Synthesis,Structure And Properties Of Metal-Organic Supramolecular Polymers Based On Chiral Terpyridine And Metal Ions

In this thesis,a novel chiral bidentate terpyridine ligand L was successfully designed and synthesized based on chiralized pinene-fused terpyridine framework.Two new metal-organic supramolecular including[Zn₄L₄]?PF₆?₈?C1?and[Cd₃L₃]?PF₆?₆?C2?compounds were successfully constructed by the self-assembly of this novel ligand L with the transition metal ions Zn?II?and Cd?II?in a mixed solution.ThestructuresoftheligandLandthecorresponding metallo-supramoleculars were characterized by 1D and 2D nuclear magnetic resonance spectroscopy?NMR?,electrospray ionization mass spectrometry?ESI-MS?,traveling-wave ion mobility mass spectrometry?TWIM-MS?.The optical properties of the ligand and two metallomacrocycles were fully investigated by ultraviolet visible?UV-Vis?,fluorescence?FL?,circular dichroism?CD?and circularly polarized luminescence?CPL?.The theoretical spectrums of UV-Vis and CD were calculated by the density functional theory?DFT?method,which are in accordance with the experimental results.The details are as follows:1.Synthesis of the chiral bidentate terpyridine ligandCompound L was obtained through Suzuki coupling reaction using chiral terpyridine ligand 7 and compound 11 as the starting materials catalyzed by Pd?PPh₃?₄?Scheme 1?.The new compound L was characterized by NMR and ESI-MS.2.Synthesis of metallo-supramolecularsTwo new metallo-supramoleculars C1 and C2 had been prepared via self-assembly of chiral bidentate terpyridine ligand L with Zn²⁺and Cd²⁺in mixture solvent of CHCl₃/MeOH.The structures of two compounds were further characterized by NMR,ESI-MS and TWIM-MS.It was confirmed that ligand L and Zn²⁺self-assembled to form a tetrameric coumpound C1 of[4+4]structure?Figure1?a??,and a trimeric compound C2 of[3+3]architecture was formed when Cd²⁺was added instead?Figure 1?b??.3.Optical propertiesThe optical properties of ligand L and two metal-organic supramoleculars C1and C2 were studied by UV-Vis,FL,CD and CPL.In UV-Vis spectra,a ligand-to-metal charge transfer?LMCT?transition was observed in two metallo-supramolecular systems.The CD spectrum showed a characteristic transition absorption peak produced by the metal ion.The peak of characteristic circularly polarized fluorescence emission from metal ions was also observed from CPL spectrum,and the asymmetry factors of the three are all 10^-4.Therefore,the introduction of the chiral tripyridine ligand successfully induced the optical activity of the ground state and the excited state of the metal ion center.In addition,the theoretical spectras of UV-Vis and CD were calculated by density functional theory?DFT?method,which confirmed the rationality of the experimental results.