Howard W. Turner

Kombinatorische Materialforschung und Katalyse

Nach dem Paradigmenwechsel, der in der pharmazeutischen Industrie stattfand, als durch kombinatorische Methoden der Prozes zur Entdeckung neuer Wirkstoffe unwiderruflich verandert wurde, werden nun kombinatorische Methoden in zunehmendem Mase auch zur Entdeckung und Optimierung neuer und effizienterer Katalysatoren und Materialien eingesetzt (siehe Abbildung). Mit der Entwicklung und dem Einzug neuer kombinatorischer Synthese- und Screening-Methoden, kombiniert mit integrierter Datenverwaltung, eroffnet die Anwendung dieser Methoden in den Materialwissenschaften und der Katalysatorforschung ein enormes Potential und erweckt hohe Erwartungen in dieser neuen und aufregenden Disziplin.

Applications of Combinatorial Methods in Catalysis

With rising economic demands for higher efficiency and productivity in research and development, combinatorial catalysis is increasingly being implemented to bring more catalysts per unit time to the marketplace. High-throughput automated synthesis and advanced screening technologies are now being applied to the discovery of more efficient homogeneous as well as heterogeneous catalysts and materials. The combinatorial process allows the exploration of large and diverse compositional and parameter spaces by establishing an integrated workflow of rapid parallel or combinatorial synthesis of large numbers of catalytic materials, subsequent high-throughput assaying of these compounds and large-scale data analysis. The number of experiments that can be screened has risen by orders of magnitude resulting in a much higher probability of discovering new catalysts or materials. The goal of this review is to provide an overview of selected advances that have been made in this rapidly growing field in both academia and industry over the past several years.

A convenient palladium/ligand catalyst for Suzuki cross-coupling reactions of arylboronic acids and aryl chlorides

Abstract The Pd/ligand A catalyst efficiently catalyzes general Suzuki biaryl cross-coupling reactions of arylboronic acids and aryl chlorides.

General and efficient palladium-catalyzed aminations of aryl chlorides

Pd(dba)2/Ligand A catalyst efficiently catalyzes the aminations of a variety of aryl chlorides with a variety of amines in high rates, selectivities, and isolated yields.

Combinatorial methods in homogeneous and heterogeneous catalysis

Abstract The past year has seen significant advances in the development of combinatorial approaches to the discovery and optimization of homogeneous and heterogeneous catalysts. The highlights include the development of modular approaches to the synthesis of libraries of organometallic complexes and catalysts, novel indirect screening methods, and automated syntheses and screening of high density solid state libraries.

Solid‐Phase Synthesis and Encoding Strategies for Olefin Polymerization Catalyst Libraries

Active polymerization catalysts, novel resin-bound diimine complexes of nickel(II) and palladium(II) are obtained by combinatorial synthesis and combined in a catalyst library. By tagging with fluorescent markers, the catalysts can be coded. Therefore, after cleavage of the tag from the polymer-coated resin, HPLC can be used to determine the pathway along which the products were formed.

Kombinatorische Parallelsynthese und Hochgeschwindigkeitsrasterung von Heterogenkatalysator-Bibliotheken

Weniger als eine Minute war notig, um die katalytische Aktivitat und die Selektivitat eines Elements in einer kombinatorischen Bibliothek aus ternaren Rh-Pd-Pt-Cu-Legierungen zu bestimmen. Damit genugten zwei Stunden fast, um eine Bibliothek aus 136 Elementen zu uberprufen. Die Bibliotheken enthielten die Elemente (ca. 2–4 μg Material jeweils) in zweidimensionaler Anordnung und wurden mit Dunnschichttechniken synthetisiert. Zur Analyse wurden sie unter Einsatz von Rastertechniken, die mit Massenspektrometrie gekoppelt waren (siehe Bild), vermessen.

Combinatorial heterogeneous catalysis: oxidative dehydrogenation of ethane to ethylene, selective oxidation of ethane to acetic acid, and selective ammoxidation of propane to acrylonitrile

The application of combinatorial methods to three reactions catalyzed by multimetal oxides is described. Catalysts for the oxidative dehydrogenation of ethane to ethylene were tested using a 121- or 144-channel scanning mass spectrometer primary screening reactor and a 48-channel fixed bed secondary screening reactor; catalysts for the selective oxidation of ethane to acetic acid were tested using a 256-channel massively parallel microfluidic reactor primary screen alone, and catalysts for the selective ammoxidation of propane to acrylonitrile were tested using the massively parallel microfluidic reactor and an eight-channel fixed bed secondary/tertiary screening reactor. The details regarding catalyst design, synthesis, and screening are presented. This work has resulted in both the confirmation of published results and the generation of new lead materials for all three chemistries.

Parallel solid-phase synthesis, screening, and encoding strategies for olefin-polymerization catalysts

Abstract A solid-phase protocol has been developed that allows for the parallel synthesis, screening, and chemical encoding of nickel (II) and palladium (II) olefin-polymerization catalysts. These catalysts display activity profiles comparable to the analogous homogeneous catalyst systems prepared by traditional methods. A chemical encoding strategy has also been developed which enables the chemical history of pooled solid-phase catalysts to be evaluated.

Gas phase oxidation of ethane to acetic acid using high-throughput screening in a massively parallel microfluidic reactor system

Abstract High-throughput primary synthesis and screening methods have been applied to the heterogeneously-catalyzed gas phase oxidation of ethane to acetic acid using mixed metal oxide catalysts. The discovery libraries consisted of 16×16 arrays of 256 catalysts on 3″×3″ quartz wafers. Catalysts were prepared using automated liquid-dispensing techniques and screened in parallel for catalytic activity in a Symyx Technologies 256-channel microfluidic reactor. Product detection was performed using parallel colorimetric techniques on products adsorbed on silica-coated glass TLC plates. This workflow allows the screening of more than 3000 samples per day. Promising leads were confirmed in focus libraries and are being optimized in secondary screening. MoV was identified as the most active binary of redox metals and was subsequently doped with main group, rare earth, and transition metals to form ternaries. Prior art MoVX (X=Nb, Ni, Sb) catalysts were successfully reproduced and it was shown that Pd doping significantly increases the catalytic activity of these systems. Three novel MoVY ternary systems were discovered.