Organometallic oligomers based on bis(arylacetylide)bis(P-chirogenic phosphine)platinum(II) complexes: synthesis and photonic properties.

A series of P-chirogenic oligomers of the type (-C≡C-aryl-C≡C-PtL2-)n [L = (R)- and (S)-P(Ph)(iPr)(C17H35); aryl = 1,4-benzene, 2,1,3-benzothiadiazole] along the corresponding achiral analogues (L = PBu3) and model complexes PhC≡CPtL2C≡CPh were prepared from the ephedrine strategy and were fully characterized [(1)H, (31)P NMR; IR; small-angle X-ray scattering (SAXS); gel permeation chromatography (GPC); thermal gravimetric analysis (TGA); circular dichroism, UV-vis, and luminescence spectroscopy; photophysics, and degree of anisotropy measurements]. From the CD measurements, the chiral environment of the phosphine ligands is modestly felt by the aryl moieties. Concurrently, the TGA shows that the P(C17H35)(Ph)(i-Pr)-containing materials are more stable than those containing the shorter chain ligand PBu3, and exhibits red-shifted absorption and emission bands compared to those including the PBu3 ligands. The presence of the long chain on the phosphorus atoms does not greatly alter the photophysical parameters, notably the emission lifetimes, and fast triplet energy transfer terminal* → central unit has been deduced from the absence of luminescence arising from the terminal units.