Synthesis and structural characterisation of luminescent di- and tri-nuclear palladium(II) acetylide complexes as building blocks for metallodendrimers

Abstract

The reaction of the starting complex trans-Pd(PEt 3) 2Cl 2 with branched alkynyl ligands, 1,3,5-triethynylbenzene (L1) and 1,3-diethynyl-5-triisopropylsilylethynylbenzene (L2), in the presence of HNEt 2 and copper(I) catalyst led to formation of the respective luminescent branched acetylide complexes, 1,3,5-[Cl(Et 3P) 2PdC≡C] 3C 6 H 3 1 and 1,3-[Cl(Et 3P) 2 PdC≡C] 2-5-[( iPr) 3SiC≡C] C 6H 3 2, which can serve as building blocks for the construction of metallodendrimers either by a divergent or a convergent approach. Photophysical studies of these complexes showed the di- and tri-nuclear palladium complexes 1 and 2 are emissive in EtOH-MeOH (4:1, v/v) glass at low temperature. Synthesis of the first generation metallodendrimers using 1 as a building block has also been attempted and shows promising results.