Manganese Oxide Nanomaterials And Copper, And Cobalt-based Organic - Inorganic Hybrid Materials Synthesis, Characterization And Properties

The 21st century is the era of chemical materials.The new materials will lead to the rapid development of technology and the related industries,and even lead to new industries and technical fields.Materials science has become an interdisciplinary comprehensive discipline.As a forerunner of the materials science development,the design and synthesis of nano-materials are the foundation of the application and the further development of materials.It is still a hot research field for materials that how to develop new methods to design and synthesis of nano-materials and how to realization the control of nano-particles size,distribution,morphology and surface modification.In addition,in emerging fields such as nano-technology and bio-engineering of the continuing need to have different physical and chemical properties of new materials.Organic-inorganic hybrid materials combining the properties of the inorganic and organic species at the molecular level,which provide a possibility,to change the composition and structure of the materials by chemical methods at the same time.It is one of the subjects of concern for chemists and materials scientists and has many potential applications as important multifunctional materials.Our group researched in liquid-liquid system,extraction chemistry,and inorganic chemical materials for a long time and has accumulated a rich of experience in the solution structure of liquid-liquid system,solution structure and interphases transfer,as well as the preparation of functional materials.On the basis of previous work of our group,this thesis try to find a new liquid synthetic system to control synthesize of a special morphology of inorganic nano-materials and provides a new way to the preparation,assembly, modification of nano-materials;In addition,we had prepared a novel organicinorganic hybrid materials through ion exchange reaction that insert organic ligands in the layered inorganic materials and combining the magnetism of the inorganic part with the physical properties of inserted molecules,such as chiralitv and/or luminescence properties,which provide a experimental and theoretical basis for the liquid-phase synthesis of functional materials,the development of the inorganic materials and organic materials complementary functions,the design and synthesis of a specific composition,structure and functions of the new Organic-inorganic hybrid materials.The main results summarized are list as follows.1.Synthesis,Characterization and mechanism research of inorganic nano-materials(a)Single-crystalβ-MnO₂ nanotubes with diameters in the range 200-500 nm and lengths up to several micrometers were successfully prepared by a simple hydrothermal method through oxidizing MnSO₄ with NaClO₃ in the presence of poly(vinyl pyrrolidone)(PVP).Based on a series of experimental analysis and discussions,the formation mechanism of these nanostructures was discussed briefly and found that the formation process ofβ-MnO₂ nanotubes follow a nucleation-dissolution-anisotropic growth-recrystallization mechanism.The present study has enlarged the family of nanotubes available, and offers a possible new,general route to one-dimensional single-crystalline nanotubes of other materials.(b)A convenient hydrothermal processing followed by a post-heat treatment route is proposed to synthesize well-dispersed branchedβ-MnO₂ multipods from branchedγ-MnOOH precursor.The key steps in our approach are as follows:By controlling the reactants concentration and reaction time,the monoclinic phase of MnOOH with novel branched multipods nanostructures was synthesized via the hydrothermal reaction of MnSO₄·H₂O and NaClO₃ at 160℃for 200 minutes;Then,the as-prepared branchedγ-MnOOH multipods were heated in air atmosphere at 400℃for 2 h,the branchedβ-MnO₂ nanostructures could be successfully obtained and without changing the precursory morphologies.These new structures presented here enrich the nanoscale community with new basic materials and offers a new approach for increasing structural complexity and enabling greater potential applications. Furthermore.the briefly discuss about their formation mechanisms provide insight into the formation processing of other transition metal oxide multipods (c)γ-manganese dioxides with novel saucer-shaped hexagonal nanoplatelets structure have been successfully synthesized via a simple chemical route using manganese nitrate as the manganese source and sodium chlorate as oxidant reagent without the addition of any surfactants or organic templates.The hexgonal nanoplatelets have edge lengths about of 250 nm with the thickness only several tens of nanometers and characterized using a variety of technical measurement methods.A possible formation mechanism of this novel morphology of nanoplates was proposed by tracking the crystallization and morphology of the products at different reaction stages.The magnetic properties of the products were investigated by a Quantum Design SQUID (superconducting quantum interference device)magnetometer and exhibit a paramagnetic behavior.The present study has offers a possible new,simple route for bulk synthesis of two-dimensionalγ-MnO₂ nanoplatelets and enlarged the family of MnO₂ available.2.The Preparation and Characterization of Organic-Inorganic Hybrid Materials.(a)Layered hydroxide metal acetates Co₂(OH)₃(CH₃COO)·H₂O with an interlayer spacing of 12.82(?)has been synthesized conveniently and rapidly as aggregates of thin crumpled sheets by a new method main routes conducted in ethanol-aqueous mixed solvents media.From the elemental analysis,in combination with the results obtained from thermal gravimetric measurements, the stoichiometry of the product was found to be Co₂(OH)_3.3 (CH₃COO)_0.7·2H₂O.The anhydrous form also can be easily obtained by moderate heating at 120℃only for one hour.The layered hydroxide cobalt acetates showing very interesting magnetic properties and its applications in the fields of anionic exchange reactions as good candidates made such an effective and facile approach very exciting for the preparation of hybrid organic-inorganic compounds.(b)We report the preparation,structure and physical properties of a series of multilayer multifunctional materials transition metal(â…¡)hydroxycitronellicates. These are prepared by anion-exchange reactions,starting from transition metal hydroxy-acetate layers M(â…¡)₂(OH)₃(OAc)·H₂O(M=Cu,Co). The acetate ion is substituted for citronellic acid,which was one of several chiral 2- or 3-methyl branched acids.Similar exchange reactions are carried out with recemic,R and S chiral 2- or 3-methyl branched citronellic acids.The compounds,of general formulation M₂(OH)_(4-x)(C₁₀H₁₇O₂)X·zH₂O,exhibit a layered structure with a step-like variation of the basal spacing,according to inorganic metal hydroxy-acetate parity.Powder X-ray diffraction,IR spectroscopy,scanning electron microscope,as well as magnetic measurements etc.variety of techniques have been used in the characterization of the as-prepared samples.This study provides new insight on the multifunctional materials based on the grafting of optically active chiral organic ligants into inorganic magnetic layers.