Bao, L, Jones, LO, Garrote Cañas, AM et al. (6 more authors) (2022) Multipurpose made colorimetric materials for amines, pH change and metal ion detection. RSC Advances, 12 (5). pp. 2684-2692. ISSN 2046-2069
Abstract
Sensors are routinely developed for specific applications, but multipurpose sensors are challenging, due to stability and poor functional design. We report organic materials that operate in solution and gas phase. They show a strong response behaviour to at least three types of environmental changes: pH, amine and metal ion binding/detection. We have confirmed and validated our findings using various analytical and computational methods. We found that the changes in polarity of the solvent and pH not only red shift the tail of the absorption spectra, but also extend the peak optical absorption of these structures by up to 100 nm, with consequential effects on the optical gap and colour changes of the materials. Acid–base response has been studied by spectrophotometric titrations with trifluoroacetic acid (TFA) and triethyl amine (TEA). The experiments show excellent reversibility with greater sensitivity to base than acid for all compounds. Analysis into metal sensing using Zn(II) and Cu(II) ions as analytes show that the materials can successfully bind the cations forming stable complexes. Moreover, a strong suppression of signal with copper gives an operative modality to detect the copper ion as low as 2.5 × 10−6 M. The formation of the metal complexes was also confirmed by growing crystals using a slow diffusion method; subsequent single crystal X-ray analysis reveals the ratio of ligand to metal to be 2 to 1. To test sensitivity towards various amine vapours, paper-based sensors have been fabricated. The sensors show a detection capability at 1 ppm of amine concentration. We have employed CIE L*a*b* colour space as the evaluation method, this provides numeric comparison of the samples from different series and allows comparison of small colour differences, which are generally undetectable by the human-eye. It shows that the CIE L*a*b* method can assess both sensitivity to a particular class of analytes and a specificity response to individual amines in this subclass offering an inexpensive and versatile methodology.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Royal Society of Chemistry 2022. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial 3.0 Unported (CC BY-NC 3.0) |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemistry (Leeds) > Colour Science (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 31 Jan 2022 11:24 |
Last Modified: | 31 Jan 2022 11:24 |
Status: | Published |
Publisher: | Royal Society of Chemistry (RSC) |
Identification Number: | 10.1039/d1ra07811a |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:182924 |