Herein, the effect of the alkali cation (Li + ,Na + ,K + , and Cs + )inalkaline electrolytes with and without Fe impurities is investigated for enhancing the activity of nickel oxyhydroxide (NiOOH) for the oxygen evolution reaction (OER). Cyclic voltammograms showthat Fe impurities have asignificant catalytic effect on OER activity;h owever,b oth under purified and unpurified conditions,the trend in OER activity is Cs + > Na + > K + > Li + ,suggesting an intrinsic cation effect of the OER activity on Fe-free Ni oxyhydroxide.I nsitu surface enhanced Raman spectroscopy( SERS), shows this cation dependence is related to the formation of superoxo OER intermediate (NiOO À ). The electrochemically active surface area, evaluated by electrochemical impedance spectroscopy (EIS), is not influenced significantly by the cation. We postulate that the cations interact with the NiÀOO À species leading to the formation of NiOO À ÀM + species that is stabilized better by bigger cations (Cs + ). This species would then act as the precursor to O 2 evolution, explaining the higher activity.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Herein, the effect of the alkali cation (Li + ,Na + ,K + , and Cs + )inalkaline electrolytes with and without Fe impurities is investigated for enhancing the activity of nickel oxyhydroxide (NiOOH) for the oxygen evolution reaction (OER). Cyclic voltammograms showthat Fe impurities have asignificant catalytic effect on OER activity;h owever,b oth under purified and unpurified conditions,the trend in OER activity is Cs + > Na + > K + > Li + ,suggesting an intrinsic cation effect of the OER activity on Fe-free Ni oxyhydroxide.I nsitu surface enhanced Raman spectroscopy( SERS), shows this cation dependence is related to the formation of superoxo OER intermediate (NiOO À ). The electrochemically active surface area, evaluated by electrochemical impedance spectroscopy (EIS), is not influenced significantly by the cation. We postulate that the cations interact with the NiÀOO À species leading to the formation of NiOO À ÀM + species that is stabilized better by bigger cations (Cs + ). This species would then act as the precursor to O 2 evolution, explaining the higher activity.

To gain better understanding of the stabilizing interactions between metal ions and DNA quadruplexes, dispersion-corrected density functional theory (DFT-D) based calculations were performed on double-, triple- and four-layer guanine tetrads...

Thioamides and selenoamides are better hydrogen‐bond donors than carboxamides because their amino groups are more positively charged. Quantum chemical analyses reveal that this counterintuitive phenomenon, which cannot be explained by the electronegativity, originates from the larger electronic density flow from the nitrogen lone pair of the NH2 group towards the lower‐lying π* orbital on the C=S or C=Se bond. This difference can be traced back to the effective steric size of the chalcogen atoms. More information can be found in the Research Article by C. Nieuwland and C. Fonseca Guerra (DOI: 10.1002/chem.202200755).

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It has been experimentally observed that water–ice-embedded polycyclic aromatic hydrocarbons (PAHs) form radical cations when exposed to vacuum UV irradiation, whereas ammonia-embedded PAHs lead to the formation of radical anions. In this study, we explain this phenomenon by investigating the fundamental electronic differences between water and ammonia, the implications of these differences on the PAH–water and PAH–ammonia interaction, and the possible ionization pathways in these complexes using density functional theory (DFT) computations. In the framework of the Kohn–Sham molecular orbital (MO) theory, we show that the ionic state of the PAH photoproducts results from the degree of occupied–occupied MO mixing between the PAHs and the matrix molecules. When interacting with the PAH, the lone pair-type highest occupied molecular orbital (HOMO) of water has poor orbital overlap and is too low in energy to mix with the filled π-orbitals of the PAH. As the lone-pair HOMO of ammonia is significantly higher in energy and has better overlap with filled π-orbitals of the PAH, the subsequent Pauli repulsion leads to mixed MOs with both PAH and ammonia character. By time-dependent DFT calculations, we demonstrate that the formation of mixed PAH–ammonia MOs opens alternative charge-transfer excitation pathways as now electronic density from ammonia can be transferred to unoccupied PAH levels, yielding anionic PAHs. As this pathway is much less available for water-embedded PAHs, charge transfer mainly occurs from localized PAH MOs to mixed PAH–water virtual levels, leading to cationic PAHs.

The formation of guanine quadruplexes (GQ) in DNA is crucial in telomere homeostasis and regulation of gene expression. Pollution metals can interfere with these DNA superstructures upon coordination. In this work, we study the affinity of the internal GQ channel site towards alkaline earth metal (Mg2+, Ca2+, Sr2+, and Ba2+), and (post‐)transition metal (Zn2+, Cd2+, Hg2+, and Pb2+) cations using density functional theory computations. We find that divalent cations generally bind to the GQ cavity with a higher affinity than conventional monovalent cations (e. g. K+). Importantly, we establish the nature of the cation‐GQ interaction and highlight the relationship between ionic and nuclear charge, and the electrostatic and covalent interactions. The covalent interaction strength plays an important role in the cation affinity and can be traced back to the relative stabilization of cations’ unoccupied atomic orbitals. Overall, our findings contribute to a deeper understanding of how pollution metals could induce genomic instability.

The amino groups of thio-and selenoamides can act as stronger hydrogen-bond donors than of carboxamides, despite the lower electronegativity of S and Se. This phenomenon has been experimentally explored, particularly in organocatalysis, but a sound electronic explanation is lacking. Our quantum chemical investigations show that the NH 2 groups in thio-and selenoamides are more positively charged than in carboxamides. This originates from the larger electronic density flow from the nitrogen lone pair of the NH 2 group towards the lower-lying π* C=S and π* C=Se orbitals than to the high-lying π* C=O orbital. The relative energies of the π* orbitals result from the overlap between the chalcogen np and carbon 2p atomic orbitals, which is set by the carbonchalcogen equilibrium distance, a consequence of the Pauli repulsion between the two bonded atoms. Thus, neither the electronegativity nor the often-suggested polarizability but the steric size of the chalcogen atom determines the amide's hydrogen-bond donor capability.