Anion interaction with ferrocene-functionalised cyclic and open-chain polyaza and aza-oxa cycloalkanes

A family of ferrocene-functionalised receptors of different topologies have been used as receptors for anions. The compounds have been designed to contain both amine nitrogen and ether oxygen atoms and comprises from monoaza to pentaaza derivatives both open-chain (L1, L2, L3) or cyclic (L4, L5) and having from one to five ferrocenyl groups. Solution studies directed to determine the protonation constants of L1, L2 and L3 have been carried out in water (0.1 mol dm3 KNO3, 25 °C) and those of L4 and L5 in 1,4-dioxane-water (70:30 v/v, 0.1 mol dm -3 KNO 3, 25 °C). The protonation behaviour of the receptors can be explained taking into account electrostatic considerations. Speciation studies in…