Research originating from the laboratory of Assistant Professor of Chemistry Max Majireck has been published in the journal Molecules. Co-authors on the research article include Jon Shapiro ’17, Justin Sonberg ’18, Ben Schafer ’17, Chris Williams ’17, and Hannah Ferris ’16, Dr. Eric Reinheimer (Rigaku Oxford Diffraction), and Majireck’s former undergraduate advisor Professor Chuck Kriley (Grove City College). The publication is titled “Synthesis, Characterization, and Computational Modeling of N-(1-Ethoxyvinyl)pyridinium Triflates, an Unusual Class of Pyridinium Salts.”
The work describes the discovery of a novel and potentially valuable class of compound known as an N-(1-alkoxyvinyl) pyridinium salt. During the past 80 years, only a few scattered reports have been published on similar types of compounds, but since most were found to be unstable, very little follow-up research has been conducted within this compound class, despite their potential for useful applications as in the synthesis of organic compounds (e.g., antibiotics).
Majireck’s lab initially discovered this new class of compound when attempting to synthesize a natural product with anti-HIV activity. While that specific experiment failed, the group identified an interesting side product in their reaction which ended up being the first example of an N-(1-alkoxyvinyl) pyridinium salt, which was also surprisingly stable. However, it took a while longer to determine the identity of this new compound with absolute certainty.
The Majireck group gathered an extensive set of data using both standard and advanced techniques in nuclear magnetic resonance, infrared spectroscopy, and mass spectrometry. Such information is usually sufficient to identify the structure of a new compound, but Majireck said, “We had to be extra skeptical of our own interpretations of this data, given the unusual nature of the finding and predicted instability of this new compound. And there were some other possibilities that we could not rule out with our data alone.” So, Majireck contacted Kriley for his expertise in x-ray crystallography and Kriley described the structure determined from his x-ray data.
Due to the rarity of this initial finding, Majireck’s lab expanded their research to include other examples of this compound class. They first collaborated with Reinheimer, a professional crystallographer at Rigaku Oxford Diffraction with access to state-of-the art x-ray diffractometers. The high-quality data from this collaboration was instrumental for publishing this research in a peer-reviewed journal, given that it was able to unambiguously prove the structure of this rare compound. Simultaneously, Majireck’s lab optimized a protocol for synthesis of N-(1-alkoxyvinyl) pyridinium salts and expanded the scope of their protocol to multiple compounds having similar structures – all but one was found to be stable.
Despite finding other examples of this new compound class, the question of exactly why these compounds were so stable still puzzled the Majireck team. They then sought the expertise of Prof. Adam Van Wynsberghe, an expert in computational, theoretical, and physical chemistry. By computationally modeling the structure and dynamic nature of these compounds (i.e., how the molecule moves), the research team gained further insight into the chemical behavior and stability of these compounds that could not be obtained otherwise.
Future work by the Majireck lab will focus on finding new uses for N-(1-alkoxyvinyl) pyridinium salts. “As a class, pyridinium salts are actually one of the most widely used type of chemical reagents, or ‘building blocks,’ in organic synthesis,” said Majireck. “However, our compounds bear a structure that is highly unique and multi-functional, which provides numerous possibilities for developing entirely new chemical reactions that are not possible with known pyridinium salts.”
When Majireck’s group presented their preliminary data at the National Meeting of the American Chemical Society, it generated much excitement and interested researchers.