Dalia Biswas
Associate Professor of Chemistry, Chair of Chemistry
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Hall of Science 338
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509-527-5953 (phone)509-527-5904 (fax)
Associate Professor of Chemistry Dalia Biswas joined the Chemistry department at Whitman as a tenure-track assistant professor in the fall of 2011, following her role as a visiting professor during the 2010-11 academic year. Before her tenure at Whitman, Biswas conducted postdoctoral research in bioinorganic chemistry with Professors David Dooley and Robert Szilagyi at Montana State University. She earned her Ph.D. in inorganic chemistry from The University of Montana under the supervision of Professor Edward Rosenberg.
Biswas's academic journey began in Bangladesh, where she obtained a B.Sc. honors degree in chemistry from Jahangirnagar University in Dhaka. Her path from a small southwestern town in Bangladesh to prestigious academic institutions in the US exemplifies her dedication and passion for chemistry.
Currently, Biswas's research focuses on data chemistry and computational chemistry. Her projects involve computational modeling of the active sites of various molybdenum enzymes, such as CO dehydrogenase and sulfite oxidases. These enzymes are crucial in the global nitrogen, carbon, and oxygen cycles, as they transfer oxygen atoms between substrates and split water molecules. This research has the potential to revolutionize our understanding of energy production and aid in the design of catalysts for similar chemical transformations. In 2023, Biswas became a Data Chemist Network (DCN) affiliate with the NSF Center for Computer-Assisted Synthesis, contributing to various data chemistry projects within the center's scope.
At Whitman, Biswas teaches a wide range of courses, including General Chemistry Lecture and Lab, Advanced General Chemistry, Organic Laboratory Techniques, Computational Chemistry, and Biochemistry. Her vision of integrating computational chemistry into the chemistry curriculum has been successful. With the support of her colleagues, she led the design of the state-of-the-art Wilke Family Computational Lab, benefiting many students across various science disciplines.
Courses
- General Chemistry I (CHEM 125) & II (CHEM 126) Lecture
- General Chemistry I (CHEM 135) and II (CHEM 136) Lab
- Advanced General Chemistry Lecture and Lab (CHEM 140)
- Organic Lab Techniques I (CHEM 251) & II (CHEM 252)
- Computational Chemistry (CHEM 275)
- Inorganic Chemistry (CHEM 360)
- Advanced Synthesis (CHEM 370)
- Biochemistry (BBMB 325)
- Chemistry Seminar (CHEM 401 & CHEM 402)
- Computational Biochemistry (CHEM 425)
Education
Ph.D Inorganic Chemistry
The University of Montana
2005
B.Sc. Chemistry Honors
Jahangirnagar University, Dhaka, Bangladesh
1998
Awards
Suzanne L. Martin Award for Excellence in Mentoring, Whitman College, 2017-2018.
Outstanding Foreign Student Award, The University of Montana, Missoula, MT, 2005.
Diversity Student Achievement Award, The University of Montana, Missoula, MT, 2005.
Bertha Morton Scholarship for outstanding graduate student, The University of Montana, Missoula, MT, 2002.
Lola Walsh Anacker Scholarship for outstanding female graduate student, Department of Chemistry, The University of Montana, Missoula, MT, 2002.
Computational Simulations & Biomimetic Models
Biogeochemical carbon, nitrogen, water, and sulfur cycles are important in many aspects of our life. During these complex cycles, small molecules (such as CO2, CO, N2, and H2) are made more reactive at ambient temperatures and pressures. The enzymes involved generally contain complex inorganic active sites and understanding the activation of inert molecules by these sites is still one of the most challenging areas at the interface of chemistry and biology. Studying this active site should significantly enhance our understanding of how biological systems achieve high reaction rates, exquisite selectivity, and chemically challenging transformations under ambient conditions. Understanding how nature works so efficiently can have implications for developing future environmentally friendly “green” catalysts.
Professor Biswas' research interest is to investigate the molybdenum-catalyzed transformation of CO, which is an intermediate in the carbon cycle. Aerobic and anaerobic microorganisms catalyze the conversion of toxic carbon monoxide to less-toxic carbon dioxide, and play an important role in the regulation of atmospheric CO levels by removing an estimated 108 tons of CO from the atmosphere annually. More importantly, CO transformation is unique in the sense that it utilizes acid-base and redox reactions, and also involves the splitting of a water molecule during the catalytic cycle to generate two electrons and two protons. The two protons and electrons produced in the reaction can be utilized to generate hydrogen gas, an alternative fuel source. This is an extremely challenging transformation, and many researchers are actively investigating the viability of this process. Activation of CO occurs at a binuclear Mo-Cu center in carbon monoxide dehydrogenase (shown in Figure).
