Quang (Mike) Shen

BS, Furman University, 1970; PhD, Oregon State University, 1974

University of Trondheim (Norway), 1975-77; North Dakota State University, 1977-80

General and physical chemistry, instrumental analysis

• Teaching Interests: Physical Chemistry, General Chemistry
• Research Interests: Gas phase electron diffraction, conformational analysis and barriers to internal rotation, vibrational spectroscopy, molecular structure and dynamics

• Shen, Q, Brown, J.W., Richardson, A.D., and Hagen, K.,  "The molecular structure and conformation of trichloronitromethane as determined by gas-phase electron diffraction and theoretical calculations," J. Mol. Struct. 830, 204-207 (2007)
• Shen, Q., Brown, J.W., Malona, J.A.*, Cochran, J.C., and Richardson, A.D., "Molecular structure and conformation of chloronitromethane as determined by gas-phase electron diffraction and theoretical calculations," J. Phys. Chem. A 110, 7491-7495 (2006)
• Q. Shen, and M. Traetteberg, “The Molecular Structure of 2,2,4,4,6,6-Hexamethyl -3,5-trimethylenecyclohexane As Determined by Gas-phase Electron Diffraction” J. Org. Chem., 69, 2094-98 (2004).
• Shen, Q., and Traetteberg, M., “A Reinvestigation of the Molecular Structure of 4,4,8,8,12,12-Hexamethyltrispiro[2,1,2,1,2,1]dodecane” J. Mol. Struct. 657, 185-189 (2003).
• Shen, Q., and Traetteberg, M., “The Molecular Structure of the anti Conformation of Vinylcyclopropane As Determined by Combined Electron Diffraction and Microwave Analysis” J. Mol. Struct.,654, 161-165 (2003).
• Shen, Q., Walker, JP*, Traetteberg, M., “Molecular Structure and Conformation of 2,2 Dichlorocyclopropylbenzene as Determined by Ab Initio Calculations and Gas-Phase Electron Diffraction“ J. Mol. Struct. 648, 75-80( 2003).
• Hagen, K.; Shen, Q.; Carter, R.;* Marion, M.* “Molecular Structure and Conformation of 1,1-Dicholor-2-propanone, CHCl₂–C(=O)–CH₃, as Determined by Gas-Phase Electron Diffraction and ab initio Molecular Orbital Calculations,” J. Phys. Chem. A  106, 4263–4266 (2002).
• Shen, Q., Wells, C.*, Traetteberg , M., Bohn, R.K., Willis, A., and Knee, J., “The Molecular Structure and Conformation of Cyclopropylbenzene as Determined by Ab Initio Molecular Orbital Calculations, Pulsed-Jet Fourier Transform Microwave Spectroscopic and Gas-Phase Electron Diffraction Investigations,” J. Org. Chem. 66, 5840-5845 (2001).
• Bickford, C., and Shen, Q., “Molecular structure and pseudorotational motion of bromocyclopentane as determined by gas-phase electron diffraction,” J. Mol. Struct. 567-568, 269-274 (2001).
• Shen, Q., Kuhns, J.*, Hagen, K., and Richardson, A.D., “The molecular structure of 2-bromostyrene and (E)b-bromostyrene obtained by gas-phase electron diffraction and ab intio molecular orbital calculations,” J. Mol. Struct. 567-568, 73-83 (2001).

Asterisks indicate undergraduate student co-authors who conducted their research in collaboration with a faculty member at Colgate.

NSF, Petroleum Research Foundation and Research Corporation grants

My research interest is in the area of gas phase molecular structure determination. I am interested in the accurate measurement of molecular structures using the technique of electron diffraction which involves the computer analysis of diffraction patterns generated by intersecting a beam of electron with a stream of gaseous sample. The analysis is frequently augmented by ab initio molecular orbital calculations.

My research efforts have been focused in the following areas: a) cyclic compounds with low frequency torsional motions, b) equilibrium conformational compositions of organic compounds and c) sterically congested molecules.

The non-planarity of cyclopentane and substituted cyclopentanes are known to undergo low frequency pseudorotational motion where the puckered atom moved freely about the ring from one position to another. We have found that substituted cyclopentanes underwent pseudorotational motion with a low energy barrier. We are extending this project to other substituted cyclopentanes and cycloheptanes.

Electron diffraction can be used to study both the structure and the conformation composition of the sample. Different conformations give different diffraction patterns which are recorded as data and careful analyses of these data can resolve the structures and the compositions of the conformers. In addition temperature variation of the composition can be used to calculate thermodynamic quantities like entropy and enthalpy differences between the different rotatomers. We have studied systems like allyl halides, substituted acetones and substituted propenes and butenes.

The structural features of sterically congested molecules can provide insight into the nature of chemical bonding when they are compared with the unstrained systems. We have studied the structures of (E) and (Z)1,2,3 trichloropropenes, and (Z) and (E) ß-bromostyrenes and others.

Year in and year out, I've had the opportunity to teach and interact with capable, intelligent, and motivated students. One of the best collaborative learning environments is Colgate's summer research program where students and faculty work side by side in the laboratory collecting and analyzing data, and developing new models to test hypotheses.