Synthesis and photophysical studies of crown ether-bodipy dyes and the fabrication of bodipy embedded fluorescent nanofibers

Abstract

This study has three major objectives: 1) to synthesize a series of structurally related BODIPY dyes, 2) to fabricate BODIPY embedded electrospun nanofibers, and 3) to investigate and characterize the photophysical properties of all synthesized BODIPY dyes with a special focus on their ability to generate singlet oxygen. This thesis first explores the acid catalysed condensation reaction to produce two structurally analogous meso-substituted BODIPY dyes based on cuminaldehyde and 4-dimethylaminobenzaldehdye. In order to enhance the rate of ISC and promote the generation of reactive oxygen species bromine atoms were then attached to the BODIPY 2,6-positions. These BODIPY dyes were then embedded in a polystyrene solution and electrospun into nanofibers. The resulting nanofibers were found to be highly fluorescent, but were no longer able to generate singlet oxygen. Ion-sensitive BODIPYs were prepared from the dibrominated BODIPY dyes by employing a modified Knoevenagel condensation reaction to form a styryl bond with 4'-formylbenzo-15-crown-5 at the 3,5-position of the BODIPY core. Changes in the morphology and position of the absorption and emission spectra of these crown ether-styryl BODIPY dyes were observed in the presence of sodium ions. These results imply that crown ether-substituted BODIPY dyes could function as ion sensors.