The optimal salt concentration used in metal-ion energy storage devices has long focused heavily on 1 M electrolytes; however, recent evidence suggests taking a deeper look at electrolyte properties as a function of salt concentration. Toward that goal, the effect of concentration on solvation properties for a prototype sodium electrolyte is considered with potential applications for sodium-ion and sodium−air technologies. An empirical force field for sodium triflate in digylme, an electrolyte already in use with sodium−air systems, was developed from ab initio molecular dynamics simulations in conjunction with the variational force-matching method. Atomistic simulations of this electrolyte along with Fourier transform infrared (FTIR) experimental studies validate the qualitative accuracy of the model and demonstrate its transferability across different concentrations. The solvation structure and the extent of ion pairing effects in the electrolyte were considered for concentrations ranging from 0.25 to 2.0 M in the sodium salt. Ion pairing effects are seen even at dilute concentrations of 0.5 M in both simulations and experiments, with a transition from solvent-separated species to direct contact ion pairs as the concentration increased to 1.5 M. With further increase in the concentration, evidence for ion aggregation is also presented.

The convergence of DFT‐computed interaction energies with increasing binding site model size was assessed. The data show that while accurate intercalator interaction energies can be derived from binding site models featuring only the flanking nucleotides for uncharged intercalators that bind parallel to the DNA base pairs, errors remain significant even when including distant nucleotides for intercalators that are charged, exhibit groove‐binding tails that engage in noncovalent interactions with distant nucleotides, or that bind perpendicular to the DNA base pairs. Consequently, binding site models that include at least three adjacent nucleotides are required to consistently predict converged binding energies. The computationally inexpensive HF‐3c method is shown to provide reliable interaction energies and can be routinely applied to such large models.

A series of aryl-substituted naphthyridine-based sensors for 9-alkylguanine was analyzed using density functional theory and correlated ab initio methods. First, the 2-acetamido-1,8-naphthyridine backbone of these sensors was examined with rigorous ab initio methods and was shown to exhibit a guanine-binding energy commensurate with that of cytosine. Second, computational analyses of a guanine-specific fluorescent sensor from Fang and co-workers (Org. Lett. 2016, 18, 1724) resulted in a revised binding model and showed that π-stacking interactions with a pendant pyrenyl group are vital for strong guanine binding. Finally, 24 related guanine sensors with varying aryl groups were studied. Overall, it was found that both the geometry and the point of attachment of the pendant aryl groups significantly impact the guanine-binding affinity. This occurs through both the direct modulation of the π-stacking interactions with guanine and the secondary geometric effects that influence the strength and number of hydrogen bonds between guanine and the ethylenediamine linker connecting the arene to the naphthyridine backbone.