Photocyclisation of 2-pyridyl phenyl ketone. A reaction driven by hydrogen bonding

Photoinduced Oxygen Uptake of Diphenylamines in Solution and Their Ring Closure Revisited

“…It may be formed in two dehydrogention steps: the first yields superoxide O 2 •-and the corresponding carbazole radical and the second converts both into H 2 O 2 and carbazole. A corresponding O 2 -mediated sequence SCHEME 1 SCHEME 2 has been suggested by Bortolus et al 23 for closure into the pyrrole ring.…”

Role of micellar inclusion in the photochemistry of 2-pyridyl phenyl ketone. A steady-state and laser flash photolytic study

“…The spectral and kinetic data obtained are reported in Table 2 ) of 2-PPK is similar to that previously found in pure water. 2 Two transients were observed (first-order decay), a shortlived one, T 1 (t 1 = 420 ns at 330 nm in an oxygen-free solution, quenching by oxygen, k ox = 2.8 Â 10 9 dm 3 mol À1 s…”

“…The close similarity of the photobehavior of a water solution and a dilute micellar solution at the earliest irradiation times (spectrum A) allows one to hypothesize a reaction mechanism analogous to that proposed in water. 2 The photochemistry originates from the shortlived triplet n,p * state, which is here revealed indirectly by biphenyl sensitization occurring in the micelle. Sensitization of biphenyl occurs since the triplet energies of 2-PPK 15 and biphenyl 16 match (E T % 65.5 kcal mol…”

Unravelling the Fast Photocyclisation Reaction Mechanism(s) of 2-Benzoylpyridine in Aqueous Solvent by Time-resolved Spectroscopy

“…The different positions of N-substituents within the aromatic rings can significantly change the photophysical properties and photochemical reactivity of the BPy nπ* triplet state. [2,3] By studying 2-BPy, 3-BPy and 4-BPy (where the number represents the N atom position within the aromatic rings) in different solvents with steady-state and laser flash photolysis measurements, Favaro and coworkers found that the lifetimes and reactivity of the triplet states 3-BPy and 4-BPy are very similar to those of BP [2] while they observed appreciable differences and an unusual photodegradation behavior for 2-BPy. [3] The fast intramolecular photocyclisation reaction occurs for 2-BPy in solvents that have H-bonding ability, but the reaction mechanism(s) for this reaction appears quite complex and controversial.…”

“…[1][2][3] Benzoylpyridines (BPy) are similar to BP and may be employed as potential photosensitizers due to their better water solubility than BP and they are particularly interesting since they contain heteroaromatic ring(s) with the nitrogen atom able to appear at different positions in the molecule. The different positions of N-substituents within the aromatic rings can significantly change the photophysical properties and photochemical reactivity of the BPy nπ* triplet state.…”