Source Newsroom: Indiana State University
Nov. 6, 2015 - Two Indiana State University undergraduates will present their research findings about how molecules interact at a national conference this spring.
One might recall from science classes that particles of the same charge, such as two negatives or two positives, repel each other and that particles of opposite charge attract. “Electrostatics” describes this idea.
Students Rebecca Rudisell and Patrick Cheek, under the guidance of Eric Glendening, chair of the physics and chemistry department, examined a class of like-charged compounds held together by hydrogen bonds — anti-electrostatic hydrogen bonds — that defy this well-known rule.
“Hydrogen bonds are extremely important, because our proteins, our DNA — it’s all held together by these strange interactions called hydrogen bonds,” Glendening said. “What we find in these anti-electrostatic hydrogen bonding systems is that pairs of molecules that have the same charge nevertheless stick together, and they stick together because of these hydrogen bonds. And so, there’s maybe something a little more special to hydrogen bonds than what has been known before.”
This special ability of hydrogen bonds recently caused a controversy in the scientific community when researchers from the University of Wisconsin and England published the article “Anti-electrostatic Hydrogen Bonds.” The controversy highlights the capacity of current chemical models to account for this phenomenon, which may occur in water when larger, oppositely charged molecules come in contact, Glendening said.
“The problem is that some models that chemists use would never be able to predict that something like this could form in water and that is, to some extent, where the debate is,” Glendening said. “We want models that are very accurate, but how do we develop those models?”
Glendening, Rudisell and Cheek wanted to gain insight into the controversy. The students completed their study as part of Indiana State’s Summer Undergraduate Research Experience (SURE) program. They presented their findings, “The Nature of the Anti-Electrostatic Hydrogen Bond,” at the Center for Student Research and Creativity’s Fall Exposium on Oct. 8.
The students used quantum mechanical models to make predictions about the chemical systems, forgoing the crude chemical models that were currently in use for simulating proteins and DNA. Developing models is common in chemistry and physics to study concepts that cannot be directly observed. As best as Glendening is aware, the anti-electrostatic hydrogen bond systems have not been observed previously in the laboratory — but calculations suggest that they can exist.
“When students have a research experience, they are really doing science,” Glendening said. “Research has been published on (anti-electrostatic hydrogen bonding), but nothing like we’ve done here. Rebecca and Patrick know something now about these systems that most chemists out there are not aware of. They learned something from their effort that contributes to the overall knowledge that we have about chemical systems. Ultimately, that’s the best part of engaging students in research activity.”
Rudisell, a sophomore history major from Harmony who is minoring in science, said she values the hands-on learning and increased understanding of chemistry, as well as the indirect benefits of the experience.
“It was interesting, and because of the knowledge I gained, I feel like I can understand my chemistry classes easier,” said Rudisell, who is completing pre-requisites for veterinary medicine. “Presenting the research during (SURE’s) weekly meetings got me used to talking in front of people.”
Learning to use this technology was a valuable addition to the students’ skills.
“(It’s) sometimes hard to understand what you are really plugging in and especially the results you are receiving,” Cheek said. “You really must know how to interpret your data, whether it is computational or physical. If you don’t know what your data means then you really have nothing — that was certainly a big takeaway from the research.”
Cheek, a senior from Franklin double-majoring in biology and chemistry with a concentration in biochemistry, also vouched for the benefits of exploring the subject matter.
“I learned so much in so little time, and it was cool to think that (we) were working and focusing on something that is not fully understood,” Cheek said. “Especially towards the end, I was really able to understand what it is like to perform research and be able to push the bounds of that research and provoke questions and ideas and even test those theories and ideas.”
Rudisell and Cheek will travel to San Diego during spring break to attend the National American Chemical Society Meeting, presenting their research in an undergraduate session. More than 12,000 chemists from around the world will attend this meeting.