MOLECULAR STRUCTURES OF DEUTERATED ISOTOPOLOGUES OF 2-AMINOPYRIDINE AND MICROWAVE SPECTROMETER DEVELOPMENT

Abstract

This project had two main goals: develop a program to run a microwave spectrometer and use the technique of microwave spectroscopy to determine the molecular structure of three deuterated isotopologues of 2-aminopyridine. The first goal was achieved by using LabVIEW 2019 SP1 software to develop a program that allows for manual and automated measurements of rotational transitions. To achieve the second goal, the isotopologues of 2-aminopyridine were first synthesized via deuterium substitution of the parent molecule. High-level calculations using ab initio and density functional theory (DFT) methods and various basis sets were performed to predict rotational constants, quadrupole coupling constants, and frequencies of rotational transitions. Transitions were measured in the region of 4.4-10.9 GHz for each of the isotopologues of 2-aminopyridine, with both a and b-type transitions detected for two isotopologues. Measured rotational transitions were fit to a rigid asymmetric rotor for the isotopologues to determine experimental values of rotational constants of the molecule and quadrupole coupling constants for the 14N and 2H atoms within each isotopologue. The findings of this molecular study will be used to investigate the rotational structure of hydrogen-bonded complexes of 2-aminopyridine with small organic molecules. The spectrometer program will be used to measure rotational transitions for various other molecules and complexes.