In this paper we report the effects of five imidazolium cations with varying alkyl chain lengths to study the effects of cation size on capacitance versus voltage behavior. The cations include ethyl-, butyl-, hexyl-, octyl-, and decyl-3methylimidazolium, all paired with a triflate anion. We analyze the capacitance with respect to the cation alkyl chain length qualitatively and quantitatively by analyzing changes in the capacitance−potential curvature shape and magnitude across several standard scanning protocols and electrochemical techniques. Further, three transport properties (viscosity, diffusion coefficient, and electrical conductivity) are experimentally determined and integrated into the outcomes. Ultimately, we find higher viscosities, lower diffusion coefficients, and lower electrical conductivities when the alkyl chain length is increased. Also, capacitance values increase with cation size, except 1-octyl-3methylimidazolium, which does not follow an otherwise linear trend. This capacitive increase is most pronounced when sweeping the potential in the cathodic direction. These findings challenge the conventional hypothesis that increasing the length of the alkyl chain of imidazolium cations diminishes the capacitance and ionic liquid performance in charge storage.

Ionic liquids (ILs) add complexity to electrochemical interfaces that cannot be adequately treated with traditional double layer models. We present a series of carefully controlled capacitance measurements to optimize the collection of reproducible and uniform capacitance-potential datasets. We quantitatively evaluate analysis methods on the experimentally observed capacitance of l-ethyl-3-methylimidazolium trifluoromethauesulfonate [Emim][TFO] IL at the gold-IL interface. The major outcomes of our work are to identify how experimental data collection methods affect capacitive hysteresis, and to suggest a systematic approach to collect reproducible capacitance data for IL systems. We evaluate different potential scan directions, examine varying potential sweep rates, and capacitance collection methods. We find that faster scan rates can mitigate the capacitive hysteresis between the anodic and cathodic scans for a particular collection technique. However, faster scan rates also result in more variation between the collection techniques. We also find that decreasing the effective potential sweep rate reduces hysteresis between different collection techniques when other factors are held constant. It is crucial for researchers to consistently report the direction of the potential sweep and the effective rate of potential sweep. Our data suggest that using slower effective potential perturbation rates would reduce discrepancies in capacitance data collected from different laboratories under different experimental conditions.

Sunlight-driven photochemical reactions are an important tool for sustainable organic synthesis. However, compared with ground states, for which the effects of structure on properties and reactivity are well established, the understanding of excited states is limited. In particular, an improved understanding of aromaticity and antiaromaticity in excited states is necessary to develop strategic photochemical methods for synthesizing polycyclic aromatic compounds.Herein, using density functional theory (DFT)-optimized structures, the ground singlet (S 0 ) and lowest triplet (T 1 ) states of coronene and corannulene were compared. Bond length analysis demonstrated that both triplet corannulene and triplet coronene bear a partial resemblance to benzene. Nucleusindependent chemical shift (NICS(0), NICS(1.7) ZZ , NICS scans) and anisotropy of the induced current density (ACID) calculations were carried out to compare the induced magnetic currents in these molecules. This analysis demonstrated rather weak π-conjugation and partial antiaromaticity in the S 0 state of each molecule. In contrast, a combination of circular induced currents and pronounced antiaromaticity was found in the T 1 state of each molecule. However, the T 1 of corannulene exhibited higher stability, which should facilitate functionalization. Consequently, corannulene is considered more suitable for photochemical applications.