In this chapter we are concerned with the mechanisms of organic photochemical reactions. Two important features of mechanisms are the correlation of molecular structure with reactivity and the investigation and establishment of the details of the elementary steps involved in a photochemical process as *R proceeds to P. We shall be concerned with the experimental tools for characterizing the str...

We have developed a photochemical model of thrombotic middle cerebral artery (MCA) occlusion in the guinea pig for investigating factors contributing to the development of cerebral infarction. In this model, cyclic flow reductions (CFRs) after recanalization of the MCA are a common observation and might contribute to the development of cerebral infarction. Therefore, we sought to measure the ti...

We present an efficient method for the simulation of time-resolved photoelectron imaging (TRPEI) spectra in polyatomic molecules. Our approach combines trajectory-based molecular dynamics that account for non-adiabatic effects using surface hopping, with an approximate treatment of the photoionization process using Dyson orbitals as initial and Coulomb waves as final electron states. The method...

The photochemical properties of two basic easily synthesized isatin N(2)-phenylhydrazones were investigated. Contrary to the corresponding isatin N(2)-diphenylhydrazones, only Z-isomers were isolated from the reaction mixtures during the synthesis due to their stabilization by intramolecular hydrogen bonding. Although the presence of the C=N double bond creates conditions for the formation of a...

The increasing need for more efficient synthetic methods and sustainable processes can be seen as a major driving force for new inventions; it also stimulates the creative rethinking of known concepts, which, in turn, will lead to the development of innovative chemistry. For example, starting from the challenge to mimic and understand enzymatic transformations, organocatalysis has now become an...

In our continued effort to address the challenges of selective sp3 C-H fluorination on complex molecules, we report a sensitized aliphatic fluorination directed by terpenoidal enones using catalytic benzil and visible light (white LEDs). This sensitized approach is mild, simple to set up, and an economical alternative to our previous protocol based on direct excitation using UV light in a speci...

The PsbS protein of photosystem II functions in the regulation of photosynthetic light harvesting. Along with a low thylakoid lumen pH and the presence of de-epoxidized xanthophylls, PsbS is necessary for photoprotective thermal dissipation (qE) of excess absorbed light energy in plants, measured as non-photochemical quenching of chlorophyll fluorescence. What is known about PsbS in relation to...

Twenty years ago (Fowweather, 1928) a method for the preparation of gold sols for the Lange test on cerebrospinal fluids was published in which gold potassium bromide is reduced by potassium oxalate under the action of daylight. Temperature and light intensity were found to be complementary to some extent; thus it was found advisable to carry out the reaction at a somewhat raised temperature in...