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Boston College Graduate Student Symposium
October 14, 2013 9:00 a.m. – 5:30 p.m.
Connors Family Retreat and Conference Center Dover, MA
Dear Friends and Colleagues:
Welcome to the 2013 Boston College Chemistry Department Graduate Student Symposium! This annual symposium provides a platform for graduate students in the department to share their exciting research accomplishments with fellow students and faculty. We have an impressive lineup of speakers and poster presenters, and we hope that you enjoy this opportunity to learn about the diverse areas of research currently ongoing in the Chemistry Department.
In addition to the poster session and student presentations, it
is our pleasure to welcome Dr. Alex Hird, a scientist at AstraZeneca in Waltham, MA, and a Boston College graduate student alumnus. We are very grateful to Dr. Hird for his participation in this event, and for giving us insight into his successful career path and serving as an exceptional role model for current graduate students.
Please enjoy your day at the beautiful Connors Family
Retreat Center!
Sincerely,
Kyle Cole, Lauren Blair, Breanna Zerfas (Chemistry GSA) Professor Abhishek Chatterjee
Schedule of Events:
***Buses depart from Merkert Chemistry Center at 7:45am*** 8:15 am – 9:00 am
Breakfast
9:00 am – 9:25 am
Student Presentation 1 – Miao Yu
9:25 am – 9:50 am
Student Presentation 2 – Nicholas Pace
9:50 am – 10:15 am
Student Presentation 3 – Hilan Kaplan
10:15 am – 10:30 am
Break – Coffee, bathroom, etc.
10:30 am – 10:55 am
Student Presentation 4 – Jia Zhuang
10:55 am – 11:20 am
Student Presentation 5 – Andrew Baggett
11:20 am – 12:30 pm
Student Poster Session 1 – Brian Sneed, Jessica Drake, Yue Zhao, Chun Du, Nick Mszar, Kyung Lee, Elsie Yu, Lisa Stankee, Jacob Ishibashi, Thomas Caya
12:30 pm – 1:30 pm
Lunch
1:30 pm – 1:55 pm
Student Presentation 6 – Tao He
1:55 pm – 2:20 pm
Student Presentation 7 – Zhiyong Yu
2:20 pm – 2:45 pm
Student Presentation 8 – Jin Xie
2:45 pm – 4:00 pm Student Poster Session 2 – Maggie Sheehan, Ashley Biernesser, Azade Hosseini, Pengcheng Dai/Wei Li, MJ Koh, Hao Wu, Shalise Couvertier, Hyelee Lee, Bowman Potter
4:00 pm – 5:00 pm
Keynote Speaker and Awards
***Buses depart for Boston College around 5:15 pm***
Student Poster Session
Greystone Meeting Room 11:20 am - 12:45 pm 3:00 pm - 4:00 pm
Organic and Organometallic Chemistry Hoveyda Group "Enantioselective Allenylsilane Additions to Imines Promoted by an NHC–Copper Complex" ~ Nick Mszar "Readily Accessible and Easily Modifiable Stereogenic-at-Ru Catalysts Based on Rational Design: Applications Toward Z-selective Olefin Metathesis" ~ MJ Koh "Flourine as an Organizational Feature in the Catalytic Enantioselective Synthesis of Alcohols" ~ Kyung A Lee "Enantioselective Allene Additions to Boc Aldimines Catalyzed by an Aminophenol Catalyst" ~ Hao Wu "Mo-Catalyzed Cross-Metathesis for the Formation of Various Z-Alkenes" ~ Elsie Yu Morken Group "Alkoxide-Directed Diboration of Alkenes" ~ Thomas Caya "Enantiotopic-Group-Selective Cross Couplings: A New Strategy for Construction of Nonracemic Boronates" ~ Bowman Potter Byers Group "Substoichiometric Additives Promote Hydrogenation of Carbon Dioxide to Formic Acid"
~ Jessica Drake
"Redox Controlled Polymerization of Lactide Catalyzed by Bis(Imino)Pyridine Iron Complexes"
~ Ashley Biernesser Liu Group "Boron-Nitrogen-Containing Acenes: Synthesis, Reactivity, and Potential Application in Neutron Detection"
~ Jacob Ishibashi "Site-Selective Functionalization of Complex Molecules & Binding of BN Heterocycles Inside the Modular Cavity of Engineered T4 Lysozymes"
~ Hyelee Lee Chemical Biology and Biochemistry Weerapana Group "Lysine Directed Chemical Probe Library Reveals Potent GSTP1 Inhibitor"
~ Lisa Stankee "Investigating Cysteine-Mediated Protein Activities in Complex Proteomes"
~ Shalise Couvertier Gao Group "Covalent Targeting of Bacterial Lipids with Polyboronic Acids" ~ Yue Zhao “Designing Peptide Scaffolds for PS Recognition” ~ Azade Hosseini
Physical and Theoretical Chemistry Wang Group "Hematite Based Photoelectrode for Solar Water Splitting " ~ Chun Du "Platinum and Pyridinium Co-Catalyzed CO2 Reduction on Si Nanowire Photocathode" ~ Pengcheng Dai and Wei Li Tsung Group “Encapsulation of Metal Nanoparticles in Nanoporous Materials for Catalysis”
