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Research

Electron transfer and optically switachble molecular materials with non-innocent ligands

Electron transfer and optically switachble molecular materials with non-innocent ligands

Complexes that display electrochromic behavior are ideal optically switchable materials. In this project we try to combine the redox and optical properties of non-innocent ligands to generate metal complexes that display strong redox-switchable NIR absorptions. A long term goal of this project is to perform such processes on surfaces with an aim of generating smart
optical windows.

Metal complexes of mesionic/abnormal carbenes and catalysis

Metal complexes of mesionic/abnormal carbenes and catalysis

Mesoionic carbenes are a new class of carbene ligands that are making their mark as potent ligands in metal catalyzed reactions. In recent years we have shown that metal complexes of such ligands can be used to generate highly potent catalysts for C-C cross-coupling reactions, C-H oxygentation, cycloaddition reactions, transfer hydrogenation reactions, and α-arylation reactions of amides. One line of current interest in this field is the generation of multinuclear metal complexes to test possible catalytic cooperativity in these metal complexes.

Metal complexes of bidentate and tripodal “click”-triazole-ligands and catalysis

Metal complexes of bidentate and tripodal “click”-triazole-ligands and catalysis

Bidentate as well as tripodal ligands containing triazole donors can be synthesized through the so-called “Click” reaction in high yield and selectivity. We have been using metal complexes of such tripodal ligands as potent catalysts for C-H oxygentation and amination reactions, N-arylation reactions, and for olefin poly- and oligomerization.

Non-innocent ligands in homogeneous catalysis

Non-innocent ligands in homogeneous catalysis

While our other projects on catalysis deal with relatively “conventional” modes for performing these reactions, in this project we try to actively use electron and protons from ligands for performing catalytic bond formation and activation reactions. Recent success in this direction has been the (electro)catalytic formation of C-C bonds, the reduction of C=O groups and cyclization reactions by using these unconventional catalytic modes. This project aims at cooperatively using the electrons of the metal centers and the non-innocent ligands for generating potent homogeneous catalysts.

Small molecule activation and bio-inspired catalysis

Small molecule activation and bio-inspired catalysis

Nature has mastered the art of using electrons from so-called non-innocent ligands for generating highly potent transition metal catalysts for performing activation of small molecules and their catalytic transformation. Taking inspiration from nature, in this project we try to use the special electron reservoir properties of quinones and mesoionic carbenes
for generating metal complexes for the activation and production of H2, and for the activation of O2, CO2 and H2O. Incorporation of non-innocent ligands in the metal complexes make the multi-electron and proton transfer required for such transformation readily available. We then try to couple the activation of these small molecules to using them for catalytic transformations to generate useful fine chemicals.

Metal complexes of “click”-derived tripodal ligands for photochemical and electrochemical bond activation reactions

Metal complexes of “click”-derived tripodal ligands for photochemical and electrochemical bond activation reactions

Tripodal triazole containing ligands designed through Click chemistry provide ideal coordination environments at metal centers for performing photochemical and electrochemical bond activation reactions. In this project we try to tune the electrochemical
and photochemical reactivity at the metal centers through targeted variation of the steric and electronic properties of the tripodal ligands. Advanced photochemical measurements are sometimes carried out with our collaboration partners.

Magnetisch schaltbare molekulare Materialien

Magnetisch schaltbare molekulare Materialien

We believe that ligands such as quinones, triazoles and mesoionic carbenes have highpotential in generating magnetically switchable molecular materials. Recent success in our group in this direction has been observation of spin crossover at room temperatures together with a large hysteresis for Fe(II) and Co(II) complexes, and the observation of single ion magnet behavior for Co(II) complexes. This project is performed in collaboration with groups that specialize in molecular magnetism and in theoretical chemistry. Such fascinating molecules might one day find applications as molecular data storage materials.

Metal complexes for (potential) medicinal applications

Metal complexes for (potential) medicinal applications

A new field in which our group has started working is the use of metal complexes of diazenes, triazoles and mesoionic carbenes for (potential) applications in anti-tumor and anti-bacterial research. This project is carried out in collaboration with biochemists and medicinal chemists.