Preparation method of metalloporphyrin framework nanocrystalline structure
Technical Field
The invention belongs to the technical field of metal organic frameworks, and particularly relates to a metalloporphyrin framework nanocrystal structure, a preparation method and morphology control thereof, in particular to a preparation method of a metalloporphyrin framework two-dimensional monodisperse nanosheet and a two-dimensional/three-dimensional hierarchical flower-like nanostructure.
Background
The Metal Organic Framework (MOF) is a crystalline porous material formed by connecting metal ions and organic ligands, has the advantages of adjustable structure and function, large surface area, ordered pore diameter arrangement and the like, and has application potential in the aspects of catalysis, gas adsorption, drug delivery, electronics and photoelectron sensors. At present, the MOF nano materials are various and can be divided into zero-dimensional, one-dimensional, two-dimensional and three-dimensional in terms of structure, and the two-dimensional MOF nano materials have the advantages of large specific surface area, easiness in contact with reactants, short electron transfer path, easiness in processing into films and the like, and are attracted by attention in recent years. The two-dimensional/three-dimensional hierarchical structure is a unique open structure and is provided with special transmission channels, but a compact hierarchical structure is easy to form, and the transmission channels are blocked and the mass transfer efficiency is reduced due to the excessively compact structure. Therefore, the control of the morphology of the controllable nano material is significant.
At present, the monodisperse two-dimensional MOF nanosheet can be synthesized by self-assembly through a wet chemical method, but the first-order crystal nucleus formed by reaction is easy to collide and aggregate in a solution, so that the monodisperse two-dimensional MOF nanosheet is difficult to obtain. Therefore, it is necessary to develop a simple method for preparing monodisperse two-dimensional MOF nanosheets.
Disclosure of Invention
The purpose of the invention is as follows: in order to overcome the defects in the prior art, the invention provides a preparation method of a metalloporphyrin framework two-dimensional monodisperse nanosheet and a two-dimensional/three-dimensional hierarchical flower-like nanostructure. By introducing the polyether sulfone filtering membrane, a two-dimensional monodisperse nanosheet can be obtained, and a two-dimensional/three-dimensional hierarchical flower-shaped nanostructure can be obtained under the condition without the polyether sulfone filtering membrane. The method has simple process and strong repeatability, and meets the requirement of environmental friendliness.
The technical scheme is as follows: in order to achieve the purpose, the invention adopts the technical scheme that:
the preparation method of the metalloporphyrin framework two-dimensional monodisperse nanosheet comprises the following steps:
a solution of 5,10,15, 20-tetrapyridylporphyrin (TPyP, 1-5mM) in acetic acid was added slowly dropwise to copper acetate monohydrate (CuAc)2·H2O, 5-10mM) and sodium dodecyl sulfate (SDS, 6-8mM) and uniformly mixing. And then filtering the mixed solution by using a polyether sulfone filter membrane, standing for 24 hours in a thermostat at 25-35 ℃, centrifuging the obtained product, and washing by using deionized water to obtain the metalloporphyrin framework two-dimensional monodisperse nanosheet.
The preparation method of the metalloporphyrin framework two-dimensional/three-dimensional hierarchical flower-like nano structure comprises the following steps:
TPyP (1-5mM) in acetic acid was slowly added dropwise to CuAc2·H2Mixing O (5-10mM) and SDS (6-8mM) in water solution. And then standing the mixed solution in a thermostat at 25-35 ℃ for 24h, centrifuging the obtained product, and washing with deionized water to obtain the metalloporphyrin framework two-dimensional/three-dimensional hierarchical flower-like nanostructure.
Further, the thickness of the two-dimensional monodisperse nanosheet obtained in the preparation method of the metalloporphyrin framework two-dimensional monodisperse nanosheet is 80-100nm, and the average radial length is 700-800 nm.
Furthermore, the pore diameter of the polyether sulfone filtering membrane applied in the preparation method of the metalloporphyrin framework two-dimensional monodisperse nanosheet is 0.22 μm.
Further, the metalloporphyrin framework two-dimensional/three-dimensional hierarchical flower-like nanostructure obtained in the preparation method of the metalloporphyrin framework two-dimensional/three-dimensional hierarchical flower-like nanostructure comprises a two-stage structure, wherein the one-stage structure is a flower-like nanosphere and is assembled by a two-stage nano sheet structure. Wherein the average diameter of the flower-like nanospheres is 1.2-1.5 μm, and the thickness of the nanosheets is 80-100 nm.
Compared with the prior art, the technical scheme of the invention has the following advantages:
1. the polyether sulfone is filtered and introduced into a wet chemical reaction process, the morphology of the metalloporphyrin framework nanocrystal is effectively regulated and controlled, a two-dimensional monodisperse nanosheet is obtained after filtering, and a two-dimensional/three-dimensional hierarchical flower-shaped nanostructure is obtained without filtering.
2. The process is simple, has strong repeatability and meets the requirement of environmental friendliness.
Drawings
FIG. 1 is a schematic view of the filtration operation of the present invention
FIG. 2 is a scanning electron microscope image of two-dimensional monodisperse nanosheets obtained by the reaction of example 1 of the present invention.
FIG. 3 is a high-power scanning electron microscope image of the two-dimensional monodisperse nanosheet obtained by the reaction of example 1 of the present invention.
