10/23/18 - 9:45 AM to 10:45 AM
Gassman Lectureship #2: Professor Emeritus Klaus Müllen
Paul G. Gassman Lectureship in Chemistry
Dendrimers: Organic Functional Nanoparticles by Design
Micelles formed by assembly of small or polymeric emulsifiers (amphiphiles) in aqueous or organic solvents constitute miniaturized reaction vessels for various chemical reactions in geometric confinement, and give access to organic and inorganic nanoparticles. Herein, inverse mini-emulsion polymerizations will appear as a particularly useful protocol for making such nanoparticles. A special case is core-shell particles since they allow the combination of diverse chemical, physical and biological properties. Among these are hydrophobized inorganic particles for incorporation into organic matrices, immobilization of metallocene catalysts for polyolefin synthesis, or enzyme induced cleavage of peptide shells for releasing therapeutic drugs. Chemical functionalization, both in the interior and on the surface of nanoparticles, is thus a key process. But there remain uncertainties regarding the size of the particles as well as the number and location of active groups. Dendrimers, three-dimensional, highly branched polymers, hold promise for better size control and precise nanosite definition of functional units, despite slightly more synthetic effort. However, many dendrimers are made from conformationally flexible bonds and are thus not shape-persistent, and this hampers the desired control over the function of guest molecules. We introduce a unique class of polyphenylene dendrimers (PPDs) which are only made from twisted, tightly packed, interlocked benzene rings. Their advantages are:
- monodisperse, defect free structures in spite of molecular weights up to 1.8 MDa: the perfection arises from the build-up via repetitive Diels-Alder cycloaddition reactions;
- thermal and chemical stability; and
- site-specific chemical functionalization in the core, scaffold and on the surface.
It is this design that yields highly sophisticated functions. We describe light harvesting, catalysis, sensing after uptake of guest molecules and drug release. A particularly exciting case is the formation of polar and unpolar “patches” on the surfaces that enables transfection of an adenovirus.
Macromol. Chem. Phys. Rapid Commun. 2016, 20, 1633; J. Amer. Chem. Soc. 2015, 137, 6097; Adv. Healthcare Mater. 2015, 4, 377; Macromolecules 2014, 47, 191; Nature Nanotechnology 2014, 9, 131 and 182; Chem. Rev. 2016, 116, 2103; Angew. Chem. Int. Ed. 2017, 56, 10602; ChemBioChem. 2017, 18, 960.
Professor Müllen's broad research interests range from the development of new polymer-forming reactions, including methods of organometallic chemistry, to the chemistry and physics of small molecules, graphenes, dendrimers and biosynthetic hybrids. His work further encompasses the formation of multi-dimensional polymers with complex shape-persistent architectures, nanocomposites, and molecular materials with liquid crystalline properties for electronic and optoelectronic devices. His research targets include:
- graphenes and carbon materials;
- new polymer-forming reactions including methods of organometallic chemistry;
- multi-dimensional polymers with complex shape-persistent architectures;
- functional polymeric networks, in particular for catalytic purposes;
- dyes and pigments;
- chemistry and physics of single molecules;
- molecular materials with liquid crystalline properties for electronic and optoelectronic devices;
- biosynthetic hybrids; and
Klaus Müllen was director at the Max Planck Institute for Polymer Research. He now holds an emeritus position for continuation of his research there and is fellow of the Gutenberg Research College of Mainz University. His broad research interests range from new polymer-forming reactions, to the chemistry and physics of single molecules as well as graphenes, dendrimers and biosynthetic hybrids. He published about 1,900 papers. He received the Max Planck Forschungspreis, Philip Morris Forschungspreis; Nozoe-Award; Science Award of the “Stifterverband”; Innovation Award of the State of North Rhine Westphalia; Nikolaus August Otto Award; Society of Polymer Science Japan International Award; Americal Chemical Society (ACS) Award in Polymer Chemistry; Tsungming Tu Award, Taiwan; BASF-Award for Organic Electronics; Franco-German Award of the Sociéte Chimique de France; Adolf-von-Baeyer-Medal; Utz-Hellmuth-Felcht Award, SGL Group; China Nano Award; Carl Friedrich Gauß-Medal, van’t Hoff Award of the Royal Netherlands Academy of Sciences as well as the Hermann-Staudinger Award and the Award of the Academy of Sciences and Humanities in Hamburg. From 2008-09, he served as president of the German Chemical Society (GDCh). In 2013-14, he was president of the German Association for the Advancement of Science and Medicine. He is member of the American Academy of Arts & Sciences, North-Rhine-Westphalian Academy for Sciences and Art, National Academy Leopoldina, European Academy of Sciences, Braunschweigische Wissenschaftliche Gesellschaft and Academia Europaea. In 2010, he received an Advanced European Research Grant for his work on nanographenes. He is associate editor of the Journal of the American Chemical Society.
In honor of Regents Professor Paul G. Gassman
Regents Professor Paul G. Gassman died in April 1993, at the age of 57. He was internationally known in the chemical community, and left behind a legacy of achievement. During his career, he served as mentor and adviser to 85 doctoral and master’s candidates as well as dozens of postdoctoral associates and undergraduate students. Numerous awards, honors, and honorary degrees were bestowed in recognition of his contributions to research and his service to the scientific, professional, and university communities. Some of these awards include election to the National Academy of Sciences (1989) and to the American Academy of Arts and Sciences (1992); the James Flack Norris Award in Physical Organic Chemistry (1985); Arthur C. Cope Scholar Award (1986); and the National Catalyst Award of the Chemical Manufacturers Association (1990). He served as president of the American Chemical Society in 1990. He was co-chair of the organizing committees of the National Organic Symposium (1991) and the National Conferences on Undergraduate Research meeting (1992), on the University of Minnesota campus. It was his wish that a lectureship be established to bring distinguished organic chemists to the Department of Chemistry.