CN101195741A - Zinc-containing hydrotalcite with strong fluorescence and preparation method thereof - Google Patents

Abstract

The class involved in the present invention has the following simplified formula: [M ²⁺ _1-x-y Zn ²⁺ _x Al ³⁺ _y (OH) ^-1 ₂ ]A ^n- _y/n D _x/m zB] Fluorescent zinc-containing hydrotalcites (Zn-LLDHs) and its preparation method are through replacing divalent magnesium ions (Mg ²⁺ ) in magnesium-aluminum hydrotalcites with an appropriate amount of divalent zinc ions (Zn ²⁺ ), simultaneously with dissolved Or coordinate with ligands such as 8-hydroxyquinoline dispersed in the interlayer lipophilic anion. Effectively prevent the fluorescence quenching of zinc ions (Zn ²⁺ ) as the luminescent center, and the ligands or mixed ligands dissolved in the interlayer anions form with the zinc ions (Zn ²⁺ ) embedded in the plate layer The special assembly structure of Zn improves the asymmetry of the coordinated zinc ions (Zn ²⁺ ) as the luminescent center, and at the same time, the thermal stability of (Zn-LLDHs) is improved due to the protective effect of the layered structure of the hydrotalcite. Thus, a new type of highly fluorescent zinc-containing hydrotalcite, which is different from the usual non-fluorescent zinc-containing hydrotalcite, can emit strong fluorescence from the corresponding zinc coordination chelate.

Description

Zinc-containing hydrotalcite with strong fluorescence and preparation method thereof

Technical field:

The invention relates to a class of zinc-containing hydrotalcites with strong fluorescence and a preparation method thereof

Background technique:

The simplest general formula is [M ²⁺ _1-x M ³⁺ _x (OH) ₂ ]A ^n- _x/n .yH ₂ O] hydrotalcites (layered double hydroxi-des, LDHs), the M ²⁺ is a divalent cation such as Mg, Ni, Cu or Zn, M ³⁺ is an isomorphic trivalent cation such as Al ^3+, etc., ^An- is an interlayer anion such as CO ₃ ^2- , Cl ^- , SO ₄ ^{2 -} , NO ₃ ^- or other organic anions. Since M ²⁺ is partially substituted by M ³⁺ isomorphously, the hydrotalcite slabs are positively charged, and the anions intercalated between the layers are connected to the slabs with weak chemical bonds to balance the excess positive charges on the slabs, accompanied by certain The amount of water molecules fills the interlayer. Due to the substitutability of the plate cations of LDHs and the switchability of the interlayer anions, various inorganic and organic anions, isopoly and heteropolyanions, and complex anions can be inserted into the layers to assemble a layer of supramolecular structure. Or trivalent cations (Al ³⁺ ) are replaced by other isomorphic or near-isomorphic trivalent cations, thus different series of intercalation hydrotalcite-like compounds (LLDHs) can be obtained. So far, researchers from various countries have conducted extensive research and application exploration on the synthesis and preparation methods of LDHs and LLDHs, as well as in ion exchange, adsorption, separation, catalysis, and medicine.

In recent years, the research on the preparation and characteristics of various functional hydrotalcites has received special attention. Since rare earths with a special sub-electron layer structure and various multivalent and variable-valence transition metal elements have various optical, electrical, magnetic, and catalytic functions, rare earths and multivalent and variable-valence transition metal ions are introduced into the hydrotalcite structure to obtain Functional hydrotalcites have become one of the hotspots in the field of hydrotalcite research. In 2005, Duan Xue et al. proposed a patent application for "Rare Earth Complex Intercalated Hydrotalcite with Fluorescent Properties and Its Preparation Method" (Patent Application No.: 200510012245.7; Publication No.: CN1715365A,), which is intercalated between hydrotalcite layers through ion exchange The aminocarboxyl complexes of Eu and other rare earth ions are introduced to obtain fluorescent hydrotalcites. In addition, L. Latterini et al. inserted azo and other dyes into the interlayer of hydrotalcite through ion exchange to obtain hybrid materials with optical and electrical functions.

Invention content:

The invention relates to a class of zinc-containing hydrotalcites with strong fluorescence and a preparation method thereof.

