A Redox-Driven Fluorescence “Off–On” Molecular Switch Based on a 1,1′-Unsymmetrically Substituted Ferrocenyl Coumarin System: Mimicking Combinational Logic Operation

Bhatta, Sushil Ranjan; Bheemireddy, Varun; Thakur, Arunabha

doi:10.1021/acs.organomet.6b00883

Cited by 34 publications

(16 citation statements)

References 70 publications

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“…The sole purpose of including ferrocene into the model of the probe is to carry out the various electrochemical studies of metal binding phenomenon because of its inherent reversible electrochemical nature. , Among the various electrochemical studies known, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) experiments are explored for the cation recognition mechanism study for the receptor 5 . A reversible one-electron oxidation process is observed for the receptor 5 (2.5 × 10 –4 M) with a redox wave at E 1/2 = 0.504 V due to oxidation of the Fe(II) of ferrocene to Fe(III) of ferrocenium ion and vice versa.…”

Section: Resultssupporting

confidence: 84%

Microwave-Assisted Neat Synthesis of a Ferrocene Appended Phenolphthalein Diyne: A Designed Synthetic Scaffold for Hg²⁺ Ion

et al. 2020

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A C2-symmetric internally conjugated 1,3-dialkyne system 5, containing phenolphthalein as a fluorophore and ferrocene as a redox moiety, has been synthesized via a microwave-assisted synthetic procedure. Compound 5 was synthesized by Cu-catalyzed Glaser–Hay coupling using a microwave reactor in neat condition for the first time. Compound 5 was found to be highly selective toward Fe3+, Cu2+, and Hg2+ ions via multichannels. Interestingly, Fe3+ and Cu2+ ions simply promote the oxidation of ferrocene unit to ferrocenium ion without binding to the receptor, whereas Hg2+ binds with the receptor 5 (ΔE 1/2 = 71 mV). The oxidation and binding phenomena were investigated by optical and electrochemical analyses. Furthermore, the binding site of Hg2+ ion with our designed probe was confirmed by 1H, 13C NMR and IR titrations, which indicated that conjugated dialkyne unit interacts with Hg2+ ion by a favorable soft–soft interaction. Both receptor 5 and its metal complex, [5·2Hg2+], are stable in the physiological pH range (pH = 6–7) and thermally stable up to 78 °C. The experimental results of metal binding have been further supported by quantum chemical calculations (DFT), which explore the favorable geometry of the free ligand as well as its Hg2+ complex.

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Section: Resultssupporting

confidence: 84%

Microwave-Assisted Neat Synthesis of a Ferrocene Appended Phenolphthalein Diyne: A Designed Synthetic Scaffold for Hg²⁺ Ion

et al. 2020

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“…Therefore, the development of PET-based sensors and switches is becoming of great interest to scientists. Different design strategies are being employed in the development of PET-based sensor molecules, with the most commonly exploited approach of a “fluorophore–spacer–receptor” configuration in which donor (mostly nitrogen-containing groups) and acceptor units are present. − On the contrary, relatively fewer examples are known where the PET is triggered by the oxidation of a donor unit (ferrocene moiety), − and the process can be modulated between fluorescence “on” and “off” states by controlling the redox property of the donor unit.…”

Section: Introductionmentioning

confidence: 99%

Oxidation-Induced Differentially Selective Turn-On Fluorescence via Photoinduced Electron Transfer Based on a Ferrocene-Appended Coumarin–Quinoline Platform: Application in Cascaded Molecular Logic

et al. 2020

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Differentially selective molecular sensors that exhibit differential response toward multiple analytes are cost-effective and in high demand for various practical applications. A novel, highly differentially selective electrochemical and fluorescent chemosensor, 5, based on a ferrocene-appended coumarin–quinoline platform has been designed and synthesized. Our designed probe is very specific toward Fe3+ via a reversible redox process, whereas it detects Cu2+ via irreversible oxidation. Interestingly, it exhibits differential affinity toward the Cu+ ion via complexation. High-resolution mass spectrometry, 1H NMR titration, and IR spectral studies revealed the formation of a bidentate Cu+ complex involving an O atom of the amide group attached to the quinoline ring and a N atom of imine unit, and this observation was further supported by quantum-chemical calculations. The metal binding responses were further investigated by UV–vis, fluorescence spectroscopy, and electrochemical analysis. Upon the addition of Fe3+ and Cu2+ ions, the fluorescence emission of probe 5 shows a “turn-on” signal due to inhibition of the photoinduced electron transfer (PET) process from a donor ferrocene unit to an excited-state fluorophore. The addition of sodium l-ascorbate (LAS) as a reducing agent causes fluorescence “turn off” for the Fe3+ ion because of reemergence of the PET process but not for the Cu2+ ion because it oxidizes the ferrocene unit to a ferrocenium ion with its concomitant reduction to Cu+, which further complexes with 5. Thermodynamic calculations using the Weller equation along with density functional theory calculations validate the feasibility of the PET process. A unique combination of Fe3+, LAS, and Cu2+ ions has been used to produce a molecular system demonstrating combinational “AND–OR” logic operation.

