Upcoming Events
Would you like to learn more about Phillips 66 and their Technology division? Representatives from Phillips 66 are hosting a “Meet & Greet” for graduate students and post-docs on September 25, from 6:00 to 7:00pm in Hach Hall atrium. Phillip 66 representatives will be available to answer any questions you may have about Phillips 66 and/or the application process. Graduate students and post-docs looking for employment in 2019/2020 are encouraged to bring resumes for opportunities to meet with the recruiters on Thursday September 26, for pre-inte
Department of Chemistry, Tufts University
(VanVeller)
The Kritzer Lab uses innovative molecules to block disease-associated proteins, often in ways
traditional "drug-like" molecules cannot. Several projects are exploring new ways to
synthesize and screen constrained peptides, which are molecules with unique abilities to bind
protein surfaces and block protein-protein interactions. Discovering new bioactive molecules
is only the first step. however. In several other projects, we are exploring new methods for
measuring cell penetration, which is the most difficult roadblock for many emerging
therapeutics including peptide therapeutics, protein therapeutics, RNA therapeutics, and gene
editing.
Science Journalist, Bloomsbury Sigma Publishing
(Winter)
Kit Chapman will tell the thrilling history of creating elements past uranium - from the first steps during the Manhattan Project to the modern experiments rewriting our understanding of the chemical world. From flying planes into mushroom clouds to some of the most powerful research machines in the world, this will reshape everything you think you know about scientific discovery. Kit will also discuss his own path to becoming an author and science journalist, and give tips and advice for those who want to write their own scientific tales.
Department of Mechanical & Materials Engineering, Florida International University
(Miller)
Nanoscale precursors have been found useful in thin film generating for a variety of applications, from optoelectronics to medical devices. When endowed with adequate functionality, nanostructured chalcogenides are readily dispersible in various solvents to create colloidal solutions. Such dispersions, often called inks, could be easily coated in large areas on conducting substrates, conferring an inexpensive and robust method to construct thin films that could be useful in a plethora of applications, including energy generation; specifically, in thin-film photovoltaics. The processing required for obtaining uniform and dense nanostructured coatings is governed by the ability to tailor particle size, particle size distribution, nanoprecursors' surface and to select appropriate dispersion reagents. Each type of nanostructure is unique, and finding a specific set of conditions requires an in-depth analysis of properties such as surface identity and morphology. With melting occurring at several hundred degrees lower than the melting point in bulk, the thermal treatment of NP precursors enables fabrication of uniform, crystalline thin-films on inexpensive substrates which only sustain moderate processing temperatures. The operating hypothesis is that the final crystalline film will mirror the nanoprecursors composition prior to the thermal treatment. Therefore, tremendous efforts have been reported toward rigorous control of nanoparticles composition.
The presentation will outline our discoveries in the synthesis of nanostructured materials for thin-film chalcogenide photovoltaics (PV), including Cu2ZnSnS4, Fe2GeS4, and Cu3VS4, and will dive into preparative methods for a new class of materials, 2D chalcogenides, the focus of our most recent endeavors.
Department of Chemistry & Biochemistry, Miami University
(Holme)
Learning chemistry requires students to become fluent in the symbolic language of chemistry. Developing expertise, however, requires that students move beyond manipulating symbols to create explanations using particulate models of matter for observations in the laboratory. Failure to accurately interpret and connect these multiple representations of matter is one source of students’ misconceptions. Our research group designs measurement tools to advance our understanding of how students understand and interpret representations for a variety of core concepts. Creating such measures presents multiple challenges with regard to establishing the precision and accuracy of the data. Insights regarding the underlying assumptions and appropriateness of commonly used psychometrics will be examined. Findings regarding students’ reasoning and misconceptions will be presented with examples drawn from general chemistry, organic chemistry, physical chemistry, and biochemistry courses.
