Design,Synthesis And Anion Recognition Properties Of 4,5-Diferrocene Substituted Imidazole Derivatives

Anion plays an extremely important role in chemistry,biology,medicine,environmental science and other related fields.Recently,a series of receptors of ferrocene substituted-imidazole have been synthesized and achieved better results in selective recognition of different anions.Termini diferrocene substituted building blocks attached to a heterocyclic core including nitrogen have gained topical interest,due to their conceivable application as model compounds in the study of electron transfer in the mixed-valent species.In this thesis,diferrocene and aromatic groups,such as nitrobenzene will be introduced into imidazole in order to design four new imidazole acceptors.The binding events between the diferrocene substituted-midazole and anion are based on(N-H)+…X type ionized hydrogen bonds which can be detected by electrochemical or UV-vis spectroscopy change or,more directly,a colorimetric change detectable by the naked eye.The thesis also presents the synthesis and the electron-transfer characteristics of diferrocene-based pyrrole through spectro-electrochemical method.1.Four kinds of novel termini ferrocene-based imidazoles(9a-9d)have been designed and structurally characterized by IR,MS,1H NMR,13C NMR and HRMS.The electrochemical and spectro-electrochemical(UV-vis-near-IRspectroscopy)properties of these species were studied.These organometallic compounds display two well-resolved electrochemically reversible one-electron-transfer processes.The spectro-electrochemical studies reveal that ferrocenyl units interact strongly with the heterocycle,existing Cp→FeⅢ transition(LMCT)and Imidazole→FeⅢ transition(LMCT).2.The binding properties between receptor and anion have been examined by cyclic voltammetry(CV),chromogenic sensors,NMR titration and UV-vis titration.CV results showed that receptor 9a-9d all can be used as ion recognition for the selectively detection of H2PO4-and F-in acetonitrile.Upon addition of 6 eq H2PO4-anion,a new strong oxidation peak appeared.On stepwise addition of F-anion to a solution of receptor 9d in CH3CN,a electrochemical shift of the oxidation wave to 271 mV(△Epa=-176 mV),however the presence of Cl-、Br-、AcO-、HSO44-anions had little effect on the CV(△Epa<40 mV).UV-vis titrations demonstrated that the receptors 9d showed affinity and high selectivity for F-,HSO4-anion in acetonitrile.Upon addition of 20 eq F-,the original absorption peak of the 9d on the 306 nm,381 nm increased or even occured blue shift.And a new absorption peak generated at 477 nm place.On stepwise addition of HSO4-anion to a solution of receptor 9d in CH3CN,the original absorption peak of the 9d on the 306 nm increased,381 nm decreased and generated two new peaks at 343 nm,475 nm respectively.Job’s cuver revealed that the receptor could bind anions through(N-H)+…X-hydrogen bonds forming 1:2 stoichiometric complexes.1H NMR titrations demonstrated that the receptor have high selectivity for the F-ion in DMSO-d6 on account of the intensity of the imidazole N-H resonance decreased gradually and disappeared along with the increase of F-and had a triplet around the 16 ppm region for the HF2-ion.the Nitro substituted at the p-site(the receptor 9d)can be used as chromogenic sensors for the selectively detection of F-.3.A series of novel termini ferrocene-based pyrrole have been prepared and characterizeed using NMR,IR,and UVvis spectroscopy as well as X-ray crystal-lography.The electronic properties of these compounds were investigated using cyclic voltammetry and spectro-electrochemical.These organo-metallic compounds display two electrochemically reversible one-electrontransfer processes.The spectro-electrochemical studies reveal that ferrocenyl units interact strongly with the heterocycle,existing Cp→FeⅢ transition(LMCT),Pyrazole→FeⅢ transition(LMCT)as well as IVCT.