Study On Self-assembled Syntheses,structures And Chemical Sensing Properties Of Acylhydrazidate-based Coordination Polymers

As a novel material,coordination polymers?CPs?are formed by coordination reactions between metal ions?or metal clusters?and monodentate or multidentate organic ligands under corresponding conditions.With the development of CPs,a variety of synthetic methods are constantly being developed.It has received extensive attention in the scientific community due to its diverse structure and properties in gas storage and separation,magnetic,catalytic,and chemical sensing.Among them,as a convenient synthesis method,the in situ formation reaction of ligands has been widely used.And a large number of coordination polymers materials based on the methods have been reported.But the in situ acylation reaction between aromatic organic ligands containing ortho-carboxy groups and hydrazine hydrate is an important one.In recent years,our research group has synthesized a large number of in situ acylated CPs materials.We studied their synthesis conditions,photoluminenscence,magnetic properties,N₂ adsorption and I₂ adsorption.However,the chemical sensing properties of hydrazide coordination polymers have not been involved.Based on previous research,this paper mainly studies the synthesis of a series of metal-organic coordination polymers and one hydrazide supramolecular compound by self-assembly synthesis among organic acid ligands with ortho-carboxy groups,Hydrazine hydrate,and main group,transition or rare-earth metal cations under hydrothermal conditions.And they were characterized by X-ray single crystal diffraction,infrared analysis,thermogravimetric analysis,elemental analysis,PXRD and other means.In addition,we systematically studied its photoluminenscence properties,chemical sensing properties and sensing mechanism.This work provides experiences for the performance development of hydrazide-based coordination polymers in the future.The paper is divided into six chapters:The first chapter is the introduction,which introduces the concept,development status of the coordination polymer,the in situ formation reactions of ligands,the main applications of the coordination polymer materials,and the significance,innovation and research results of this paper.The second chapter introduces the experimental principles,test instruments and chemicals and reagents.Chapter three describes a compound of 1?[Zn₂?apo?₂]?H₂O,H₂?apo?=4,5-diamino-1,2-dihydropyridazine-3,6-diol?obtained by in situ acylation under hydrothermal conditions.The asymmetric units of 1 formed the 1-D chain structures by"interlocking"linkages,and the two-dimensional layered structures is formed between adjacent chains by coordination bonds between metal centers and phthaloyl hydrazide molecules.The factors affecting the reaction system,such as the stirring time,the pH of the reaction system,the reaction temperature and the types of metal centers,are discussed from the synthetic process.In addition,we studied the photoluminescence properties of 1.Based on the larger excitation wavelength and much high photoluminescence lifetimes of compound 1,we further studied the qualitative and quantitative detection of 1 on nitro-explosives and Cr₂O₇^2-and also carried out the UV-vis absorption mechanism of chemical sensing.This work is the first case to study the chemical sensing properties of hydrazide-based coordination polymers.The fourth chapter introduces the oxalic acid,H₄pda[H₄pda=4,4'-?2,2-diperfluoropropane?-diphthalic acid]and the main group metal cations[MgCl₂?6H₂O],transition metal cations[CdCl₂?2.5H₂O,ZnCl₂,FeCl₃?6H₂O andCo?NO₃?₃?6H₂O],and rare earth metal cations[Er?NO₃?₃?6H₂O]synthesized a series of dihydrazide coordination polymers 2-8 under the hydrothermal conditions.They are Mg?pbd??H₂O?]?H₂O?2?,[Fe?pbd??H₂O?]?H₂O?3?,[Zn?pbd??H₂O?]?H₂O?4?, [Cd?pbd??H₂O?]?H₂O?5?,[Pb?pbd?]?6?,[Er₂?pbd?₂?ox??H₂O?₂]?5H₂O?7?and[Co?Pbd??H₂O?]?H₂O?8?[H₂pbd= 6,6'-?perfluoropropane-2,2-diyl?bis?2,3-dihydrophthalazine-1,4-dione?].The compounds 2-5 and 8 synthesized isomorphic.The metal centers[Mg²⁺,Fe³⁺,Zn²⁺, Cd²⁺and Co²⁺]and H₂pdb are connected to each other to form a one-dimensional chain structure,and the adjacent chains are extended to 2-5 and 8 of two-dimensional single-layer structures by the coordination bonds.A three-dimensional cluster-like coordination polymer material of Pb₂O₈ was synthesized from the main metal center(Pb²⁺)and pbd^2-.Finally,the clusters were connected by H₂pdb into a three-dimensional network structure.Compound 7 having a two-dimensional two-layer structure was synthesized from a rare earth metal center(Er³⁺),pbd^2-and oxalic acid.It was found that the double-layer structure is a two-dimensional double-layered pore structure.The two-dimensional single-layer structure isomorphic with compounds 2-5and 8 is connected by oxalic acid,the connecting"bridge".The photoluminescence properties of compounds 4,5,6 and 7 were also studied in this paper.The stabilities and sensing abilities for Cr₂O₇^2-were also carried out.Similarly,we studied theUV-visible absorption mechanism of chemical sensing Cr₂O₇^2-.Among the four compounds,Compound 6 has the best chemical sensing properties.In the fifth chapter,two kinds of monohydrazide-tetracarboxylic acid coordination polymers[Sr₂?dtba??H₂O?]?9?and[Ba₅?Hdtba?₂?H₂O?₄?ox?]?6H₂O?N₂H₄?10?[H₆dtba=5,5'-?1,4-dioxo-1,2,3,4-tetrahydrophthalazine-6,7-diyl?bis?oxy?diisophthalic acid)]were synthesized by hydrothermal in situ acylation under certain reaction conditions.The experimental results show that both compounds 9 and 10 are 3-D network structures.The photoluminescence properties of these two compounds and the properties of chemical sensing properties for nitro-explosives were also studied.And the energy absorption competition mechanism and energy transfer mechanism of fluorescence sensing were further discussed.In addition,using Cr?NO₃?₃?6H₂O and oxalic acid induced H₄sdpa?H₄sdpa=4,4'-sulfonyldiphthalic acid?to synthesize 3-D supramolecularcompound[sdpd]??H₂O??11?[H₄sdpd=6,6'-sulfonylbis?2,3-dihydrophthalazine-1,4-dione?].Under the condition,H₄sdpa reacts with hydrazine hydrate to obtain 11,which is formed by the?????interaction of the H₄sdpd intermoleculars.Compound 11 has a blue light emission behavior.The sixth chapter is the conclusions and prospects of the thesis on this research topic.