Department of Chemistry, Princeton University
(Stanley)
A general approach by our group for the development of new catalytic synthetic methods that occur with higher efficiency and selectivity, use simpler reagents, and proceed with lower energy demand involves new ancillary ligand design coupled with fundamental studies of how metal-ligand bonding dictates catalytic reactivity. In this context, the presentation will focus on our recent efforts to discover new phosphorus- and sulfur-based ligands and associated metal catalysts that manifest special properties from seemingly "weak" interactions, for instance dispersion. In one case, low-coordinate Pd complexes possessing polarizable diamondoid substituents are shown to enable a new transmetalation mechanism under exceptionally mild conditions, facilitate the first ever characterization and reactivity studies of monoligated Pd(0) – the true active catalyst in modern cross-coupling reactions, and direct visible light-induced bond weakening. Studies of oxidative dehydrogenative coupling reactions will also showcase evidence for a distinct C−H bond activation mechanism that we describe as electrophilic CMD or "eCMD", which has characteristics distinct from the established concerted metalation-deprotonation (CMD) pathway for C−H functionalization. Transition state analyses suggest this reaction pathway could be a general class of C−H activation that to date has been convoluted with CMD, and selection rules have been identified for predicting what catalyst structures manifest either classic CMD or eCMD, each of which occurs with characteristic substrate preferences and selectivity.
Department of Chemistry & Biomolecular Sciences, University of Ottawa
(Rossini)
We report on recent advances from our laboratory in the framework of the following two broad research themes: (i) non-covalent electrophilic interactions studied via solid-state NMR spectroscopy and (ii) dynamics and equivalence from J splittings associated with pairs of quadrupolar nuclei in solids.
The hydrogen bond is widely recognized as a ubiquitous non-covalent interaction. More recently, a number of related interactions, named after the electrophilic site, have taken on increased prominence in chemistry, biochemistry, materials science, and crystal engineering. For example, the halogen bond results from the donation of electrons from a Lewis base (Y) towards the electron-deficient s-hole found on the halogen atom opposite a covalent bond, i.e., R-X…Y. We report on multinuclear powder and single-crystal solid-state magnetic resonance studies of a range of cocrystals and materials featuring halogen bonds, chalcogen bonds, and tetrel bonds [1]. In addition to establishing relationships between the various NMR parameters and the nature of these electrophilic interactions, we also describe a case study focussing on real-time in-situ kinetic monitoring via 31P CP/MAS NMR of mechanochemical halogen bond formation in the NMR rotor [2]. Our most recent work on the catalysis of dynamical processes via halogen bonding, as studied by deuterium NMR will also be discussed.
In the second part of the talk, we describe two-dimensional double-quantum filtered J-resolved solid-state NMR experiments as applied to homonuclear pairs of quadrupolar nuclei. Such experiments provide valuable information on crystallographic symmetry, bond order, electronic structure, and molecular dynamics. Results for 11B-11B and 71Ga-71Ga spin pairs in singly, doubly, and triply-bonded systems will be presented [3,4]. The crucial role of dynamics in the interpretation of the experimental data will be highlighted for a series of synthetically important electron-precise dianionic diboranes featuring two-centre two-electron bonds [5].
References
[1] P. M. J. Szell and D. L. Bryce. (2016) In: Modern Magnetic Resonance, G. Webb, Ed., Springer, Cham. https://doi.org/10.1007/978-3-319-28275-6_92-1
[2] Y. Xu, L. Champion, B. Gabidullin, and D. L. Bryce. Chem Commun., 53, 9930-9933 (2017). http://dx.doi.org/10.1039/C7CC05051H
[3] L. Kobera, S. A. Southern, G. Kumar Rao, D. S. Richeson, and D. L. Bryce. Chem. Eur. J., 22, 9565-9573 (2016). http://dx.doi.org/10.1002/chem.201600999
[4] F. A. Perras, W. C. Ewing, T. Dellermann, J. Böhnke, S. Ullrich, T. Schäfer, H. Braunschweig, and D. L. Bryce. Chem. Sci. 6, 3378-3382 (2015). http://dx.doi.org/10.1039/C5SC00644A
[5] Y. T. A. Wong, J. Landmann, M. Finze, and D. L. Bryce. J. Am. Chem. Soc., 139, 8200-8211 (2017). http://dx.doi.org/10.1021/jacs.7b01783
Yen Nguyen Final Oral - VanVeller Group
Javier Grajeda
Eastman Chemical Company
(Vela)
Department of Chemistry & Biochemistry, The University of Toledo
(Anderson)
Tuberculosis is responsible for 1.5 million deaths each year. This is more than any other infectious disease caused by a single pathogen and no new first-line drugs for TB have entered the clinic in more than 50 years. My group combines structure/function relationship studies on Mycobacterium tuberculosis drug targets with library screening to improve the TB drug pipeline. The complementary tools of X-ray crystallography and enzyme kinetics/inhibition studies form the basis for identifying new TB-active compounds as well as the characterization of known anti-tubercular compounds with ambiguous mechanism-of-action. In particular, our studies have clarified the mechanism-of-action of Isoxyl, Thiacetazone, and Ebselen anti-bacterial activity against M. tuberculosis and shown that covalent modification of cysteine residues on bacterial protein targets is a valuable inhibitory mechanism. This presentation will discuss how we are applying that understanding and building upon those observations to develop second-generation, dual-function covalent inhibitors of mycobacterial mycolyltransferases. Preliminary results suggest that these compounds function synergistically with b-lactams in non-pathogenic mycobacteria and we are working to understand the mechanistic basis of this apparent synergy.
