Electrochemical properties of tetraethynylethenes, fully cross-conjugated Π-chromophores, and tetraethynylethene-based carbon-rich molecular rods and dehydroannulenes

The redox properties of tetraethynylethenes and carbon-rich molecular rods and dehydroannulenes built from these fully cross-conjugated molecular construction units are reported here for the first time. All monomeric and oligomeric cyclic and acyclic tetraethynylethenes are difficult to oxidize but undergo stepwise reductions, with the number of distinct steps increasing with the length of the linearly conjugated all-carbon backbone and the size of the Π system. The reductions are also facilitated when the length of the carbon backbone and the number of Π electrons in the molecules increase.