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“…The calculated structural features of 1 are in good agreement with the crystal structure data. The geometry optimization of 2 resulted in a structure where both the arms are held in an eclipsed conformation, which is unusual for most of the disubstituted ferrocene-triazole derivatives . The stabilization of this configuration can be attributed to the C–H···O and C–H···N type hydrogen bonding interaction between the arms of 2 .…”

Section: Resultsmentioning

confidence: 97%

An Efficient Molecular Tool with Ferrocene Backbone: Discriminating Fe³⁺ from Fe²⁺ in Aqueous Media

Bhatta

Bheemireddy²,

Vijaykumar³

et al. 2017

Organometallics

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Two novel molecular probes with ferrocene backbone have been designed and synthesized for the first time, and they were subsequently found capable of distinguishing Fe3+ and Fe2+ ion in aqueous media. The discrimination of both the oxidation states (II/III) of iron by these receptors can be established either from a striking shift in redox potential (1: ΔE 1/2 ≈ 90 mV and 2: ΔE 1/2 ≈ 59 mV) for Fe2+ ion or from UV–vis absorption studies (using light-absorption ratio variation approach (LARVA)). Moreover, the discrimination of Fe2+ and Fe3+ cations could be performed by naked-eye observation because of the development of different colors upon interaction with these probes which act as indicators for the in situ qualitative detection of Fe3+ and Fe2+. The limits of detection of Fe2+ and Fe3+ cations with receptor 2 were found to be as low as 30 and 15 parts per billion (ppb), respectively. The probable binding modes of these receptors with Fe2+ have also been suggested on the basis of the 1H NMR spectroscopic titration, electrospray ionization mass spectrometry (ESI-MS), Job’s plot, and computational (DFT) studies along with electrochemical and spectro-photochemical data. Single crystal X-ray diffraction analysis of 1 revealed that its solid-state structure was stabilized via intermolecular C–H/O and O–H/N hydrogen bonds and by C–H/π interactions. Interestingly, detailed theoretical calculations (DFT) indicated that hydroxymethyl (−CH2OH) group attached to naphthalene unit plays a pivotal role in sensing Fe2+/3+ ion selectively and in the stabilization of 2 in unusual eclipsed configuration through C–H···O type hydrogen bonding.

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A Redox-Driven Fluorescence “Off–On” Molecular Switch Based on a 1,1′-Unsymmetrically Substituted Ferrocenyl Coumarin System: Mimicking Combinational Logic Operation

Cited by 34 publications

References 70 publications

Microwave-Assisted Neat Synthesis of a Ferrocene Appended Phenolphthalein Diyne: A Designed Synthetic Scaffold for Hg²⁺ Ion

Microwave-Assisted Neat Synthesis of a Ferrocene Appended Phenolphthalein Diyne: A Designed Synthetic Scaffold for Hg²⁺ Ion

Oxidation-Induced Differentially Selective Turn-On Fluorescence via Photoinduced Electron Transfer Based on a Ferrocene-Appended Coumarin–Quinoline Platform: Application in Cascaded Molecular Logic

An Efficient Molecular Tool with Ferrocene Backbone: Discriminating Fe³⁺ from Fe²⁺ in Aqueous Media

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A Redox-Driven Fluorescence “Off–On” Molecular Switch Based on a 1,1′-Unsymmetrically Substituted Ferrocenyl Coumarin System: Mimicking Combinational Logic Operation

Cited by 34 publications

References 70 publications

Microwave-Assisted Neat Synthesis of a Ferrocene Appended Phenolphthalein Diyne: A Designed Synthetic Scaffold for Hg2+ Ion

Microwave-Assisted Neat Synthesis of a Ferrocene Appended Phenolphthalein Diyne: A Designed Synthetic Scaffold for Hg2+ Ion

Oxidation-Induced Differentially Selective Turn-On Fluorescence via Photoinduced Electron Transfer Based on a Ferrocene-Appended Coumarin–Quinoline Platform: Application in Cascaded Molecular Logic

An Efficient Molecular Tool with Ferrocene Backbone: Discriminating Fe3+ from Fe2+ in Aqueous Media

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Product

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Microwave-Assisted Neat Synthesis of a Ferrocene Appended Phenolphthalein Diyne: A Designed Synthetic Scaffold for Hg²⁺ Ion

Microwave-Assisted Neat Synthesis of a Ferrocene Appended Phenolphthalein Diyne: A Designed Synthetic Scaffold for Hg²⁺ Ion

An Efficient Molecular Tool with Ferrocene Backbone: Discriminating Fe³⁺ from Fe²⁺ in Aqueous Media