Previous to our discussion, we first recall the geometric and electronic structures of one-dimension alkyne chain (C2nH2) and cyclo-[2n]-carbon (Figure ). Two Lewis structures of cyclo-[2n]-carbon molecules, namely average-bonding and single-triplet alternating model, have been proposed in previous references (Figure ). However, it was until recent synthesis via atom manipulation by K. Kaiser et. al. that two neighboring bond lengths in cyclo-[2n]-carbon are observed to be unequal. Lu et. al. demonstrated that the geometric structure of cyclo-[2n]-carbon should be a betweenness of two models through wavefunction analyses based on DFT calculations. For alkyne chain, the two orthogonal π-conjugated systems are identical, whereas for those in cyclo-[2n]-carbon, the two orthogonal π-conjugated systems are different depending on the direction of 2p orbitals involved in the conjugated systems, and can be classified as in-plane and out-plane (Figure ). For cyclo-[2n]-carbon with infinite n, taking a local part of structure will be the same as alkyne chain, i.e. with the ring size (n) increasing, the difference between two π-conjugated systems in cyclo-[2n]-carbon becomes diminished.