Utopian visions of the nanotechnology revolution suggest that one day we’ll be able to put tiny machines inside our body to perform routine screening and maintenance. But we’re a long way off from that future, as most of the nanoscale “machinery” we’ve created requires extensive intervention or carefully prepared conditions in order to do anything. But a report in today’s Nature describes an impressive feat of molecule-scale engineering: a four-wheel drive “car” that can run across any conductive surface, powered by electrons.
The whole thing is a single molecule. Its core is formed by two hubs that have a five-ringed structure at their core. The hubs are connected by a rigid rod formed from carbon atoms, held together by triple bonds. Each hub is flanked by two “wheels,” each consisting of a three-ringed structure. The bulk of the molecule is a carbon backbone, with a small number of nitrogen and sulfur molecules thrown in.
The key to the system is the bond between the wheel and its hub, which is a double bond formed between two carbon atoms. Electrons can cause this double bond to rotate, which places part of the wheel in close proximity to a bulky side-molecule attached to the hub. This bulky piece acts a bit like a ratchet; the wheel requires some vibrational energy to get past it. Once it does, it’s positioned so that another dose of electrons can cause it to rotate again.
Nenhum comentário:
Postar um comentário