As we all know, zinc coordination chelates such as 8-hydroxyquinoline zinc (Znq ₂ ) with good thermal stability, broad excitation band and high fluorescence efficiency, as a class of fluorescent metal complexes with excellent comprehensive properties, have been studied all the time. It is one of the first choice fluorescent materials for light-emitting or display devices, but its difficulty in large-area film formation and high cost is still a problem that plagues its further application, and has become the focus of researchers.

Based on the above research background, the present invention uses an appropriate amount of divalent zinc ions (Zn ²⁺ ) to replace the divalent magnesium ions (Mg ²⁺ ) in magnesium aluminum hydrotalcite, and simultaneously dissolves or disperses the measured ligands such as 8-hydroxyquinoline In lipophilic anions such as stearate between zinc-containing hydrotalcite layers, it is coordinated with divalent zinc ions (Zn ²⁺ ) evenly distributed on the metal hydroxide plate layer of hydrotalcite, so that 8- Ligands such as hydroxyquinoline are "suspended" on the surface of the hydroxide plate due to the coordination with zinc ions (Zn ²⁺ ), and each unit is isolated and fixed on it, thus assembling and forming a completely different The special coordination complex structure of zinc coordination chelates such as zinc 8-hydroxyquinoline, because the special structure has a larger structure than free or "free" zinc coordination chelates such as zinc 8-hydroxyquinoline asymmetry, which will improve the fluorescence efficiency of its luminescent center; in addition, because the divalent zinc ions (Zn ²⁺ ) are uniformly dispersed and fixed on the plate layer, it can effectively prevent the possible fluorescence quenching caused by the agglomeration of each luminescent unit. At the same time, due to the protective effect of the layered structure of this type of hydrotalcite, its thermal stability is improved. Thus, a new type of highly fluorescent zinc-containing hydrotalcite that can emit strong fluorescence from the corresponding zinc coordination chelate, which is different from the usual non-fluorescent magnesium-aluminum hydrotalcite or zinc-aluminum hydrotalcite, is obtained.

Concrete content of the present invention is as follows:

1. A class of zinc-containing hydrotalcites (Zn-LLDHs) with strong fluorescence that the present invention relates to has the following simplified chemical formula: [M ²⁺ _1-xy Zn ²⁺ _x Al ³⁺ _y (OH) ^-1 ₂ ]A ^n- _y/n D _x/m zB],

Among them, M ²⁺ is divalent metal cations such as magnesium, zinc, copper, nickel, etc. except zinc ion (Zn ²⁺ ); Zn ²⁺ is divalent zinc ion (Zn ²⁺ ), and x is Zn ²⁺ /(M ²⁺ +Zn ²⁺ ) molar ratio; Al ³⁺ is trivalent aluminum ion, y=Al ³⁺ /(M ²⁺ +Zn ²⁺ +Al ³⁺ ) molar ratio, y=0.33 or 0.25; ( OH) ^-1 is a monovalent hydroxide anion, A ^n- is an anion or a mixed anion, and its average valence n=1~2; D is a ligand or a mixed ligand, and its average coordination number m=2~3; B is the neutral molecule contained in hydrotalcite-like, z is the number of neutral molecules;

Among them, zinc ions (Zn ²⁺ ) are dispersed in the non-zinc metal hydroxide layer of the hydrotalcite; A ^n- is an interlayer anion; ligand D is soluble in the interlayer anion A ^n- , and Zn ²⁺ coordination on the board.

2. The zinc-containing hydrotalcite (Zn-LLDHs) with strong fluorescence of the present invention, its simplified chemical formula

Zn ²⁺ content x in [M ²⁺ _1-xy Zn ²⁺ _x Al ³⁺ _y (OH) ^-1 ₂ ]A ^n- _y/n D _x/m zB] = 0.5-0.005.

3. The zinc-containing hydrotalcites (Zn-LLDHs) with strong fluorescence of the present invention, its [M ²⁺ _1-xy Zn ²⁺ _x Al ³⁺ _y (OH) ^-1 ₂ ]A ^n- _y/n D The ligand D in _x/m zB] is 8-hydroxyquinoline, 3,5 dibromosalicylaldehyde acetal 8 aminoquinoline and its 5 or 2-substituted derivatives; acetylacetone (acac) and dibenzoyl Methane (DBM) β-diketones; Schiff base, bis-Schiff base and their substituted derivatives; o-phenanthroline; bipyridine; quercetin ((3,5,7,3′,4′-penta Hydroxyflavone, Quercetin) etc. or a mixture thereof.

