Preparation And Sensing Application Of Luminescent Lanthanide Coordination Polymers

In recent years, the coordination polymers?CPs? using lanthanide ions as the central ions are increasingly concerned by more and more researchers. The main reason is lanthanide ions have the following advantages: unique light, electromagnetic properties, strong coordination, multiple sites and so on. The lanthanide coordination polymers have a wide range of potential applications in the fields of adsorption,separation, selective catalysis, biological sensing and optoelectronic materials. In this paper, we used different organic acids and amino acids as ligands and lanthanide ions(Eu³⁺, Tb³⁺) as central ions to synthesis a series of new fluorescent probes for biological sensing analysis. The fluorescent probes have a good dispersion and bio-compatibility which synthesized by biological ligands and lanthanide ions.Conducive to the development of biological researches based on the lanthanide coordination polymers, the main works are summarized as follows:1. Analysis of mercury ion(Hg²⁺) by using Eu-coordination polymer as the fluorescent probeIn this work, we used the lanthanide ion(Eu³⁺) as the central ion and the isophthalic acid?IPA? as ligand. Then a new type of coordination polymer nanoparticles?CPNPs? Eu/IPA CPNPs was synthesized by one-step solvent thermal method. We found that the absorption spectra of imidazole-4,5-dicarboxylic acid?Im?is greatly overlapped with the excitation spectra of Eu/IPA CPNPs. Therefore, we used Im as absorber to emerge the inner filter effect?IFE? with Eu/IPA CPNPs. Then we found the red fluorescence of Eu/IPA CPNPs quenched significantly after reaction with Im. In addition, Hg²⁺ and Im are able to generate new white precipitate complexes Hg/Im based on the strong coordination reaction. As a result, Im which in the surface of Eu/IPA CPNPs was falling down; then the IFE between Eu/IPA CPNPs and Im was blocked; eventually the red fluorescence of Eu/IPA CPNPs was turned on.We developed a simple, high sensitive fluorescence sensing method to detecte Hg²⁺,while the linear range of the Hg²⁺ is 2 nm to 2 ?M, and the detection limit was 2 nm.Lastly, we realized the detection of Hg²⁺ in urine.2. Lanthanide Tb³⁺ coordination polymer ratio fluorescence sensing detection of hydrogen sulfide?H₂S?In this paper, we used CDs@ZIF-8?Tb³⁺ and guanine nucleotide?GMP? through self-assembled method stirring in room temperature to synthesis a nanoparticles CDs@ZIF-8@Tb/GMP NPs who can emit strong blue and green fluorescence in 450 nm and 545 nm. Due to the paramagnetic of Cu²⁺ when CDs@ZIF-8@Tb/GMP NPs meet with Cu²⁺ in solvent, the Cu²⁺ would coordinate with phosphate groups of GMP from CDs@ZIF-8@Tb/GMP NPs. As a result, the inner energy transmition between Tb³⁺ and GMP was blocked lead to the green fluorescence of CDs@ZIF-8@Tb/GMP NPs was quenched. After the addition of H₂ S, a black precipitate CuS was formed due to the strong combination of H₂ S and Cu²⁺. Then the Cu²⁺ which was on the surface of CDs@ZIF-8@Tb/GMP NPs would pulled down then the inner energy transmition between Tb³⁺ and GMP was restorde. Finally, the green fluorescence of CDs@ZIF-8@Tb/GMP NPs was turned on. The ratio of F545/F450 showed a good linearity with H₂ S concentration when it ranged in 0.5-100 ?M, the detection limit was 150 nM. Finally we achieved the detection of H₂ S in serum.3. Lanthanide Eu³⁺ coordination polymer ratio fluorescence sensing detection of hydroxyl radical?·OH?We established a method for the detection of ·OH based on the ratio fluorescence by using Eu³⁺ coordination polymer. In this paper, we used the lanthanide ion Eu³⁺ as metal centre ion and 2,6-pyridinedicarboxylic acid?DPA? as ligand, through one-step solvothermal method to achieve a higher red fluorescent polymer Eu/DPA CPs. Then,we stirred Eu/DPA CPs with terephthalic acid?TA? at room temperature to form the idol coordination polymer Eu/DPA-TA CPs which emit red fluorescent and its max emission peak located at 615 nm. TA is known as the fluorescent probe of ·OH,because TA is very easy to be oxidized by ·OH to generate 2-hydroxyterephthalic acid who can emit strong blue fluorescence and its characteristic emission peak located at445 nm. Therefore, when Eu/DPA-TA CPs meet with ·OH, TA is easy to be oxidized to emit strong blue fluorescence, but the red fluorescence of Eu/DPA-TA CPs is weakly affected by ·OH. As a result, we have established a new type of ratio fluorescence method to detect ·OH. The ratio of F445/F615 showed a good linearity with·OH concentration when it ranged in 0.8-200 ?M, and the detection limit was 500 nM under the noise ratio was 3.