Graduate Student Sarah Johnson will present her research to the department.

Abstract:

Although hydrogen fluoride (HF) is a prototypical weak acid, estimates of the point at which proton transfer becomes energetically favorable in binary (HF)_m(H₂O)_n clusters varies widely. For a single HF molecule (i.e. m=1), values at which proton transfer becomes energetically competitive ranges from n=6 to n≥10 depending on the electronic structure methods employed and structures considered. In this work, (HF)_m(H₂O)_n clusters, where m+n≤8, are optimized with resolution-of-the-identity second-order Møller-Plesset perturbation theory (RI-MP2) with a series of Dunning’s correlation consistent basis sets with diffuse functions on non-hydrogen atoms (aug-cc-pVXZ for O and F, cc-pVXZ for H where X=D, T, denoted haXZ). More than 190 unique structures have been identified, and harmonic vibrational frequencies confirm that each one corresponds to a minimum on the potential energy surface (i.e. no imaginary frequencies, n_i=0). For the lowest-lying RI-MP2/haTZ minimum associated with each value of m and n, explicitly-correlated coupled-cluster single point energy computations that include all single and double substitutions as well as a perturbative treatment of connected triple substitutions (CCSD(T)-F12) are used to estimate the relative electronic energies of the species near the complete basis set (CBS) limit. The smallest cluster for which the lowest-energy structure exhibits proton transfer is (HF)₂(H₂O)₄. Most of the proton transfer structures characterized share a common hydrogen bonding topology. Specifically, the proton donor(s) tend to accept two hydrogen bonds, while the proton acceptor(s) tend to donate two hydrogen bonds.

Graduate Student Louis McNamara will present his dissertation research to the department.

Dr. Joshua Sharp (UM Pharmacy) will present “Probing Structure-Function Relationships in Glycobiology by Mass Spectrometry” to the department

Dr. Mark Johnson (Yale University) will present “Capture and characterization of reaction intermediates in homogeneous catalysis” to the department.

Mark A. Johnson is an American physical chemist and a professor of chemistry at Yale University. He received his Ph.D at Stanford University in 1983. Since 2011, Johnson is co-editor-in-chief of Annual Review of Physical Chemistry. He became a Fellow of the American Physical Society in 1999, a Fellow of the American Association for the Advancement of Science in 2005, a Fellow of the American Academy of Arts and Sciences in 2009, and a Fellow of the American Chemical Society in 2010. He received the Alexander von Humboldt Senior Research Award in 2012.

Yusuke Takahashi will present his dissertion research “Synthetic Study of Karlotoxins and Investigation of α-Diaminoboryl Carbanion Chemistry” to the department.

Dr. Hemali Rathnayake (Western Kentucky) will present “Innovative Energy Harvesting Nanostructures, their Assembly, and Performance towards Multi-Junction Device Architecture” to the department.

Abstract: It is essential to develop novel organic-inorganic hybrid materials having both improved optoelectronic and well defined self-assembly properties. To improve the progress of organic-based devices, synthetic methods need to be developed to make well-defined three-dimensional structures with a controlled size and shape in conjunction with delicately organized self-assembly properties. Here I will discuss novel energy harvesting nanostructures derived from organic polymeric systems, organic-inorganic hybrids, metal-organic hybrid systems and their application for multi-junction organic solar cells. This work will contribute to the fundamental knowledge in this discipline by developing better synthetic methodologies, designing novel hybrid nanostructures, and fabricating low-cost, flexible solar panels with new device architecture. An improvement in efficiency is realized by obtaining nanoscale phase separation using these hybrid materials as well as fine-tuning the band gaps of multi-junction active layers.

Brief Bio: Hemali obtained her Ph.D under the supervision of Prof. Paul M. Lahti, UMass Amherst, Department of Chemistry in 2007. Just after she finished her Ph.D, she joined Emrick’s Research group at Polymer Science & Engineering, UMass Amherst for her postdoctoral research experience. During her Postdoctoral period, she has worked on various projects on developing new polymer-nanocomposites and hybrid nanostructures. In July 2009, she joined the Chemistry department at WKU as an Assistant Professor and currently she is an Associate professor and has a strong materials research group which focuses energy harvesting nanostructures for solar cells and thermoelectric devices.

Dr. Kenneth Ray (Celgene Corp.) will present a seminar to the department.

Graduate Student Chen Wang will Present “Aluminum Anodization in Haloaluminate Molten Salts/Ionic Liquids” to the Department.

Abstract:

The anodization of aluminum was examined in the low-melting inorganic molten salt (mp 86 ⁰C), LiAlBr₄-NaAlCl₄-KAlCl₄ (3:5:2) molten salt¹ and the room-temperature ionic liquid, AlCl₃-1-Ethyl-3-methylimidazolium Chloride in an undivided electrochemical cell. In both cases, the primary three-electron anodization reaction

Al + 7AlCl₄^– <–> Al₂Cl₇^– + 3e^–

proceeds under mixed kinetic and mass-transport control at low anodic potentials. At more positive potentials, the anodization reaction transitions to a mass-transport-limited process resulting from the steady-state formation and dissolution of a passive layer of AlCl₃ on the Al electrode surface.² In the LiAlBr₄-NaAlCl₄-KAlCl₄ (3:5:2) molten salt, the heterogeneous rate constant at the equilibrium potential, k⁰, was found to 6.6 x 10^-7 cm s^-1 at 151 ^◦C. However, k⁰ cannot be measured directly in the room-temperature IL, as a result of the back reaction associated with the reducible Al³⁺ (Al₂Cl₇^–). However, it is possible to measure the exchange current density, j_o, by using the classical Tafel analysis based on the Butler-Volmer kinetic approach.³ The apparent activation energies of the reaction shown above are similar in the two molten salts/ionic liquids examined in this research, indicating that the electrode reactions in these two different ionic solvents may be similar.

References:

1) H. A. Hjuler, S. von Winbush, R. W. Berg, and N. J. Bjerrum, J. Electrochem. Soc., 136, 901 (1989).

2.) G. L. Holleck and J. Giner, J. Electrochem. Soc., 119, 1161 (1972)

3.) A. J. Bard, L. R. Faulkner, Electrochemical Methods: Fundamentals and Applications, New York: Wiley, 2000.

Graduate Student Divya Nallamothu will Present a Seminar to the Department.

Dr. Richard Cole (University of New Orleans) will present a seminar to the department