4. The zinc-containing hydrotalcites (Zn-LLDHs) with strong fluorescence of the present invention, wherein the ligand D is pre-mixed in C _12-20 fatty acid sodium, C _12-20 fatty sodium sulfonate, C _0-12 alkyl Sodium benzoate, sodium C _0-12 alkylbenzene sulfonate, sodium salicylate or their mixtures, thus the ligand D in (Zn-LLDHs) prepared by co-precipitation method is soluble in the interlayer anion A ^n- , while coordinating with Zn ²⁺ dispersed on hydrotalcite-like divalent non-Zn metal hydroxide laminates.

5. The zinc-containing hydrotalcites (Zn-LLDHs) with strong fluorescence of the present invention, its [M ²⁺ _1-xy Zn ²⁺ _x Al ³⁺ _y (OH) ^-1 ₂ ]A ^n- _y/n D _x/m zB], which is miscible in interlayer anions, such as C _12-20 fatty acid sodium, C _12-20 fatty sodium sulfonate, sodium benzoate, sodium benzenesulfonate, sodium salicylate or a mixture of ligands D The content is one-half to one-third of the molar content x of zinc ions (Zn ²⁺ ).

6. As mentioned above, reduce the zinc ion content (x) in the hydroxide plate layer in the hydrotalcite to a certain amount, and at the same time mix and disperse an appropriate amount of ligands such as 8-hydroxyquinoline or their mixed ligands In the lipophilic anion between the hydrotalcite or hydrotalcite-like layers, and coordinate with the zinc ion (Zn ²⁺ ) dispersed on the hydroxide plate layer, it prevents the zinc ion (Zn ²⁺ ) as the luminescent center The possible fluorescence extinction, and the 8-hydroxyquinoline ligand or its mixed ligands that are soluble in the interlayer anion are coordinated with the divalent zinc ions (Zn ²⁺ ) embedded in the hydroxide layer. The special assembly structure improves the asymmetry of the coordinated zinc ions (Zn ²⁺ ) as the luminescent center, thus obtaining a class of hydrotalcites that can emit strong fluorescence from the corresponding zinc coordination chelates, which is different from the usual non-fluorescent zinc-containing hydrotalcites. Novel highly fluorescent zinc-containing hydrotalcites.

_7. ^{Strongly fluorescent} _zinc ^{- containing} _{hydrotalcites (} ^_ _{_ _} Zn-LLDHs) are prepared by co-precipitation method. The specific basic steps that the co-precipitation method preparation method takes are: prepare the aqueous solution (A) containing xmol soluble zinc-containing salt and an appropriate amount of NaOH; prepare the aqueous solution (B) containing (1-x)mol soluble magnesium salt; prepare the aqueous solution (B) containing (x /n) mol of sodium lipophilic organic acid, (x/m) mol of ligand or mixed ligand in aqueous solution (C). Under strong stirring, or under the action of ultrasonic waves, or microwaves, simultaneously add solutions (A) and (B) to solution (C) dropwise, adjust the reaction mixture slurry to PH = 9-13 with an appropriate concentration of sodium hydroxide aqueous solution, and then Aging at 60-80°C for 6-12 hours, suction filtration, washing the filter cake with water until pH = 7-8, suction filtration after the precipitate, drying the filter cake at 100-110°C for 2 hours to obtain strong fluorescence zinc-containing hydrotalcites (Zn-LLDHs).

Detailed ways:

The following non-limiting examples will further illustrate the highly fluorescent zinc-containing hydrotalcite of the present invention and its preparation method, which will contribute to the understanding of the present invention and its advantages, but not as a limitation of the present invention.

Example 1.

