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

Mathew J Bryant ,C Stubbs,Sara Fuertes ,Jeppe Christensen ,Elena Madrid ,Mariolino Carta ,Stephen C Parker ,Lauren E Hatcher ,Lynne H Thomas ,Christopher H Woodall ,Jonathan M Skelton ,Richard Malpass‐Evans ,Christine M Beavers ,David R Carbery ,Anuradha Pallipurath ,Thomas Robinson ,Neil B Mckeown ,Frank Marken ,Fabienne Pradaux-Caggiano ,Simon J Teat ,Mark R Warren ,Aron Walsh ,Paul R Raithby

doi:10.1038/s41467-017-01941-2

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.

Highlights

Selective, robust and cost-effective chemical sensors for detecting small volatile-organic compounds (VOCs) have widespread applications in industry, healthcare and environmental monitoring
This study has highlighted the potential of Pt(II)-pincer systems as a platform for vapochromic VOC sensing
The subsecond response time is unprecedented for this class of system and further broadens the range of potential applications

Summary

Introduction

Robust and cost-effective chemical sensors for detecting small volatile-organic compounds (VOCs) have widespread applications in industry, healthcare and environmental monitoring. The rapid vapochromic response can be rationalised from the crystal structure, and in combination with quantumchemical 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. Minor changes to the local environment of the molecules in the solid state, e.g., due to external stimuli such as temperature[8], pressure[9, 10], exposure to chemical vapour[3, 4, 11, 12], or mechanical stress[13], can perturb these interactions and induce substantial changes in absorption and emission properties. SO2 could subsequently be removed by a flow of N2 gas, confirming it to be a reversible process

Methods

Results

Conclusion