Synthesis And Properties Of Coordination Polymers Based On Tetraoxaspiro And Tetrazine Pyridine Ligand

Coordination polymers(CPs)have great application value in optical,electrical,magnetic and other macroscopical fields.However tremendous scientific challenges remain for obtaining expected structures and properties due to the diversity of organic ligands and limitation of many indeterminate factors in the self-assembly processes of complexes.Chiral spirocyclic ligands and tetrazine pyridine ligands are the most attractive members of organic ligands,however,only a few coordination polymers with spirocyclic and tetrazine pyridine ligands as bridging ligands have been reported.Thus,much effort must be invested to explore these unknown areas.In addition,in coordination polymers,metal organic frameworks(MOFs)are widely used in gas storage,drug delivery,probe detection and so on because of their permanent porosity,high surface area and tunable pore volume properties.In the strategy of constructing porous MOFs,the "pillar-layer" method is one of the effective methods for the synthesis of porous structures.By this method,the structure of various MOFs could be predicted,in which tetrazine pyridine ligands are one of the suitable "pillar" ligands.However,the study of the complexes of tetrazine pyrazine ligands is not rich enough,and more efforts need to be devoted to mining.Herein,we designed and synthesized rac-(R,S)-3,9-bis(pyridin-3-yl)-2,4,8,10-tetraoxaspiro[5.5]undecane((R,S)-bptu)ligand and its five new complexes,{[Cu[(R,S)-bptu]Cl2]·0.5NMP}n(1),{[Zn[(R,S)-bptu]Cl2]·CH3CN}n(2),{Cd2[(R,S)-bptu]2Cl4(NMP)2}n(3),{[Cd[(R,S)-bptu]2Cl2]·2CH3CN}n(4),{Cd3[(R,S)-bptu]2Cl6(DMF)2}n(5).Among them,1 and 3 are mesomeric 1D chains while 2 is racemic compound;however,4 and 5 exhibit two different 2D mesomeric layers.Structural multiformity suggests that the coordination preferences(cis-and trans-configurations)of(R,S)-bptu play a leading role in the self-assembly of complexes:cis-bptu tends to form one dimensional structures 1-3,while trans-bptu is easier to construct higher dimensional structures 4-5.The diverse geometry of metal ions,different solvent system,the coordinated/free solvent and the secondary building units(SBUs)affect the diversification of the structure.The investigation of magnetic property manifests that antiferromagnetic character exist between the neighbouring metal ions in 1.Furthermore,the solid state fluorescence properties of 2-5 are investigated in the at normal atmospheric temperature and 4 shows superior selective and hypersensitive sensing for Fe3+ions.In addition,the "pillar" tetrazine ligand 3,6-di(pyridine-4-yl)-1,2,4,5-tetrazine(dptz),metal ions(Zn(?),Cd(?),Co(?))and different carboxylic acid ligands were used to build four complexes 6-9,{[Zn(dptz)(btpc)]·CH3CN}n(6),[Cd(dptz)0.5(btpc)(DMF)]n(7),[Co(dptz)(btpc)(EtOH)2]n(8),{[Co(dptz)(Hbtc)]·CH3OH·DMF}n(9).6 and 7 with solid-state fluorescence properties are two different 3D "pillar-layer" structures;complex 8 that is a 2D layer has a certain adsorption effect on methyl orange(MO),which can be used as a dye adsorbent to reduce methyl orange in wastewater;9 is a microporous 2D complex and has certain adsorption ability for CO2 at different temperature.Under UV irradiation,degradation rate of MO is 85.6%in the presence of 9 which is an excellent photocatalyst for degradation of MO,and the magnetic property of 9 is characterized and founds that there is an antiferromagnetic character between Co(II)ions.There are four chapters in this paper:Chapter 1:we present the concept and application of coordination polymers,the idea of selecting and the research results obtained in this paper.Chapter 2:we design and synthesize a new chiral ligand(R,S)-bptu and five new complexes are obtained based on it.The structure,basic characterization and property of these complexes are studied.We discuss detailedly influencing factors on final structure of complexes,such as coordination configuration of organic ligands,diverse geometry of metal ions,solvent systems,the coordinated/free solvent and SBUs.The study of property show that complex 1 has antiferromagnetic character,2-5 have good solid state fluorescent properties and 4 can be used as a fluorescent sensors for the detection of Fe3+ ions.Chapter 3:we offer the structures and properties of four novel complexes,which are synthesized by the "pillar" tetrazine dptz ligand and different carboxylic auxililiary ligands under hydrothermal conditions.The structures and properties of four complexes have been characterized and investigated.9 is a 2D complex with pore size,which exhibits different adsorption capacity to CO2 at different temperatures.Under the irradiation of ultraviolet lamp,the degradation rate of methyl orange in the presence of 9 is up to 85.6%,which is a good photocatalyst for degradation of MO,the magnetic properties of 9 are characterized and found that there is antiferromagnetic character between Co(?)ions.In addition,the dyes adsorption of 8 and the solid-state fluorescence properties of 6 and 7 are discussed.