ABSTRACT
BODIPYs have a well-established role in biological sciences as chemosensors and versatile biological markers due to their chemical reactivity, which allows for fine-tuning of their photophysical characteristics. In this work, we combined the unique reactivity of arylazo sulfones with the advantages of a "sunflow" reactor to develop a fast, efficient, and versatile method for the photochemical arylation of BODIPYs and other chromophores. This approach resulted in red-shifted emitting fluorophores due to extended electronic delocalization at the 3- and 5-positions of the BODIPY core. This method represents an advantageous approach for BODIPY functionalization compared to existing strategies.
ABSTRACT
The photochemistry of tris(2,4-dibromophenyl)amine was investigated via time-resolved nanosecond spectroscopy. The tris(2,4-dibromophenyl)amine radical cation ("Magic Green") was immediately detected after the laser pulse; this intermediate then cyclizes to N-aryl-4a,4b-dihydrocarbazole radical cation. The latter transient reacted with molecular oxygen to provide the corresponding hydroperoxyl radical, which smoothly co-oxidize sulfides into sulfoxides. On the other hand, the photogenerated "Magic Green" was exploited to promote the co-oxidation of nucleophilic triarylphosphines to triarylphosphine oxides through an electron transfer process preventing the amine cyclization. In this case, the intermediate Ar3 POOâ¢+ was found to play a key role in phosphine oxide formation.
ABSTRACT
The photochemistry of tris( p-bromophenyl)amine was investigated in a nitrogen- and oxygen-flushed solution under laser flash photolysis conditions. The detected intermediates were the corresponding amine radical cation ("Magic Blue") and the N-phenyl-4a,4b-dihydrocarbazole radical cation that, under an oxygen atmosphere, is converted to the corresponding hydroperoxyl radical. The role of the last species was supported by the smooth co-oxidation of sulfides to sulfoxides. On the other hand, co-oxidation of nucleophilic triarylphosphines to triarylphosphine oxides arose from an electron transfer between the photogenerated "Magic Blue" and phosphine that prevented the amine cyclization. In this case, intermediate Ar3POOâ¢+ was found to play a key role in phosphine oxide formation.
ABSTRACT
The oxidation of triphenylphosphine in the presence of various photocatalytic systems (dicyanoanthracene/biphenyl, N-methylquinolinium, triphenylpyrylium, and thiatriphenylpyrylium tetrafluoroborate) was investigated by means of both steady state and laser flash photolysis experiments. The effect of different additives (including 1,4-benzoquinone, diphenylsulfoxide, tetramethylethylene, and sodium azide) on the photosensitized oxidation was investigated in order to fully characterize the involved intermediates. Photoinduced electron transfer and final regeneration of the catalyst occur when dicyanoanthracene and N-methylquinolinium are used, while in cage oxygen transfer to the photoexcited (thio)pyrylium derivatives have been characterized in the last two cases.