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Difunctionalised Chemosensors Containing Electroactive and Fluorescent Signalling Subunits
Author(s) -
Sance Félix,
Benito Angel,
Hernández Francisco J.,
Lloris José M.,
MartínezMáñez Ramón,
Pardo Teresa,
Soto Juan
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200203)2002:4<866::aid-ejic866>3.0.co;2-6
Subject(s) - chemistry , electrochemistry , fluorescence , protonation , metal ions in aqueous solution , metal , ligand (biochemistry) , potentiometric titration , stability constants of complexes , redox , crystallography , ferrocene , anthracene , inorganic chemistry , stereochemistry , ion , photochemistry , receptor , electrode , organic chemistry , physics , quantum mechanics , biochemistry
The new ligands 13‐anthrylmethyl‐7‐ferrocenylmethyl‐1,4,10‐trioxa‐7,13‐diaza‐cyclopentadecane (L 1 ) and 1‐anthrylmethyl‐4,8,11‐ferrocenylmethyl‐1,4,8,11‐tetraaza‐cyclotetradecane (L 2 ) have been synthesised, characterised, and their potential activity as chemosensors towards the metal cations Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ and Pb 2+ studied in 1,4‐dioxane/water (70:30, v/v). Both ligands L 1 and L 2 are difunctionalised receptors containing redox‐active (ferrocene) and fluorescent (anthracene) signalling subunits. The crystal structures of [H 2 L 1 ][PF 6 ] 2 and [CuL 2 ][PF 6 ] 2 were determined by single‐crystal X‐ray procedures. Potentiometric experiments in dioxane/water (70:30, v/v; 0.1 M KNO 3 ; 25.0 ± 0.1 °C) for L 1 and L 2 allowed the determination of protonation constants and complex stability constants with the Cu 2+ and Pb 2+ metal ions. They form stable complexes with both ligands and show stability constants with values close to those reported for similar complexes. The electrochemical and fluorescence behaviour of L 1 and L 2 was studied as a function of the pH and in the presence of the Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ , and Pb 2+ metal cations. The fluorescence and electrochemical response of L 1 and L 2 is pH‐dependent. Ligand L 1 was able to electrochemically and selectively sense Pb 2+ whereas L 2 sensed Cu 2+ , Zn 2+ , and Cd 2+ using electrochemical techniques. The maximum electrochemical shift (ca. 57 mV) was found for L 2 in the presence of Cu 2+ at pH = 8. Fluorescence studies showed that the emission intensities of L 1 and L 2 were selectively enhanced in the presence of Cu 2+ . Additionally, the [Cu(L 2 )] 2+ complex acted as anion‐sensing receptor in acetonitrile. The oxidation potential of the ferrocenyl group of the [Cu(L 2 )] 2+ complex was cathodically shifted upon addition of anions. The largest electrochemical shift was observed in the presence of fluoride (210 mV). The fluorescence emission of the anthracene groups in [Cu(L 2 )] 2+ was enhanced in the presence of fluoride, nitrate, and dihydrogenophosphate.