Excited states articles from across Nature Portfolio

Icosahedral carboranes have long been considered to be aromatic but the extent of conjugation between these clusters and their substituents is still being debated. Here the authors demonstrate carboranes as conjugated bridges in optical functional chromophores.

The authors demonstrate that the band structure of graphene nanoribbons is modulated by cove edges, brightening the luminescence 4-fold via emission from otherwise dark twilight states. High spectral resolution of the optical response reveals strong vibron-electron coupling

Malakar et al. investigate the photochemical dynamics in the isomerization of bacteriorhodopsin light and dark-adapted forms and in the first photocycle intermediate, K. The results prompt a reevaluation of the counter ion model, revealing that a different protonation then that shown in the classic quadrupole so far considered must be employed to account for the experimental data.

Understanding excitonic optical excitations is integral to improving optoelectronic and photovoltaic semiconductor devices. Here, Bennecke et al. use photoemission exciton tomography to unravel the multiorbital electron and hole contributions of entangled excitonic states in the prototypical organic semiconductor C60.

Controlling excited-state reactivity is a long-standing challenge in photochemistry, as desired pathways may be inaccessible or compete with unwanted channels, which is problematic for applications. Here, the authors show that 2,3,5-trifluorination on the phenolate ring of the green fluorescent protein chromophore leads to both pathway selectivity and doubles the photoisomerization quantum yield.

Photoredox catalysis is an important approach for synthesizing fine chemicals from olefins, but the limited lifetime of radical cation intermediates severely restricts the efficiency. Here, the authors report that Ag3PO4 can efficiently catalyze intramolecular and intermolecular [2 + 2] and Diels–Alder cycloadditions under visible-light irradiation.

Trans–cis photoisomerization is a fundamental photochemical reaction that is thought to proceed through an intermediate with a perpendicular conformation. However, unambiguous identification of this state has proved challenging. The combination of state-of-the-art ultrafast spectroscopy and quantum chemical calculations now provides evidence for its structural observation in stilbene photoisomerization.

Rajeev K. Dubey and Frank Würthner discuss the colourful character of perylene bisimides and the impact of aggregation on their functional properties.

Photoredox catalysts offer a promising approach to performing reactions with high energetic requirements, however, the influence of solvent and counter ions is not fully understood. Now, a microwave-based technique is shown to give direct insight into their effects on charge reorganization during catalysis.

The tris(2,2′-bipyridine)ruthenium(II) cation, or ‘rubipy’ to its friends, has had a significant influence on our understanding of the photophysics of transition metal complexes, and has also helped revolutionize organic photochemistry, explains Daniela M. Arias-Rotondo.

Excited anion states provide doorways for molecular electron capture. Now, two-dimensional photoelectron spectroscopy of cluster anions has been shown to be a powerful tool for revealing the role of the local environment in facilitating the process.