Synthesis of light-harvesting dendrimers focally anchored with crown ethers or terpyridine ligands

Abstract

Crown ethers and terpyridine ligands have been successfully attached to the focal point of light harvesting phenylacetylene monodendrons through Pd-catalyzed coupling reactions. The structures of these functional monodendrons were characterized by ¹H and ¹³C NMR spectroscopy, mass spectrometry and elemental analysis. Such binding-ligand anchored dendrons exhibit broad absorption, large molar extenction coefficients and high fluoresence quantum yields. Coordination of crown ethers with alkali ions results in a significant increase in absorption strength in the UV range, but little alteration in either intensity or position of fluorescence emission. Coordination of terpyridine ligands with Ru²⁺, however, does efficiently quench the fluorescence from the dendrons, albeit only the smallest dendron exhibits efficient binding.