DOI: 10.57715/unr/hk32nt
title: Raw data on the time-course of absorbance change at 470 nm for a kinetic study of H2O2-based 2,6-dimethoxyphenol oxidation catalyzed by [Cu(phen)(CH3CO2)2] complex

description: Introduction This dataset contains the raw data from a kinetic study on the oxidation of 2,6-dimethoxyphenol (2,6-DMP) —a syringyl model compound representative of dimethoxylated phenolic lignin units— in the presence of the Cu(II) complex [Cu(phen)(CH3CO2)2] (phen = 1,10-phenanthroline) and using hydrogen peroxide (H2O2) as the terminal oxidant. These data were generated with the aim of evaluating the catalytic efficiency of the Cu(II) complex and providing insights into the mechanism by which it participates in the transformation of dimethoxylated aromatic structures, which are particularly abundant in hardwood lignins (50–80 %). This information provides a fundamental basis for guiding the design of more efficient catalysts with potential applications in large-scale biorefinery processes. Abbreviations 2,6-DMP: 2,6-dimethoxyphenol or syringol AU: Absorbance Units Cat: Catalyst MeCN: Acetonitrile phen: 1,10-phenanthroline Methodology The kinetics of 2,6-DMP oxidation by H2O2 catalyzed by the [Cu(phen)(CH3CO2)2] complex were evaluated at 25 °C in a reaction medium consisting of phosphate buffer (pH 7) and MeCN in a 5:1 ratio. The starting concentrations of the catalyst (0–0.035 mM), 2,6-DMP (0.04–1.9 mM), and H2O2 (0.69–8.6 mM) were varied individually. In each run, the formation of coerulignone was monitored over time by following the increase in absorbance at 470 nm. In a typical experiment, 2.5 mL of buffer solution containing the appropriate amount of 2,6-DMP was mixed with 10 μL of an H2O2 solution in acetone (with the concentration adjusted as needed). To start the reaction, 0.5 mL of a solution of the complex in MeCN—whose concentration was adjusted according to the specific kinetic assay—was added. The mixture was maintained under magnetic stirring, and the absorbance at 470 nm was 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 470 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 organized into a series of distinct CSV files. Each file contains raw, time-series absorbance data at 470 nm for experiments where the concentration of one reactant (catalyst, H2O2 or 2,6-DMP) was varied individually, while the other two were kept constant. catalyst.csv – Contains raw, time-series absorbance data at 470 nm from experiments conducted in phosphate buffer (pH 7):MeCN (5:1) at 25 °C, with varying starting catalyst concentrations and fixed initial concentrations of 2,6-DMP and H2O2. dmp.csv – Contains raw, time-series absorbance data at 470 nm from experiments conducted in phosphate buffer (pH 7):MeCN (5:1) at 25 °C, with varying starting 2,6-DMP concentrations and fixed initial concentrations of H2O2 and catalyst. hydrogen_peroxide.csv – Contains raw, time-series absorbance data at 470 nm from experiments conducted in phosphate buffer (pH 7):MeCN (5:1) at 25 °C, with varying starting H2O2 concentrations and constant initial concentrations of 2,6-DMP and catalyst. Data dictionary abs470: Absorbance recorded at 470 nm (AU) conc_cat_mM: Starting concentration of catalyst (mM) conc_h2o2_mM: Starting concentration of H2O2 (mM) conc_dmp_mM: Starting concentration of 2,6-DMP (mM) time_s: Time since the start of the reaction (s) Value of the data The raw kinetic data of time-course of absorbance at 470 nm presented here can be used to determine the initial rates of coerulignone formation, which is the compound responsible for the monitored absorption maximum. Subsequently, the rates obtained under different experimental conditions can be analyzed collectively to model the rate law of coerulignone formation and to propose a reaction mechanism which accounts for the catalytic activity of the peroxidase mimic complex [Cu(phen)(CH3CO2)2]. The value of these data lies in their potential to guide the rational design of more efficient catalysts for the H2O2-oxidation of dimethoxylated phenolic compounds, which represent structural models of the syringyl units present in lignin—an aspect of particular relevance in the development of sustainable strategies for the valorization of this biopolymer. Since the conversion of lignin into high value-added chemicals remains a major challenge in large-scale biorefinery processes, the information presented here provides a fundamental basis for optimizing catalytic systems capable of transforming this biopolymer into precursors of functional materials, fuels, and compounds of industrial interest.