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Scientific orientation of the Sundermeyer lab: Facets of "Green Chemistry"

Traditionally, the Sundermeyer group is engaged in all aspects of bonding interactions of organic molecules and ligands with metal surfaces and metal cations in complexes. Due to the quite diverse collaborations and third-party funding from and with governmental institutions as well as with chemical industry, quite broad facets of this field of research are covered by one or two PhD students per facet. The main focus of the research group is focusing on basic research close to application related to special topics of sustainable chemistry, so-called "Green Chemistry". Functional molecules of metals form the organometallic focus. A classic among the "Green Chemistry" topics is catalysis. Here the focus is on the activation of triplet oxygen by copper or cobalt catalysts for oxidation reactions, the (oxy)carbonylation of nitro and amino aromatics in methanol to carbamates and dimethyl carbonate, a non-toxic methylating agent, substitute for highly toxic dimethyl sulfate and phosgene in the technical production of important polymers such as polycarbonates and polyurethanes. Biodegradable polymers are obtained via catalytic copolymerization of the greenhouse gas CO2 with alkylene oxides. Other reactions of CO2 are also coming into focus. Classic organometallic topics feature metallated phosphorus ylides as constrained geometry ligands. They are used in phospha-bridged ansa-metallocene catalysts or [Cp-PN] or [Cp-PC] half-sandwich chelate complexes of rare earth metals for the synthesis of polyisoprene (natural rubber); they are used in carbodiphosphorane-pincer ligand complexes for the ring-opening polymerization of dilactide to biodegradable polyesters etc.

A second pillar is concerned with materials of efficient energy conversion and storage, such as the design of stereorigid Cu(I) complexes as singlet (TADF) emitters for OLED displays of tomorrow. Moderate successes in the design of dye-sensitized solar cells led us to focus more on the central problem of redox-active ionic liquids as redox mediators in these solar cells: Liquid ferrocenyl-phosphonium and -sulfonium electrolytes or ionic liquids with redox-active polysulfide anions are investigated in more detail. New electrolytes and solid electrolyte interphase (SEI) formers for lithium ion batteries are being designed and investigated with respect to a planned interregional SFB. "Green Chemistry" also concerns the development of new processes for the synthesis of important key compounds for the production of III-V semiconductors, such as a patented autocatalytic direct synthesis of trimethylgallium from gallium, methyl chloride and aluminum in an inorganic ionic liquid. The latter process has made it into large-scale industrial production and will provide the technological basis for more energy-efficient, resource-saving, drastically waste-reduced generation and use of regenerative energies through GaAs photovoltaics and GaInN LEDs. Other volatile and thermally decomposable MOCVD precursor molecules of Ga, In, Sc, Y, La, Nb, Ta, Mo, W, Ru, and Co metals for applications in micro- and nanoelectronics are also being redesigned, synthesized, and patented. Not via the gas phase, but via a "printed electronics" strategy from solution, it is possible to deposit metal chalcogenide semiconductor materials of the metals Ga, In, Sn, Bi, Cu and Mo (CIGS, CZTS, Bi2Te3, MoS2) via spin coating as thin films on wafers.

Last but not least, the Sundermeyer lab is involved in the design of the strongest known uncharged metal-free N, P or C superbases ever described as well as the strongest uncharged Lewis superacids described so far - with much higher fluoride affinity than the reference SbF5. Superbases and superacids: Chemistry at its Limits!

New methods of organic synthetic chemistry are being developed in the last facet discussed here: Polyheteroaromatic compounds are being explored as precursors for the (surface) synthesis of aza-functionalized polyaromatic hydrocarbons (N-PAH) as part of a currently funded excellence initiative. Molecular wires of organic polymers, molecular cutouts of the graphene structure, potential azagraphenes and the selective functionalization of probably the most important organic semiconductors and dyes of technical chemistry are the focus of the ongoing work. The results of our research group have been published in 55 patent families and about 240 book and journal publications so far. Our motto is, for the reasons mentioned above: Diversity Rocks Chemistry!