The 8th
Annual
NC
Undergraduate
Summer Research Symposium
NSF Chemistry REU Program
abstracts
Abstracts are listed in alphabetical
order by the last name of the corresponding author.
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Arroyo-Pacheco, Alejandro D. |
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Home Institution: |
University of Puerto Rico, Río Piedras Campus |
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Program: |
NSF Chemistry REU Program |
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College: |
PAMS |
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Department(s): |
Chemistry |
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Research Mentor(s): |
Daniel L. Comins/Chemistry Sergey Tsukanov/Chemistry |
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Title of Presentation: |
New Chiral Auxiliaries for Asymmetric Synthesis of
Piperidine Derivatives |
Asymmetric synthesis is a very important and highly
developing area in modern chemistry.
There are several methods used in asymmetric synthesis, among them:
biocatalysis, organocatalysis, and metal catalyzed organic synthesis. This
research project focuses on the synthesis and application of chiral
auxiliaries. Generally, chiral
auxiliaries are enantiopure compounds which provide a strong predisposition for
the formation of one enantiomer over the other.
Chiral auxiliaries should be synthesized in a few steps, starting with
commercially available starting material and easily recycled after the desired
reaction. This research project
commenced with the synthesis of the chiral auxiliary starting from (S)-methyl
lactate. Treatment of 4-methoxypyridine
with the newly synthesized auxiliary will result in the formation of a chiral
N-acylpyridinium salt. This salt will be reacted with a variety of
organometallic nucleophiles to test the efficiency of asymmetric induction and
compare the ratios of diastereomers with previously reported data from known
auxiliaries.
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Brumby,
Breland G. |
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Home Institution: |
Sewanee: University of the
South |
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Program: |
NSF Chemistry REU Program |
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College: |
PAMS |
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Department(s): |
Chemistry |
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Research Mentor(s): |
James D. Martin/Chemistry Robert Wilcox/Chemistry |
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Title of Presentation: |
A Comparison of the
Sorptive Capabilities of Zinc Chloride and the CZX Halozeotype Materials |
Increased environmental ammonia concentrations, inhaled
by humans and animals, can cause a variety of respiratory problems.1, 2
High risk areas include confined poultry and swine operations, and a good
ammonia sorbent would be useful to create safer conditions in these
environments. ZnCl2 is known
to form adducts with ammonia in the atmosphere as well as in aqueous solutions.3 The halozeotype materials, similar to
zeolites except using ZnCl2 instead of SiO2 as the parent
material, made primarily of ZnCl2 have a channel structure, which
may facilitate faster or higher concentrations of ammonia being sorbed.4 A comparative study between ZnCl2
and these halozeptype materials, [HNMe3][CuZn5Cl12],
[H2NEt2[CuZn5Cl12], and [H2NMe2]n[CunZn6-nCl12]
(n=1,2), will be completed to determine the best sorbent material for
ammonia. Moles of ammonia sorbed and
overall percentage of weight gain will be determined. Structural re-arrangements, if any, induced
by the sorption of ammonia will be examined by X-ray diffraction.
1 Mitloehner
FM, Calvo MS. J Agric Saf Health.
2008 Apr; 14(2): 163-87.
2 Jones,
J.B., C.M. Wathes, and A.J.F. Webster. 1997.
Behavioral response of pigs to atmospheric ammonia. In Proc.
Fifth International Symposium on Livestock Environment, 875-882. St. Joseph, Mich.:ASAE.
3 H.
Fortier, P. Westreich, S. Selig, C. Zelenietz, J.R. Dahn. J.
Colloid Interface Sci. 320 (2008) 423-435.
4 James
D. Martin, Kevin B. Greenwood. Angew. Chem. Int. Ed. Engl. 1997, 36, No. 19.
|
Garcia, Deborah |
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Home Institution: |
Interamerican
University |
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Program: |
NSF Chemistry REU Program |
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College: |
PAMS |
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Department(s): |
Chemistry |
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Research Mentor(s): |
Jonathan S. Lindsey/Chemistry Marcin Ptaszek/Chemistry |
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Title of Presentation: |
Investigation
of Porphyrin Formation under Plausible Prebiotic Earth Conditions |
Since really early mankind has been theorizing on
how life emerged. Upon many possible explanations it is evident that key
aspects of the origin of life include photosynthesis and redox processes. In
both of these processes the tetrapyrrolic species such as porphyrins play a
crucial role. Therefore porphyrins may be central to how life emerged due to
their role in both processes. The main
purpose of this research is to find routes of how the very first porphyrins
were created under simple prebiotic conditions starting from very simple,
prebiotically available substrates. Formation of the porphyrin was successfully
done in the past using aminolevulinic acid and a β-ketoester (methyl 4-methoxyacetoacetate),1
but the reaction only proceeded at high temperature (95°C). In order to investigate
milder conditions for prebiotic porphyrin synthesis, a variety of β-ketoesters with different
leaving groups are being prepared. In the second phase of the experiment, β-ketoester with long alkyl
substituents are being synthesized. Formation of the corresponding pyrrole
(upon reaction with aminolevulinic acid) and consequently porphyrins from the β-ketoester derivatives are
being explored under various conditions. The reaction of such β-ketoesters may enable
formation of porphyrins under mild conditions, and also yield hydrophobic
porphyrins that spontaneously incorporate into membranous assemblies.
