When designing new chemical sensors and switches, it is desirable to synthesise materials that are able to retain their structural features even after the uptake of a small molecule. Usually to achieve this, polymeric materials are used with extensive strong bonding that are able to withstand structural changes. 
Wojciech Grochala and his team began investigating macrocyclic nickel complexes and discovered a complex that could absorb, then desorb water with retention of its crystallinity. The molecular crystal consists of an almost square planar coordination of nickel(II) supported by a 10 membered, tetradentate sulfur macrocycle. During their investigations, the team discovered that the uptake and release of water vapour was reversible and was accompanied by a change in colour and magnetic susceptibility. The flexible nature of the macrocyclic ligand allows for Ni(12aneS4)(BF4)2 to keep its crystallinity upon water uptake which is rare for molecular crystals and a stark contrast to previously studied coordination polymers.
This exciting finding opens up the possibility of nickel molecular crystals being used as moisture sensors in the future.
To find out more, download the full Dalton Transactions paper:
Chemo-switched chromatic, magnetic and structural changes with retention of molecular crystallinity, Ni(12aneS4)(BF4)2
Andrew J. Churchard, Mariana Derzsi, Zvonko Jagličić, Arndt Remhof and Wojciech Grochala
The presence of C–F bonds in organic compounds has a dramatic influence on their physical, chemical and biological properties. Metal mediated reactions that result in C–F bond formation or C–F bond activation have attracted considerable attention as the demand for organofluorine compounds has increased. Metal-catalysed decarboxylative cross-coupling reactions using trifluoracetate as a cheap source of introducing “CF3” represents an attractive approach. Until now, little has been known about the fragmentation mechanisms of metal trifluoracetates. In this Dalton Transactions HOT article, Rijs and O’Hair use a combination of gas-phase 3D quadrupole ion trap mass spectrometry experiments and density functional theory (DFT) calculations to examine the mechanism of thermal decomposition of fluorinated coinage metal carboxylates. Synthetic chemists should be able to use these results to design new ways of incorporating CF3 and F fragments using trifluoroacetate.
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