Electrochemical and DFT studies on palladacycles revealed an increase in the metal–metal distance in the complexes leads to higher oxidation potentials.

Poly(triacetylenes) are rodlike molecules with electrons delocalized over a one-dimensional path. We show that they exhibit a power-law dependence of the second-order hyperpolarizability $\gamma$ on the monomer unit $n$ for short molecules and a smooth saturation toward a linear increase in longer molecules. The power law of $\gamma \propto n^a$ with $a\approx 2.5$ from dengenerate four-wave mixing and third-harmonic generation measurements is in good agreement with quantum-chemical calculations. The critical conjugation length for saturation in the three cases is shown to be approximately 60 carbon–carbon bonds, which indicates the upper boundary for the electron delocalization in such a one-dimensional molecular wire.