Size dependent ion-exchange of large mixed-metal complexes into Nafion<sup>®</sup> membranes

Naughton, Elise Michele; Zhang, Mingqiang; Troya, Diego; Brewer, Karen J.; Moore, Robert B.

doi:10.1039/c5py00714c

Cited by 4 publications

(2 citation statements)

References 40 publications

(86 reference statements)

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“…Figure a presents a schematic of this hypothesis. We infer from the loss of activity with increasing water content that resorcinol immobilization and thus product formation occurs at the vicinity of the PSA groups at the hydrophilic cluster/hydrophobic matrix interphase associated with the complex morphology of this material. − Thus, protons in the bulk phase of the hydrophilic cluster cannot catalyze the reaction. Direct evidence of these immobilization sites could possibly be obtained utilizing neutron scattering with isotope-labeled molecules that can delineate the morphology of the various chemical species in this complex system.…”

Section: Resultsmentioning

confidence: 99%

Water-Resistant Polymeric Acid Membrane Catalyst for Acetone Detection in the Exhaled Breath of Diabetics

et al. 2018

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Endogenous volatile organic compounds (VOCs) such as acetone in exhaled human breath are associated with metabolic conditions in the bloodstream. Development of compact, rapid detectors of exhaled breath chemical composition in clinical settings is challenging due to the small sample size that can be collected during a single exhalation as well as spectroscopic interference by the abundance of water. In this paper, we show that the activity of a catalytic polymer membrane (Nafion 117) toward the heterogeneous condensation reaction of immobilized resorcinol reagent with gas-phase acetone can be preserved even at 100% ambient relative humidity through the incorporation of organic acids such as vanillic or tiglic. The reaction produces a colored flavan product that permits highly selective and sensitive correlation to acetone concentration in exhaled breath. Such behavior suggests solvent displacement, analogous to homogeneous liquid-phase systems. However, unlike classic acid-base equilibria, the extent of optode water resistance is shown to increase with the pK of the imbibed organic acid while peak signal intensity of the imbibed acid undergoes a bathochromic shift to longer wavelengths. These observations are consistent with competition between organic acid deprotonation by water in a mixed solvent system on the one hand and immobilization on the other. Finally, we demonstrate how when applied to the direct chemical analysis of acetone in exhaled human breath, the approach yields excellent correlation to blood glucose in diabetics.

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Section: Resultsmentioning

confidence: 99%

Water-Resistant Polymeric Acid Membrane Catalyst for Acetone Detection in the Exhaled Breath of Diabetics

et al. 2018

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“…It is plausible that the Nafion layer in ds-Nf-Fe4′T-S-ECD acts as a trapping film that retains EC molecules in close proximity to the electrode surface. This trapping in the Nafion channels can take place via both physisorption and electrostatic/ion–exchange interactions. − The electrochemical behavior of metal complexes ion-exchanged into Nafion films has been extensively studied in the literature. − On the other hand, N-quaternization of only one outer pyridine unit of iron(II) 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine complex (to form Fe4′T motifs on the surface of the support) result in a charge gradient within the molecule, which leads to a deep blue color of the materials. In contrast, nonquaternized iron(II) 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine complex or the product of its double quaternization have a purple-violet color .…”

Section: Resultsmentioning

confidence: 99%

Nonconventional Symmetric Double-Side Electrochromic Devices Employing a Nafion Conductive Layer to Unlock Superior Durability

