# chem: strange transitions: tying a crystal into a knot

<< Single crystals are typically brittle, inelastic materials. Such mechanical responses limit their use in practical applications, particularly in flexible electronics and optical devices >>

AA << describe single crystals of a well-known coordination compound—copper(II) acetylacetonate—that are flexible enough to be reversibly tied into a knot >>

Anna Worthy, Arnaud Grosjean, et al. Atomic resolution of structural changes in elastic crystals of copper(II) acetylacetonate. Nature Chemistry. doi: 10.1038/nchem.2848. Aug 28, 2017

http://www.nature.com/nchem/journal/vaop/ncurrent/full/nchem.2848.html

<< crystals exhibit traditional characteristics of not only hard matter, but soft matter like nylon >> John McMurtrie

<< Under strain the molecules in the crystal reversibly rotate and reorganise to allow the compression and expansion required for elasticity and still maintain the integrity of the crystal structure >> Jack Clegg

Bendable crystals tie current thinking in knots. Aug 29, 2017.

https://m.phys.org/news/2017-08-bendable-crystals-current.html