Saarland University is a modern research university located in Saarbrücken, the capital of the German state of Saarland, and Homburg. It was founded in 1948 in Homburg in co-operation with France and is organized in eight faculties that cover all major fields of science. The university is particularly well known for research and education in computer science, computational linguistics and materials science, consistently ranking among the top in the country in those fields. In 2007, the university was recognized as an excellence center for computer science in Germany.Thanks to bilingual German and French staff, the University has an international profile, which has been underlined by its proclamation as "European University" in 1950 and by establishment of Europa-Institut as its "crown and symbol" in 1951.Nine academics have been honored with the highest German research prize, the Gottfried Wilhelm Leibniz Prize, while working at Saarland University. Wikipedia.
Schneider H.-J.,Saarland University
Accounts of Chemical Research
The process of learning by doing has fueled supramolecular chemistry and, more specifically, the understanding of noncovalent aromatic interactions in synthetic and natural systems. The preparation of new host molecules and the investigation of their complexations have produced many insights into significant noncovalent binding mechanisms. In this Account, we attempt to discuss significant binding contributions involving aromatic units and their practical applications. We use typical examples from our group and the literature, but this Account is not a comprehensive view of the field.Other than systems with saturated frameworks, host compounds based on arenes offer better controlled conformations and active interactions with many guest molecules. Because of their fluorescent properties, larger aryl systems are particularly suitable for sensors. The noncovalent interactions observed with different supramolecular complexes can be compared and exploited for interactions with biopolymers such as nucleic acids. Complexes formed with cyclophanes have been a constant source of inspiration for understanding noncovalent forces and their use for the design of functional supramolecular systems. Other than cyclodextrins or ionophores, which occur in nature, arene-based macrocycles are synthetic and provide more opportunities for structural variations than other macrocycles. These derivatives allow researchers to study and to exploit an unusually broad variety of binding mechanisms in both aqueous and organic media.Systematic analyses of complexes with different substituents and structures in solution, based also on flat aromatic systems such as porphyrins, can lead to a consistent picture of the noncovalent forces that dominate in these systems. These studies have elucidated attractive interactions between many heteroatoms and π systems including cyclopropanes. Through systematic analysis of the equilibrium measurements one can derive binding free energy increments for different interactions. The increments are usually additive and provide predictive tools for the design of new supramolecular systems, benchmarks for computational approaches, and an aid for drug design. In aqueous media, the major noncovalent forces between different aryl systems or between arenes and heteroatoms of larger polarizibility are dispersive, and hydrophobic forces play a minor role. In several examples, we show that electrostatic forces also contribute significantly if donor and acceptor groups show complimentarity.In early investigations, researchers found cation-π and, to a lesser degree, anion-π interactions with several cyclophanes in systems where the host or the guest molecules bear charges in an orientation that facilitates contact between charged and aryl portions of the molecules. In supramolecular complexes, hydrogen bonding effects are usually only visible in apolar media, but very strong acceptors such as phenolate anions can also work in water. To facilitate potential applications, researchers have primarily developed water-soluble, arene-containing receptors through the implementation of permanent charges. Supramolecular complexes that mimic enzymes can also rely on aryl interactions. Examples in this Account illustrate that the conformation of host-guest complexes may differ significantly between the solid and solution state, and suitable spectroscopic methods are needed to observe and control these conformations. © 2012 American Chemical Society. Source
Schneider H.-J.,Saarland University
Hydrogen bonds with organic fluorine are discussed on the background of an ongoing controversy, with an overview on the different methods of investigation, and with many examples, reaching from simple complexes to those involving nucleic acids. Often overlooked experimental values for the free energy of hydrogen bond involving C-F as acceptor depend on the solvent; in CCl 4 they amount with moderately acidic donors to ΔG = 6 kJ mol -1, much higher than with other halogens, placing fluorine as an acceptor between alkanes and arenes. The measured ΔG values increase from primary to secondary to tertiary C-F moieties, ab initio calculations predict an increase from sp 3 to sp 2 to sp 1 carbon. Simultaneous action of several X-H⋯F bridges can lead, even in polar media such as CDCl 3/CD 3CN, to binding constants of 70 [M -1]. Spectroscopic measurements unequivocally establish the presence of such hydrogen bonds, furnishing H⋯F distances as small as 2.02 Å, and X-H⋯F angles close to 180°, which generally agrees with most computational analyses. All computations point to dominating dispersive contributions, in particular for the very weak C-H⋯F interactions. In contrast, crystallographic analyses have led to controversial conclusions. Screening of databases, essentially based on X-ray determinations, often showed only very few structures with short H⋯F distances, for which reason the existence of such hydrogen bonds has been generally questioned. Some database evaluations, however, have shown enough cases for interactions between fluorine and X-H donors, mostly with H⋯F distances around 2.5 Å and X-H⋯F angles around 130°, which makes it difficult to distinguish hydrogen bonds from dispersive interactions. In several cases intermolecular H⋯F bridges dominate, and play a significant role in packing motifs, even when the underlying molecules tend to form only intramolecular bridges in solution. Generally, structures with intramolecular bonds give a clearer picture of X-H⋯F geometries. The limitations in deriving from crystal studies non-covalent binding mechanisms for weak single interactions are discussed. © 2012 The Royal Society of Chemistry. Source
Saarland University | Date: 2013-06-24
A method for displaying pixels on display devices, comprising: generating one or more pixels by one or more pixel sources; Providing one or more display devices for displaying pixels; transmitting the one or more generated pixels to one or more display devices for displaying the pixels via a network based on a network transmission protocol; and displaying the pixels on the display devices, wherein a plurality of the display devices are synchronized with each other for displaying the pixels and that preferably based on the synchronized display devices a plurality of the pixel sources are synchronized with the plurality of synchronized display devices via the network for synchronous displaying the pixels on the plurality of the display devices. The present invention further relates to a system for displaying pixels on display devices.
Saarland University | Date: 2015-07-29
The invention relates to a process for producing one or more polyunsaturated fatty acids by means of heterologous gene expression comprising the steps of providing a production organism which comprises a heterologous gene cluster encoding a polyunsaturated fatty acid biosynthetic pathway encompassing a subsequence ER encoding an enoylreductase and a subsequence AT encoding an acyltransferase,
Saarland University | Date: 2014-04-22
The present invention relates to novel combinations of active ingredients for use in the prevention and/or treatment of tumors. The tumors treated by the composition according to the invention overexpress SEC62 gene and overproduce Sec62 protein. The combination of active ingredients comprises at least a SERCA inhibitor and at least a Calmodulin antagonist.