A new multifunctional ferrocenyl-substituted ferrocenophane derivative: optical and electronic properties and selective recognition of Mg2+ ions.
The synthesis, characterisation, and X-ray structure of a new strained asymmetric diferrocene derivative (2) is reported. Compound 2 acts as a highly specific electrochemical and optical Mg(2+) ion sensor, as revealed by spectroscopic and electrochemical techniques. Thus, in the presence of Mg(2+), a new redox peak appears in the cyclic voltammogram (CV) that is anodically shifted compared to the E(1/2) of the free receptor (DeltaE(1/2)=340 mV). Diferrocene derivative 2 also gives a highly visual response upon addition of Mg(2+), namely a change of colour from orange to deep purple. In addition, compound 2 does not show any significant sensing activity in the presence of Ca(2+) or alkaline ions. On protonation, it is converted into the stable diferrocenylcarbenium salt 4, in which two different modes of stabilisation of the alpha-carbocationic centre are clearly demonstrated by a combination of (1)H NMR and (57)Fe Mössbauer spectroscopic measurements. Finally, by a partial (chemical or electrochemical) oxidation, compound 2 forms the asymmetric mixed-valence species 2(+), which can be isolated as the solid salt 6 by using CF(3)SO(3) (-) as a counterion. This mixed-valence species shows a fast intramolecular electron-transfer process, as ascertained by several spectroscopic techniques.
Lopez
Juan Luis
JL
Universidad de Murcia, Departamento de Química Orgánica, Facultad de Química, Campus de Espinardo, 30100 Murcia, Spain.
Tárraga
Alberto
A
Espinosa
Arturo
A
Velasco
M Desamparados
MD
Molina
Pedro
P
Lloveras
Vega
V
Vidal-Gancedo
José
J
Rovira
Concepció
C
Veciana
Jaume
J
Evans
David J
DJ
Wurst
K
K
D004583:Electrons; D005296:Ferrous Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry*; D000075163:Metallocenes; D008956:Models, Chemical; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis*
D005296:Ferrous Compounds; D000075163:Metallocenes; D009942:Organometallic Compounds; D008274:Magnesium; C004998:ferrocene