Syntheses、Theoretical Caiculation And Ion Recognition Properties Of New Host Molecules Based On Coumarin-Hydrazone

We designed and synthesized a series of novel host molecules based oncoumarin-thiazole-hydrazone-unctional structure. Cations and anions recognationproperties of these host molecules were studied by UV^-Vis absorption spectroscopy,electrochemical properties and quantum chemical calculations. The main researchresults of this article includes the following aspects:1.10new host molecules based on coumarin-thiazole-hydrazone-functionalwere synthesized. We divided them into three systems:1) host molecules1-3containing two hydrogen bonds of the phenolic hydroxyl group and the hydrazonegroup forbody;2) host molecules4-6containing two coumarin fluorophore;3) themain molecule7-10containing C=N cis-trans isomerization groups and N^-Hhydrogen bond donor. Characterization by NMR, MS, FT-IR to figure out molecules’structure.2. By using UV^-Vis absorption spectroscopy, we studied recognition propertiesof host molecules1-10with different cations (Mn²⁺, Fe³⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Cu⁺,Zn²⁺, Hg²⁺). The results indicate that the coumarin^-thiazol^-hydrazone^-salicylaldehydeskeleton structure of the host molecules1^-3in DMF can recognize Co²⁺because theUV^-Vis absorption spectrum changed significantly.By using UV-Vis absorption spectroscopy, we studied recognition propertiesof host molecules1^-10in DMF/H₂O （8:2V/V） with different anions （F^-, Cl^-, Br^-, I^-,NO₂^-, H₂PO₄^-, CH₃COO^-, HSO₃^-）. The results showed that host molecules1,4,6,10can recognize HSO₃^-, but host molecules7can recognize HSO₃^-, F^-, CH₃COO^-.3. Host molecules4,5can recognize Co²⁺by naked eye because the colour ofsolution changed from yellow to pink. The host molecule6can recognize Cu²⁺bynaked eye because the colour of solution changed from yellow to colorless. The hostmolecule7can recognize Co²⁺because the colour of solution changed from yellow topale blue, and can also recognize Ni²⁺because the colour of solution changed fromyellow to purple.4. From the results of electrochemical experiment, we find that among differentcations(Mn²⁺、Fe³⁺、Fe²⁺、Co²⁺、Ni²⁺、Cu²⁺、Cu⁺、Zn²⁺、Hg²⁺), only the existenceof Hg²⁺make cyclic voltammetry signals changed for host molecules1^-10. Reversible single oxidative peak became into quasi-reversible double oxidative peaks,with the potential-shift ranged from0.06to0.1V, and the reductive peak currentdecreased significantly. Generally, these host molecules showed ability ofelectrochemical recognition to Hg²⁺.5. By using Density Functional Theory PBE0/6-31G（d）, we optimized theground-state geometry for all the host molecules. We used Gaussian09packagePBE0/6-31G （d） to calculate the molecular frontier orbitals and the electrostaticpotential. Electronic structure calculations provide a theoretical basis for the furtherresearch.