Mo is coordinated to the dithiolate of the molybdopterin-cytosine dinucleotide (MCD) cofactor with two oxo and sulfido ligands. The catalytically active state has been characterized structurally and is believed to be the oxidized form, Mo VI-Cu I. CO is proposed to bind at the active site pocket of the oxidized state between the Mo and the Cu atom, and interacts with the bridging sulfur. During the catalytic cycle, CO is oxidized while Mo is reduced from a +6 to +4 oxidation state while the Cu remains at a +1 oxidation state. Structural and spectroscopic data are in agreement as to the geometric environment around the Mo-Cu center; however, they significantly differ in regards to several key bond distances. These distance anomalies could be due to radiation damage during X-ray data collection and/or the different physical states of the enzyme. Furthermore, electronic communication between the Mo-Cu center in CODH appears to be critical because the enzyme is non-functional in the absence of Cu. A linear Cu concentration dependence on specific activities has been reported, which suggests that the redox inactive Cu center plays a critical role in enzyme functionality.
Here are some of the specific research questions that are being explored in the Biswas laboratory:
- How does the protein environment tune the active site in biological CO conversion?
- What is the significance of the redox inactive yet obligatory Cu center in CODH?
- What is the molecular mechanism of CO to CO2 conversion?
- What are the key design parameters for creating improved synthetic models that mimic the CODH active site?
Current Projects
The Biswas Lab is employing quantum mechanical calculation to find structurally and theoretically converged computational models for the active and intermediate states of CODH which will assist in addressing the first three questions specified above. Knowledge from the computational studies will be utilized to design and synthesize model complexes of this enzyme that have potential promise in environmental and industrial applications for cleaner energy.
Computational Resources
Cowley, R.E.; Cirera, J.; Qayyum, M. F.; Rokhsana, D.; Hedman, B.; Hodgson, K. O.; Dooley, D.M.; Solomon, E. I. Structure of the Reduced Copper Active Site in Pre-Processed Galactose Oxidase: Ligand Tuning for One-Electron O2 Activation in Cofactor Biogenesis, Journal of American Chemical Society, 2016, 138 (40), 13219-13229 (DOI: 10.1021/jacs.6b05792)
Rokhsana, D.; Large, T.; Dienst, M.; Retegan, M., Neese, F. A realistic in silico model for structure/function studies of molybdenum-copper CO dehydrogenase, Journal of Biological Inorganic Chemistry, 2016, 21(4), 491-499 (DOI: 10.1007/s00775-016-1359-6)
Schofield, J. A., Brennessel, W. W., Urnezius, E., Rokhsana, D., Boshart, M. D., Juers, D. H., Holland, P. L. and Machonkin, T. E. (2015), Metal–Halogen Secondary Bonding in a 2,5-Dichlorohydroquinonate Cobalt(II) Complex: Insight into Substrate Coordination in the Chlorohydroquinone Dioxygenase PcpA. European Journal of Inorganic Chemistry, 2015: 4643–4647.
Machonkin, T. E.; Boshart, M. D.; Schofield, J. A.; Rodriguez, M. M.; Grubel, K.; Rokhsana, D.; Brennessel, W. W.; Holland, P. L. Structural and Spectroscopic Characterization of Iron(II), Cobalt(II), and Nickel(II) Ortho-Dihalophenolate Complexes: Insights into Metal-Halogen Secondary Bonding, Inorganic Chemistry, (2014), 53(18), 9837-9848.
Rokhsana, D.; Howells A. E,; Dooley D.M.; Szilagyi, R. K. “The Role of the Tyr-Cys Crosslink to the active site properties of galactose oxidase” Inorganic Chemistry, 2012, 51(6), 3513-3512.
Rokhsana, D.; Shepard, E. M.; Brown, D. E.; Dooley, D. M. (2011) Amine Oxidase and Galactose Oxidase, in Copper-Oxygen Chemistry (eds K. D. Karlin and S. Itoh), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9781118094365.ch3
Begum, N.; Hyder, M.L.; Hassan, M. R.; Kabir, S. E.; Bennett, D. W.; Haworth, D. T.; Siddiquee, T. A.; Rokhsana, D.; Sharmin, A.; Rosenberg, E. “ Facile E-E and E-C bond activation of PhEEPh (E = Te, Se, S) by ruthenium carbonyl clusters: Formation of Di- and triruthenium complexes bearing bridging dppm and phenylchalcogenide and capping chalcogenido ligands” Organometallics, 2008, 27, 1550-1560.
