Electron Affinity Equilibrium Studies of Synthesized N 1-and N 2-Phenyl-1,2,3-Triazole Isomers through Potassium Metal Reduction

Substituted 1,2,3-triazoles have displayed use as effective agents in numerous pharmaceuticals. Specifically, compounds containing substituents at the N1 and N2 position have shown promise as antifungal and anticancer agents. The medicinal potential of these compounds can be derived from their structural stability, polarity, and ability to hydrogen bond to macromolecules. Numerous studies have investigated the electronic and chemical properties of the unique -system of these triazoles, yet few have studied them upon the addition of an electron.Our previous work involving low temperature EPR studies of N1- and N2-alkyltriazole anion radicals reveal that much of the electron spin density resides within the N3 moiety of the triazole ring. Given the importance and application of both isomers, a comparison of the electron affinity of these anion radicals is desired. For the N1- and N2-alkyl triazoles, this was not possible due to the short lifetime of the N1-alkyl anion radical species. Phenyl substituted triazoles are expected to exhibit greater stability as anion radicals since the unpaired electron can delocalize throughout the -system. As such, the difference in electron affinity of both N1 and N2-Phenyltriazoles is of interest to us. N1 and N2-Phenyltriazoles were successfully synthesized using methods developed by Patterson et al. (2020) and Chen et al. (2020), respectively. The low-temperature potassium metal reductions were performed in THF, and stable anion radicals of each were generated. EPR spectra have been successfully obtained and simulated, and the hyperfine coupling constants (hfccs) were carefully measured for the individual anion radical species and assigned with the support of DFT calculations. Our results indicate a majority of the spin density resides on the N1 and N3 atoms in the N2-phenyltriazole species, while most spin resides on the N2 atom in the N1- isomer. Reduction experiments on mixtures of the two species in the presence of a deficient number of electrons we performed to determine an equilibrium constant for the relative electron affinity of the two isomers. Through numerous reduction experiments on predetermined ratios of the N1- and N2-isomers, the results reveal a significantly higher affinity for the N2-isomer