DOI: 10.57715/unr/ngwtc1
title: Raw data on the time-course of absorbance change at 500 nm for a kinetic study of H2O2-based phenol oxidation catalyzed by [Cu(Py2pn)(ClO4)2] complex

description: Introduction This dataset contains the raw data from a kinetic study on the oxidation of phenol (PhOH) —the simplest model system for the phenolic units present in lignin— catalyzed by the Cu(II) complex [Cu(Py2pn)(ClO4)2] (Py2pn = N,N’-bis(2-pyridinylmethylene)propane-1,3-diamine), which mimics the action of peroxidase enzymes. The reactions were carried out in the presence of 4-aminoantipyrine (4-AAP) and using hydrogen peroxide (H2O2) as terminal oxidant. These data were generated to evaluate the catalytic efficiency of the Cu(II) complex in the oxidation of PhOH, a key model molecule in lignin degradation studies. Their analysis enables a more detailed understanding of the mechanism by which the complex [Cu(Py2pn)(ClO4)2] catalyzes the oxidation of this substrate, providing valuable insights for the rational design of more efficient catalysts in large-scale biorefinery processes. Abbreviations 4-AAP: 4-Aminoantipyrine AU: Absorbance Units Cat: Catalyst DMF: Dimethylformamide MeCN: Acetonitrile PhOH: Phenol Py2pn: N,N’-bis(2- pyridinylmethylen)propane-1,3-diamine Methodology The kinetics of PhOH oxidation by H2O2 catalyzed by [Cu(Py2pn)(ClO4)2] complex were evaluated at 25°C and 50°C in two different reaction media: phosphate buffer (pH 7):MeCN in a 5:1 ratio, and borate buffer (pH 9):DMF in a 5:1 ratio. In the presence of 4-AAP, the formation of the p-quinoneimide product was monitored over time by following the increase in absorbance at 500 nm. The initial concentration of 4-AAP was kept constant in all experiments ([4-AAP]0 = 0.68 mM), while the starting concentrations of the catalyst (0–0.045 mM), PhOH (0.05–3 mM), and H2O2 (0.17–17 mM) were varied individually. In a typical experiment, 2.5 mL of buffer solution containing the appropriate amount of PhOH was mixed with 10 μL of an H2O2 solution in acetone (the concentration was adjusted as needed). To start the reaction, 0.5 mL of a solution of the complex in MeCN or DMF—whose concentration was adjusted according to the specific kinetic assay—was added, and the mixture was maintained under magnetic stirring, with the absorbance at 500 nm recorded at 10-second intervals. Quality of data To ensure reproducibility and quality of data generation and collection, each kinetic assay was performed in duplicate, yielding two independent sets of time-series absorbance data at 500 nm for each experimental condition. Additionally, the procedure included beginning the absorbance recording 30 s after the addition of the catalyst. Consistency between replicates was evaluated using quantitative and visual analyses, and a thorough review was conducted in order to identify any outliers or inconsistencies in the spectrophotometric data. Table of contents The kinetic data are stored in individual CSV files, organized in a folder structure based on reaction medium composition and temperature. Within each subfolder corresponding to a specific condition (a combination of reaction medium composition and temperature), each file contains raw, time-series absorbance data at 500 nm for experiments conducted under that condition, in which the starting concentration of one reactant (PhOH, catalyst, or H₂O₂) is varied individually. The following presents the organization of the dataset files within the folder structure according to the reaction medium composition (phosphate buffer (pH 7):MeCN or borate buffer (pH 9):DMF) and temperature: pH_7_mecn Temp_25C hydrogen_peroxide_pH7_25C.csv – Contains raw, time-series absorbance data at 500 nm for experiments conducted at pH 7 and 25°C with varying starting H2O2 concentrations and constant initial concentrations of PhOH and catalyst. phenol_pH7_25C.csv – Contains raw, time-series absorbance data at 500 nm for experiments conducted at pH 7 and 25°C with varying starting PhOH concentrations and fixed initial concentrations of H2O2 and catalyst. catalyst_pH7_25C.csv – Contains raw, time-series absorbance data at 500 nm for experiments conducted at pH 7 and 25°C with varying starting catalyst concentrations and fixed initial concentrations of PhOH and H2O2. Temp_50C hydrogen_peroxide_pH7_50C.csv – Contains raw, time-series absorbance data at 500 nm for experiments conducted at pH 7 and 50°C with varying starting H2O2 concentrations and constant initial concentrations of PhOH and catalyst. phenol_pH7_50C.csv – Contains raw, time-series absorbance data at 500 nm for experiments conducted at pH 7 and 50°C with varying starting PhOH concentrations and constant initial concentrations of H2O2 and catalyst. catalyst_pH7_50C.csv – Contains raw, time-series absorbance data at 500 nm for experiments conducted at pH 7 and 50°C with varying starting catalyst concentrations and fixed initial concentrations of PhOH and H2O2. pH_9_dmf Temp_25C hydrogen_peroxide_pH9_25C.csv – Contains raw, time-series absorbance data at 500 nm for experiments conducted at pH 9 and 25°C with varying starting H2O2 concentrations and fixed initial concentrations of PhOH and catalyst. phenol_pH9_25C.csv – Contains raw, time-series absorbance data at 500 nm for experiments conducted at pH 9 and 25°C with varying starting PhOH concentrations and constant initial concentrations of H2O2 and catalyst. catalyst_pH9_25C.csv – Contains raw, time-series absorbance data at 500 nm for experiments conducted at pH 9 and 25°C with varying starting catalyst concentrations and constant initial concentrations of PhOH and H2O2. Temp_50C hydrogen_peroxide_pH9_50C.csv – Contains raw, time-series absorbance data at 500 nm for experiments conducted at pH 9 and 50°C with varying starting H2O2 concentrations and fixed initial concentrations of PhOH and catalyst. phenol_pH9_50C.csv – Contains raw, time-series absorbance data at 500 nm for experiments conducted at pH 9 and 50°C with varying starting PhOH concentrations and constant initial concentrations of H2O2 and catalyst. catalyst_pH9_50C.csv – Contains raw, time-series absorbance data at 500 nm for experiments conducted at pH 9 and 50°C with varying starting catalyst concentrations and fixed initial concentrations of PhOH and H2O2. Data dictionary abs500: Absorbance recorded at 500 nm (UA) conc_cat_mM: Starting concentration of catalyst (mM) conc_h2o2_mM: Starting concentration of H2O2 (mM) conc_phoh_mM: Starting concentration of PhOH (mM) time_s: Time since the start of the reaction (s) Value of the data These raw kinetic data can be used to determine the initial rates of p-quinoneimide adduct formation, which is responsible for the monitored absorption maximum at 500 nm. Subsequently, the results for each experimental condition can be analyzed collectively to model the rate law of p-quinoneimide formation, which provides valuable information to gain mechanistic insight into the catalytic activity of the peroxidase mimic complex [Cu(Py2pn)(ClO4)2]. The value of these data lies in their contribution to the rational design of more efficient catalysts for the oxidation of phenolic compounds, which may have implications for the development of sustainable strategies for lignin valorization. Since the conversion of lignin into high-value chemicals remains a major challenge in biorefinery chemistry, this information is crucial for optimizing catalytic systems with the ability of transforming this biopolymer into precursors for functional materials, fuels, and industrially relevant compounds.