Dr. Eugenia Kharlampieva (University of Alabama Birmingham) will present a seminar to the department.

Dr. Xiaohua Huang (University of Memphis) will present a seminar to the department.

Dr. Jennifer Andrews (University of Florida) will present a seminar to the department.

Dr. Adel ElSohly will present “New Materials Empowered by Efficient Oxidative Coupling Reactions” to the department.

Dr. Michael Danquah (Chicago State) will present “Carbonate based Polymeric Nanomedicines for Treating Cancer” to the department.

Dr. Michael Findlater (Texas Tech) will present “Iron-Catalyzed Hydrosilylation of Aldehydes and Ketones” to the department

Dr. Emily Penzter (Case Western) will present “Tailoring Materials Properties using Synthetic Chemistry: Janus Graphene Oxide Nanosheets” to the department.

Graduate Student Aron Huckaba will Present his Dissertation Seminar to the Department

Abstract:
One of the most important questions humanity will face in the next 100 years is going to be “What will happen when oil runs out?” This dissertation defense describes efforts to utilize solar energy to improve renewable energy technology in two ways to generate electricity and synthetic fuels. First, through the improvement of dye sensitized solar cells1 by the synthesis of sensitizers with indolizine donor subunits, which was shown to be the strongest reported donor subunit,2 the development of indolizine dyes substituted with non-conjugated surface blocking groups, and the improvement of indolizine dye visible light absorption. Second, this defense describes efforts to close the carbon cycle through utilization of solar energy in the photocatalytic reduction of CO2.3 The  described efforts regard the improvement of known Re-tricrbaonyl-bipyridyl catalysts through pyridyl substitution with N-heterocyclic carbene (NHC) ligands, which resulted in complexes with increased stability to air and moisture.4 The Re-NHC catalysts are just the fourth series of photocatalysts known to reduce CO2 without a photosensitizer.

References:
(1) (a): Hagfeldt, A.; Boschloo, G.; Sun, L.; Kloo, L.; Pettersson, H. Chem. Rev. 2010,
110, 6595. (b): Urbani, M.; Grätzel, M.; Nazeeruddin, M. K.; Torres, T. Chem.
Rev. 2014, 114, 12330.
(2) Huckaba, A. J.; Giordano, F.; McNamara, L. E.; Dreux, K. M.; Hammer, N. I.;
Tschumper, G. S.; Zakeeruddin, S. M.; Grätzel, M.; Nazeeruddin, M. K.; Delcamp,
J. H. Adv. Energy Mater. 2014, Early View, DOI: 10.1002/aenm.201401629.
(3) (a): Benson, E. E.; Kubiak, C. P.; Sathrum, A. J.; Smieja, J. M. Chem. Soc. Rev.
2009, 38, 89. (b): Schneider, J.; Jia, H.; Muckerman, J. T.; Fujita E. Chem. Soc.
Rev. 2012, 41, 2036-2051.
(4) (a): Hawecker, J.; Lehn, J.-M.; Ziessel, R. J. Chem. Soc. Chem. Commun. 1983,
536. (b): Vaughan, J. G.; Reid, B. L.; Wright, P. J.; Ramchandani, S.; Skelton, B.
W.; Raiteri, P.; Muzzioli,

Graduate Student Derek Bussan will Present “Mercury Methylation Potentials in Wetland Sediments Using Species-Specific Isotope Dilution-GC-ICP-MS” to the Department.

Abstract:

Mercury (Hg) is a global pollutant that can affect both human and ecological systems. Recognizing this, >100 nations, including the U.S., signed the Minamata Treaty in 2013 to reduce Hg emissions. Hg is dispersed globally through the atmosphere and deposits to terrestrial and aquatic ecosystems, where it can be converted to methylmercury (MeHg).¹ Wetland sediments are of particular interest because they are known to be “hot-spots” for Hg methylation. Humans are exposed to MeHg through consumption of fish and shellfish. MeHg is capable of crossing the blood brain- and placental- barriers, and exposure in-utero has been linked to subtle developmental deficits.² In the present study we used species-specific enriched isotope tracers to, for the first time, to investigate Hg transformations in an old growth cypress wetland located at Sky Lake in the Mississippi Delta.  Methylation rates increased with temperature from ~1% day^-1 in the winter to ~5% day^-1 in the summer. Methylation rates generally were higher in open water areas compared to the swamp. We also developed a novel analytical technique for the direct analysis of Hg in environmental solids by ICP-MS.³ This method utilized a direct mercury analyzer (DMA) based on sample combustion, preconcentration by amalgamation with gold, and atomic absorption spectrophotometry to introduce Hg to a sector field ICP-MS. The combined system (DMA-ICP-MS) was optimized and evaluated for the determination of Hg in environmental samples using both external calibration and isotope dilution for quantitation. The method was validated using certified reference materials, including sediment, leaves, and fish-muscle tissue. The limit of detection was ~0.37 pg, about two orders of magnitude lower than the DMA system alone. Precision was generally <7% relative standard deviation, and total analyses time per sample was <8 min. The DMA-ICP-MS system has several advantages over both the DMA alone and conventional cold-vapor AAS for the determination of mercury, including increased sensitivity, lower detection limits, decreased potential for sample contamination, and applicability to Hg stable isotope tracer studies. Finally, the effects of biochar and activated carbon on Hg methylation rates were evaluated.

1. N. Pirrone, et al., Atmospheric Chemistry and Physics, 2010, 10, 5951-5964.
2. L. E. Davis, et al., Annals of neurology, 1994, 35, 680-688.
3. D. Bussan, R. Sessums, J. Cizdziel, Journal of Analytical Atomic Spectroscopy, 2015, DOI: 10.1039/C5JA00087D

Graduate Student Asantha Dharmaratne will Present “Effective Tuning of Bimetallic Composition of Gold-Copper Nanomolecules” to the Department.

Abstract:

The elemental composition of the nanomaterial or the nanoalloy plays a vital role toward the applications of future nano devices. The introduction of a foreign metallic atom into a parent nanomolecule would enhance the properties including electronic, optical, and catalytic. During a technologically advanced era, such modified nanomolecules will have a crucial impact on catalysts, sensors, and energy sources.^1,2 Here we report a one-phase synthesis of 144-atom gold copper bimetallic nanoalloys for the first time. The mass spectrometric investigation reveals a possible incorporation of copper atoms interdispersed in the inner-core of the proposed Au₁₄₄(SR)₆₀ nanomolecule.^3,4

References

(1) Ruiz, A.; Arbiol, J.; Cirera, A.; Cornet, A.; Morante, J. R. Materials Science and Engineering: C  2002, 19, 105.

(2) Yacamán, M. J.; Ascencio, J. A.; Tehuacanero, S.; Marín, M. Topics in Catalysis 2002, 18, 167.

(3) Dharmaratne, A. C.; Dass, A. Chemical communications 2014, 50, 1722.

(4)  Olga Lopez-Acevedo, J. A., Robert L. Whetten, Henrik Grönbeck, and Hannu Häkkinen j. phys.  Chem. C 2009, 113, 5035.

Figure 1. Expanded view of the 2+ of ESI-MS data. The average number of Au and Cu atoms is denoted above each peak envelope.