Prepare an aqueous solution (A) containing 1.67×10 ^-3 mol of NaAlO ₂ and 0.835×10 ^-3 mol mol NaOH; prepare an aqueous solution (B) of MgCl ₂ containing 5.01×10 ^-5 mol of ZnCl ₂ and 4.96×10 ^-3 mol; Prepare an ethanol-water mixed solution (C) containing 5.0×10 ^-3 mol sodium hexadecyl fatty acid and 0.25×10 ^-5 mol 8-hydroxyquinoline. Under the action of ultrasonic waves, add solutions (A) and (B) to (C) solution dropwise at the same time, adjust the reaction mixture slurry to PH=12 with 20% aqueous sodium hydroxide solution, age at 80°C for 12 hours, and filter with suction 1. Wash the filter cake with water until the pH of the filter is 7-8, soak it with a small amount of absolute ethanol, wash the precipitate and filter it with suction, and dry the filter cake at 105±5°C for 2 hours to obtain a zinc-containing hydrotalcite with strong fluorescence Sample (Zn- _LLDHS ). Excited by ultraviolet light, it emits the strong characteristic blue-green fluorescence (502nm) of 8-hydroxyquinoline zinc, and the fluorescence intensity reaches 4.7×10 ⁴ (au).

Example 2.

Prepare an aqueous solution (A) containing 1.67×10 ^-3 mol of NaAlO ₂ and 0.835×10 ^-3 mol mol NaOH; prepare an aqueous solution (B) of MgCl ₂ containing 2.5×10 ^-3 mol of ZnCl ₂ and 2.5×10 ^-3 mol; Prepare an ethanol-water mixed solution (C) containing 1.67×10 ^-3 mol sodium dodecylbenzenesulfonate and 0.25×10 ^-5 mol 8-hydroxyquinoline. Under the action of ultrasonic waves, add solutions (A) and (B) to (C) solution dropwise at the same time, adjust the reaction mixture slurry to PH=12 with 20% aqueous sodium hydroxide solution, age at 80°C for 12 hours, and filter with suction 1. Wash the filter cake with water until the pH of the filter is 7-8, soak it with a small amount of absolute ethanol, wash the precipitate and filter it with suction, and dry the filter cake at 105±5°C for 2 hours to obtain a zinc-containing hydrotalcite with strong fluorescence Sample (Zn- _LLDHS ). Excited by ultraviolet light, it emits the characteristic blue-green fluorescence (502nm) of 8-hydroxyquinoline zinc, and the fluorescence intensity reaches 0.5×10 ³ (au).

Example 3.

Prepare an aqueous solution (A) containing 1.67×10 ^-3 mol NaAlO ₂ and 0.835×10 ^-3 mol mol NaOH; prepare an aqueous solution (B) containing 2.5×10 ^-5 mol ZnCl ₂ and 5.0×10 ^-3 mol MgCl ₂ ; Prepare an ethanol-water mixed solution (C) containing 5.0×10 ^-3 mol sodium stearate and 0.125×10 ^-5 mol 8-hydroxyquinoline. Under vigorous stirring, simultaneously add solutions (A) and (B) to solution (C) dropwise, adjust the reaction mixture slurry to PH=12 with 20% aqueous sodium hydroxide solution, age at 80°C for 12 hours, and filter with suction 1. Wash the filter cake with water until the pH of the filter is 7-8, soak it with a small amount of absolute ethanol, wash the precipitate and filter it with suction, and dry the filter cake at 105±5°C for 2 hours to obtain a zinc-containing hydrotalcite with strong fluorescence Sample (Zn- _LLDHS ). Excited by ultraviolet light, it emits the strong characteristic blue-green fluorescence (502nm) of 8-hydroxyquinoline zinc, and the fluorescence intensity reaches 3.9×10 ⁵ (au).

Example 4.

Prepare an aqueous solution (A) containing 1.67×10 ^-3 mol NaAlO ₂ and 0.835×10 ^-3 mol mol NaOH; prepare an aqueous solution (B) containing 2.5×10 ^-5 mol ZnCl ₂ and 5.0×10 ^-3 mol MgCl ₂ ; Prepare an ethanol-water mixed solution (C) containing 5.0×10 ^-3 mol sodium stearate and 0.125×10 ^-5 mol 3,5 dichlorosalicylaldehyde 8-aminoquinoline ((DCSAQ)). Under vigorous stirring, simultaneously add solutions (A) and (B) to solution (C) dropwise, adjust the reaction mixture slurry to PH=12 with 20% aqueous sodium hydroxide solution, age at 80°C for 12 hours, and filter with suction 1. Wash the filter cake with water until the pH of the filter is 7-8, soak it with a small amount of absolute ethanol, wash the precipitate and filter it with suction, and dry the filter cake at 105±5°C for 2 hours to obtain a zinc-containing hydrotalcite with strong fluorescence Sample (Zn- _LLDHS ). Excited by ultraviolet light, it emits the strong characteristic blue-green fluorescence (508nm) of 8-hydroxyquinoline zinc, and the fluorescence intensity reaches 7.2×10 ⁵ (au).

