William C. Trogler - US grants

This award from the Inorganic, Bioinorganic and Organometallic Chemistry Program will support an annual workshop in organometallic chemistry. The participants in the workshop will be organometallic chemists from industry and academic institutions, as well as from private and government research organizations. The goals of the workshop are to facilitate communication among researchers in the different kinds of organizations and to foster the exchange of new ideas much earlier than is possible through formal publications. The format of the workshop is designed to encourage maximum participation by all attendees, and the plan for choosing attendees will ensure broadly based participation. The topics to be discussed at the workshop will span a broad range from synthesis of new organometallic compounds to the utilization of such compounds as catalysts or as precursors for making new materials.

William C. Trogler of the University of California at San Diego will study the synthesis, structure and reaction mechanisms of 17-electron organometallic radicals as part of this project within the Inorganic, Bioinorganic and Organometallic Chemistry Program. The goal is to develop catalysts for new chemical transformations that could be applied to the synthesis of specialty chemicals and medicinal compounds. Another thrust of the project is the investigation of late transition metal coordination complexes as possible reagents for the activation of nitrogen-hydrogen and oxygen-hydrogen bonds in order to facilitate insertion of unsaturated organic compounds such as olefins into the metal-nitrogen and metal-oxygen bonds, respectively. This area is also aimed at better defining the requirements for catalytic addition of ammonia, amines and alcohols to carbon-carbon double bonds. Compounds to be employed in the first part of the project are neutral electron rich 18-electron complexes which can be electrochemically oxidized to give stable or short-lived cationic radicals. Representative of these are dicarbonyl(olefin)cyclobutadieneiron, (tertiary- phosphine)(olefin)cyclopentadienylcobalt and bis(olefin)cyclopentadienylrhodium. Compounds employed in the second part of the study will be mainly from the platinum group of metals.

9355039 Sinha This proposal requests support for 5 graduate research traineeships in atmospheric chemistry. The research and education program described involves the study of a variety of problems in stratospheric and tropospheric chemistry. In addition to graduate research, a complete graduate education curriculum in environmental science, with an emphasis on the atmosphere, is described. The five individual research programs described are involved in a variety of interdisciplinary and collaborative work. Interactions between these groups foster and excellent environment for learning all aspects of atmospheric chemistry. The collective group meetings and course offerings provide a sound foundation for the proposed training program. Problem solving is emphasized in the educational process. ***

By means of this award, the Inorganic, Bioninorganic, and Organometallic Chemistry Program and the Atmospheric Chemistry Program provide support for an interdisciplinary project on sources of atmospheric nitrous oxide. The work will be carried out by Dr. William C. Trogler and Dr. Mark H. Thiemens of the Chemistry Department of the University of California at San Diego. They will examine the mechanism of decomposition of ammonium nitrate, the reaction of hydroxylamine and nitric oxide, and other reactions by which nitrous oxide might be produced. The influence of aerosols and particulates on these processes will also be investigated. The means of elucidating the reaction mechanism, as well as linking the nitrous oxide produced by various reactions to nitrous oxide in the atmosphere, will be isotopic labeling of nitrogen and oxygen. %%% The concentration of atmospheric nitrous oxide has been increasing in recent years, but the sources of this increase are not well understood. Trogler and Thiemens will investigate the details of nitrous oxide production from various reactions that model potential environmental sources. Trogler's expertise in reaction mechanisms, catalysis, and photochemistry, and Thiemens' in gas phase kinetics and mass spectrometry will be helpful in this collaborative effort to examine these reactions under relevant conditions. Nitrous oxide is a greenhouse gas and is also involved in the atmospheric ozone balance.

ABSTRACT CHE-9319400 PI: Trogler Inst: U of Cal San Diego With this grant, the Inorganic, Bioinorganic, and Organometallic Chemistry Program supports research on reactions of carbon disulfide and carbonyl sulfide relevant to their behavior in the atmospheric sulfur cycle by Dr. William C. Trogler of the Chemistry Department, University of California at San Diego. Photoinduced oxidation with molecular oxygen, solution hydrolysis reactions including photochemistry, and catalytic oxidation by metal oxide components of aerosols will be investigated. Carbonyl sulfide, a regulated emission product, is an impurity in refinery and synthesis gas which can cause technical problems as a catalyst poison. Carbon disulfide is a neurotoxic byproduct of the production of rayon and carbon black. The fundamental chemistry of these atmospheric gases will be better characterized in order to understand the atmospheric sulfur cycle. In addition, their role in the production of stratospheric sulfate aerosols, which effect solar reflectivity and have been linked to global ozone depletion, will be examined.

