TUNING OF THE ELECTROCHEMICAL RECOGNITION OF SUBSTRATES AS A FUNCTIONOF THE PROTON CONCENTRATION IN SOLUTION USING PH-RESPONSIVE REDOX-ACTIVE RECEPTOR MOLECULES
Mjl. Tendero et al., TUNING OF THE ELECTROCHEMICAL RECOGNITION OF SUBSTRATES AS A FUNCTIONOF THE PROTON CONCENTRATION IN SOLUTION USING PH-RESPONSIVE REDOX-ACTIVE RECEPTOR MOLECULES, Journal of the Chemical Society. Dalton transactions, (3), 1996, pp. 343-351
Reaction Of ferrocene-1,1'-dicarbaldehyde and ethane-1,2-diamine yield
ed the Schiff-base derivative 19,22-tetraaza[6.6](1,1')ferrocenophane-
1,5-diene, 1 the molecular structure of which has been determined by s
ingle-crystal X-ray analysis. Hydrogenation of 1 with LiAlH4 resulted
in the corresponding amine 2,5,19,22-tetraaza-[6.6](1,1') ferrocenopha
ne 2 which was characterised crystallographically. The protonation beh
aviour of 2 (denoted as L) and its complex formation with copper(II),
nickel(II) and zinc(II) has been studied by potentiometric titrations
in tetrahydrofuran-water (70:30 v/v) (0.1 mol dm(-3) NBu(4)ClO(4), 25
degrees C). The complexes [M(HL)](3+), [ML](2+), [M(OH)](+) and [ML(OH
)(2)] age formed. An electrochemical study of compound 2 has also been
performed under the same conditions at which the potentiometry was ca
rried out and the pK(a) values for the mixed valence (FeFeIII)-Fe-II a
nd oxidised (FeFeIII)-Fe-III species determined by fitting the curve o
f E(1/2) versus pH. From those data the Pourbaix diagram of the redox-
active 2 has been calculated. Compound 2 can be considered as a select
ive electrochemical sensor for copper(II).