Mechanistic Insights into UV Spectral Changes of Pyruvic Acid and Pyruvate Part 1: Interaction with Water Molecules

Abstract

We investigate how the UV spectra of pyruvic acid (PA) and pyruvate are impacted by interactions with water molecules. In particular, we would like to understand the mechanistic origin of the blue shift in the n →− π∗ transition. Pyruvic acid is the simplest α-keto organic acid and is common in the environment. We use density functional theory to optimize geometries to determine excitation energies and find that the excitation energies of the two main pyruvic acid conformers and pyruvate blue shift when interacting with 1 to 4 water molecules, both in vacuo and in a solvent. The excitation wavelength is blue-shifted by 0.9-9.2 nm when adding water molecules to the lowest energy conformer of PA. Calculations of the UV spectra of pyruvic acid (PA) and pyruvate are crucial for understanding the impact of the interactions with water molecules.