TY - JOUR

T1 - Fluorescent Pyranoindole Congeners

T2 - Synthesis and Photophysical Properties of Pyrano[3,2-f], [2,3-g], [2,3-f], and [2,3-e]Indoles

AU - Sharapov, Ainur D

AU - Fatykhov, Ramil F

AU - Khalymbadzha, Igor A

AU - Valieva, Maria I

AU - Nikonov, Igor L

AU - Taniya, Olga S

AU - Kopchuk, Dmitry S

AU - Zyryanov, Grigory V

AU - Potapova, Anastasya P

AU - Novikov, Alexander S

AU - Sharutin, Vladimir V

AU - Chupakhin, Oleg N

N1 - Sharapov, A.D.; Fatykhov, R.F.; Khalymbadzha, I.A.; Valieva, M.I.; Nikonov, I.L.; Taniya, O.S.; Kopchuk, D.S.; Zyryanov, G.V.; Potapova, A.P.; Novikov, A.S.; Sharutin, V.V.; Chupakhin, O.N. Fluorescent Pyranoindole Congeners: Synthesis and Photophysical Properties of Pyrano[3,2-f], [2,3-g], [2,3-f], and [2,3-e]Indoles. Molecules 2022, 27, 8867. https://doi.org/10.3390/molecules27248867

PY - 2022/12/13

Y1 - 2022/12/13

N2 - This paper reports the synthesis of four types of annulated pyranoindole congeners: pyrano[3,2-f]indole, pyrano[2,3-g]indole, pyrano[2,3-f]indole, and pyrano[2,3-e]indole and photophysical studies in this series. The synthesis of pyrano[3,2-f], [2,3-g], and [2,3-e]indoles involve a tandem of Bischler-Möhlau reaction of 3-aminophenol with benzoin to form 6-hydroxy- or 4-hydroxyindole followed by Pechmann condensation of these hydroxyindoles with β-ketoesters. Pyrano[2,3-f]indoles were synthesized through the Nenitzescu reaction of p-benzoquinone and ethyl aminocrotonates and subsequent Pechmann condensation of the obtained 5-hydroxyindole derivatives. Among the pyranoindoles studied, the most promising were pyrano[3,2-f] and [2,3-g]indoles. These compounds were characterized by moderate to high quantum yields (30-89%) and a large (9000-15,000 cm-1) Stokes shift. More detailed photophysical studies were carried out for a series of the most promising derivatives of pyrano[3,2-f] and [2,3-g]indoles to demonstrate their positive solvatochromism, and the data collected was analyzed using Lippert-Mataga equation. Quantum chemical calculations were performed to deepen the knowledge of the absorption and emission properties of pyrano[3,2-f] and [2,3-g]indoles as well as to explain their unusual geometries and electronic structures.

AB - This paper reports the synthesis of four types of annulated pyranoindole congeners: pyrano[3,2-f]indole, pyrano[2,3-g]indole, pyrano[2,3-f]indole, and pyrano[2,3-e]indole and photophysical studies in this series. The synthesis of pyrano[3,2-f], [2,3-g], and [2,3-e]indoles involve a tandem of Bischler-Möhlau reaction of 3-aminophenol with benzoin to form 6-hydroxy- or 4-hydroxyindole followed by Pechmann condensation of these hydroxyindoles with β-ketoesters. Pyrano[2,3-f]indoles were synthesized through the Nenitzescu reaction of p-benzoquinone and ethyl aminocrotonates and subsequent Pechmann condensation of the obtained 5-hydroxyindole derivatives. Among the pyranoindoles studied, the most promising were pyrano[3,2-f] and [2,3-g]indoles. These compounds were characterized by moderate to high quantum yields (30-89%) and a large (9000-15,000 cm-1) Stokes shift. More detailed photophysical studies were carried out for a series of the most promising derivatives of pyrano[3,2-f] and [2,3-g]indoles to demonstrate their positive solvatochromism, and the data collected was analyzed using Lippert-Mataga equation. Quantum chemical calculations were performed to deepen the knowledge of the absorption and emission properties of pyrano[3,2-f] and [2,3-g]indoles as well as to explain their unusual geometries and electronic structures.

KW - Chemical Phenomena

KW - Coloring Agents

KW - Indoles/chemistry

U2 - 10.3390/molecules27248867

DO - 10.3390/molecules27248867

M3 - Article

C2 - 36557999

VL - 27

JO - Molecules

JF - Molecules

SN - 1420-3049

IS - 24

M1 - 8867

ER -