Department of Chemistry, Dartmouth College
(Zhao)
Nature long ago solved problems plaguing contemporary chemists with polydispersity and controlled synthesis at the nanoscale. The blueprint of life, DNAs, are synthesized with high precision with the aid of multiple hydrogen bonding interactions. Our research program aims to develop smart organic and polymeric materials with multivalent hydrogen bonding interactions with functions that are currently beyond our grasp. In this talk, I will be presenting two major projects in our group: (1) developing smart 3D printing materials that change their shapes upon external stimuli; and (2) designing elastic crystalline porous organic frameworks for radioactive iodine removal. I will share my experience of designing smart materials from an organic/materials chemist’s perspective and using 3D printers for education and outreach activities.
Department of Chemistry, Pennsylvania State University
(Kovnir)
Multi-component nanoparticles offer unique opportunities to combine different properties in a single construct, enabling both multi-functionality and the emergence of new synergistic functions. Synthesizing such multi-component nanoparticles requires simultaneous control over size, shape, composition, and structure, as well as interfaces and spatial arrangements. We have been developing two complementary strategies for synthesizing multi-component nanoparticles. The first approach involves heterogeneous seeded growth, where interfaces and asymmetry are introduced by sequentially growing new nanoparticles off of the surfaces of existing nanoparticles. Complex hybrid nanoparticles of a growing number of materials, configurations, and morphologies can now be synthesized. The second approach involves sequential partial cation exchange reactions, where interfaces and asymmetry are introduced by compositional modifications that are made within an existing nanoparticle. A growing library of complex heterostructured metal sulfide nanoparticles can now be rationally designed and then readily synthesized.
Department of Chemistry, Rice University
(VanVeller)
Chemists are fascinated by metalloenzymes and their chemistry. The reactivity and selectivity of enzyme processes would be powerful practical advances if harnessed in designed transition-metal catalysts. But designing enzyme-like catalysts from scratch has proven exceedingly challenging. Substrate selectivity in polyfunctional environments and highly reactive intermediates incompatible with the bulk aqueous media are properties that are typically too complex and challenging to replicate in simplified, designed systems. Our own efforts have taken advantage of diverse concepts, such as molecular recognition, biomimetic assembly, and structure–function relationships to pursue new methods for site-selective chemistry.
The University of Texas at Dallas
(Zaikina)
The discovery and characterization of novel intermetallic compounds is important for broadening the understanding of structure-property relationships of magnetic materials. Our current research interests in superconductivity and unusual magnetism rely heavily on the intimate relationship between structure and physical properties. Likewise, the determination of anisotropic physical properties from high quality single crystals is vital in probing the intrinsic electrical and the competing magnetic interactions to understand the chemistry and physics of these materials. The discovery of novel magnetic and electronic properties in low-dimensional materials has led to the pursuit of hierarchical materials with specific substructures. Low-dimensional solids are highly anisotropic by nature and show promise in new quantum materials leading to exotic physical properties not realized in three dimensional materials. In this talk, I will highlight the crystal growth, characterization, and properties of germanides and stannides and layered antimonides and the potential for compounds in reduced dimensions.
