Functionalized Paddle Wheel Complexes from BODIPY Carboxylic Acids

Abstract

AbstractA series of BODIPY carboxylic acids carrying aromatic linking units between the luminophor and the carboxylate functional group was prepared using Sonogashira and Stille type coupling protocols. Ferrocene and hydroquinone units could be introduced by either of these methods. Metal complex formation of the BODIPY carboxylic acid ligands was investigated with the divalent metal ions of copper and rhodium. Copper forms insoluble material, which crystallized in one case. The X‐ray crystallographic analysis shows the presence of a BODIPY‐appended paddle wheel complex with typical Cu···Cu and Cu–O distances and four BODIPY units in a distance of 9.681 Å and 9.747 Å from the dinuclear center. Treatment with donor solvents results in the decomposition/monomerization of the compound, which could be shown crystallographically for pyridine. Rhodium(II) ions form soluble paddle wheel complexes with four different BODIPY carboxylates. The crystallographic analysis of one example shows the isostructural nature of the dirhodium and the dicopper derivatives. Optical spectroscopy and cyclic voltammetry provide first insights into efficient intramolecular energy‐ and electron transfer pathways for the rhodium complexes.