Chemistry

Canadian Journal of Chemistry, Volume 103, Issue 5, Page 153-160, May 2025.
The use of low-cost, widely available environmental friendly catalysts may strengthen the sustainability of lignocellulosic biomass conversion into levulinic esters. In this respect, the present study aimed to optimize the methyl esterification reaction between levulinic acid (LVA) and aluminum sulfate [Al2(SO4)3] with a view to producing methyl levulinate (MLV). The Box–Behnken design for three factors was applied to investigate the influence of reaction time (60, 120, and 180 min), alcohol:acid molar ratio (4:1, 8:1, and 12:1), and catalyst concentration (0.02, 0.04, and 0.06 mol L−1) on LVA conversion into MLV. The reactions occurred in a Parr Instruments stainless steel reactor, at a temperature of 140 ºC and 733 rpm rotation. The results indicated that the interaction between molar ratio and catalyst concentration has a significant influence on LVA conversion. The regression model obtained is significant and predictive, with an R2 value of 0.86. Analyses of response surfaces showed that a 60 min reaction time produces high conversion, irrespective of the amount of catalyst. Fixing the shortest reaction time and lowest Al2(SO4)3 concentration, the molar ratio indicated for the reaction would be 1:6. The levels selected provide conversions varying from 86.83% to 99.27%, demonstrating the efficiency of a low-cost catalyst at low concentrations.

Canadian Journal of Chemistry, Volume 103, Issue 5, Page 161-173, May 2025.
Detection of infrared (IR) spectrum features of target molecules can be achieved by comparison of experimentally measured spectra to template spectra within a database. The focus of this study is the scalability of density functional theory (DFT)-calculated IR spectra with respect to macroscales, characteristic of dielectric response as measured using IR spectroscopic methods, and demonstration that IR-spectrum databases can be constructed with respect to classes of target molecules, where DFT-calculated spectra provide a complementary extension of experimentally measured IR spectra. A case-study analysis concerning IR-spectra scalability for a set of common explosives, including TNT, is described. This analysis provides an example of calculating template spectra for potential detection of target molecules, where DFT-calculated IR spectra are frequently more convenient than laboratory measurements using IR spectroscopic methods. We have shown that DFT-calculated spectra can be included within template-spectrum databases, and their ability to show very good correlation with measured spectra.

Canadian Journal of Chemistry, Volume 103, Issue 5, Page 174-183, May 2025.
Surface modification is a crucial strategy to enhance material performance and expand their applications across diverse fields. Among these, nature-inspired hydrophobic coatings have gained attention for their ability to address challenges such as environmental pollution, surface degradation, and efficiency loss in various industries, including optoelectronics, automotive, and outdoor structures. In this work, we present a comparative study of commercial alkyl- and perfluoroalkyl silanes, (H3C(H2C)16H2CSiCl3) and (F3C(F2C)5(H2C)2SiCl3), dip coated on regular glass, with a focus on their stability and performance upon waterfall simulation and outdoor exposure. These coatings’ wettability, optical properties, and stability on nanotextured glass are also studied. A video-based goniometer was used to study the wetting properties. Roughness, topography, and optical properties of the resulting surfaces were investigated by atomic force microscopy and UV–Vis–NIR spectroscopy. At low deposition times, we were able to spot the presence of agglomerated regions of polymerized short perfluoroalkyl chains, leading to a rougher and less uniform film. In contrast, we observed smoother coating with fewer polymerized aggregates for long alkyl chains. We found that an enhancement in hydrophobicity and a decrease in reflectance was achieved with a short perfluorinated alkyl chain. When applied to nanotextured glass, the observed increase in reflectance for both coatings, at 500 nm, was likely due to the coating’s thickness effect. Texturing combined with surface roughness significantly increased the water contact angle, while only lowering the surface energy of regular glass without altering its structure resulted in less increase in water contact angle. These coatings can serve as hydrophobic surfaces and protective coatings against outdoor conditions, including dust accumulation, UV irradiation, ice adhesion, and corrosion.

Canadian Journal of Chemistry, Volume 103, Issue 5, Page 184-194, May 2025.
This study investigates the impact of power density on the surface properties of ethylene tetrafluoroethylene (ETFE) films treated with atmospheric pressure nitrogen plasma. Increasing power density consistently enhances the wettability of treated substrates. ATR-FTIR and XPS analyses reveal the formation of C=C bonds, C=CF2 stretching vibrations, defluorination, and the introduction of oxygenated and nitrogenated functionalities. T-peel tests with acrylic adhesive tape show substantial increases in peel strength post-treatment, with higher power densities yielding more uniform modifications. Reducing polymer line speed further enhances peel strength. Long-term aging tests indicate minimal peel strength reduction after 340 days. The study emphasizes controlling plasma treatment parameters to optimize ETFE film bonding properties, benefiting diverse applications.

Canadian Journal of Chemistry, Ahead of Print.

Nature, Published online: 30 May 2025; doi:10.1038/d41586-025-01692-x

In warming coastal seas, a crucial ecosystem is being replaced by ‘turfs’ of red algae, which release chemicals that suppress kelp survival.

Nature, Published online: 30 May 2025; doi:10.1038/d41586-025-01728-2

US–China tariff war threatens global public health

Nature, Published online: 30 May 2025; doi:10.1038/d41586-025-01650-7

Governments and companies are investing billions of dollars in efforts to remove greenhouse gases from the atmosphere, but will it pay off?