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Since its discovery in the early 1950s, ferrocene is the most thoroughly studied compounds in chemistry, people have exploited a large number of ferrocene-based ligands. Ferrocene and its derivatives have been widely applied in numerous areas, such as organic synthesis, biochemical and medical, catalysis, materials for electronics, electrochemical molecular recognition, supramolecular assembly compounds and so on. The design and synthesis of novel ferrocene-based ligands, research of new methods to synthesize them also have received considerable attention in recent years. As we all know, ferrocenyl-bearing hydrazones andβ-diketones can form stable complexes with various metal ions. However, little effort has been devoted to the study on their electrochemical sensing properties. Taking these into consideration, in the paper, we have designed and synthesized three new receptors, based ferrocene-containing pyridine moiety, twoβ-diketones and one hydrazone. The electrochemical properties of FcL1, FcL2 and FcL3 have been studied by cyclic voltammetry in ethanol electrolyte, and in the presence of metal cations (Ni2+, Co2+, Cu2+, Mn2+, Cd2+, Hg2+and Zn2+). We choose the mono-diktone to synthesized complexes. The electrochemical properties of the complexes have been studied by cyclic voltammetry in acetonitrile electrolyte. Cyclic voltammetry curves show that the ligands and the complexes exhibit expected reversible one-electron oxidation of ferrocenyl, and a higher redox potential than ferrocene.1. Methyl-6-ferrocenoylacetyl-2-pyridine carboxylate (FcL1) and 1, 1’-(2,6-bispyridyl) bis-3-ferrocenyl-1,3-propanedione (FcL2) were prepared by condensation of acetylferrocene with dimethyl-2, 6-pyridinedicarboxylate, using different molar ratios and characterized by FT-IR,1HNMR,13CNMR,UV-Vis spectra as well as elemental analysis.2. Methyl-6-ferrocenoylacetyl-2-pyridine carboxylate (FcL1) forms complexes with Tb(Ⅲ), Eu(Ⅲ), Gd(Ⅲ), Sm(Ⅲ) and forms complexes with Zn(Ⅱ), Hg(Ⅱ), Co(Ⅱ), Cu(Ⅱ), Mn(Ⅱ) and Cr(Ⅱ) in good yield. The complexes were characterized by FT-IR, TG-DTA and UV-Vis titration as well as elemental analysis, and their electrochemical behavior was investigated by cyclic voltammetry. The results suggested that the ligand and the complexes exhibit expected reversible one-electron oxidation of ferrocenyl, and higher redox potential than ferrocene.3. Synthesis of ferrocenecarboxaldehyde-2,6- dipicolinoyhydrazone (FcL3) was prepared by using 2,6-dipicolinoyhydrazine and ferrocenecarboxaldehyde in ethanol and characterized by FT-IR,1HNMR, 13CNMR, UV-Vis spectra as well as elemental analysis.4. The electrochemical properties of FcL1, FcL2 and FcL3 have been studied by cyclic voltammetry in ethanol electrolyte, and in the presence of metal cations (Ni2+, Co2+, Cu2+, Mn2+, Cd2+, Hg2+and Zn2+). Cyclic voltammetry curves show that these compounds are able to recognize potentiometrically a metal cation. It has been shown that FcL1 can be used, through an electrochemical response, to detect Cu2+ and Cd2+ FcL2 to detect Cu2+ and Mn2+, and FcL3 to detect Hg2+ and Mn2+ in a non-aqueous environment.
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