Solvent‐Sensitive Emitting Urea‐Bridged bis‐BODIPYs: Ready Access by a One‐Pot Tandem Staudinger/Aza‐Wittig Ureation

• Published in: Chemistry : a European journal Vol. 23; no. 69; pp. 17511 - 17520
• Main Authors: Cristóbal López, J., del Rio, Mayca, Oliden, Ainhoa, Bañuelos, Jorge, López‐Arbeloa, Iñigo, García‐Moreno, Inmaculada, Gómez, Ana M.
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 11.12.2017; Wiley Subscription Services, Inc
• Subjects: aza-Wittig; Charge transfer; Chemistry; Chemistry, Multidisciplinary; Conjugation; Emission; Fluorescence; Light effects; Microprocessors; Physical Sciences; Science & Technology; Solvents; Staudinger reaction; Urea; Ureas; ureation; BORON DIPYRROMETHENE DYES; ELECTROGENERATED CHEMILUMINESCENCE; PHOTODYNAMIC THERAPY; SPECTROSCOPIC PROPERTIES; EFFICIENT SYNTHESIS; DIFLUORIDE BODIPY; charge transfer; Staudinger reaction; fluorescence; AXIAL CHIRALITY; FLUORESCENT-PROBES; aza-Wittig; ureation; TRIPLET EXCITED-STATE; CARBON-DIOXIDE
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201703383

Herein we describe the synthesis, and computationally aided photophysical characterization of a new set of urea‐bridged bis‐BODIPY derivatives. These new dyads are efficiently obtained by a one‐pot tandem Staudinger/aza‐Wittig ureation protocol, from easily accessible meso‐phenyl ortho‐azidomethyl BODIPYs. These symmetric bis‐BODIPYs outstand by a high absorption probability and excellent fluorescence and laser emission in less polar media. Nevertheless, this emission ability decreases in more polar media, which is ascribed to a light‐induced charge‐transfer from the urea spacer to the dipyrrin core, a process that can be modulated by appropriate changes in the substitution pattern of the BODIPY core. Furthermore, this ureation protocol can also be employed for the direct conjugation of our BODIPY‐azides to amine‐containing compounds, thus providing access to fluorescent non‐symmetric ureas. Urea‐bridged bis‐BODIPYs, obtained by a one‐pot tandem ureation protocol from meso‐phenyl ortho‐azidomethyl BODIPYs, display a high absorption probability and excellent fluorescence and laser emission in less polar media. Their emission ability decreases in more polar media, possibly by a light‐induced charge transfer, a process that can be modulated by appropriate changes in the substitution pattern of the BODIPY core.