Photophysical studies of 2, 6-dibrominated BODIPY dyes substituted with 4-benzyloxystyryl substituents

A series of novel 2,6-dibrominated BODIPY dyes with styryl groups at the 3,5-positions has been prepared, and their photophysical properties have been analyzed to assess their potential utility for use as photosensitizers in photodynamic therapy and in bioimaging

A Photo-Favorskii Ring Contraction Reaction: The Effect of Ring

The effect of ring size on the photo-Favorskii induced ring-contraction reaction of the hydroxybenzocycloalkanonyl acetate and mesylate esters (7a–d, 8a–c) has provided new insight into the mechanism of the rearrangement. By monotonically decreasing the ring size in these cyclic derivatives, the increasing ring strain imposed on the formation of the elusive bicyclic spirocyclopropanone 20 results in a divergence away from rearrangement and toward solvolysis. Cycloalkanones of seven or eight carbons undergo a highly efficient photo-Favorskii rearrangement with ring contraction paralleling the photochemistry of p-hydroxyphenacyl esters. In contrast, the five-carbon ring does not rearrange but is diverted to the photosolvolysis channel avoiding the increased strain energy that would accompany the formation of the spirobicyclic ketone, the “Favorskii intermediate 20”. The six-carbon analogue demonstrates the bifurcation in reaction channels, yielding a solvent-sensitive mixture of both. Employing a combination of time-resolved absorption measurements, quantum yield determinations, isotopic labeling, and solvent variation studies coupled with theoretical treatment, a more comprehensive mechanistic description of the rearrangement has emerged

A New Photoremovable Protecting Group Containing 2-Methyl-1,4-Naphthoquinone: Steady State and Transient Spectroscopic Studies

The 2-methyl-1, 4-naphthoquinone moiety has been proposed as a photoremovable protecting group when substituted with carboxylate in different solvents upon irradiation. Picoseconds pump-probe investigations in different solvents afforded the rate constants of intersystem crossing from singlet to triplet to be around 1011 s-1 and the lifetime of the triplet state was about 0.7 ns in methanol and 0.12 µs in the mixture water-acetonitrile

Photophysical studies of 2, 6-dibrominated BODIPY dyes substituted with 4-benzyloxystyryl substituents

A series of novel 2,6-dibrominated BODIPY dyes with styryl groups at the 3,5-positions has been prepared, and their photophysical properties have been analyzed to assess their potential utility for use as photosensitizers in photodynamic therapy and in bioimaging