Aminopterin

Methotrexate (MTX), a widely used anticancer drug, is a refractory organic pollutant posing serious threats to ecosystems and human health.This study focuses on the development of a novel catalyst composed of Ce-based high-entropy metal oxides (NHEMO) supported on nepheline for the catalytic wet peroxide oxidation (CWPO) process, targeting MTX degradation in simulated wastewater.The NHEMO catalyst exhibited a unique high-entropy structure that enhances catalytic performance by facilitating diverse electronic interactions, which was confirmed through X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses showing a well-defined crystal structure and uniform dispersion of metal oxides.Addnl., XPS and energy-dispersive X-ray spectroscopy (EDS) revealed a stable metal composition and high oxidation states of active metal sites.At a reaction temperature of 160 °C, with a residence time of 150 s and an oxidation coefficient of 5, the catalyst achieved a MTX removal rate of 93.49 % and a COD (COD) removal of 99.95 %.D. Functional Theory (DFT) calculations further demonstrated that H2O2 decomposes into both adsorbed (surface-bound) and free (solution-phase) hydroxyl radicals (.OH).These radicals synergistically degrade MTX through both radical and non-radical pathways, ensuring comprehensive pollutant breakdown.The catalyst also showed excellent stability and a very low metal dissolution rate during the reaction, maintaining high catalytic activity after repeated recycling.This catalyst offers high cost-effectiveness, activity, and stability, providing a promising solution for treating refractory organic pollutants in pharmaceutical wastewater.

Pterins are naturally occurring compounds widespread in living organisms. 5,6,7,8-Tetrahydrobiopterin (H₄Bip) is a cofactor of several key enzymes, including NO-synthases and phenylalanine hydroxylase, whereas tetrahydrocyanopterin is a photoreceptor molecule in cyanobacteria. In this regard, tetrahydropterins (H₄pterins) photochemistry and photophysics have been attracting our attention. H₄pterins photodegrade in presence of molecular oxygen yielding dihydropterins (H₂pterins) and oxidized pterins. Meanwhile, the excited states dynamics of H₄pterins on a femto- and picosecond time-scale remains unclear. To shed light on this area, we perform time-resolved spectroscopy of H₄Bip using fluorescence up-conversion as well as transient absorption spectroscopy techniques along with TD-DFT non-adiabatic molecular dynamics. We show that the lowest H₄Bip exited state has a lifetime of ca. 200 fs. Using the BHandHLYP functional and multireference spin-flip (MRSF) method we demonstrate that starting from the S₄ state, H₄Bip passes to the S₁ state within 50 fs, and after 200 fs a conical intersection with the ground S₀ state is achieved. As a whole, the excited state behavior of H₄Bip is similar to DNA nucleobases, in particular guanine. These findings allow us to make some speculations about the biochemical role of H₄pterins photophysics.