Carbyne ( a.k.a. Linear Acetylenic Carbon - LAC) is a monovalent allotrope of carbon with three non-bonded electrons having the chemical structure (−C≡C−)n in a (long) repeating chain, with alternating single and triple bonds.
In the same way that graphene is the ultimate 2D carbon system made by isolating a single, one atom thick layer from graphite, carbyne represents the ultimate 1D carbon system - a 'chain' with a diameter of one only atom.
Since the 1960s, numerous laboratory studies have claimed to have observed (and/or created) carbyne.
Theoretical calculations show that carbyne chains would, per density, be the strongest material known. Considerably exceeding the tensile strength of diamond, graphene and fullerenes.
So far, its existence has been confirmed in short, self-linked (endohedral) chains of up to 6000 atoms long.
Because of the lack of truly isolated carbyne chains for experimentation, its chemical and electronic properties are as yet unknown, and restricted to theoretical models. Some researchers assert that it cannot stably exist in any but the shortest of chains. The limit so far observed is around 40 atoms.
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