A rapidly-reversible absorptive and emissive vapochromic Pt(II) pincer-based chemical sensor

Abstract

Selective, robust and cost-effective chemical sensors for detecting small volatile-organic compounds (VOCs) have widespread applications in industry, healthcare and environmental monitoring. Here we design a Pt(II) pincer-type material with selective absorptive and emissive responses to methanol and water. The yellow anhydrous form converts reversibly on a subsecond timescale to a red hydrate in the presence of parts-per-thousand levels of atmospheric water vapour. Exposure to methanol induces a similarly-rapid and reversible colour change to a blue methanol solvate. Stable smart coatings on glass demonstrate robust switching over 104 cycles, and flexible microporous polymer membranes incorporating microcrystals of the complex show identical vapochromic behaviour. The rapid vapochromic response can be rationalised from the crystal structure, and in combination with quantum-chemical modelling, we provide a complete microscopic picture of the switching mechanism. We discuss how this multiscale design approach can be used to obtain new compounds with tailored VOC selectivity and spectral responses.

Cyclometallated tridentate platinum(ii) arylacetylide complexes: old wine in new bottles

“…So it is perfectly possible to have solvent present without losing the PtÁ Á ÁPt interaction and its associated luminescence properties, but small alterations in the PtÁ Á ÁPt separation, with a resulting change in colour, makes some of these complexes ideal sensors for specific gases and volatile organic compounds. 11 A careful examination of the pincer and alkynyl ligand substituents in the two classes of cyclometallated systems suggests that short PtÁ Á ÁPt interactions are less likely to occur when the ligands are bulky, preventing the close approach of the metal centres, but with the small number of crystal structures available to study this hypothesis is not conclusive. Similarly, for the cyclometallated systems with 5,6-5 and 5,6,6type pincer ligands there are insufficient examples to draw firm conclusions about the factors that favour short PtÁ Á ÁPt intermolecular contacts in these complexes in the solid-state.…”

“…that occupies the fourth coordination position on the Pt(II) centre also plays an important role in the solid-state aggregation and the formation of intermolecular interactions. 11 A significant strategic advantage of having a cyclometallated pincer ligand co-ordinated to the Pt(II) centre over their N^N^N analogues is the formation of the Pt-C bond(s) that occurs through deprotonation of one or more of the aromatic C-H bonds, formally generating negatively charged ''C'' units. The ''C À '' bonded to the metal acts as a very strong s-donor providing the metal with a very strong ligand-field while p-acceptor character is maintained through any co-ordinated pyridine rings.…”

“…1b). 11 Having established the basic design features for improving the luminescent properties of cyclometallated Pt(II) pincer complexes over the N^N^N-type analogues there are a number of chemical and structural features that can be manipulated in order to improve the solution and solid-state luminescence properties further. These include:…”

In situ non-invasive Raman spectroscopic characterisation of succinic acid polymorphism during segmented flow crystallisation

“…Data processing was carried out using a modified version of the 'Mayapy' python code published elsewhere. 24 Processing was carried out in three steps as follows:…”

Infinite coordination polymer networks: metallogelation of aminopyridine conjugates and in situ silver nanoparticle formation

“…[19] Potential applications of metallogels in cosmetics, lubrication, magnetic materials and sensors for dye molecules have been demonstrated in the literature. [20][21][22] Further, properties such as the self-assembly induced luminescence provides promising applications in optoelectronics [23] and in developing vapochromic sensors [24] . Recently, terpyridine ligands containing perfluoroalkyl chains have been reported to exhibit anion selective gelation and rapid self-healing properties.…”