difference between this embodiment and Example 2 is that the rare earth complex was replaced with Eu(TTA)3TPTZ, resulting in a cyclohexane-Eu(TTA)3TPTZ rare earth nanocrystal solution. The structural formula of Eu(TTA)3TPTZ is as follows:

[0115]

[0116] Photoluminescence lifetime of nanocrystalline solution: 527 μs; Photoluminescence quantum efficiency: 26.4%, see [link to relevant documentation]. Figure 13 and Figure 14 .

[0117] Example 7

[0118] The only difference between this embodiment and Example 2 is that the rare earth complex was replaced with Eu(dbm)3TPTZ, resulting in a cyclohexane-Eu(dbm)3TPTZ rare earth nanocrystal solution. The structural formula of Eu(dbm)3TPTZ is as follows:

[0119]

[0120] Luminescence lifetime: 581 μs; Photoluminescence quantum efficiency: 14.8%, see [link to relevant documentation]. Figure 15 and Figure 16 .

[0121] Example 8

[0122] The only difference between this embodiment and Example 1 is that the rare earth complex was replaced with Eu(dbm)3bipy, and the volume of n-hexane was 3 mL, resulting in a n-hexane-Eu(dbm)3bipy rare earth nanocrystal solution. The structural formula of Eu(dbm)3bipy is:

[0123]

[0124] Photoluminescence lifetime of nanocrystalline solution: 727.8 μs; Photoluminescence quantum efficiency: 15.9%, see [link to relevant documentation]. Figure 17 and Figure 18 .

[0125] Comparative Example 3

[0126] Eu(dbm)3bipy was dissolved in dichloromethane to prepare a dichloromethane solution of Eu(dbm)3bipy with the same concentration and volume as in Example 8.

[0127] Dichloromethane solution luminescence lifetime: 94.6 μs; photoluminescence quantum efficiency: 1.98%, see [link to relevant documentation]. Figure 17 .

[0128] Example 9

[0129] The only difference between this embodiment and Example 8 is that the rare earth complex is replaced with Eu(dbm)3tbbipy, resulting in a hexane-Eu(dbm)3tbbipy rare earth nanocrystal solution. The structural formula of Eu(dbm)3tbbipy is:

[0130]

[0131] Photoluminescence lifetime of nanocrystalline solution: 711.2 μs; Photoluminescence quantum efficiency: 14.2%, see [link to relevant documentation]. Figure 19 and Figure 20 .

[0132] Example 10

[0133] The only difference between this embodiment and Example 8 is that the rare earth complex is replaced with Eu(dbm)3dmbipy, resulting in a hexane-Eu(dbm)3dmbipy rare earth nanocrystal solution. The structural formula of Eu(dbm)3dmbipy is:

[0134]

[0135] Photoluminescence lifetime of nanocrystalline solution: 720.8 μs; Photoluminescence quantum efficiency: 15.4%, see [link to relevant documentation]. Figure 21 and Figure 22 .

[0136] Comparative Example 4

[0137] Eu(dbm)3dmbipy was dissolved in dichloromethane to prepare a dichloromethane solution of Eu(dbm)3dmbipy with the same concentration and volume as in Example 10.

[0138] Dichloromethane solution luminescence lifetime: 112.1 μs; photoluminescence quantum efficiency: 3.1%, see [link to relevant documentation]. Figure 21 and Figure 22 .

[0139] Example 11

[0140] The only difference between this embodiment and Example 8 is that the rare earth complex was replaced with Eu(dbm)3PBO, resulting in a hexane-Eu(dbm)3PBO rare earth nanocrystal solution. The structural formula of Eu(dbm)3PBO is:

[0141]

[0142] Photoluminescence lifetime of nanocrystalline solution: 751.8 μs; Photoluminescence quantum efficiency: 15.4%, see [link to relevant documentation]. Figure 23 and Figure 24 .

[0143] Comparative Example 5

[0144] Eu(dbm)3PBO was dissolved in dichloromethane to prepare a dichloromethane solution of Eu(dbm)3PBO with the same concentration and volume as in Example 11.

[0145] Dichloromethane solution luminescence lifetime: 95.0 μs; photoluminescence quantum efficiency: 1.02%, see [link to relevant documentation]. Figure 23 and Figure 24 .

[0146] Example 12

[0147] The only difference between this embodiment and Example 8 is that the rare earth complex is replaced with Eu(dbm)3phen, resulting in a hexane-Eu(dbm)3phen rare earth nanocrystal solution. The structural formula of Eu(dbm)3phen is:

[0148]

[0149] Photoluminescence lifetime of nanocrystalline solution: 760.7 μs; Photoluminescence quantum efficiency: 18.2%, see [link to relevant documentation]. Figure 25 and Figure 26 .

[0150] Comparative Example 6

[0151] Eu(dbm)3phen was dissolved in dichloromethane to prepare a dichloromethane solution of Eu(dbm)3phen with the same concentration and volume as in Example 12.

[0152] Dichloromethane solution luminescence lifetime: 116.5 μs; photoluminescence quantum efficiency: 4.01%, see [link to relevant documentation]. Figure 25 and Figure 26 .