~ Maggie Sheehan “Design of Metal Nanocrystals for Energy Conversion Electrocatalysis”
~ Brian Sneed
Student Lecture Abstracts - Group 1
Charles River Meeting Room 9:00 am – 10:15 am
Application of Z- and Enantioselective Catalytic Olefin Metathesis to a Concise Total Synthesis of (+)-Neopeltolide
Miao Yu and Amir H. Hoveyda
Significant advances in our laboratories during the past five years have led to the development of the first class of efficient catalysts that promote highly Z-selective olefin metathesis reactions. Recently, we successfully completed a concise diastereo- and enantioslective total synthesis of anti-cancer agent neopeltolide wherein several Mo-catalyzed Z- and enantioselective olefin metathesis reactions are at center stage. The acyclic segment of the natural product, containing two Z alkenes, is identical to that of the naturally occurring cytotoxic agent leucoscandrolide. Another notable feature of the synthesis includes an efficient enantioselective (pinacolato)boron [B(pin)] conjugate addition to an acyclic enoate catalyzed by a chiral N-heterocyclic carbene, representing another set of transformations designed and developed in our group.
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O Me
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N
HNOMe
O
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OMeMe
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OPefficient'
ring*closingmetathesis
O
O
Me
O
OP
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OH
Me
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OP
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OH
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enantioselectivering*opening/cross*metathesis
HO OO
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HNOMe
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Z*selective'cross*metathesis
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OH
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catalytic'cross*Coupling
B(pin)
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neopeltolide(highly'potent'anti*tumor)
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HNOMe
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leucoscandrolide(cytotoxic)
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enantioselectiveB(pin)'conj.'addn/ox.
Z*selective'cross*metathesis
A Competitive Chemical-Proteomic Platform to Identify Zn2+-Binding Cysteines
Nicholas J. Pace and Eranthie Weerapana Of the biologically relevant metal ions, Zn2+ has been known to play significant catalytic, structural, and regulatory roles within proteins. Previous methods to detect Zn2+-chelated proteins rely on combinations of structural analysis and computational predictions. With the ever-increasing number of recognized Zn2+-chelating proteins, these methods lack the ability to globally evaluate Zn2+-binding within a complex proteome. Our approach takes advantage of the reduced nucleophilicity of cysteine residues upon metal-binding by utilizing cysteine-reactive chemical probes that preferentially bind the more nucleophilic apo-form. Coupling our cysteine-reactive probes to gel and mass spectrometry-based proteomic techniques facilitates identification and quantification of each identified cysteine’s affinity towards Zn2+. Towards this end, a peptide-based probe that binds the Zn2+-binding cysteine of sorbitol dehydrogenase (SORD) demonstrated this apparent decrease in nucleophilicity when treating the proteome with Zn2+ and conversely, an increase in nucleophilicity when administering a Zn2+-chelator, EDTA. Additionally, our platform also identified the active-site cysteine of glutathione S-transferase omega (GSTO1) as a potential Zn2+-chelation site. Upon further interrogation, recombinant GSTO1 administered Zn2+ ions results in a dose-dependent decrease in GSTO1 activity. Furthermore, we apply a promiscuous cysteine-reactive probe to globally identify putative Zn2+-binding cysteines across ~900 cysteines in the human proteome. This proteomic study identified several well-characterized Zn2+-binding proteins, as well as, numerous uncharacterized proteins from functionally distinct classes. This versatile platform can be adapted to evaluate cysteine binding to other biologically relevant metal ions within diverse proteomes, and complement the current structural and computational methods that are available.
