Molecular Orbital Calculations --- and Other Fun Things We Did on Our Summer Vacation
"You learn to be a scientist by doing science, not by studying science." Senior chemistry faculty member Heinz Koch (pronounced "coke") coined that saying some time ago. He and Vincent DeTuri have been busy this past year working to show they still believe it. DeTuri is a Camille and Henry Dreyfus scholar/fellow who in 1999 came to work for two years with Koch. During his initial year DeTuri taught physical chemistry, as well as a new course he designed on computational chemistry. He also supervised the senior honors thesis of Jason Nichols '00, which dealt with ab initio (from scratch) molecular orbital calculations on organic reactions that have long been the topic of Koch's research group.
This all sounds pretty complicated. When asked to synopsize his research for the average nonchemist, Koch says, "Most scientists run experiments to prove theories. They never like to get 'no' answers that disprove their theories. But to me the fun is getting a 'no' answer, because it's a challenge to figure out why. I've been swimming against the stream for decades."
Koch started swimming upstream in the 1960s, when he realized that not much work had been done on the reaction of carbanions with the solvent methanol. He decided to investigate these interactions in the lab with his undergraduates. Instead of the single product he and his students expected, however, there were three. "Yet everything in the literature pointed to one compound," he re-calls. "These unexpected results show that you never prove a mechanism. New experimental data keep coming up with something different. So our initial simple experimentation has taken all these years, because we're still trying to find out what's going on!"
Since Koch's arrival in fall 1965, more than 90 Ithaca College undergraduates have worked with him, investigating how chemical reactions proceed in solution. They've been studying the reactions of a base, methoxide ion, with a carbon acid. The acidic hydrogen of the carbon acid can be exchanged with one of its two isotopes, deuterium and tritium, which can be part of the methanol solvent. The researchers then observe and measure various reactions of the molecules during this proton transfer. Studies on deuterium are made at Ithaca College, but the work using the radioactive tritium is done at the University of Leiden in the Netherlands. Since 1976, 29 IC students have carried out some of their studies at Leiden, and 23 Leiden undergraduates have worked with Koch's research group at Ithaca.
To correctly interpret the experimental data, the researchers need to know the acidity of the carbon compounds. But that had long been impossible, because the compounds decompose under normal solution conditions. This problem could only be overcome if the acidity were measured in the "gas phase" --- a vacuum --- but the College doesn't have the instrumentation necessary to perform such measurements. So in the mid-1990s Koch started a second collaboration, with Kyushu University in Japan, where the equipment is available.
Computational methods are now sophisticated enough --- and desktop PCs fast enough --- to deal with large molecules. These aren't just any old calculations: each one can take 20 to 30 days, even using sophisticated equipment. In 1998 Koch wrote a successful proposal for a grant from the Aldan Trust to fund computers and software that allow IC undergraduates to do high-level calculations and other molecular modeling experiments to complement lab work. Nichols spent that summer at the University of Wageningen in the Netherlands, learning how to do the ab initio molecular orbital calculations needed to model the reactions. The next academic year, Koch attended a workshop by Wavefunction, a company that develops software for molecular modeling. This proved so useful that the chemistry department also sent Nichols and Neal Abrams '00 to attend a workshop. But, says Koch, "we were still not up to speed performing these calculations until Vince DeTuri came. DeTuri has been invaluable, as his doctoral studies in the field of chemical physics included gas-phase experimental work as well as high-level calculations."
With DeTuri's help, Nichols presented a poster on the calculations at last spring's annual meeting of the American Chemical Society. At the same meeting Abrams, who had spent the summer of 1999 working at Leiden, presented a poster that dealt with the related experimental lab work. Six Ithaca College chemistry alumni, all now holders of doctorates from prestigious institutions, were in the audience.
Last summer Koch and DeTuri continued working with undergraduates. Brian Hoyt '02, Brian Jackson'02, Jordan Killeen '03, Marcos Pires '02, and Anne Ruminski '03 participated in research that was supported by departmental funds and a grant from ACS's Petroleum Research Fund. Ruminski says she definitely enjoyed the experience. "I learned a lot that I wouldn't have learned in the classroom. [Professors Koch and DeTuri] build a good environment to work in. They listen to what you have to say and help you understand."
With the help of Abrams and of David Pysnik, a Sidney High School chemistry teacher who has a large mobile lab for chemical analysis he calls the "Sidney Science Express," Koch and DeTuri introduced several high school students last summer to the joys of doing chemistry. Koch had received a Project SEED grant from ACS to support the visit of Sheila Diaz and Smith Kidkarndee, seniors at IC's partner institution the Frederick Douglass Academy in Harlem. Local high school juniors Michael Egan and Tom Jenkins and sophomore Erica Schlesinger also took part in several weeks of analytical chemistry, using both the Sidney Science Express and the IC labs. They enjoyed it so much and did so well that they will probably return this summer, when they have been invited to work with the main research group.
"It All Makes Sense"
This semester DeTuri is teaching a course on instrumental analysis. He is doing high-level calculations with the IC students from the summer and two second-year students: Ryan Adler, who began doing calculations last semester, and Jan Pawlicki, who had done calculations with DeTuri during the second semester of her freshman year. "Dr. DeTuri explains things very well," says Pawlicki. "It all makes sense, the way he puts it together."
"I've had a good time with the students," says DeTuri. "It's also great that Heinz's knowledge and mine complement one another. My strength is in the calculations, and Heinz's is in the synthetic organic chemistry. So I've taught Heinz how to do the calculations, and he's taught me how to schmooze. No, just kidding. He's good at the organic chemistry, which isn't my forte, and he's helping me with that."
"Dr. Koch found me a program in Ulm where I got to work in graduate laboratories," says Will Pomerantz '02, who plans to continue studying organic chemistry in graduate school. "It was a great opportunity." But, he adds, "my favorite thing is doing research with Dr. Koch."