Using a bio-inspired copper complex to investigate reactive mass transfer around an oxygen bubble rising freely in a thin-gap cell.

Eight new zinc complexes of bisguanidine ligands have been structurally characterised and tested for the polymerisation of lactide. Initially this necessitated the preparation of the new six bisguanidine ligands [TMG 2 thf, DMEG 2 thf, trans-TMG 2 (1,2)ch, trans-DMEG 2 (1,2)ch, R,R-TMG 2 (1,2)ch, R,R-DMEG 2 (1,2)ch]. With these ligands in hand, zinc chlorido complexes could be obtained, which were characterized by X-ray crystallography and NMR spectroscopy. Furthermore, two new zinc chlorido complexes are reported, based on previous bisguanidine ligands [TMG 2 (1,3)ch, DMEG 2 (1,3)ch]. All complexes show a distorted tetrahedral coordination geometry. These eight complexes are utilised as catalysts in melt polymerization

Model complexes for copper proteins such as hemocyanin or tyrosinase have been investigated in detail during the last four decades due to their potential to become valuable catalysts for selective oxidations of organic substrates. However, so far most of these compounds can only be investigated in aprotic solvents at lower temperatures. Therefore, industrial applications on a larger scale are still missing. In contrast the copper(I) complex with the ligand tris[2‐(1,4‐diisopropylimidazolyl)]phosphine can form a quite stable dinuclear copper peroxido complex in the protic solvent methanol at room temperature. The kinetic analysis of the reaction of [Cu(PimiPr2)(CH3CN)]CF3SO3 with dioxygen in methanol is reported. The results allowed to obtain rate constants and activation parameters (ΔH# = 25 ± 2 kJ mol–1 and ΔS# = –121 ± 8 J mol–1 K–1) for the formation of the reactive intermediate, a mononuclear copper superoxido complex, prior to the consecutive reaction to a dinuclear peroxido complex.

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The reaction of Cu(I) bisguanidine complexes with nitric oxide and the formation of intermediate species were monitored via UV-vis spectroscopy at low temperature, with the occurrence of characteristic absorption bands. The origin of the emerging species and their character were substantiated by electron paramagnetic resonance (EPR) measurements and density functional theory (DFT) studies showing a delocalized {CuNO} 11 radical species. Furthermore, this system was transferred to the SuperFocus mixer setup, which allows rapid mixing and the determination of decay constants at ambient temperatures of the thermally sensitive species. However, these experiments demonstrated the limits of these systems, such as the NO saturation in organic solvents and a preferably precise temperature control within the SuperFocus mixer, which should be addressed in the future.