Rokhsana, D.; Dooley, D. M.; Szilagyi, R. K . “Systematic development of computational models for the catalytic site in galactose oxidase: impact of outer-sphere residues on the geometric and electronic structures” Journal of Biological Inorganic Chemistry,2008, 13, 371-383
Rokhsana, D.; Dooley, D. M.; Szilagyi, R. K. “Structure of the oxidized active site of galactose oxidase from realistic in silico models” Journal of the American Chemical Society, 2006, 128(49), 15550-15551.
Begum, N.; Hyder, Md. I.; Kabir, S. E.; Hossain, G. M. G.; Nordlander, E.; Rokhsana, D.; Rosenberg, E. “ Dithiolate complexes of manganese and rhenium: X-ray structure and properties of an unusual mixed valence cluster Mn 3(CO) 6(m-h 2-SCH 2CH 2CH 2S) 3” Inorganic Chemistry, 2005, 44(26), 9887-9894.
Mottalib, Md. A; Begum, N.; Abedin, S. M. T.; Akter, T.; Kabir, S. E.; Miah, Md. A. Rokhsana, D.; Rosenberg, E.; Hossain, G. M. G.; Hardcastle, K. I. “Reactions of electron-deficient triosmium clusters with diazomethane: electrochemical properties and computational studies of charge distribution” Organometallics, 2005, 24(20), 4747-4759.
Kabir, S. E.; Miah, Md. A.; Sarker, N. C.; Hossain, G. M. G.; Hardcastle, K. I.; Rokhsana, D.; Rosenberg, E. “Reactions of the unsaturated triosmium cluster [(μ-H) Os 3(CO) 8 (Ph 2PCH 2P(Ph)C 6H 4)] with HX (X = Cl, Br, F, CF 3CO 2,CH 3CO 2): X ray structures of [(μ-H)Os 3 (CO) 7(η 1-Cl)( μ -Cl) 2(μ -dppm)], [(μ-H) 2Os 3(CO) 8(Ph 2PCH 2P(Ph)C 6H 4)] +[CF 3O] - and the two isomers of [(μ-H)Os 3(CO) 8(μ-Cl)(μ-dppm)]” Journal of Organometallic Chemistry, 2005, 690, 3044-3053.
Begum, N.; Deeming, A.; Islam, M.; Kabir, S.; Rokhsana, D.; Rosenberg, E. “Reactions of benzothiazolide triosmium clusters with tetramethylthiourea” Journal of Organometallic Chemistry, 2004, 689(16), 2633-2640.
Nervi, C.; Gobetto, R.; Milone, L.; Viale, A.; Rosenberg, E.; Spada, F.; Rokhsana, D.; Fiedler, J. “Solution properties, electrochemical behavior and protein interactions of water soluble triosmium carbonyl clusters” Journal of Organometallic Chemistry, 2004, 689(10), 1796-1805
Rosenberg, E.; Rokhsana, D.; Nervi, C.; Gobetto, R.; Milone, L.; Viale, A.; Fiedler, J.; Botavina, M. A. “Synthesis, reduction chemistry, and spectroscopic and computational studies of isomeric quinoline carboxaldehyde triosmium clusters” Organometallics, 2004, 23(2), 215-223
Nervi, C.; Gobetto, R.; Milone, L.; Viale, A.; Rosenberg, E.; Rokhsana, D.; Fiedler, J. “Spectroscopic and computational investigations of stable radical anions of triosmium benzoheterocycle clusters” Chemistry-A European Journal, 2003, 9(23), 5749-5756.
Rosenberg, E.; Abedin, M. J.; Rokhsana, D.; Viale, A.; Dastru', W.; Gobetto, R.; Milone, L.; Hardcastle, K . “Ligand dependent structural changes in the acid-base chemistry of electron deficient benzoheterocycle triosmium clusters” Inorganic Chimica Acta, 2002, 334, 343-354
Rosenberg, E.; Abedin, M. J.; Rokhsana, D.;Osella, D.; Milone, L.; Nervi, C.; Fiedler, J. “ The electrochemical behavior of electron deficient benzoheterocycle triosmium clusters” Inorganic Chimica Acta, 2000, 300-302, 769-777