Mjl. Tendero et al., HIGHLY BRANCHED FERROCENE-FUNCTIONALIZED POLYAZACYCLOALKANES AS ELECTROACTIVE RECEPTORS FOR TRANSITION-METAL IONS, Journal of the Chemical Society. Dalton transactions, (14), 1996, pp. 2923-2927
Reaction of N,N',N '',N'''-tetrakis (2-aminoethyl)-1,4,8,11-tetraazacy
clotetradecane (taec) with ferrocenecarbaldehyde and further reduction
with LiAlH4 resulted in the synthesis of the redox-active receptor N,
N',N enyl-3-azabutyl)-1,4,8,11-tetraazacyclotetradecane (tfabc); The p
rotonation behaviour of tfabc and its complex formation with Cu-II, Zn
-II and Cd-II have been studied in tetrahydrofuran-water (70:30 v/v) (
0.1 mol dm(-3) NBu(4)(t)ClO(4), 25 degrees C). The potentiometric and
electrochemical data indicate the formation of 1:1 and 1:2 (tfabc:M(2)) stoichiometries. The E(1/2) values for tfabc shift as a function of
the pH from 389 (pH 10) to 482 mV (pH 2.5) and E(1/2) vs. pH curves f
or the tfabc-H+-M(2+) systems (M = Cu, Zn or Cd) show that tfabc elect
rochemically recognises the presence of copper(II) selectively at pH <
5. The shift of E(1/2) appears to be caused by electrostatic forces a
nd the E(1/2) vs. pH curves can be predicted in terms of the distribut
ion diagrams of the tfabc-H+-M(2+) systems.