Synthesis And Properties Of Core-modified Octaphyrin Radical And BODIPY Derivatives

With the development of the research on free radicals,researchers realized that porphyrin and related molecules have excellent?-conjugate system to stabilize free radicals.Among them,expanded porphyrins attracted considerable attention due to their flexible molecular skeleton and a large?-conjugated system,which can be used as an ideal platform for obtaining stable free radicals.In this thesis,we first chose core-modified octaphyrins as the platform to investigate the properties to stabilize radical cation.Secondly,we focused on the study the properties of BODIPY derivatives which are one kinds of excellent fluorescent chromophores and can be used as fluorescent probes in many fields.In this part,a novel type of BODIPY derivatives with large red-shift to the absorption spectra have been synthesized.Then we used it as fluorescent probe for detection Hg²⁺ion and it shown high sensitive and selective properties to Hg²⁺ion in the solution.First,we synthesized a series of core-modified octaphyrin with thiophene rings,and then oxidized with it with Hg?ClO₄?₂ to get core-modified octaphyrin radical cations.The substituents on the meso-aryl were-C₆F₅,-C₆H₅NO₂,-C₆H₅COOCH₃.The molecular structure of the complexes was confirmed by nuclear magnetic resonance?NMR?spectroscopy,high-resolution mass spectrometry?MS?and X-ray single crystal diffraction analysis.The neutral core-modified octaphyrin molecular adopts a"figure-of-eight"twisted conformation while the protonated form shown an untwisted planar structure.Analysis of the nuclear independent chemical shift?NICS?and the anisotropy?ACID?spectrum of the induced current density further confirmed the non-aromaticity of the neutral octaphyrin and the aromaticity of the oxidized radical cation.Secondly,the ultraviolet absorption spectrum?UV-vis?of titration of core-modified octaphyrin with TFA and Hg?ClO₄?₂,separately,in dichloromethane solution showed that both the protonation and oxidation undergoes two well-defined steps.During the oxidation process,the absorption peak of the compound undergoes a relative red shift and a characteristic band formed by free radical cations appears at2100 nm.In addition,through electron spin resonance?ESR?and superconducting quantum interference?SQUID?measurements,proved that there is a strong antiferromagnetic interaction between the molecules.Finally,the CV chart of core-modified octaphyrin and its free radicals was measured in dichloromethane.The core-modified octaphyrin compound has a two-stage reversible oxidation process and a three-stage reduction process,and the radical cation has a two-stage irreversible oxidation process and five-stage reduction process,the redox half-wave potentials of the compounds are shifted to the positive direction due to the different electron-withdrawing abilities of the meso-position substituents.Secondly,we synthesized a meso-COOCH₃ substituted BODIPY derivative intermediate,and then used it as raw material to perform a Knoevenagel condensation reaction with 2-pyrrolylcarboxaldehyde to obtain a new long-wavelength BODIPY by introduced a pyrrole vinyl structure to 3-position.This novel BODIPY derivative shown specific sensitive and selective properties to Hg²⁺ion.When Hg²⁺ion was added to the dichloromethane solution of the compound,the UV-Vis spectrum undergoes a significant blue shift.With the increase of Hg²⁺ion concentration,the fluorescence intensity will be completely quenched.Through competitive experiments on metal cations,the results shown that the BODIPY complex has highly selective for Hg²⁺ion.