1 “Simple Formation of an Abiotic Porphyrinogen in
Aqueous Solution,” Lindsey, J. S.; Ptaszek, M.; Taniguchi, M. Orig. Life Evol.
Biosph. 2009, in press; DOI: 10.1007/s11084-009-9168-3.
|
Hudson-Davis,
Morgan L. |
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Home Institution: |
Georgia Southern
University |
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Program: |
NSF Chemistry REU Program |
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College: |
PAMS |
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Department(s): |
Chemistry |
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Research Mentor(s): |
Bruce M. Novak/Chemistry Joseph D. DeSousa/Chemistry |
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Title of Presentation: |
Synthesis and Characterization of Asymmetric
Polyguanides |
Guanidine (CH5N3) is a high nitrogen-content molecule
known for its high pKa value and ubiquity in nature and chemistry. With a pKa of 13.6, guanidine is one of the
most basic of the common functional groups.
It can be used in many applications, such as explosives, plastics and
rocket fuel. Guanidine and its dimer
derivative, biguanide, exhibit numerous biological activities and are common
functional groups in several pharmaceutical drugs. Beyond the dimer, there is only limited
evidence to support the successful synthesis of a triguanide compound, and
today, biguanide is accepted as the largest derivative of guanidine to be
synthesized without undo adverse side reactions or byproducts. The remarkable properties and characteristics
of guanidine and biguanide drive an interest in developing synthetic routes to
the larger derivatives. For instance,
the creation of certain polyguanides is appealing because they may function as
enhanced catalysts in enantioselective reactions or even induce chirality. Through polymerization and deprotection
chemistry of asymmetric carbodimide monomers, high molecular weight compounds
with guanidine functionality have been prepared in this study. Evidence of asymmetric polyguanide synthesis
is substantiated by proton nuclear magnetic resonance and infrared
spectroscopy.
|
Kimes, Keri L. |
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Home Institution: |
Shippensburg |
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Program: |
NSF Chemistry REU Program |
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College: |
PAMS |
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Department(s): |
Chemistry |
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Research Mentor(s): |
Leslie Sombers/Analytical Chemistry Audrey Sanford/Analytical Chemistry James Roberts/Analytical Chemistry Leyda Lugo/Analytical Chemistry |
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Title of Presentation: |
Comparison of Platinum, Platinized Carbon,
and Carbon Disc-Microelectrodes in the Detection of Hydrogen Peroxide Using
Fast Scan Cylic Voltammetry |
Hydrogen peroxide is a common byproduct in many
biology processes, including cellular respiration, and is potentially
toxic. When not decomposed by enzymatic
peroxidase, it can form radicals which have the potential of irreversibly
modifying DNA, lipid, and protein structures as well as functions. Peroxide and its derivative superoxide radicals
have been implicated as a major contributor to DNA mutation, lipid membrane
disruption, and Parkinson’s disease.
Traditionally, platinum electrodes are used to detect hydrogen peroxide
because they offer a catalytic surface for H2O2 oxidation,
yielding a more reactive surface with better sensitivity. However, these electrodes are not feasible
for in vivo use due to rapid
biofouling. Carbon microelectrodes are most commonly used in vivo, however, H2O2 is not easily detected
at these electrodes. In this work,
platinum wire, carbon fiber, and platinized carbon fiber microelectrodes were
characterized and compared in their sensitivity for the detection of H2O2
by fast scan cyclic voltammetry.
Suitable applied waveforms and scan rates were tested to optimize
sensitivity on platinum electrodes in order to determine the highest degree of
sensitivity and selectivity toward H2O2. The optimal applied waveform was then tested
using carbon fiber and platinized carbon fiber disc microelectrodes. Platinum wire disc electrodes were found to
have slightly better sensitivity than carbon fiber electrodes. Platinized carbon fiber electrodes showed a
sevenfold improvement in sensitivity over both platinum wire and carbon fiber
microelectrodes for detection of H2O2. The increased sensitivity to H2O2
at platinized carbon microelectrodes may offer a medium between better
sensitivity in vivo and increased
resistance to biofouling.
