Synthesis of Coumarin/Pyrrole-Fused Heterocycles and Their Photochemical and Redox-Switching Properties

Two coumarin/pyrrole-fused heterocycles were synthesized to investigate their photochemical and redox-switching properties. Photooxidation of the colorless diphenyl-substituted pyrrolocoumarin resulted in a distinct change to red and a sharp decrease in fluorescence intensity. The photooxidized product can be swiftly reverted to the original form by NaCNBH₃ reduction or hydrogenation

Visible Light Photoredox Catalysis: Synthesis of Indazolo[2,3‑<i>a</i>]quinolines from 2‑(2-Nitrophenyl)-1,2,3,4-tetrahydroquinolines

The synthesis of indazolo[2,3-<i>a</i>]quinoline derivatives in moderate to good yields from 2-(2-nitrophenyl)-1,2,3,4-tetrahydroquinolines via visible light photoredox catalysis is reported. The reaction involves a novel ruthenium-catalyzed intramolecular formation of the N–N bond of the indazole ring

Synthesis of Coumarin/Pyrrole-Fused Heterocycles and Their Photochemical and Redox-Switching Properties

Two coumarin/pyrrole-fused heterocycles were synthesized to investigate their photochemical and redox-switching properties. Photooxidation of the colorless diphenyl-substituted pyrrolocoumarin resulted in a distinct change to red and a sharp decrease in fluorescence intensity. The photooxidized product can be swiftly reverted to the original form by NaCNBH₃ reduction or hydrogenation

Photochromism of <i>o</i>‑Nitrophenyl-Substituted Oxazabicycles

The <i>o</i>-nitrophenyl-substituted oxazabicycle <b>1</b> was prepared via a one-pot tandem multicomponent reaction. Upon exposure to UV light in CH₂Cl₂, it turned purple and reverted back to its original color while being heated. The in situ trapping of the photogenerated product with trimethylsilyl cyanide yielded the adduct <b>4</b>, which confirmed the formation of the ring-opened zwitterionic species <b>2</b>. The EPR spectroscopic data, PBN spin-trapping experiments, and spectroelectrochemical studies of the model compound <b>7</b> provided evidence to support that the photochromism of <b>1</b> involved the zwitterionic biradical intermediate <b>5</b>, generated by photoinduced intramolecular electron transfer from the amine moiety to the nearby <i>o</i>-nitrophenyl group. Further, two photogenerated side products responsible for the photofatigue of <b>1</b> were isolated and characterized, and a possible mechanism for their formation was proposed

Synthesis of Coumarin/Pyrrole-Fused Heterocycles and Their Photochemical and Redox-Switching Properties

Two coumarin/pyrrole-fused heterocycles were synthesized to investigate their photochemical and redox-switching properties. Photooxidation of the colorless diphenyl-substituted pyrrolocoumarin resulted in a distinct change to red and a sharp decrease in fluorescence intensity. The photooxidized product can be swiftly reverted to the original form by NaCNBH₃ reduction or hydrogenation

Visible Light Photoredox Catalysis: Synthesis of Indazolo[2,3‑<i>a</i>]quinolines from 2‑(2-Nitrophenyl)-1,2,3,4-tetrahydroquinolines

The synthesis of indazolo[2,3-<i>a</i>]quinoline derivatives in moderate to good yields from 2-(2-nitrophenyl)-1,2,3,4-tetrahydroquinolines via visible light photoredox catalysis is reported. The reaction involves a novel ruthenium-catalyzed intramolecular formation of the N–N bond of the indazole ring

Visible Light Photoredox Catalysis: Synthesis of Indazolo[2,3‑<i>a</i>]quinolines from 2‑(2-Nitrophenyl)-1,2,3,4-tetrahydroquinolines

The synthesis of indazolo[2,3-<i>a</i>]quinoline derivatives in moderate to good yields from 2-(2-nitrophenyl)-1,2,3,4-tetrahydroquinolines via visible light photoredox catalysis is reported. The reaction involves a novel ruthenium-catalyzed intramolecular formation of the N–N bond of the indazole ring

Photochromism of <i>o</i>‑Nitrophenyl-Substituted Oxazabicycles

The <i>o</i>-nitrophenyl-substituted oxazabicycle <b>1</b> was prepared via a one-pot tandem multicomponent reaction. Upon exposure to UV light in CH₂Cl₂, it turned purple and reverted back to its original color while being heated. The in situ trapping of the photogenerated product with trimethylsilyl cyanide yielded the adduct <b>4</b>, which confirmed the formation of the ring-opened zwitterionic species <b>2</b>. The EPR spectroscopic data, PBN spin-trapping experiments, and spectroelectrochemical studies of the model compound <b>7</b> provided evidence to support that the photochromism of <b>1</b> involved the zwitterionic biradical intermediate <b>5</b>, generated by photoinduced intramolecular electron transfer from the amine moiety to the nearby <i>o</i>-nitrophenyl group. Further, two photogenerated side products responsible for the photofatigue of <b>1</b> were isolated and characterized, and a possible mechanism for their formation was proposed

Synthesis of Coumarin/Pyrrole-Fused Heterocycles and Their Photochemical and Redox-Switching Properties

Two coumarin/pyrrole-fused heterocycles were synthesized to investigate their photochemical and redox-switching properties. Photooxidation of the colorless diphenyl-substituted pyrrolocoumarin resulted in a distinct change to red and a sharp decrease in fluorescence intensity. The photooxidized product can be swiftly reverted to the original form by NaCNBH₃ reduction or hydrogenation

Photochromism of <i>o</i>‑Nitrophenyl-Substituted Oxazabicycles

The <i>o</i>-nitrophenyl-substituted oxazabicycle <b>1</b> was prepared via a one-pot tandem multicomponent reaction. Upon exposure to UV light in CH₂Cl₂, it turned purple and reverted back to its original color while being heated. The in situ trapping of the photogenerated product with trimethylsilyl cyanide yielded the adduct <b>4</b>, which confirmed the formation of the ring-opened zwitterionic species <b>2</b>. The EPR spectroscopic data, PBN spin-trapping experiments, and spectroelectrochemical studies of the model compound <b>7</b> provided evidence to support that the photochromism of <b>1</b> involved the zwitterionic biradical intermediate <b>5</b>, generated by photoinduced intramolecular electron transfer from the amine moiety to the nearby <i>o</i>-nitrophenyl group. Further, two photogenerated side products responsible for the photofatigue of <b>1</b> were isolated and characterized, and a possible mechanism for their formation was proposed