FIG. 4 is a scanning electron microscope image of the two-dimensional/three-dimensional hierarchical flower-like nanostructure obtained by the reaction of example 2 of the present invention.
FIG. 5 is a graph showing the time-lapse response of examples 1 and 2 of the present invention.
FIG. 6 is a scanning electron microscope image of the two-dimensional monodisperse nanosheets obtained by the reaction of example 3 of the present invention.
Detailed Description
The invention discloses a metal porphyrin framework two-dimensional monodisperse nano-sheet and a two-dimensional/three-dimensional stereoA method for preparing a volume-graded flower-shaped nano structure. The synthesis method comprises the following steps: mixing acetic acid solution of 5,10,15, 20-tetrapyridylporphyrin (TPyP) with copper acetate monohydrate (CuAc)2·H2O) and Sodium Dodecyl Sulfate (SDS) are uniformly mixed, and the mixed solution is kept still in a thermostat for 24 hours at the temperature of 25-35 ℃ to obtain a two-dimensional/three-dimensional hierarchical flower-shaped nano structure of the metalloporphyrin framework; mixing the above TPyP and CuAc2·H2O, SDS, filtering the mixed solution by a polyether sulfone filter membrane, and standing for 24 hours in a thermostat at 25-35 ℃ to obtain the metalloporphyrin framework two-dimensional monodisperse nanosheet. The invention introduces the filtered reaction liquid into the wet chemical reaction process, thereby realizing the effective regulation and control of the metal porphyrin framework nanocrystalline morphology, having simple manufacturing process and good repeatability, and meeting the requirement of environmental protection. The invention is further described with reference to the following figures and examples.
The technical solutions of the present invention are further described in detail by the following specific examples, but it should be noted that the following examples are only used for describing the content of the present invention and do not limit the scope of the present invention.
Embodiment 1 a method for preparing a metalloporphyrin framework two-dimensional monodisperse nanosheet, comprising the steps of:
1mL of TPyP (2.5mM) in acetic acid was slowly added dropwise to 15mL of CuAc2·H2O (8.34mM) and 15mL SDS (8mM) were mixed in a mixed aqueous solution and the mixture was homogenized. And then filtering the mixed solution by using a polyether sulfone filter membrane, standing in a thermostat at 30 ℃, timing, centrifuging the obtained product after 24 hours, and washing by using deionized water to obtain the metalloporphyrin framework two-dimensional monodisperse nanosheet.
Example 1 filtration operation as shown in fig. 1, a syringe and a polyethersulfone filter head were used to form a filtration apparatus, and the syringe was squeezed to separate out the reaction solution through a polyethersulfone filtration membrane, thereby obtaining a filtered reaction solution.
The morphology of the obtained two-dimensional monodisperse nanosheets is analyzed by a scanning electron microscope (as shown in fig. 2 and 3), and it can be seen from the figure that the two-dimensional monodisperse nanosheets obtained in example 1 are of a square sheet structure, uniform in size, good in monodispersity, and about 700-800nm in average radial length. From fig. 3 it can be seen that the two-dimensional monodisperse nanoplatelets are approximately 80-100nm thick.
Embodiment 2 a method for preparing a metalloporphyrin framework two-dimensional/three-dimensional hierarchical flower-like nanostructure, comprising the following steps:
1mL of TPyP (2.5mM) in acetic acid was slowly added dropwise to 15mL of CuAc2·H2O (8.34mM) and 15mL SDS (8mM) were mixed in a mixed aqueous solution and the mixture was homogenized. And standing the mixed solution in a thermostat at 30 ℃, timing, centrifuging the product after 24 hours, and washing the product by deionized water to obtain the metalloporphyrin framework two-dimensional/three-dimensional hierarchical flower-like nanostructure.
The two-dimensional/three-dimensional hierarchical flower-like nanostructure morphology obtained was analyzed by scanning electron microscopy (see fig. 4), and it can be seen from the figure that the two-dimensional/three-dimensional hierarchical structure obtained in example 2 comprises a two-stage structure, which is flower-like nanospheres and assembled from two-stage nanosheet-like structures. Wherein the average diameter of the flower-like nanospheres is 1.2-1.5 μm, and the thickness of the nanosheets is 80-100 nm.
As can be seen from FIG. 5, the solution in example 1 began to become cloudy after 0.5h, indicating that the reaction had begun, and was substantially complete after 1h, and the solution became in suspension after 24 h. However, in example 2, the solution was not filtered until the solution became cloudy after 3 hours and completely settled after 24 hours, demonstrating that filtration can accelerate the reaction rate.
Embodiment 3 a method for preparing a metalloporphyrin framework two-dimensional monodisperse nanosheet, comprising the steps of:
1mL of TPyP (2mM) in acetic acid was added slowly dropwise to 15mL of CuAc2·H2O (7mM) and 15mL of SDS (8mM) were mixed in a mixed aqueous solution and the mixture was homogenized. And then filtering the mixed solution by using a polyether sulfone filter membrane, standing for 24 hours in a thermostat at 30 ℃, centrifuging the obtained product, and washing by using deionized water to obtain the metalloporphyrin framework two-dimensional monodisperse nanosheet.
As can be seen from FIG. 6, the two-dimensional monodisperse nanosheet obtained in example 3 has a square plate-like structure, uniform size, good monodispersity, and an average radial length of about 700-800nm, which is consistent with the results of example 1.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.