Merry Christmas – Ho Ho Ho

Dave T. tells us of his crystallographic Christmas inspiration!

What does it look like?

What is it?

Sitting at my desk on the last working Friday of the year, just minutes away from a barbeque, Dr Maynard-Casely lays down the challenge for a "cheesy-corny Christmas-themed post". Distracted by Steve Smith's century (on captaincy debut), thinking was not easy, until my mind turned to a project in which I am currently involved.

The complex shown above is a trinuclear complex containing three holmium ions – HoHoHo. This was reported in 2005 by Junk and Deacon and contains quinolinolate anions as the ligating groups. This anion is typically used in gravimetric analysis as it coordinates to metal ions to form highly insoluble complexes. A derivative of this ligand has been used in anti-diarrhoea medication and is also being investigated in anti-Alzheimer's medication.

The structure has three holmium atoms in close proximity, bridged by the oxygen atoms of the quinolinolate ligands. A recent analogue of this compound containing dysprosium in place of holmium has been shown to act as a single molecule magnet at low temperatures (Chilton et al., Inorg. Chem., 2014, 53, 2528). This means that each molecule acts like a minute magnet, albeit at temperatures below that of liquid nitrogen. Solid state packing of these complexes is, unsurprisingly, dominated by pi-pi interactions.

Where did the structure come from?

The structure was published in Z. Anorg. Allg. Chem., 2005, 631, 2647.

Tags: molecular   Christmas   Alzheimer's disease