Abstract
Host-guest chemistry involves the binding of a specific substrate in a receptor via molecular recognition based on supramolecular interactions. Metal-containing derivatives of receptors for the selective supramolecular binding of dihydroxybenzene substrates, which receptors model oxygen binding enzymes both in structure and in function are described in this thesis with the ultimate goal to realize biomimetic catalysis. A PY2-appended receptor 1 and a TPA-appended receptor 2 and the bis-copper(I) complexes thereof have been synthesised and characterized, inter alia by NMR, UV-Vis and XAS spectroscopy. These studies indicate that two Cu(I) ions are bound. Studies on the binding and activation of dioxygen by Cu(I) complexes of 1 and 2 show that the copper(I) complex of 1 forms a stable æ ?2:?2 Cu2O2 complex at -80`C, which complex is similar to that found in hemocyanin. For the Cu(I) complex of 2 a valence change to Cu(II) was observed but no well defined copper dioxygen complexes. A new setup for measuring both UV-Vis and XAS data on the same sample at low temperature under exclusion of air was designed. Catalytic studies showed that the Cu(I) complex of 2 is active in the oxidation of 2,4 di-tert-butylcatechol to the quinone, whereas the Cu(I)2O2 complex of receptor 1 is active in the radical C-C coupling of 2,4 di tert-butylphenol to the dimeric product (TON=10). A new TPA appended cyclodextrin receptor was prepared; the purification, however, proved to be very difficult. Preliminary catalytic studies using a iron(II) complex of a protected variant of this receptor showed an enhancement of the rate of epoxidation of norbornene. Fluorous phase chemistry involves the use of (per)fluorinated solvents, which form a third liquid phase, in addition to the aqueous and hydrocarbon phases. A novel cyclodextrin derivative with seven fluorinated tails was synthesised and shown to solubilize an aromatic guest in the fluorous phase.
