Abstract
Chromogenic salts based on the negatively solvatochromic pyridinium N-phenolate betaines 2,6-diphenyl-4-(2,4,6-triphenyl-N-pyridino)-phenolate (Reichardt’s dye 30) and 2,6-dichloro-4-(2,4,6-triphenyl-N-pyridino)-phenolate (Reichardt’s dye 33) proved to be promising probes for the colorimetric detection of bases, including hydroxide ion, ammonia, and aliphatic amines. Specifically, the protonated halide forms of these two dyes were ion exchanged to generate lipophilic bis(trifluoromethylsulfonyl)imide derivatives, denoted [ET(30)][Tf2N] and [ET(33)][Tf2N], respectively. When dissolved in 95 vol% EtOH, these essentially colorless solutions displayed dramatic “alkalinochromic” color-on switching due to phenolic deprotonation to generate the zwitterionic form of the dyes with their characteristic charge-transfer absorption. The extent of the colorimetric response varied with the base strength for the aliphatic amines tested (i.e., propylamine, ethanolamine, ethylenediamine, diethylenetriamine, triethylamine, triethanolamine), being loosely correlated with the pKb of the amine. In addition, we demonstrated proof of concept for the vapochromic detection of ammonia and aliphatic amines by dissolution of the chromogenic probes in the ionic liquid 1-propyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide. We also showed that the dyed ionic liquid can be successfully immobilized within silica sol-gel ionogels to generate more practical and robust sensory platforms. This strategy represents a useful addition to existing colorimetric sensor arrays targeting amines and other basic species. In particular, the differential response of the two different probes offers a measure of chemical selectivity which will be of interest for detecting biogenic amines in food safety applications, among other areas.
References
Gong W-L, Sears KJ, Alleman JE, Blatchley ER. Toxicity of model aliphatic amines and their chlorinated forms. Environ Toxicol Chem. 2004;23:239–44.
Bang JH, Lim SH, Park E, Suslick KS. Chemically responsive nanoporous pigments: colorimetric sensor arrays and the identification of aliphatic amines. Langmuir. 2008;24:13168–72.
Rakow NA, Sen A, Janzen MC, Ponder JB, Suslick KS. Molecular recognition and discrimination of amines with a colorimetric array. Angew Chem Int Ed. 2005;44:4528–32.
Jane H, Ralph PT. Optical gas sensing: a review. Meas Sci Technol. 2013;24:012004.
Siraj N, El-Zahab B, Hamdan S, Karam TE, Haber LH, Li M, et al. Fluorescence, phosphorescence, and chemiluminescence. Anal Chem. 2016;88:170–202.
Tao S, Xu L, Fanguy JC. Optical fiber ammonia sensing probes using reagent immobilized porous silica coating as transducers. Sensors Actuators B Chem. 2006;115:158–63.
Oberg KI, Hodyss R, Beauchamp JL. Simple optical sensor for amine vapors based on dyed silica microspheres. Sensors Actuators B Chem. 2006;115:79–85.
Waich K, Mayr T, Klimant I. Fluorescence sensors for trace monitoring of dissolved ammonia. Talanta. 2008;77:66–72.
Preininger C, Mohr GJ, Klimant I, Wolfbeis OS. Ammonia fluorosensors based on reversible lactonization of polymer-entrapped rhodamine dyes, and the effects of plasticizers. Anal Chim Acta. 1996;334:113–23.
Courbat J, Briand D, Damon-Lacoste J, Wöllenstein J, de Rooij NF. Evaluation of pH indicator-based colorimetric films for ammonia detection using optical waveguides. Sensors Actuators B Chem. 2009;143:62–70.
Wöllenstein J, Peter C, Schiel M, Schmitt K. Colorimetric gas sensors for the detection of ammonia, nitrogen dioxide and carbon monoxide: current status and research trends. SENSOR + TEST Conferences - SENSOR Proceedings. 2011;D3 - Gas Sensors I:562–7.
Galpothdeniya WIS, Regmi BP, McCarter KS, de Rooy SL, Siraj N, Warner IM. Virtual colorimetric sensor array: single ionic liquid for solvent discrimination. Anal Chem. 2015;87:4464–71.
Galpothdeniya WIS, McCarter KS, De Rooy SL, Regmi BP, Das S, Hasan F, et al. Ionic liquid-based optoelectronic sensor arrays for chemical detection. RSC Adv. 2014;4:7225–34.
Zhang Y, Lim L-T. Colorimetric array indicator for NH3 and CO2 detection. Sensors Actuators B Chem. 2018;255:3216–26.
Machado VG, Stock RI, Reichardt C. Pyridinium N-phenolate betaine dyes. Chem Rev. 2014;114:10429–75.
