Synthesis, Optical, Electrochemical, and Theoretical Studies of Dipolar Ruthenium Alkynyl Complexes with Oligo(phenylenevinylene) Bridges.

Abstract

The syntheses of oligo(p-phenylenevinylene)s (OPVs) end-functionalized with a ligated ruthenium alkynyl unit as a donor and a nitro as acceptor, namely trans-[Ru{C≡C-1-C6 H4 -4-(E)-CH=CH-1-C6 H2 -2,5-Et2 -4-(E)-CH=CH-1-C6 H2 -2,5-Et2 -4-(E)-CH=CH-1-C6 H4 -4-NO2 }Cl(dppe)2 ] (Ru4), trans-[Ru{C≡C-1-C6 H4 -4-(E)-CH=CH-1-C6 H2 -2,5-Et2 -4-(E)-CH=CH-1-C6 H2 -2,5-Et2 -4-(E)-CH=CH-1-C6 H2 -2,5-(n-hexyl)2 -4-(E)-CH=CH-1-C6 H2 -2,5-(n-hexyl)2 -4-(E)-CH=CH-1-C6 H4 -4-NO2 }Cl(dppe)2 ] (Ru6), and trans-[Ru{C≡C-1-C6 H4 -4-(E)-CH=CH-1-C6 H2 -2,5-Et2 -4-(E)-CH=CH-1-C6 H2 -2,5-Et2 -4-(E)-CH=CH-1-C6 H2 -2,5-(n-hexyl)2 -4-(E)-CH=CH-1-C6 H2 -2,5-(n-hexyl)2 -4-(E)-CH=CH-1-C6 H2 -2,5-(2-ethyl-n-hexyl)2 -4-(E)-CH=CH-1-C6 H2 -2,5-(2-ethyl-n-hexyl)2 -4-(E)-CH=CH-1-C6 H4 -4-NO2 }Cl(dppe)2 ] (Ru8), are reported, together with those of precursor alkynes. Their electrochemical properties were assessed by cyclic voltammetry (CV), their linear optical and quadratic nonlinear optical (NLO) properties assayed by UV/Vis-NIR spectroscopy and hyper-Rayleigh scattering studies at 1064 nm, respectively, and their linear optical properties in the formally RuIII state examined by UV/Vis-NIR spectroelectrochemistry. Computational studies employing time-dependent density functional theory were undertaken on model complexes to rationalize the optical observations.