Versatile strategy to access fully functionalized benzodifurans: redox-active chromophores for the construction of extended pi-conjugated materials.
An efficient synthetic approach to construct a fully substituted benzo[1,2-b:4,5-b']difuran (BDF) 2a via base-catalyzed double annulations is presented. Compound 2a can readily undergo Suzuki, Heck, and Sonogashira coupling reactions to afford in good yields a manifold of extended pi-conjugated BDF derivatives, e.g., with pyridine termini (4-6) and with different spacers. These are highly luminescent materials that undergo two reversible one-electron oxidations. Remarkably, their photophysical and electrochemical properties can be largely tuned by methylation or protonation. Consequently, they can function as pH-dependent fluorescence switches. Finally, the observed electronic properties are explained on the basis of density functional theory.
Yi
Chenyi
C
Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
Blum
Carmen
C
Lehmann
Mario
M
Keller
Stephan
S
Liu
Shi-Xia
SX
Frei
Gabriela
G
Neels
Antonia
A
Hauser
Jürg
J
Schürch
Stefan
S
Decurtins
Silvio
S
D001572:Benzofurans / Q000138:chemical synthesis* / Q000737:chemistry; D003198:Computer Simulation; D006863:Hydrogen-Ion Concentration; D049449:Luminescence; D008163:Luminescent Measurements; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011725:Pyridines / Q000737:chemistry*
D001572:Benzofurans; D011725:Pyridines; C023666:pyridine