[0153] Example 13 Identification of Cyclohexane Rare Earth Nanocrystals in Fingerprint Development

[0154] Imprinting fingerprints onto a clean glass plate, then spraying the cyclohexane rare earth nanocrystal solution from Example 2 onto the fingerprint area, and allowing it to stand for several seconds before irradiating with a UV lamp will produce a fingerprint pattern with alternating light and dark areas. Figure 27 .

[0155] Example 14

[0156] The only difference between this embodiment and Example 13 is the use of the n-hexane rare earth nanocrystal solution from Example 1. The image obtained under ultraviolet light is shown below. Figure 28 .

[0157] Example 15

[0158] The only difference between this embodiment and Example 13 is the use of the petroleum ether rare earth nanocrystal solution from Example 3. The image obtained under ultraviolet light is shown below. Figure 29 .

[0159] The embodiments of the technical solution of the present invention have been described above by way of example. It should be understood that the protection scope of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the protection scope of the claims of this application.

Claims

1. A method for preparing rare earth nanocrystals based on oleylamine surfactants in a nonpolar solvent, comprising the following steps: The rare earth complex was dissolved in a nonpolar solvent, and an oleylamine surfactant was added and stirred to obtain the rare earth nanocrystals. The selected rare earth complex has the following structure: Where n is selected from 0, 1, 2, 3, 4, 5 or 6; Q is selected from alkali metals; R1 and R2 may be the same or different, and are independently selected from each other without substitution or arbitrarily selected by one, two or more Rs. 11 The following groups are substituted: C 1-6 Alkyl, C 6-14 Aryl, 5-14 quinone heteroaryl; each R 11 They are the same or different, and are independently selected from halogens and C. 6-14 Aryl, 5-14 heteroaryl, (C 6-14 (aryl)2-N-; M is selected from lanthanide rare earth elements; Lg1 is selected from neutral ligands that can form two coordinations with M; Lg2 is selected from neutral ligands that can form tricoordinates with M; The nonpolar solvent is selected from at least one of n-hexane, cyclohexane, or petroleum ether; The oleylamines indicate that the surfactant is selected from C. 6-20 alkenyl-NH2, C 6-20 alkenyl-NH(C) 1-6 Alkyl), C 6-20 alkenyl-N(C) 1-6 Alkyl)2, C 6-20 alkenyl-NH-C 1-6 Alkyl-NH2.

2. The method according to claim 1, characterized in that, Q is selected from Li, Na, K, and Cs; Preferably, M is selected from lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium; preferably europium. Preferably, the oleylamine surfactant is selected from C 10-18 alkenyl-NH2, C 10-18 alkenyl-NH(C) 1-6 Alkyl), C 10-18 alkenyl-N(C) 1-6 Alkyl)2, C 10-18 alkenyl-NH-C 1-6 Alkyl-NH2, such as oleylamine, linoleylamine, N,N-dimethyl-9-octadeceneamine, N-9-octadecene-1,3-propanediamine; oleylamine is preferred.

3. The method according to claim 1 or 2, characterized in that, R1 and R2 may be the same or different, and are independently selected from C. 1-6 Alkyl, Halogenated C 1-6 Alkyl, C 6-10 Aryl, C 13-14 Aryl, 5-6 member heteroaryl, 9-14 member heteroaryl, (C 6-10 Aryl)2-NC 6-10 Aryl, C 6-10 Aryl-C 6-10 Aryl, Halogenated C 6-10 Aryl, 9-14 heteroaryl-C 6-10 Aryl; Preferably, R1 and R2 are the same or different, and are independently selected from methyl, tert-butyl, trifluoromethyl, phenyl, thiophene, pentafluoroethyl, pyridyl, naphthyl, fluorenyl, carbazole, diphenylaminophenyl, biphenyl, bromophenyl, and carbazoleylphenyl.

4. The method according to any one of claims 1-3, characterized in that, The β-diketone anionic ligand shown in Formula A The form after coordination with M; the definitions of R1 and R2 as described in any one of claims 1-3; Preferably, the β-diketone anionic ligands represented by Formula A are selected from:

5. The method according to any one of claims 1-4, characterized in that, The neutral ligand is selected from nitrogen-containing or oxygen-containing ligands, for example from:

6. The method according to any one of claims 1-5, characterized in that, The selected rare earth complexes are selected from octagonal or ninagonal complexes formed by rare earth metal M with the anionic ligand and / or the neutral ligand; Preferably, the rare earth complex is selected from:

7. The method according to any one of claims 1-6, characterized in that, The weight ratio of the rare earth complex to the volume ratio of the nonpolar solvent is selected from 1 mg:(1-100) mL, for example 1 mg:(2-50) mL; Preferably, the weight ratio of the rare earth complex to the volume ratio of the oleylamine surfactant is selected from 1 mg:(1-200) μL, for example 1 mg:(5-100) μL.

8. Rare earth nanocrystals prepared by the method according to any one of claims 1-7.

9. The application of the rare earth nanocrystals described in claim 8 in fingerprint development.

10. A method for fingerprint development, comprising spraying a solution of the rare earth nanocrystals of claim 8 onto a carrier containing a fingerprint to be detected, and observing the fingerprint imprint under an ultraviolet lamp.

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