Giants in chemistry are not what you think they are

06 December 2013 - Giantism

giant with far end fading away in the distance.PNGA recent xkcd comic demonstrating various degrees of large in astronomical telescopes reminded this blog of the preoccupation of some chemists with giants. Giants appear to pop up in the strangest of places. Take for example a giant spokewheel here. Considering that this conjugated macrocycle is only 6 nanometer in diameter puts some perspective on the use of the word "giant" in chemistry. Another such giant of chemistry is the Mo72Fe30 cluster Keplerate reported here. In host-guest chemistry if the guest is already big - a fullerene - then the host must certainly by a giant according to the authors of this article. In one of the illustrations the far end of a cage structure is faded. For dramatic effect only because the edge length is just 3.9 nm. How bad can your eyesight be. Supramolecular chemistry is already concerned with molecules larger than your average molecule. So what about the giant metallo-supramolecular cage (1.7  1.7  2.6 nm) in this report, something like the world-champion lightweight boxing. In polymer chemistry molecules are by definition macro but this dendrimer is not just mega-large although in the mega-dalton range but apparently another giant (33 nm diameter).
Physical effects can also suffer from giantism but curiously only in the context of getting significantly smaller. We have giant negative thermal expansion here and a giant photobleaching suppression effect here. It appears chemists have already used up the phrase giant for things that are not really that big. What will they come up with when things get really big or effects really reduced?

Note added: The megaenzymes are coming! DOI