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

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.

One-Pot Synthesis of Rotationally Restricted, Conjugatable, BODIPY Derivatives from Phthalides.

O-Ethylation of phthalides with Meerwein's reagent followed by reaction of the ensuing salts with pyrrole, results in the formation of 5-alkoxy-5-phenyl dipyrromethane derivatives, which function as ready precursors of ortho-substituted 8-aryl BODIPY derivatives by reaction with borontrifluoride etherate, an overall process that can be carried out in a one-pot operation.