Synthesis, characterization and preliminary investigation of the electro redox properties of anthracenyl-functionalized terpyridyl ligands

We report the synthesis, characterization and preliminary investigation of the electro redox properties of soluble bromoterpyridine ligand precursors L1, L2 and L3 having one to three anthracenyl modules. The synthetic protocol is based on sequential palladium cross-coupling reactions between 9,10-dibromoanthracene and bromoterpyridine, 9-bromoanthracene-terpyridine or 9-bromo-dianthraceneterpyridine synthons. With increasing numbers of anthracene units on the terpyridine ligand, common absorption wavelengths at the near visible region and enhanced molar absorptivity coefficients were recorded. However, the luminescence intensity decreases with increasing length of π-conjugation relating to aggregation effects in the molecules. The cyclic voltammograms of L1 and L2 display good electro redox activity, being better than that of L3.