Remarkable catalysis of intersystem crossing of singlet (pentafluorophenyl)nitrene

General Photo‐Patterning of Polyelectrolyte Thin Films via Efficient Ionic Bis(Fluorinated Phenyl Azide) Photo‐Crosslinkers and their Post‐Deposition Modification

“…A possible reason for this may be the "heavy-atom" effect which promotes intersystem crossing. [15,17,21,33,36] Upon exchange of the Cl -with the non-nucleophilic PF 6 -, however, we obtained a DMF-soluble PDAM + PF 6 -that can be successfully photo-crosslinked with V. Therefore Cl -interferes with the bisFPA methodology, however this does not constitute a severe limitation. A compatible non-nucleophilic anion can be employed first, and the Cl -or the other desired non-compatible anions subsequently re-introduced into the film by ion-exchanged after photo-crosslinking.…”

“…Their occurrence in the solution state is already previously known. For example, laser flash photolysis has established that solvation in MeOH causes rapid intersystem crossing, probably through hydrogen-bonding stabilization of the triplet state in solution, [36] while solvation in H 2 O causes protonation of the singlet nitrene which is then attacked by H 2 O to give imine and quinone intermediates. [34,35] It will not be surprising that these occur here in the solid-state as well, thereby depleting the singlet nitrene population.…”

Photo-affinity labeling strategy to study the binding site of G protein-coupled receptors

“…The latter has made up by far the most promising development in the aryl azide series for photo-affinity labeling. They have benefited from singlet fluorinated arylnitrene which rearranges more slowly to the corresponding didehydroazepine than the unsubstituted species, thus allowing this intermediate to react with most chemical bonds [31][32][33][34][35]. However, fluorinated aryl azides can be activated only by light with wavelengths less than 300 nm, which might be unfavorable for sensitive proteins.…”

Photochemistry of Azides: The Azide/Nitrene Interface

“…Reprinted with permission from ref. 20 reagents in synthetic organic chemistry, 229 in photoaffi nity labeling, 7,230 and for the covalent modifi cation of polymer surfaces. 9,10 The effects of the number and positions of fl uorine substituents on the ring expansion of phenylnitrene have been extensively investigated by the Platz group.…”

“…9,10 The effects of the number and positions of fl uorine substituents on the ring expansion of phenylnitrene have been extensively investigated by the Platz group. 229,231 They concluded that fl uorine substitution at both ortho positions is required to inhibit the ring expansion effectively. 12 Similar to the case of ortho,ortho -dimethylphenyl azide, 226 photolysis of perfl uoro -and ortho,ortho -difl uorophenyl azides in an nitrogen matrix at 12 K gives only triplet nitrenes.…”