Synthesis, Characterization, and Reactivity of New Iron Complexes for Applications in Catalysis
Hilan Z. Kaplan and Jeff Byers
A family of iron complexes bearing a novel 1,3-bis(imino)-N-heterocyclic carbene (CDI) ligand has been synthesized and characterized. Through the use of X-ray crystallography, Mössbauer spectroscopy, SQUID Magnetometry, and other analytical methods, the physical and electronic structures of a series of compounds at various oxidation states have been elucidated. In addition to fully characterizing these new metal complexes, rigorous spectroscopic study has shed light on a new mode of N-heterocylic carbene−metal bonding in which the carbene can engage in single electron transfer from the metal center. The data highlights the redox non-innocent nature of the metal-bound CDI, making it a member of a particularly interesting class of ligand known to support a range of complex oxidation states for a diverse series of reactions. With the hopes of using these complexes as catalysts for polymerization and/or synthetic organic transformations, a series of stoichiometric reactions have been carried out revealing an interesting and unique reactivity profile. Finally, preliminary investigations into potential catalytic applications have demonstrated the complexes to be competent catalysts for the atom transfer radical polymerization (ATRP) of methyl methacrylate and the hydrogenation of simple alkenes.
Student Lecture Abstracts - Group 2
Charles River Meeting Room 10:30 am – 11:20 am
Encapsulation of Small Molecules in Metal Organic Framework Nanospheres for Drug Delivery
Jia Zhuang and Chia-Kuang “Frank” Tsung
Directly applying therapeutic drugs to patients suffers from the intrinsic limitations of these small molecules including poor physiological stability, non-specific targeting, and low cell membrane permeability. The design of drug carriers to deliver drugs to specific targets is one of the potential strategies to overcome these limitations. In this work we developed a pH-responsive drug delivery system (DDS) with high cellular uptake efficiency by utilizing a nano-sized metal organic framework (MOF), which possesses the advantages of both organic- and inorganic-based DDSs. The studies show that the MOF nanospheres are uniform 70 nm crystals with single-crystalline structure. The small molecules including fluorescein molecules and anticancer drug camptothecin molecules were encapsulated inside of MOF frameworks by simply introducing small molecules in the MOF synthesis solution. Then we incubated the molecule-encapsulated MOF nanospheres with MCF-7 breast cancer cell line. The confocal laser scanning microscopy study and the MTT assay data show that these molecule-encapsulated MOF nanospheres are ideal for drug delivery. The nanospheres are stable in physiological conditions and the cytotoxicity of the MOF carrier is low. The cellular uptake efficiency is high due to the 70 nm size. The drug molecules can be released after the cellular uptake because of the pH-responsive dissociation of MOF frameworks. To demonstrate the versatile potential of this MOF system, iron oxide nanoparticles were also encapsulated to the molecule-loaded MOF nanospheres, thereby endowing magnetic features to the nanospheres.
Iridium-Catalyzed Borylation and Suzuki-Miyaura Cross Coupling of 1,2-Azaborines
Andrew Baggett and Shih-Yan Liu
1,2-Azaborines are a family of aromatic heterocycles that is isosteric with the ubiquitous and biologically important family of arenes. The parent 1,2-Dihydro-1,2-azaborine is related to the quintessential aromatic compound benzene by replacement of a C=C bond unit of benzene with an isoelectronic B-N bond. Herein we describe the regioselective borylation of 1,2-azaborines to furnish azaborine boronic acid esters that are suitable partners in Suzuki-Miyaura cross coupling. This work represents the first late-stage functionalization of 1,2-azaborines at the 6 position. Additional functional group transformations of azaborine boronic acid esters will also be discussed.
Student Lecture Abstracts - Group 3
Charles River Meeting Room 1:45 pm – 3:00 pm
Fluorinated Aromatic Amino Acids Distinguish Cation-π Interactions from Membrane Insertion
Tao He, Anne Gershenson, Jianmin Gao and Mary F. Roberts
Peripheral membrane proteins can be targeted to membranes via specific lipid interactions. Molecular dynamics (MD) simulations suggest that phosphatidylcholine (PC) cation / amino acid π complexes are important for the membrane binding of Bacillus thuringenisis phosphatidylinositol-specific phospholipase C (PI-PLC). This peripheral membrane protein specifically binds to PC-rich vesicles, and both mutagenesis and MD simulations suggest that choline cation / tyrosine π complexes provide most of the binding energy. The related Staphylococcus aureus PI-PLC has little affinity for PC, but introduction of two tyrosines at Asn-254 and His-258, mimicking the Bacillus enzyme, leads to PC specificity presumably due to cation-π interactions. However, there are not facile experimental methods for differentiating cation-π interactions from membrane insertion of aromatic side chains. By site-specific incorporation of pentafluorophenylalanine (F5-F) and difluorotyrosine (F2-Y) using the pEVOL system, we can distinguish these two types of interactions. Fluorinated amino acids are more hydrophobic, and are therefore likely to enhance binding by insertion. However, the altered electrostatics of the fluorinated aromatic ring should destabilize cation-π interactions. S. aureus F249(F5-F) has higher binding affinities than wildtype for small unilamellar vesicles (SUV) at all mole fractions of PC (XPC), and a DDG relative to wildtype of -3.4 kJ/mol for binding to PC-rich SUVs (XPC=0.8) suggesting that the Phe inserts the membrane. In contrast, N254Y/H258(F2-Y) loses significant binding affinity for PC-rich vesicles compared to the parent N254Y/H258Y, with a DDG relative to N254Y/H258Y of +7.5 kJ/mol at XPC=0.8, consistent with role of Tyr residues in cation-π complexes with choline headgroups. Thus fluorinated amino acids allow us to directly test how aromatic residues interact with membranes elucidating protein membrane interactions at molecular level, and provide both a direct test of MD simulations results and data that can be used to design membrane binding interfaces.
