Studies of Organic Transformations Using Operando Spectroscopy and Computational Chemistry

Alexis Ravenscroft*, Christopher Nau*, Merfat Othman Aljhdli, Anitha S. Gowda, Novruz G. Akhmedov, Kung Wang, Brian V. Popp, Ph.D.
C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV 26506

Presentation Category: Physical Sciences & Engineering (Poster presentation)

Student’s Major: Chemistry

Modern synthetic chemistry development is guided by understanding the specific details of the chemical transformation. The RAP experience has offered opportunities to learn how to use experiment and computation to better understand chemical reactions and structural changes.

Acid-catalyzed esterification reactions were studied using in situ infrared spectroscopy. The impact of sulfuric acid catalyst was assessed by observing reaction progress. Through subsequent data analysis, kinetic parameters and the rate law were determined. A collaboration with the Wang group provided an opportunity to use computational chemistry to understand a new macrocyclic organic molecule prepared in their laboratory. They observed by 1H NMR spectroscopy that the macrocycle composed of two 2,7-dibromophenanthrene (DBPhen) and two dibenzylamine linkages adopted a single stable conformation at room temperature in which the DBPhen units adopt unique, fixed geometries. At higher temperatures (ca. 90°C) the PBPhen units interconvert between the 2 planes freely with observed coalescence of NMR signals. To understand this temperature-dependent behavior, computational studies were performed with Gaussian 19 on the WVU Thorny Flat high-performance computing cluster. Calculations revealed key details that help to explain the temperature dependent behavior, including energetically favored macrocycle conformations and the interconversion reaction pathway (likely and improbable transition states).

Funding: NSF CAREER (BVP) CHE-1752986

Program/mechanism supporting research/creative efforts: WVU's Research Apprenticeship Program (RAP) & accompanying HONR 297-level course