Computational photochemistry provides a description of light-induced chemical phenomena reaching the molecular size-scale and femtosecond time-scale resolutions. In the period 2022–2023, we can find a significant increase in the use of tools of computational photochemistry in materials science, as compared to previous years, maintaining the relative number of works in the areas of biology, medicine, nanotechnology and atmospheric chemistry. To illustrate such advances in this field, we have chosen here representative applied studies focused on the non-radiative decay paths of DNA nucleobases, the photoreductive repair of thymine dimers, photosensitisers generating singlet oxygen and oxygen-independent photoactivated therapies, conjugated organic oligomers of interest in optoelectronic devices, ionic transition metal complexes for light emitting electrochemical cells, and sulphur chemistry in planetary atmospheres. On this occasion, we also describe the new features implemented in one of the quantum-chemistry packages of software specialised in photochemistry, the OpenMolcas program.
Starting from the relevance of singlet oxygen in a plethora of research fields, the present chapter aims to provide a non-expert reader with a general background of representative applications in organic photochemistry. By encompassing a century and a half of selected synthetic organic transformations achievable via photosensitized singlet oxygen generation, the unmet challenges emerge clearly. The current critical analysis of the state-of-the art in the field, though not claiming to be exhaustive, delivers a roadmap for organic chemists fascinated by the manifold opportunities provided by singlet oxygen as both a photo-oxidation and photo-oxygenation reagent.
The synthesis of natural substances has always represented a challenge for organic chemists. The possibility of using reactions capable of generating molecular complexity in a stereocontrolled manner is the basis of a successful total synthesis. In this perspective, photochemical reactions represent an enormous resource, which must, however, be well mastered due to the complex mechanisms often involved. This chapter discusses examples taken from the recent literature, in which light-mediated reactions represent key steps, very often irreplaceable by alternative thermal processes. The chapter is divided based on the different photochemical processes involved, and each section is preceded by a brief introduction that sets the topic in the context of the relevant literature. This chapter is not a comprehensive review of all the recent total syntheses that benefited from the use of light, rather, an outlook of the general uptake of photochemical processes by the synthetic community, providing a glance of the general trend of use of photo-driven transformations in tackling the most significant synthetic challenges.
The goal of this Chapter is to provide examples attesting to the maturity of current strategies for simulating the excited-state dynamics and nonradiative processes of molecules in the gas phase. Such progress over the past few decades means that we are approaching the possibility of performing in silico photochemistry, i.e., a photochemical experiment taking place fully on the computer and allowing for the prediction of photochemical processes and observables – at least qualitatively. We provide here a brief survey of nonadiabatic molecular dynamics and the creation of a hierarchy of methods within the multiple spawning framework. We then show how nonadiabatic molecular dynamics techniques can be used in the context of atmospheric photochemistry.
A survey of the most recent advancements in the field of delayed fluorescence (DF) emission has been reported in the present chapter.
