Joseph Grabowski

Physical-Organic Chemistry: Mechanisms, Dynamics & Reactive Intermediates. Gas Phase Ion Chemistry. Organic Photochemistry. Mass Spectrometry. Environmental Chemistry. Chemical Education.

Research

Research in the Grabowski group is directed towards defining and utilizing the fundamental dynamics of organic reaction mechanisms and the intrinsic properties of reactive intermediates. To overcome limitations imposed by conventional strategies, state-of-the art experimental techniques from other fields of science are employed in characterizing all aspects of how and why organic transformations occur (i.e., what goes on, quantitatively, behind the window shade).


Emphasis is placed on conversion of specific observations and deductions to deriving unique solutions to outstanding problems. Current research efforts are equally divided between condensed-phase and gas-phase, each increasingly augmented by theoretical studies.

The focus of research in the condensed-phase is the utilization of pulsed laser photoacoustic calorimetry to determine the energetics and lifetimes of key species along reaction coordinates. Problems being uniquely solved include characterization of photodissociation processes, precise measurements of bond dissociation energies (the carbon-cobalt bond in Coenzyme B₁₂; X-H bonds in organic molecules), the dynamics of reactive intermediates which lack chromophores (e.g., simple alkyl radicals), and heats of formation, heats of solvation and heats of reaction of carbenes, diradicals, and coordinatively unsaturated organometallics.

Kinetic and thermodynamic studies of organic reactions in the gas-phase are carried out using a custom-built tandem mass spectrometer. Several of the many on-going projects include: the ionic chemistry of Freons and the feasibility of charge-induced ozone recovery schemes; characterization of substitution reactions at non-carbon centers (e.g., as postulated to occur for certain carcinogens); the competitive nature of proton transfer reactions (and their use in deriving condensed phase data); the chemistry of radicals as probed via radical ions; the specific physical properties of carbenes and diradicals; and the design and evaluation of analytically useful chemical approaches for dioxin identification and protein sequencing reactions.

Additional collaborative research projects with faculty in this department, other University of Pittsburgh Departments, and with other Universities are also underway. These include the design, construction, characterization, and utilization of a new mass spectrometer dubbed the SWISS-484 (an ESI-based, quadrupole-octopole-quadrupole instrument). Another collaboration is focused on instrument design, construction, and utilization for the real-time characterization of aerosols in the work environment. A third collaboration is the development of a Virtual Mass Spectrometry Laboratory educational tool. Several other Chemical Education web-based projects are being developed, including a student self-assessment tool for Gen Chem and for Orgo, called PittLearn.