Work was done for developing biomimetic oxidation catalysts. Two classes of metalloporphyrin catalysts were studied. The first class of catalysts studied were a novel series of highly substituted metalloporphyrins, the fluorinated iron dodecaphenylporphyrins. These homogeneous metalloporphyrin catalysts were screened for activity as catalysts in the oxidation of hydrocarbons by dioxygen. Results are discussed with respect to catalyst structural features. The second type of catalysts studied were heterogeneous catalysts consisting of metalloporphyrins applied to inorganic supports. Preliminary catalytic testing results with these materials are presented.

This project utilized Computer-Aided Molecular Design (CAMD) to develop a new class of metalloporphyrin materials for use as catalysts for two fuel cell reactions. The first reaction is the reduction of oxygen at the fuel cell cathode, and this reaction was the main focus of the research. The second reaction we attempted to catalyze was the oxidation of methanol at the anode. Two classes of novel metalloporphyrins were developed. The first class comprised the dodecaphenylporphyrins whose steric bulk forces them into a non-planar geometry having a pocket where oxygen or methanol is more tightly bound to the porphyrin than it is in the case of planar porphyrins. Significant improvements in the catalytic reduction of oxygen by the dodecaphenyl porphyrins were measured in electrochemical cells. The dodecaphenylporphyrins were further modified by fluorinating the peripheral phenyl groups to varying degrees. The fluorination strongly affected their redox potential, but no effect on their catalytic activity towards oxygen was observed. The second class of porphyrin catalysts was a series of hydrogen-bonding porphyrins whose interaction with oxygen is enhanced. Enhancements in the interaction of oxygen with the porphyrins having hydrogen bonding groups were observed spectroscopically. Computer modeling was performed using Molecular Simulations new CERIUS2 Version 1.6 and a research version of POLYGRAF from Bill Goddard's research group at the California Institute of Technology. We reoptimized the force field because of an error that was in POLYGRAF and corrected a problem in treatment of the metal in early versions of the program. This improved force field was reported in a J. Am. Chem. Soc. manuscript. Experimental measurements made on the newly developed catalysts included the electrochemical testing in a fuel cell configuration and spectroscopic measurements (UV-Vis, Raman and XPS) to characterize the catalysts.

Oxidative catalysis by metalloporphyrin systems occupies a prominent role in the current research in the fields of chemical and biological catalysis. Our particular interest and approach has been to collect in the same volume papers dealing with both the chemical and biological aspects of the reactivity of heme systems because of the realization that a better understanding of the complementary discipline can be extremely useful for the researchers from either field. The current progress of the research on synthetic metalloporphyrin catalysts has led to the development of several systems that are able to reproduce the heme-enzyme mediated oxygenation and oxidation reactions, at least in terms of reaction types, mechanisms and often rates. These achievements have stimulated the of creating metalloporphyrin catalysts which are both ambitious project efficient and stable enough to become competitive for large-scale industrial processes. Although this project is still far from being realized, the efforts in this direction parallel those aimed at the application of heme enzymes to chemical technologies, e. g. for the mild, selective oxidation of organics or the detoxification of pollutants. Both the two approaches will be advantageous because while the enzyme systems can achieve selectivities which are probably unattainable by synthetic catalysts, the latter can be active under experimental conditions that would readily inactivate the enzymes.

The activation of dioxygen by metal ions has both synthetic potential and biological relevance. Dioxygen is the cleanest oxidant for use in emission-free technologies to minimize pollution of the environment. The book gives a survey of those catalyst systems based on metal complexes which have been discovered and studied in the last decade. They activate molecular oxygen and effect the oxidation of various organic compounds under mild conditions. Much of the recent progress is due to a search for biomimetic catalysts that would duplicate the action of metalloenzymes. Mechanistic aspects are emphasized throughout the book. An introductonary chapter reviews the chemistry of transition metal dioxygen complexes, which are usually the active intermediates in the catalytic reactions discussed. Separate chapters are devoted to oxidation of saturated, unsaturated and aromatic hydrocarbons, phenols, catechols, oxo-compounds, phosphorus, sulfur and nitrogen compounds.

Novel Catalytic and Separation Process Based on Ionic Liquids presents the latest progress on the use of ionic liquids (ILs) in catalytic and separation processes. The book discusses the preparation of ILs, the characterization of IL catalysts by spectroscopic techniques, catalytic reactions over IL catalysts, separation science and technology of ILs, applications in biomass utilization, and synthesis of fine chemicals. Scientists, engineers, graduate students, managers, decision-makers, and others interested in ionic liquids will find this information very useful. The book can be used as a springboard for more advanced work in this area as it contains both theory and recent applications, research conducted, and developments in separation techniques and catalysis using ionic liquids. - Presents new preparation and advanced characterization of ionic liquids catalysts - Outlines catalytic reactions using ionic liquid, thus showing higher yields and selectivity - Presents novel separation science and technology based on ionic liquids and non-thermal processes