Synthesis, Photophysics, Electrochemistry, and Electrogenerated Chemiluminescence of a Homologous Set of BODIPY-Appended Bipyridine Derivatives

Two new 2,2'-bipyridine (bpy)-based ligands with ancillary BODIPY chromophores attached at the 4- and 4'-positions were prepared and characterized, which vary in the substitution pattern about the BODIPY periphery by either excluding (BB1) or including (BB2) a beta-alkyl substituent. Both absorb strongly throughout the visible region and are strongly emissive. The basic photophysics and electrochemical properties of BB1 and BB2 are comparable to those of the BODIPY monomers on which they are based. The solid-state structures and electronic structure calculations both indicate that there is negligible electronic communication between the BODIPY moieties and the intervening bpy spacers. Electrogenerated chemiluminescence spectra of the two bpy-BODIPY derivatives are similar to their recorded fluorescence profiles and are strongly influenced by substituents on the BODIPY chromophores. These 2,2'-bipyridine derivatives represent a new set of ligands that should find utility in applications, including light-harvesting, photocatalysis, and molecular electronics.