Example 5.

Prepare an aqueous solution (A) containing 1.67×10 ^-3 mol NaAlO ₂ and 0.835×10 ^-3 mol mol NaOH; prepare an aqueous solution (B) containing 2.5×10 ^-5 mol ZnCl ₂ and 5.0×10 ^-3 mol MgCl ₂ ; Prepare a mixed solution (C) containing 5.0×10 ^-3 mol sodium stearate and 0.125×10 ^-5 mol 8-hydroxyquinoline-p-cresol ethanol-water. Under the action of ultrasonic waves, add solutions (A) and (B) to (C) solution dropwise at the same time, adjust the reaction mixture slurry to PH=12 with 20% aqueous sodium hydroxide solution, age at 80°C for 12 hours, and filter with suction 1. Wash the filter cake with water until the pH of the filter is 7-8, soak it with a small amount of absolute ethanol, wash the precipitate and filter it with suction, and dry the filter cake at 105±5°C for 2 hours to obtain a zinc-containing hydrotalcite with strong fluorescence Sample (Zn- _LLDHS ). Excited by ultraviolet light, it emits the strong characteristic blue-green fluorescence (507-513nm) of 8-hydroxyquinoline zinc, and the fluorescence intensity reaches 1.2×10 ⁵ (au).

Example 6.

Prepare an aqueous solution (A) containing 1.67×10 ^-3 mol NaAlO ₂ and 0.835×10 ^-3 mol mol NaOH; prepare an aqueous solution (B) containing 2.5×10 ^-5 mol ZnCl ₂ and 5.0×10 ^-3 mol MgCl ₂ ; Prepare an ethanol-water mixed solution (C) containing 5.0×10 ^-3 mol sodium dodecyl fatty acid and 0.125×10 ^-5 mol hexathiophenanthroline. Under the action of ultrasonic waves, add solutions (A) and (B) to (C) solution dropwise at the same time, adjust the reaction mixture slurry to PH=12 with 20% aqueous sodium hydroxide solution, age at 80°C for 12 hours, and filter with suction 1. Wash the filter cake with water until the pH of the filter is 7-8, soak it with a small amount of absolute ethanol, wash the precipitate and filter it with suction, and dry the filter cake at 105±5°C for 2 hours to obtain a zinc-containing hydrotalcite with strong fluorescence Sample (Zn- _LLDHS ). Excited by 275nm ultraviolet light, it emits the strong characteristic blue fluorescence (470nm) of 8-hydroxyquinoline zinc, and the fluorescence intensity reaches 5.8×10 ⁴ (au).

Example 7.

Prepare an aqueous solution (A) containing 1.67×10 ^-3 mol NaAlO ₂ and 0.835×10 ^-3 mol mol NaOH; prepare an aqueous solution (B) containing 2.5×10 ^-5 mol ZnCl ₂ and 5.0×10 ^-3 mol MgCl ₂ ; Prepare an ethanol-water mixed solution (C) containing 5.0×10 ^-3 mol sodium dodecylbenzenesulfonate and 0.125×10 ^-5 mol quercetin ((3,5,7,3′4′-pentahydroxyflavone) Under the action of ultrasound, simultaneously add solutions (A) and (B) dropwise to (C) solution, adjust the reaction mixture slurry to PH=12 with 20% aqueous sodium hydroxide solution, age at 80°C for 12 hours, pump Filter and wash the filter cake with water until the pH of the filter is 7~8, soak it with a small amount of absolute ethanol, wash the precipitate and filter it with suction, and dry the filter cake at 105±5°C for 2 hours to obtain a strong fluorescent zinc-containing water. Talc sample (Zn-LLDH _S ), excited by 275nm ultraviolet light, emits strong characteristic blue fluorescence (470nm) of 8-hydroxyquinoline zinc, with a fluorescence intensity of 8.1×10 ³ (au).