DiPalo,

Ahmad,

Ebralidze

et al. 2023

ACS Appl. Mater. Interfaces

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In this work, we present a methodology to create an effective novel double-sided symmetric architecture of solid-state electrochromic devices. This principally new nonconventional configuration provides access to novel electrochromic systems that could be applicable for the creation of smart double-side signage, smart boards, nonemissive displays, and other smart interactive devices that change their color upon application of a voltage. The proposed configuration is based on the assembly of two identical electrochromic materials facing each other through an opaque optical separator. As a proof of concept, we use an electrochromic material based on bis(4′-(pyridin-4-yl)-2,2′:6′,2″-terpyridine) iron complex, covalently immobilized on screenprinted surface-extended ITO support. The symmetric configuration allows for a drastic enhancement of the overall stability of the device due to both attenuation of the counter electrode polarization and minimization of electrolyte decomposition. A nontransparent ion-permeable separator, in turn, allows observing the color change of only one of the electrodes by cutting off the optical contribution of the electrode located behind it. Further functionalization of the electrochromic material with a thin layer of Nafion is a beneficial strategy to significantly boost up long-term durability of the devices. Applying a layer of Nafion to the electrochromic material results in an increase in ionic conductivity within the device and ensures better retention of electrochromic molecules on the surface, thus minimizing device decomposition during long-term electrochemical cycling. An electrochromic device that bears Nafion-functionalized electrodes can operate (i) in the dual-side mode, where both sides demonstrate effective electrochromic performance; or (ii) in a one-side manner, where only one side of the device changes color. Notably, when operating in the one-side mode, the device withstands 70,000 cycles, after which the performance of the device can be resumed by simply turning the device to the other side (via switching the polarity of the electrodes).

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Multicolor Emission and Photophysical Properties of Proton-Responsive Cyclometallated Iridium(III) Complex in Transparent Cation-Exchange Membrane

et al. 2020

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A transparent film allowing tunable multicolor emission based on a composite of an organometallic compound and a cation-exchange membrane has been developed, in which the cyclometallated iridium(III) complex [IrIII(4Py-ppy)3] (=tris[2-(2-pyridinyl-κN)-4-(4-pyridinyl)phenyl-κC]iridium) (1) with pH-dependent emission wavelengths has been incorporated into Nafion by cation exchange. Soaking Nafion in the solution of 1 for 24 h and exposed to buffers at pH 2, 4, and 10 resulted in maximum emission wavelengths of 587, 560, and 503 nm, respectively. The photophysical properties of 1@Nafion were also enhanced, as its maximum emission wavelength was more blue-shifted than those of 602, 564, and 503 nm in the solutions. The emission quantum yields (Φ) and lifetimes (τ) of 1@Nafion prepared under an acidic condition were up to Φ = 1.8% and τ = 0.11, 0.92 μs, which are considerably higher than the corresponding solutions of Φ = 0.5% and τ = 0.02, 0.18 μs. This is attributed to the fact that 1 is surrounded by the polymer chains of Nafion and immobilized in a relatively rigid medium, which hinders non-radiative deactivation such as thermal relaxation.

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Size dependent ion-exchange of large mixed-metal complexes into Nafion^® membranes

Abstract: Ion-exchange of large multivalent cations in Nafion® membranes: kinetics of exchange and implications for more open morphological models.

Cited by 4 publications

References 40 publications

Water-Resistant Polymeric Acid Membrane Catalyst for Acetone Detection in the Exhaled Breath of Diabetics

Water-Resistant Polymeric Acid Membrane Catalyst for Acetone Detection in the Exhaled Breath of Diabetics

Nonconventional Symmetric Double-Side Electrochromic Devices Employing a Nafion Conductive Layer to Unlock Superior Durability

Multicolor Emission and Photophysical Properties of Proton-Responsive Cyclometallated Iridium(III) Complex in Transparent Cation-Exchange Membrane

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Size dependent ion-exchange of large mixed-metal complexes into Nafion® membranes

Abstract: Ion-exchange of large multivalent cations in Nafion® membranes: kinetics of exchange and implications for more open morphological models.

Cited by 4 publications

References 40 publications

Water-Resistant Polymeric Acid Membrane Catalyst for Acetone Detection in the Exhaled Breath of Diabetics

Water-Resistant Polymeric Acid Membrane Catalyst for Acetone Detection in the Exhaled Breath of Diabetics

Nonconventional Symmetric Double-Side Electrochromic Devices Employing a Nafion Conductive Layer to Unlock Superior Durability

Multicolor Emission and Photophysical Properties of Proton-Responsive Cyclometallated Iridium(III) Complex in Transparent Cation-Exchange Membrane

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Size dependent ion-exchange of large mixed-metal complexes into Nafion^® membranes