Allison Baczynski

A Convergent Approach to a New Kind of Dehydroannulene Scaffold

Dehydroannulenes come in a wide variety of macromolecular shapes and sizes, and they have shown utility and potential to function as non-metallic conductive materials, as optical materials for device construction, and as substructural components of sensors.  The target molecules of this project will ultimately provide a novel complement to dehydroannulene scaffolds previously reported, and the synthetic route should prove more simple and direct than most of the alternative synthetic protocols previously reported.

Towards the synthesis of Clathculins A and B

The two novel acyclic diaza alkenynes, clathculins A and B (1 and 2 respectively), were isolated from the Indo-Pacific sponge Clathrina aff. reticulum collected in Sodwana Bay, South Africa.1 They were isolated as an unstable mixture and their structures were reported via hydrogenation of the compounds to the saturated analogs. Our work done surrounding these compounds has been toward their synthesis and categorization. This involves the convergent route shown below.

Synthesis of (2-(Diphenylphosphino)ethyl)cyclopentadienyl Group VI Metal Carbonyl Anions

Paleoclimate Reconstruction in the Late Cretaceous of Madagascar

The Upper Cretaceous Maevarano Formation in the Mahajanga Basin of northwestern Madagascar consists of sandstones, claystones, and siltstones, many overprinted by paleosols.  These strata contain some of the most well preserved vertebrate fossils from Gondwana.  The Maevarano Formation is divided into three members, the Masorobe, the Anembalemba, and the Miadana.  This study focuses on the paleoclimate signals of the Masorobe member.  This member consists of channel and floodplain deposits, as well as possible debris flow deposits.  Clay and framework mineralogy are used to determine the degree of weathering of the sediments, which is directly related to the climate both in the source area and in the basin.  The clays are separated from the sediment with centrifuge techniques and are analyzed using x-ray diffraction.  Several samples have shown the presence of montmorillonite (saponite), and possibly sepiolite.  These clays all form in a sub-humid to arid environment (with saponite sourcing in weathered basalt).  Framework mineralogy is studied via petrographic analysis of the sand-sized grains.  The abundance of feldspar, lithic fragments and other more easily weathering minerals indicate a subhumid climate.  Preliminary estimates of rainfall have been attempted using geochemical data obtained from a previous senior thesis.  Several climofunctions were used, all of which yielded broadly similar estimates.  Paleoprecipitation estimates are all less than approximately 1100 mm per year, which agrees with the clay mineralogy and preliminary framework mineralogy.  Evidence also points to distinct seasonality, which is the probable cause of the debris flows.

Patterns of Sedimentation in the Lake Superior region: Results from radiometric dating of zircon using U-Pb isotopes

This study used radioactive isotopes of Uranium and Lead in the mineral zircon to absolute date mineral grains from sedimentary formations. This help us deduce the sources of sedimentation and the patterns of sediment transport in the Lake Superior region, based on known ages of igneous sources.

Analysis of Sediment Transport Data and Calculation of Historical Sediment Load, St. Croix River, MN/WI.

Sediment budgets in river networks are notoriously difficult to construct but can be extremely important for quantifying both short and long-term changes to fluvial environments. Adequate sediment supply is critical for in-channel, bar, and near-shore ecosystems (both aquatic and terrestrial), as well as for recreation and navigation purposes. Hydrologic and sedimentologic conditions in the St. Croix River, a tributary of the Mississippi that forms a partial border between WI and MN, play a significant role in the stability of native freshwater mussel populations. The transport of sediment controls overall geomorphology, riverbed composition, and water turbidity, all of which are important to mussel habitat. Data shows a decrease in suspended sediment concentration, a decrease in the grain size of bed sediment, and a 96% decline in the juvenile mussel population in the last decade below the only major dam in the river system. The St. Croix River is home to two federally endangered mussel species; we need to better understand the controls on sediment transport to understand the causes for this decline and to evaluate future threats to these species.

In conjunction with mussel habitat analysis, we have collected surface and near-bed suspended sediment, as well as bedload samples since 2004. Discharge in the St. Croix typically ranges from 1000-20000 cfs. Samples collected during a range of discharges (1700-10000 cfs) along with other suspended sediment transport data (1974-2003, USGS) will allow us to explore the controls on sediment transport which include discharge, water velocity, depth, shear stress, shear velocity, and stream power. Preliminary analyses show a positive correlation between suspended sediment concentration and discharges above 5000 cfs. Using these rating curves we calculate total sediment load over the past century. Further work will allow us to understand the controls on sediment transport and deposition over daily to decadal timescales, and to explore the impact of sedimentological changes on mussel populations.

Probing the Hyperconjugative Captodative Effect by Quantum Chemistry

Hetero atom substituients weaken C-H bonds by stabilizing the carbon centered radicals that form when the hydrogens are removed.  When a molecule has both a donor and an acceptor hetero atom substituient, the two atoms can work together to create a stabilization effect that is greater than the sum of the effects the individual substituents. I calculated C-H Bond Dissociation Energies using the most stable conformer of both closed-shell reactant and radical product.  I optimized all structures with the B3LYP method and the 6-31G(d) basis set, the MPWB1K method and 6-311+G(3df, 2p) basis set, and with the CBS-QB3 method. I also used the B3LYP method to calculate the vibrational frequencies of the structures to make sure the structures were at energy minima.  Also, with the vibrational frequencies I was able to calculate the zero-point correction to the electronic energy.