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Lafontaine, Scott R. |
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Home Institution: |
Kean University |
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Program: |
NSF Chemistry REU Program |
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College: |
PAMS |
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Department(s): |
Chemistry |
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Research Mentor(s): |
Catherine S. Reed/Chemistry Rob W. Huigens III/Chemistry Christian Melander/Chemistry |
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Title of Presentation: |
The Synthesis of a Diverse Set of Focused
Chemical Libraries Based on a 4-Pentylphenyl Moiety as Antibiotic and Biofilm
Modulating Small Molecules |
Bacterial biofilms are surface attached bacteria
that are encased in an extracellular matrix.
This dense protective barrier enables bacteria within the biofilm to be
more resistant to conventional antibiotics.
Unfortunately, it has been estimated that nearly 80% of all bacterial
infections are biofilm-mediated.
Recently, a library of 50 2-aminobenzimidazole (2ABI) small molecules
was synthesized and screened against Methicillin-resistant Staphylococcus
aureus (MRSA) and several strains of multidrug resistant Acinetobacter
baumannii, including several clinical isolates.
The lead 2ABI was found to have antibiotic properties against both MRSA
and A. baumannii (MIC = 12.5 to 25 μ M). A
2-aminoimidazole derivative of the lead 2ABI was synthesized and screened
against E. coli and A. baumannii biofilm formation. This 2-aminoimidazole was found not only to have
antibiotic properties against MRSA, but it also demonstrated biofilm inhibition
against E. coli and A. baumannii.
Impressively, few small molecules have been discovered to have these
properties. Several focused libraries of
this 2-aminoimidazole lead were synthesized in an attempt to identify more
potent derivatives based on the 4-pentylphenyl moiety contained in these active
structures.
|
Liang, Alexandria D. |
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Home Institution: |
New College of Florida |
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Program: |
NSF Chemistry REU Program |
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College: |
PAMS |
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Department(s): |
Chemistry |
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Research Mentor(s): |
Reza A. Ghiladi/Chemistry Jennifer D'Antonio/Chemistry |
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Title of Presentation: |
Spectroscopic
Characterization of Dehaloperoxidase Mutations: An investigation of Radical Location in the
Catalytic Mechanism |
Dehaloperoxidase (DHP) is a bifunctional enzyme,
exhibiting both peroxidase and hemoglobin activity. The peroxidase activity enables the enzyme to
oxidatively dehalogenate substrates such as trihalophenols to form
dihaloquinones. Previous studies have
suggested that the enzymatic function is dependent on the formation of an amino
acid radical. Two forms of DHP occur in
nature, DHP A and DHP B. These two
different enzymes vary by 5 amino acid residues. Comparisons between DHP A, DHP B and
mutations of each have the potential to elucidate the location of the radical
formed in the catalytic mechanism and eventually characterize the mechanistic
properties of each enzyme. The following
studies focus on DHP A, DHP B, DHP A (W120F) and DHP B
(Y38F) and will be compared to previously expressed mutation DHP A (Y38F). Kinetic studies of DHP B (Y38F) show an 18
fold increase in peroxidase activity over DHP B and a 38 fold increase over DHP
A. The cause for this increase in
activity has been studied by UV-visible, stopped-flow and EPR spectroscopies,
the details of which will be discussed here.
|
Rodríguez,
Dianny M. |
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Home Institution: |
Pontifical Catholic University of Puerto Rico |
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Program: |
NSF Chemistry REU Program |
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College: |
PAMS |
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Department(s): |
Chemistry |
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Research Mentor(s): |
Paul A. Maggard/Chemistry Lindsay C. Fuoco/Chemistry |
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Title of Presentation: |
Molten Flux Synthesis and Characterization of the
Half-Metallic Double Perovskites Sr2CrMO6 (M = Re or W) |
Magnetoresistance (MR) is characterized by the change
in a materials resistivity in response to an applied magnetic field. Much research has focused on finding
materials that display large magnetoresistance at room temperature and low
magnetic fields due to their potential applications in commercial devices such
as computer hard disk read heads. The
half-metallic double perovskite oxide Sr2FeMoO6 has drawn considerable
attention due to its high Curie temperature and observed low field
magnetoresistance, which is proposed to occur via intergrain tunneling. The magnitude of the observed intergrain
tunneling magnetoresistance (ITMR) for Sr2FeMoO6 has been shown to be synthesis
dependent with a correlation between observed MR and grain size. In this research, the less explored
half-metallic ferromagnetic double perovskite oxides Sr2CrWO6 Tc = 460 K and
Sr2CrReO6 Tc = 635 K were prepared by new molten flux method to investigate the
relationship between synthesis parameters and observed magnetoresistance. Flux synthesis is a simple alternative to the
solid state methods that has been show to produce products of high purity at
lower temperatures and shorter reactions time than the current solid state
methods and also allows for the control particle sizes by changing reaction
parameters such as flux amount and cooling rate. The purity of the flux products was confirmed
using powder X-ray diffraction. Particle
size and morphology of the flux products as a function of flux ratio and
reaction cooling time will be probed using scanning electron microscope (SEM)
and the resistivity and magnetoresistance of the flux prepared products will
also be discussed.