Target-Inspired Reaction Development: An Efficient Synthesis of (+)-Discodermolide
Zhiyong Yu and James P. Morken
(+)-Discodermolide is a marine natural product and is one of the most potent microtubule stabilizers in human cell lines. Because of its unique linear structure and important properties, a number of total syntheses of (+)-discodermolide and its derivatives have been reported. Herein, an efficient, highly convergent, and stereocontrolled total synthesis is presented. The synthesis relied on the development of three catalytic and stereoselective processes: platinum catalyzed asymmetric diene diboration, nickel catalyzed borylative diene aldehyde coupling and nickel catalyzed diastereoselective hydroboration of chiral dienes. Combination of these reactions allows preparation of the target in a short sequence.
O
HO
Me
O
OHMe
MeOH
Me
Me
Me
OH
Me
O
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NH2
O
Catalytic Stereoselective Borylative Diene Aldehyde
Coupling
Catalytic Diastereoselective Hydroboration
Asymmetric Catalytic Diboration/Homologation/
Elimination Sequence
Enabling Lithium Oxygen Battery Technology with New Electrode Materials
Jin Xie and Dunwei Wang
Lithium oxygen batteries have received significant research attention recently owing to its high energy density – at 3505 Wh/kg, it is at least five times that of lithium ion batteries. However, a number of challenges need to be addressed before the technology is ready for practical applications. For example, existing electrode materials only allow for Li-O2 battery operations with short-term stability and low round-trip efficiency. Recent research points to issues connected with the usage of carbon, whose porous form is ubiquitous in electrochemical cell designs such as fuel cells. It is recognized that the development of a non-carbon electrode material will play a positive role in solving the problems associated with carbon electrodes. Examples of the problems include oxidation of carbon and reactions with the electrolyte. It is within this context that we focused on studying an alternative structure for the purpose of air cathode designs. Our choice of material is the TiSi2 nanonet, a high surface-area, and highly conductive two-dimensional structure. On a fundamental level, our study sheds light on what issues are truly connected with the carbon electrode; on a practical level, our material choice enables the immediate advancement of Li-O2 technology. We show that when combined with an effective catalyst, Ru nanoparticles, TiSi2 nanonets exhibit excellent stability against oxidation. They also enable reversible formation and decomposition of Li2O2 with low electrochemical overpotentials. Although still in its early stage of development, this line of study by us promises to address key issues encountered in Li-O2 battery research. A new door is opened up to actualize the full potentials of this new technology.
Keynote Speaker
Charles River Meeting Room 4:00 pm – 5:00 pm
Dr. Alex Hird
AstraZeneca Waltham, MA
Education: PhD - Boston College, 2000-2005 (Advisor: Amir H. Hoveyda) BA, MSc – University of Cambridge, 1995-1999 Experience: Research Associate: GlaxoSmithKline, 2000 Scientist: Oncology Chemistry Group, AstraZeneca, 2005-2007 Senior Scientist: Oncology Chemistry Group, AstraZeneca, 2007-2013 Principal Scientist I: Oncology Chemistry Group, AstraZeneca, 2013-present
Material Applications of Synthetic Organic Chemistry ---A Short Career in Perspective
There can be no progress in materials technologies incorporating organic
compounds without the design and synthesis of new targets that meet increasingly stringent and challenging structural and electronic standards. In this talk we hope to share an understanding of organic photovoltaics (OPV) gained during our first year of employment at Konarka Technologies in Lowell MA. We will start by considering the current state of organic photovoltaics and the qualities that set OPV apart from other photovoltaic technologies. This macroscopic assessment will be followed by an elucidation of the OPV device structure and energy production mechanism with special emphasis on the design and synthesis of compounds incorporated into the active layer. A small amount of time will also be devoted to previous work at Boston College and postdoctoral work at SAFC Hitech in Haverhill, MA. Finally, we hope to share the benefit of our brief career experience as a secondary theme throughout the talk.
Boston College Department of Chemistry
Eugene F. Merkert Chemistry Center 2609 Beacon Street
Chestnut Hill, MA, 02467 www.bc.edu/chemistry