Claims (7)

1. a class of zinc-containing hydrotalcites with strong fluorescence and preparation method thereof, is characterized in that the highly fluorescent zinc-containing hydrotalcites of the present invention has the following simplified formula: [M ²⁺ _1-xy Zn ²⁺ _x Al ³⁺ _y OH) ^-1 ₂ ]A ^n- _y/n D _x/m zB], Among them, M ²⁺ is divalent metal cations such as magnesium, zinc, copper, nickel, etc. except zinc ion (Zn ²⁺ ); Zn ²⁺ is divalent zinc ion, and x is Zn ²⁺ /(M ²⁺ +Zn ^{2 +} ) molar ratio; Al ³⁺ is trivalent aluminum ion, y=Al ³⁺ /(M ²⁺ +Zn ²⁺ +Al ³⁺ ) molar ratio, y=0.33 or 0.25; (OH) ^-1 is Monovalent hydroxide anion, A ^n- is anion or mixed anion, its average valence n=1~2; D is ligand or mixed ligand, its average coordination number m=2~3; B is hydrotalcite-like The contained neutral molecules, z is the number of neutral molecules; Among them, zinc ions are dispersed in the non-zinc metal hydroxide laminate of the hydrotalcite; A ^n- is an interlayer anion; ligand D is soluble in the interlayer anion A ^n- , and Zn ²⁺ on the laminate coordination. 2. The zinc-containing hydrotalcite with strong fluorescence and its preparation method according to claim 1, characterized in that the Zn ²⁺ content x=0.5～0.005. 3. The zinc-containing hydrotalcite with strong fluorescence and its preparation method according to claim 1, characterized in that its [M ²⁺ _1-xy Zn ²⁺ _x Al ³⁺ _y (OH) ^-1 ₂ ]A The ligand D in ^n- _y/n D _x/m zB] is 8-hydroxyquinoline, 3,5 dibromosalicylaldehyde acetal 8 aminoquinoline and its 5 or 2-substituted derivatives; acetylacetone and di β-diketones such as benzoylmethane; Schiff bases, bis-Schiff bases and their substituted derivatives; o-phenanthroline; bipyridine; quercetin or their mixtures. 4. according to the zinc-containing hydrotalcite with strong fluorescence and preparation method thereof described in claim 1, it is characterized in that wherein ligand D is pre-miscible in C _12-20 fatty acid sodium, C _12-20 fatty sodium sulfonate, C _0-12 alkyl sodium benzoate, C _0-12 alkyl benzene sodium sulfonate, sodium salicylate or their mixture, thus the ligand D in the zinc-containing hydrotalcite prepared by the co-precipitation method is soluble in the interlayer Among the anions A ^n- , it coordinates with Zn ²⁺ dispersed on the hydrotalcite-like bivalent non-zinc metal hydroxide layer. 5. According to claim 1, the zinc-containing hydrotalcite with strong fluorescence and its preparation method is characterized in that its [M ²⁺ _1-xy Zn ²⁺ _x Al ³⁺ _y (OH) ^-1 ₂ ]A ^{n -} _y/n D _x/m zB] miscible in interlayer C _12-20 fatty acid sodium, C _12-20 fatty acid sodium sulfonate, sodium benzoate, sodium benzenesulfonate, sodium salicylate or their mixture anions The content of ligand D is one-half to one-third of the molar content x of zinc ions (Zn ²⁺ ). 6. the zinc-containing hydrotalcite with strong fluorescence according to claim 1 and its preparation method, is characterized in that the zinc ion (Zn ²⁺ ) content (x) in its hydroxide plate layer is reduced to a certain amount And coordinate with ligands or their mixtures that are miscible in (Zn-LLDHs) interlayer lipophilic anions, which not only prevents the fluorescence of divalent zinc ions (Zn ²⁺ ) from quenching, but also improves the coordination of zinc ions in the luminescence center. Asymmetry, so that (Zn-LLDHs) has strong fluorescence. 7. A class of zinc-containing hydrotalcites with strong fluorescence and a preparation method thereof, characterized in that the preparation is carried out by a co-precipitation method.