Tanski Research Group
The research being pursued by the Tanski group is generally in the field of transition metal coordination chemistry. Research projects are available for interested students in several fields, including asymmetric catalysis, extended structure coordination chemistry, inorganic medicinal chemistry, and X-ray crystallography. We also perform electronic structure calculations, using DFT methods with Jaguar 6.0, at the IBM Linux64 cluster at Vassar College's Scientific Visualization Laboratory (Sci Vis Lab.)
Undergraduate students at any level may receive credit or workstudy pay for time spent on research projects. See the bottom of this page for information on students currently working in the Tanski lab.
Major Research Projects:
1. Asymmetric Lewis Acid Catalysis
Multiple asymmetric induction in homogeneous catalysis by metal coordination complexes with various different combinations of chiral ligands is an attractive approach to enhancing enantioselectivity in existing catalytic processes. A specific example of such an application is the methylation of aryl aldehydes with dimethyl zinc catalyzed by Lewis acidic metal coordination complexes of chiral alkoxides and a chiral chelating ligand, L*.
In contrast to the more well studied and optimized process of ethylation with diethyl zinc, methylation results in significantly lower enantiomeric excess. We have recently shown that it is possible to modestly increase the enantiomeric excess of 1-phenylethanol obtained from the methylation of benzaldehyde by dichiral double asymmetric induction with a titanium(IV) complex of commercially available BINOL (BINOL = 1,1’-bi-2-naphthol) and the resolved chiral sec-butoxides Ti(OR-2Bu)4 or Ti(OS-2Bu)4. (MacMillan, S. N.; Ludford, K. T.; Tanski, J.M. Tetrahedron: Asymmetry 2008, 19, 543–548.) The simple resolved titanium sec-butoxides, combined with resolved BINOL of the opposite configuration designation, yielded a matched pair that mediates the addition of dimethyl zinc to benzaldehyde (>99% conversion) with higher enantioselectivity (~58%) than resolved BINOL with Ti(OiPr)4 (~46%) or the mismatched pair (~40%). In ongoing work, we are expanding the scope of the project to other chiral chelating ligands such as tetrahydrosalen and bis(phosphine oxides), and to highly Lewis acidic rare earth metals.
2. Covalent Metal Organic Networks
Metal-organic coordination network (MOCN) materials formed from rigid organic spacers and metals of known coordination tendencies have become increasingly well studied. Materials with large pores present possibilities for:
- molecular recognition,
- separation, and
- catalytic transformations
of guest molecules. In addition, chiral nanoporous materials are an emerging area of research in this field. The vast majority of networks are formed from later transition metals and rigid carboxylate or pyridine based organic spacer ligands. A key feature of MOCN materials is that considerable structural predictive ability exists over traditional solid-state inorganic compounds in their design.
We have been studying a unique class of early transition metal covalent metal-aryloxide coordination polymers synthesized from bisphenolic spacer precursors and titanium(IV) alkoxides.Depending on the nature and geometry of the precursor and the donating ability of the solvent used in the reaction, network structures of diverse dimensionality and topology may be obtained. The reaction of 4,4’-bis(hydroxyphenyl)sulfide with Ti(OiPr)4 yields three different network materials depending on the solvent below
3. X-ray Crystallography
Students work with Dr. Tanski, and other faculty members, to determine the crystal and molecular structures of compounds produced in our laboratories here at Vassar and also those from labs of our collaborators in academia and industry.
Vassar has a state-of-the-art Bruker SMART APEX2 X-ray diffractometer.
Bruker SMART APEX2 X-ray diffractometer
Laboratory:
A new laboratory with equipment for the synthesis of air and water sensitive inorganic and organometallic compounds was commissioned in the summer of 2003 in Mudd 102 center. The lab is fully equipped with 2 4-port vacuum/inert gas lines and a glovebox. Reactions are carried out using both Schlenk and swivel-frit techniques.
Vacuum Lines
Glovebox
From left: Grace Tan (Biochemistry '09), Marina Hitosugi-Levesque (Biochemistry '09), Christine Jung (Biology '09), William Jobs (Chemistry '10), Tamila Shalumova (Chemistry '11)
Tanski Research Group (2006-07)
From left: Caitlin Lim (Chemistry '07), Mike Zubrow (Biology '07), Andre Dennis (Chemistry '06), Kaysia Ludford (Chemistry '07) and Sam MacMillan (Chemistry '07)
URSI 2009
From left: Leslie Roteta (Chemistry '10) and Tamila I. Shalumova (Chemistry '11)
URSI 2008
From left: Greg Maier (Chemistry '09), Grace Tan (Biochemistry '09), Gabrielle Phillip (Biochemistry '09), Tamila Shalumova (Chemistry '11)
URSI 2007
photo credit: Walter Garschagen
Grace Tan (Biochemistry '09)and Marina Hitosugi-Levesque (Biochemistry '09)
URSI 2006
Kaysia Ludford (Chemistry '07)
URSI 2005
Kaysia Ludford (Chemistry '07) and Andre Dennis (Chemistry '06)
URSI 2004
photo credit: Walter Garschagen
Andre Dennis (Chemistry '06) and Donnele Daley (Physics '06)
Former student researchers:
Class of 2004:
1. Christine M. Phillips, graduate student in biochemistry with Prof. Drennan at MIT.
Class of 2006:
2. Donnele Daly, Vassar physics major in The Dual Degree Program with Dartmouth University’s Thayer School of Engineering, MD program at Penn State College of Medicine.
3. Andre Dennis, graduate student in inorganic chemistry with Prof. Eichhorn at the University of Maryland, College Park.
4. Michael Zubrow, MD program at SUNY Stonybrook.
Class of 2007:
5. Caitlin F. Lim, M.S. in biomedical sciences, 2008, Boston University.
6. Kaysia T. Ludford, graduate student in biochemistry with Prof. Carroll at the University of Michigan.
7. Samantha N. MacMillan, graduate student in inorganic chemistry with Prof. Peters at MIT.
8. Philipose Mulugeta, MD program at Vanderbilt University School of Medicine.
Christine Phillips (Chemistry '04) and Samantha MacMillan (Chemistry '07), now at the Chemistry graduate program at MIT