Organometallic Oligomers Based on Bis(arylacetylide)bis(P-chirogenic phosphine)platinum(II) Complexes: Synthesis and Photonic Properties

Abstract

A series of P-chirogenic oligomers of the type (CC<b>aryl</b>CCPtL₂)<i>_n</i> [L = (<i>R</i>)- and (<i>S</i>)-P­(Ph)­(<i>i</i>Pr)­(C₁₇H₃₅); <b>aryl</b> = 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 [¹H, ³¹P 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>i</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