The Advanced Materials Program in the Division of Chemistry makes this award to University of California San Diego. With the award, Professor William Trogler will study different methods such as photochemistry, chemical reduction, electro-polymerization and thermal polymerization to prepare new layered polymeric materials based on carbon diselenides, which will be free from elemental selenium. Doped thin films prepared from poly (carbonselenide)s will be studied for electrochemical, electronic conductivity and chemical redox properties. Complexation of cadmium with poly (carbondiselenide) at the surface would produce cadmium selenide nanoparticles and quantum dots with unique optical and electronic properties for potential applications in devices.

New polymeric materials based on carbon selenides and cadmium selenide quantum dots with electronic and photonic properties will be prepared. Synthetic methods to prepare poly (carbondiselenide)s free from elemental selenium and physical methods to characterize these materials would provide basic science knowledge for the future development of new electronic and photonic materials. Doped thin and flexible films of carbon diselenides would have unique electronic and photonic properties for applications in devices. The research, in addition, will provide training to graduate students in electronic and photonic materials.

This grant supports the purchase of a low temperature scanning tunneling microscope (STM) that will be used for investigations of defects and bonding sites in electronic and sensor materials. The low temperature STM provides a zero drift environment in which isolated molecules do not diffuse. In this quiet, stationary environment, the local electronic structure of single defects or bonding sites can be determined using current-voltage (dI/dV) measurements. The specific systems that will be studied with this instrument include: (a) defects at the semiconductor/gate oxide interface; (b) polysilole-based nanowire sensors; (c) halogen reactions with aluminum; (d) mixed, asymmetric metal phthalocyanine-based chemical sensors; and (e) fabrication of ordered arrays of single macromolecular assemblies. With the advent of commercial software (VASP) for calculating the electronic structures of molecules on surfaces, low temperature STM and STS studies can be directly compared to both simulated STM images and the partial density of states on single atoms. This comparison provides critical insights into the control of electronic structure on surfaces.

This instrument will have impact on a broad audience at the university. (a) The San Diego Fellowship program for entering graduate students: UCSD is donating 3 months of support for 4 entering graduate students. These fellowships will be used to support graduate students to increase the diversity of the chemistry and physics graduate programs. (b) Undergraduate research: Undergraduate students will be involved in the proposed research via the Howard Hughes Undergraduate Enrichment Program (HHUEP) and the UCSD Office of Academic Enrichment. (c) UCSD-TV and webcasts: Lectures that are appropriate for high school and college students will be recorded for both broadcast and webcast by the UCSD-TV education outreach program. (d) Teacher training: The funds support one high school science teacher per summer to work in a research laboratory at UCSD. The teacher will have the opportunity to learn how to use the telemetry system developed at the UCSD National Center for Microscopy and Imaging Research (NCMIR). The NCMIR facilities house an electron microscope that can be remotely controlled via the web, enabling teachers and students to use the SEM directly from their classrooms. (e) Industrial collaborations: The low temperature STM will be used in collaborative research projects that focus on device and sensor development and involve Motorola, Microsense, and IBM.

neoplasm /cancer education; technology /technique development

PROJECT SUMMARY (See instructions): Fluorescent reagents based on conjugate polymers have proven useful for inexpensive and field-portable detection of nanogram to femtogram levels of nitroaromatic explosives, which have been commercialized. Conjugated polymers are advantageous in such sensing applications, because delocalization of their excited state exciton along the polymer chain provides sensor amplification and remarkable sensitivity. This technology will be adapted to design tests for separating and detecting toxicants, such as polycyclic aromatic hydrocarbons, found at Superfund sites. Fluorescent polymer reagents will be end-functionalized so they can be covalently anchored to chromatographic supports in order to permit separation of mixtures. This new technology will be developed with the aim of an inexpensive kit for the rapid simultaneous separation and identification of polycyclic aromatic organic Superfund toxicants that exhibit carcinogenic and/or endocrine disrupting properties. New fluorometric reagents will also be developed to separate and identify arsenate, cadmium(ll), lead(ll), mercury(ll), and chromium(VI), which are common Superfund inorganic toxicants found in contaminated sites. Special emphasis in the proposed work centers on specific toxicants that are being examined by other investigators in the center. The most promising analyses will be multiplexed on larger chromatographic substrates for quantification using microplate imaging methods. New fluorescent reagents developed for these tests are promising in other center applications, such as visualizing and localizing toxicants within whole organisms and cells. Thin-layer-chromatographic fluorescent assays that are low cost and readily portable could also be adapted to other applications, such as screening for hyperaccumulating plants, which are being examined in the UCSD center and are interesting because of their potential in remediation of arsenic soil contamination.