Chemical Sensing,Magnetic And Thermal Properties Of Coordination Polymers Based On Carbazole-2,7-Dicarboxylic Acid

Coordination Polymers(CPs)are composed of metal ions or metal clusters with organic ligands.,which possess high porosity,small density and designability of their construction.In view of these advantages,CPs have been wildly used in multiple fields,for instance,optics,magnetism,thermal expansion,chemical sensing and so on.In this thesis,we chose carbazole-2,7-dicarboxylic acid as organic ligand to coordinate with transition/lanthanide metal ions to obtain four novel different crystalline materials.We characterized and analyzed their basic properties,and explored the application of CPs in chemical sensing,thermal expansion,magnetism and so on.The main research of this paper is as follows:1.Based on H₂L and Cd²⁺ion,a new 2D coordination polymer[Cd₂L·(H₂O)₂]_n(1)has been synthesized successfully by diffusion method under ambient conditions.In the structure of coordination polymer 1,two adjacent Cd²⁺atoms bridge through ligand bicontate,then these units extend along the b axis.The Cd-O-C chains are connected by L^2-ligand in(010)direction to form a2D coordination network.Then,the 2D coordination network construct the 3D crystal structure of coordination polymer 1 by parallel stacking.The coordination polymer 1 emits strong blue light.2.We have studied a 3D coordination polymer[Zn₈L₆(m₄-O)₂·DMSO·(H₂O)₃]·5DMSO(2).Its structure and basic properties have already been reported.The coordination polymer 2 possesses the two-fold interpenetrated 6⁶ coordination net and ligand-based blue-light emission.The luminescence titration experiments indicate that coordination polymer 2 could selectively detect Mn O₄^-by luminescent quenching in the concentration range of 0-100?M in water with K_sv of 17030 M^-1.The possible quenching mechanism has also been discussed.The above studies indicated that the coordination compound 2 is a potential fluorescence sensor for Mn O₄^-ions in water and is a high-efficiency sensing material.3.A flexible 3D coordination polymer[Ca₂Zn₂L₃·(DMF)₂]·DMF(3)has been synthesized by diffusion method under ambient conditions.The coordination polymer 3 contains a trinucleate cluster,Ca Zn₂(COO)₆(DMF)₂,which is linked by the oxygen atoms of the carboxylate groups to form the three-dimensional skeleton of coordination polymer 3.Meanwhile,the structure of coordination polymer 3 contains a channel along the a axis.Compared with the materials with similar SBU,the coordination polymer 3 exhibits anisotropic thermal expansion behavior.The coordination polymer3 have super positive thermal expansion on the a and c axes and zero expansion on the b axis.Therefore,coordination polymer 3 provides an important example for the development of luminescent coordination polymer towards hyperfunctional application.4.Based on H₂L and Mn²⁺ion,a 2D coordination polymer[Mn₃L₃]·DMA(4)has been synthesized.The structure of coordination polymer 4 contains a trinucleate cluster,[Mn₃(COO)₆],which as an SBU,is connected with four identical SBU through six carboxyl groups to form a 2D 4⁴structure network.Then,the 3D crystal structure of coordination polymer 4 is constructed by parallel interlaced ABAB stacking.Upon excitation at 311 nm,coordination polymer 4 emits blue light and the maximum emission peak is 433 nm.Coordination polymer 4 is a simple paramagnetic compound with almost negligible interaction between metal ions.