New Immobilized Catalytic Systems for Batch and Flow Applications

Durant el transcurs de la Tesi, s’ha desenvolupat un sistema catalític per reaccions aldòliques altament estereoselectives en flux continu basats en una prolina immobilitzada en una resina de poliestirè. S’ha demostrat la seva aplicació com a catalitzador per a la síntesi de diferents substrats, i la seva utilització en condicions de flux continu va permetre la preparació a mitjana escala d’un conjunt d’adductes aldòlics. A part, s’han preparat diferents aminoàcids primaris ancorats en una resina de poliestirè i s’han utilitzats com a catalitzadors per reacciones enantioselectives del tipus aldòliques i Mannich. De tots els aminoàcids provats, el derivat de treonina és el que va mostrar més eficàcia per les dues reaccions esmentades. A més, amb aquest catalitzador es va poder portar a terme una sèrie de reaccions del tipus Mannich altament enantioselectives en condicions de flux continu. Es va dur a terme eficaçment la inserció de diòxid de carboni a oxirans sota condicions suaus de reacció en presencia d’un derivat del pirogalol immobilitzat en una resina de poliestirè altament reciclable.Durante el transcurso de la Tesis, se ha desarrollado un sistema catalítico para reacciones aldólicas altamente estereoselectivas en flujo continuo basados en prolina inmovilizada en una resina de poliestireno. Se ha demostrado su aplicación como catalizador para la síntesis de diferentes substratos, y su utilización en condiciones de flujo continuo permitió la preparación a mediana escala de un conjunto de aductos aldólicos. A parte, se han preparado diferentes aminoácidos primarios anclados en resinas de poliéster y se han utilizado como catalizadores para reacciones enantioselectivas del tipo aldólicas y Mannich. De todos los aminoácidos provados, el derivado de treonina era el que mostró más eficacia para catalizar las dos reacciones comentadas. Además, con este catalizador se pudo llevar a cabo una serie de reacciones del tipo Mannich altamente enantioselectivas en condiciones de flujo continuo. Se llevó a cabo eficazmente la inserción de dióxido de carbono a oxiranos bajo condiciones suaves de reacción en presencia de un derivado del pirogalol inmovilizado en una resina de poliestireno altamente reciclable.During the course of this thesis, a catalytic system for highly stereoselective aldol reactions in continuous operation has been developed based on polystyrene-­‐ supported proline. The applicability to different substrates and the suitability of the flow system for repeated reuse allowing the medium scale preparation of a series of aldol adducts under a single set of reaction conditions has been demonstrated. Furthermore, different polystyrene-­‐supported primary amino acids have been prepared and applied as catalysts for aldol and Mannich reactions. Out of the amino acid derivatives, immobilized threonine shows the best performance in both reactions. With this catalyst, a series Mannich reactions could be conducted under continuous flow conditions. In the presence of a highly recyclable polystyrene-­‐ supported pyrogallol derivative, the insertion of carbon dioxide into oxiranes under mild conditions was accomplished

A Perfect Couple

Henseler, J., Schmidt, H. J., & Redler, J. J. (2023). Design Science and Marketing: A Perfect Couple. Journal of Creating Value. https://doi.org/10.1177/23949643231200703This special issue of the Journal on Creating Value about ‘Creating Value through Design Science’ and the articles therein aim at showcasing how design science research in the field of creating value can look like.publishersversionepub_ahead_of_prin

Nonadiabatic pumping in classical and quantum chaotic scatterers

We study directed transport in periodically forced scattering systems in the regime of fast and strong driving where the dynamics is mixed to chaotic and adiabatic approximations do not apply. The model employed is a square potential well undergoing lateral oscillations, alternatively as two- or single-parameter driving. Mechanisms of directed transport are analyzed in terms of asymmetric irregular scattering processes. Quantizing the system in the framework of Floquet scattering theory, we calculate directed currents on basis of transmission and reflection probabilities obtained by numerical wavepacket scattering. We observe classical as well as quantum transport beyond linear response, manifest in particular in a non-zero current for single-parameter driving where according to adiabatic theory, it should vanish identically.Comment: 13 pages, 8 figure

Floquet scattering in parametric electron pumps

A Floquet scattering approach to parametric electron pumps is presented and compared with Brouwer's adiabatic scattering approach [Phys. Rev. B 58, R10135 (1998)] for a simple scattering model with two harmonically oscillating delta-function barriers. For small strength of oscillating potentials these two approaches give exactly equivalent results while for large strength, these clearly deviate from each other. The validity of the adiabatic theory is also discussed by using the Wigner delay time obtained from the Floquet scattering matrix.Comment: 10 pages, 7 figure

Small Disks and Semiclassical Resonances

We study the effect on quantum spectra of the existence of small circular disks in a billiard system. In the limit where the disk radii vanish there is no effect, however this limit is approached very slowly so that even very small radii have comparatively large effects. We include diffractive orbits which scatter off the small disks in the periodic orbit expansion. This situation is formally similar to edge diffraction except that the disk radii introduce a length scale in the problem such that for wave lengths smaller than the order of the disk radius we recover the usual semi-classical approximation; however, for wave lengths larger than the order of the disk radius there is a qualitatively different behaviour. We test the theory by successfully estimating the positions of scattering resonances in geometries consisting of three and four small disks.Comment: Final published version - some changes in the discussion and the labels on one figure are correcte

Floquet Formalism of Quantum Pumps

We review Floquet formalism of quantum electron pumps. In the Floquet formalism the quantum pump is regarded as a time dependent scattering system, which allows us to go beyond the adiabatic limit. It can be shown that the well-known adiabatic formula given by Brouwer can be derived from the adiabatic limit of Floquet formalism. We compare various physical properties of the quantum pump both in the adiabatic and in the non-adiabatic regime using the Floquet theory.Comment: Latex2e 16 pages, 6 figures. A review paper to appear in Int. J. Mod. Phys.