Multi‐Redox Active Carbons and Hydrocarbons: Control of their Redox Properties and Potential Applications

Abstract

Precise control over redox properties is essential for high‐performance organic electronic devices such as organic batteries, electrochromic devices, and information storage devices. In this context, multi‐redox active carbons and hydrocarbons, represented as CxHy molecules (x≥1, y≥0), are highly sought after, because they can switch between multiple redox states. Herein, we outline the redox properties of CxHy molecules as solutes and adsorbed species. Furthermore, the limitations of evaluating their redox properties and the possible solutions are summarized. Additionally, the theoretical capacity (mAh/g) and gravimetric energy density (Wh/kg) of secondary batteries were estimated based on the redox properties of 185 CxHy molecules, which have primarily been reported in the last decade. Among them, seven CxHy molecules were found to have the potential to surpass the energy density of LiNi0.6Mn0.2Co0.2O2/graphite batteries. The use of CxHy molecules in multielectrochromic devices and multi‐bit memory is also explained. We believe that this review will encourage further utilization of CxHy molecules thereby promoting its applications in organic electronic devices.

Organophilic Clay with Useful Whiteness

“…As mentioned above, the present organophilic clay (2C18-LU) seems to be useful for applications such as cosmetics and polymer additives as well as hybrid pigments, where whiteness is required. − , In addition to the practical applications, white appearance is beneficial for application in photochemical and photophysical studies. ,− In the present study, luminescence of polyaromatic molecules was investigated to show the usefulness of 2C18-LU. Polyaromatic molecules are known as photoluminescence probes to investigate various surface/interfaces including the surfaces of clay minerals and organophilic clays, ,,, in addition to the possibility as light-harvesting and light-emitting materials. − Among the polyaromatic molecules, pyrene is a molecule used most extensively. ,,,, Here, the incorporation of pyrene into the organophilic clay was done by a mechanochemical reaction as reported previously. ,, The absorption and the photoluminescence spectra of 2C18-LU and N400 after the reaction with pyrene at a pyrene loading of 1.1 wt % are shown in Figure A. The shape and absorbance of the absorption due to the incorporated pyrene were almost the same for the two samples, though the absorbance was slightly higher for N400 due to the higher background for N400.…”

Electron transfer in polyaromatic hydrocarbons and molecular carbon nanostructures

“…The generated radical ions are also less reactive with the increase of the π-conjugation since extended π-system improves the delocalization of the charge. A recent review by Ueda et al summarizes the electrochemistry of expanded PAHs [43], i.e. nanographenes, radicaloids and macrocycles, with chemically reversible multi-redox electron transfer.…”

Ambipolar Charge Transport in Organic Semiconductors: How Intramolecular Reorganization Energy Is Controlled by Diradical Character

“…π–conjugated chromophores are active components of optoelectronic devices [ 1 , 2 , 3 , 4 , 5 , 6 ] and energy storage substrates [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Both uses of organic semiconductors benefit from suitable redox properties since oxidation and reduction are correlated with the injection of holes into the highest occupied molecular orbital (HOMO) level and electrons into the lowest unoccupied molecular orbital (LUMO) level.…”