The information that can be obtained with static ab initio electronic structure calculations of PCET, such as reaction energies or reaction barriers, is only indirectly related to the data measured in experiment. A more substantial support of the experiments can be provided by first-principles simulations of the photoinduced reaction dynamics. This includes simulating the ultrafast nonadiabatic relaxation of the initially populated excited singlet state of the complex. Such simulations were recently performed for several hydrogen-bonded complexes of azaaromatic chromophores with water molecules. and with phenol It has been shown both experimentally and theoretically that an increase in the electron-donating strength of the substrate lowers its oxidation potential, which, in turn, lowers the barrier of the PCET reaction on the S 1 potential energy surface of the complex. Nonadiabatic dynamic simulations performed for such complexes support this observation, too. A similar experiment, performed on hexaazatrinaphthylene (HATN) dissolved in water and in methanol, confirms the relation between the electron-donating strength of the substrate and the yield of the PCET reaction. The photooxidation of alcohols is generally representative of the photooxidation of organic matter, with potential applications in various fields, such as organic synthesis and renewable energy conversion. Understanding the mechanisms and factors influencing the photooxidation of organic matter via PCET is essential for developing strategies to control and optimize these processes. By harnessing the power of light and PCET, researchers aim to design innovative and sustainable solutions for environmental remediation and the degradation of organic pollutants, with potential applications in various fields, such as organic synthesis, and renewable energy conversion. The goal of this work is to elaborate a qualitative ab initio-based picture of the PCET reaction mechanism and dynamics in a photoexcited pyrido[2,3-b]pyrazine complex with methanol (PrdPyr-MeOH, Figure ), with the PrdPyr molecule representing in this study the reactive center of a HATN-like system.