Reichardt C. Solvatochromic dyes as solvent polarity indicators. Chem Rev. 1994;94:2319–58.
Sarkar A, Ali M, Baker GA, Tetin SY, Ruan Q, Pandey S. Multiprobe spectroscopic investigation of molecular-level behavior within aqueous 1-butyl-3-methylimidazolium tetrafluoroborate. J Phys Chem B. 2009;113:3088–98.
Pandey S, Baker SN, Pandey S, Baker GA. Optically responsive switchable ionic liquid for internally-referenced fluorescence monitoring and visual determination of carbon dioxide. Chem Commun. 2012;48:7043–5.
Baker SN, Baker GA, Bright FV. Temperature-dependent microscopic solvent properties of ‘dry’ and ‘wet’ 1-butyl-3-methylimidazolium hexafluorophosphate: correlation with (30) and Kamlet-Taft polarity scales. Green Chem. 2002;4:165–9.
Ribeiro EA, Sidooski T, Nandi LG, Machado VG. Interaction of protonated merocyanine dyes with amines in organic solvents. Spectrochim Acta A. 2011;81:745–53.
Onida B, Fiorilli S, Borello L, Viscardi G, Macquarrie D, Garrone E. Mechanism of the optical response of mesoporous silica impregnated with Reichardt’s dye to NH3 and other gases. J Phys Chem B. 2004;108:16617–20.
Sadaoka Y, Sakai Y, Murata Y-U. Optical humidity and ammonia gas sensors using Reichardt’s dye-polymer composites. Talanta. 1992;39:1675–9.
Fiorilli S, Onida B, Macquarrie D, Garrone E. Mesoporous SBA-15 silica impregnated with Reichardt’s dye: a material optically responding to NH3. Sensors Actuators B Chem. 2004;100:103–6.
Onida B, Borello L, Fiorilli S, Bonelli B, Arean CO, Garrone E. Mesostructured SBA-3 silica containing Reichardt’s dye as an optical ammonia sensor. Chem Commun 2004:2496–7. https://doi.org/10.1039/B409779C.
Fiorilli S, Onida B, Barolo C, Viscardi G, Brunel D, Garrone E. Tethering of modified Reichardt’s dye on SBA-15 mesoporous silica: the effect of the linker flexibility. Langmuir. 2007;23:2261–8.
Xie Z-L, Huang X, Taubert A. DyeIonogels: proton-responsive ionogels based on a dye-ionic liquid exhibiting reversible color change. Adv Funct Mater. 2014;24:2837–43.
Yung KY, Schadock-Hewitt AJ, Hunter NP, Bright FV, Baker GA. ‘Liquid litmus’: chemosensory pH-responsive photonic ionic liquids. Chem Commun. 2011;47:4775–7.
Burrell AK, Sesto RED, Baker SN, McCleskey TM, Baker GA. The large scale synthesis of pure imidazolium and pyrrolidinium ionic liquids. Green Chem. 2007;9:449–54.
Paley MS, McGill RA, Howard SC, Wallace SE, Harris JM. Solvatochromism: a new method for polymer characterization. Macromolecules. 1990;23:4557–64.
Vapor pressures were sourced from section 9 (“Physical and Chemical Properties”) of each chemical’s safety data sheet (SDS) provided on Sigma-Aldrich’s website. Available from: https://www.sigmaaldrich.com.
Trivedi S, Pandey S, Baker SN, Baker GA, Pandey S. Pronounced hydrogen bonding giving rise to apparent probe Hyperpolarity in ionic liquid mixtures with 2,2,2-trifluoroethanol. J Phys Chem B. 2012;116:1360–9.
Sarkar A, Trivedi S, Baker GA, Pandey S. Multiprobe spectroscopic evidence for “hyperpolarity” within 1-butyl-3-methylimidazolium hexafluorophosphate mixtures with tetraethylene glycol. J Phys Chem B. 2008;112:14927–36.
Acknowledgements
G. Baker acknowledges support for this research from the Research Corporation for Science Advancement. The authors thank Dr. Sudhir Ravula for helpful feedback and thoughtful discussions.
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Published in the topical collection Ionic Liquids as Tunable Materials in (Bio)Analytical Chemistry with guest editors Jared L. Anderson and Kevin D. Clark.
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Essner, J.B., Baker, G.A. Ionic liquid inspired alkalinochromic salts based on Reichardt’s dyes for the solution phase and vapochromic detection of amines. Anal Bioanal Chem 410, 4607–4613 (2018). https://doi.org/10.1007/s00216-018-1177-5
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DOI: https://doi.org/10.1007/s00216-018-1177-5