Since the industrial revolution began about 150 years ago, the concentration of greenhouse gases such as CO₂ in the atmosphere has increased dramatically, with corresponding consequences for the climate. For over 25 years, destruction of the ozone layer (pink and green regions on the globe), which is caused by chlorofluorocarbons, has also been observed. The future development of the ozone layer and of the climate are closely related to each other.

Understanding starts with distinction: Distinguishing between the thermodynamically and kinetically controlled scenarios is of critical importance when analyzing the complex phenomena in nanosynthesis, such as the growth of nanoparticles, their aggregation, and the shape evolution of polymer nanostructures. The processes are examined in detail in this Review and the mechanistic proposals are categorized in the common framework of thermodynamics and kinetics.

At a glance: Microimaging by IR microscopy is used to record the evolution of the concentration profiles of reactant and product molecules during catalytic reaction. The method is thus shown to allow a one-shot determination of effectiveness factors.

The measurement of two-dimensional species concentration profiles in the gas phase over catalytic walls is achieved by planar laser-induced fluorescence. The interaction of catalytic surface kinetics and mass transport is exemplarily studied for the reduction of NO by hydrogen to ammonia over a diesel oxidation catalyst with platinum as an active component.

Below lithium: Concerns over the future cost and sustainability of resources of lithium has led to a global trend to develop low-cost sodium-ion batteries. Central to this has been the fast-developing field of non-aqueous batteries that could employ a plethora of materials for the positive and negative electrodes, and electrolytes. Apart from sustainability, they offer structural and electrochemical benefits compared to their Li analogues.

Off the beaten path: Studies of an unusual inversion of the sense of enantioselectivity for the selenylation of aldehydes catalyzed by a diphenylprolinol ether catalyst provides support for a mechanistic concept beyond the simple steric model developed for enamine catalysis in these systems. A general role for downstream intermediates in selectivity outcomes in organocatalysis is discussed. TMS=trimethylsilyl.

Short-lived Ce³⁺ is the active and kinetically relevant intermediate during catalytic CO oxidation on a ceria-supported metal catalyst, whereas long-lived Ce³⁺ species are inactive spectators. This was shown by in situ resonant X-ray emission spectroscopy and quantitative correlation between the initial rate of Ce³⁺ formation under transient conditions and the overall CO oxidation rate.

Ion–molecule reactions: A remarkable reorganization occured in iron-containing cations under ambient conditions. Fast and effective carbon–chlorine activation and carbon–carbon coupling was observed in gas-phase mixtures containing ferrocene and dichloromethane, through reaction intermediates (see picture) that eventually extrude the iron giving ferrous chloride.

Out of the dark: Mechanochemical reaction mechanisms were studied by a laboratory Raman spectroscopy technique developed for in situ and real-time monitoring of milling reactions (see picture). The technique enabled the course of mechanochemical transformations of coordination polymers and organic materials to be followed as well as the study of liquid additives.

Active duty: An in situ titration process, using phenyl hydrazine as the titrant, is employed to quantify the number of active sites on nanocarbon catalysts for alkane oxidative dehydrogenation reactions. Using this method, the turnover frequency for conversion of the ethyl benzene substrate is used as a reliable kinetic parameter to evaluate the intrinsic activity of the nanocarbon catalysts.

More than one way to add: Theoretical calculations indicate that the silyl-triflate-catalyzed (4+3) cycloadditions of epoxy enolsilane 1 do not generally proceed via an intermediate oxyallyl cation. Instead the reaction involves an S_N2-like epoxide ring opening in concert with remote CC bond formation. TES=triethylsilyl, TfO=trifluoromethanesulfonyl.

Femtosecond optical gating (FOG) technique was employed to investigate the excitonic relaxation mechanism in a NiO-supported p-type perovskite. The effect of photoluminescence quenching and the excellent photovoltaic performance were rationalized based on this measurement.

Curly arrows from ab initio calculations: Curly arrows in reaction mechanisms are shown to correspond to changes in intrinsic bond orbitals (IBOs) along reaction paths. With this quantum chemical basis, even complex reaction mechanisms can be derived and visualized in a simple, direct, and intuitive form.

Not only in the solution phase: Highly oxidized RO₂ radicals in the atmosphere are rapidly formed by autoxidation initiated by the reaction of O₃ and OH radicals with biogenic emissions such as limonene and α-pinene. Field measurements (see picture) confirm experimental findings from a flow-tube study. The closed-shell products from this process represent important aerosol constituents influencing aerosol–cloud–climate interactions.

Run for cover: Acrolein is reduced chemoselectively on Pt(111) and Pd(111) surfaces at the C=C bond and not at the C=O bond because reaction steps involving C=O reduction become energetically unfavorable with increasing steric repulsion.

Well-established libraries of target spectra that are derived by means of careful offline analysis and identification of equilibrium data within larger kinetic datasets can be used for any particle–ligand system. Kinetics of ligand binding to nanoparticles can be derived free of assumption, in situ, and with high time resolution.

A graphical analysis to elucidate the order in catalyst uses a normalized time scale, t [cat]_Tⁿ, to adjust entire reaction profiles constructed with concentration data. Compared to methods that use rates, the normalized time scale analysis requires fewer experiments and minimizes the effects of experimental errors by using information on the entire reaction profile.

The free-energy landscape of reactions involved in the Li oxygen reduction reaction (ORR) were obtained by rotating ring disk (RRD) measurements and calculations. Differences in redox potentials of O₂/O₂⁻ and O₂/Li⁺-O₂⁻ couples vs. Li⁺/Li in dimethoxyethane (DME) and dimethylsulfoxide (DMSO) reflect the influence of increasing solvation on the free energy of O₂⁻ formation vs. Li⁺/Li and Li⁺-O₂⁻ coupling.

Middle versus end? When all other conditions are equal, bond cleavage in the middle of molecules is entropically much more favored than bond cleavage at the end. Experimental and theoretical approaches were used to study the selectivity of bond cleavage or dissociation of both covalent and supramolecular adducts. The findings have extensive implications for other fields of chemistry.

Combining two types of acidity: Periodic ab initio calculations and kinetic measurements were combined to determine the catalytically active sites of isopropanol dehydration on amorphous silica–alumina. Pseudo-bridging silanol sites, which are both Lewis and Brønsted acidic, were found to be of crucial importance in this process.