|
White,
Patrick R. |
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Home Institution: |
NCSU |
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Program: |
NSF Chemistry REU Program |
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College: |
PAMS |
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Department(s): |
Chemistry |
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Research Mentor(s): |
Jerry L. Whitten/Chemistry |
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Title of Presentation: |
Surface Area of a Molecule/Expansion of
Electrostatic Interactions |
In
this project, an analytical method for approximating the surface area of alkanes
was developed, applied to a large group of alkane molecules, and compared to
physical data. Each atom of a molecule
was approximated as a sphere of radius equal to the Van der Waal radius. The areas of each sphere were added together
and areas of overlap were subtracted.
Constants were calculated for the overlap area for several different
cases using standard bond lengths and angles of a tetrahedral molecule. These constants were then used to develop an
equation for estimating the surface area of straight chain alkanes with n
carbons. Since the geometry of branching
alkanes is much more complex, the same constants were simply applied to make a
rough estimate of the surface area.
Straight chain alkanes containing one to twenty carbons were examined
and calculated surface areas were correlated with physical data. A nearly perfect logarithmic relationship was
found between surface area and boiling point and a negative exponential
relationship was found between surface area and solubility. There did not appear to be any relationship
between surface area and melting point.
The method was then used on a sample of 60 branching alkanes with one to
ten carbons and their approximated surface areas were plotted against the same
data with the straight chain alkane data.
For melting point and solubility, the addition of the branching alkanes
created points farther away from the original correlation, but the plots still
indicated the same correlations. Melting
point data still did not indicate any clear correlation. For the second
project, a rigorous inequality was used to expand the calculation of
electrostatic interactions.
<A(1)
| 1/r | A(2)> ≥ 2<A(1) |
X(1)> + <X(1) | (1/4π)
∇2 |
X(1)>
Where
A is a given electron distribution and X is a chosen potential that can be
optimized by maximizing the right hand side of the equation
A
computer program was written to evaluate both the left and right sides of the
inequality for different test cases. For
each test case, the right side was maximized and compared to the left side to
determine error bounds. This project is
currently still in progress.
|
Yablonski,
Joshua D. |
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Home Institution: |
Millersville University |
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Program: |
NSF Chemistry REU Program |
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College: |
PAMS |
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Department(s): |
Chemistry |
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Research Mentor(s): |
Elon Ison/Chemistry Yuee Feng/Chemistry |
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Title of Presentation: |
Iridium Catalyzed Aerobic Oxidation of Alcohols |
The oxidation of alcohols to aldehydes is a fundamental
reaction of organic chemistry and the ability of this reaction to occur under
mild conditions, with less toxic starting materials is very desirable. For this research, several Cp*Ir(NHC) (Cp* =
1,2,3,4,5-pentamethyl cyclopentadiene ligand, (NHC = 1,3
dimethyl-4,5-dimethylimidazol-2-ylidene ) complexes were synthesized and tested
in oxidation reactions of primary and secondary alcohols with O2 as
an oxidant and catalytic amounts of triethylamine (TEA). Reaction conditions (temperature, concentration,
and amount of base), were optimized for conversion of benzyl alcohol to
benzaldehyde with Cp*Ir(NHC)Cl2 and 2
equivalents of AgOTf. These optimized
conditions were employed to the other catalysts and various alcohol
substrates. In addition, the electronic
effects of para-substituted benzyl alcohols on catalytic turnover were
investigated. Possible decomposition
reactions of the Cp*Ir(NHC) complexes, under the
determined reaction conditions, were also studied. Under optimal conditions, turnover numbers of
approximately 40 were achieved for the iridium catalysts.
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Last modified June 2009 by Sharon E. Hunt