Photoinduced electron transfer as a design concept for luminescent redox indicators

Magri, David C.

doi:10.1039/c5an01491c

Cited by 30 publications

(19 citation statements)

References 70 publications

(127 reference statements)

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“…At the 5‐position of the pyrazoline ring, 1 – 3 have a ferrocene (electron donor) moiety connected by a methylene spacer (Figure ), which allows for fluorescence switching based on a PET mechanism . The presence of Fe 3+ as an oxidant renders 1 – 3 as off‐on redox‐fluorescent switches .…”

Section: Figurementioning

confidence: 99%

“…In contrast to the example by Wu, we illustrate pE-pH INHIBIT logic gates with an ew structuralc onfiguration (the spaceri sl ocated between the electron donor and fluorophore rather than between the fluorophore and receptor) with fluorescencer ather than absorbance as the output and in 1:1( v/v)m ethanol/water rather than in acetonitrile.At the 5-position of the pyrazoline ring, 1-3 have aferrocene (electron donor) moiety connected by am ethylene spacer (Figure 1), which allows for fluorescences witching based on aP ET mechanism. [16] The presenceo fF e 3 + as an oxidant renders 1-3 as off-on redox-fluorescent switches. [17][18][19][20][21][22][23][24] Intrinsic to the pyrazoline (fluorophore) there is also ah ighly emissive internal charge transfer (ICT) excited state, whicha th igh proton concentrations results in fluorescenceq uenching due to protonation of the N2 nitrogen atom (receptor).…”

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Redox‐Enabled, pH‐Disabled Pyrazoline–Ferrocene INHIBIT Logic Gates

et al. 2017

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Pyrazoline-ferrocene conjugatesw ith an "electron-donorspacer-fluorophore-receptor" format are demonstrated as redox-fluorescent two-input INHIBIT logic gates.Molecular logic-basedc omputation is now firmly established as am aturing research discipline with researchers contemplating pragmatic uses for this curiosity-based science. [1][2][3][4][5] Medicalrelated innovations such as photodynamic photosensitizers, [6] drug delivery systems [7] and multi-analyte diagnostics [8] are but af ew envisioned applications. One of our visions is the realization of logic gates responsive to the physiochemical parameters of pH and potential( pE), which are fundamental to understanding metal ion solubility in geology and metallurgy as well as in medicine. [9] The development of reliable fluorescentc hemosensors and logic gates for open-shell d-metal ions, particularly Fe 3 + ,r equires overcoming several challenges including issues of solubility.[10] The vast majority of studies in this field continuet ob e reported in organic solvents, where Fe 3 + can form aqua-coordinated speciest hat act as unsuspecting weak acids.[11] Consequently,c omplexation or redox chemistry is often inferred, when matter-of-fact the fluorescent response is due to acidbase chemistry.[12] Furthermore, it is commonly taken for granted that in water Fe 3 + hydrolyses to insoluble Fe(OH) 3 above pH 4. [13] With an understanding of these issues, [10] the applicability of pE-pH logic gates in an applied setting is ar eal possibility.F or example, the detection of Fe 3 + under acidic conditions by fluorescencec ould become ar outine method for the early detection of corrosion of ferrous alloys such as steel. [14] Wu and colleagues have demonstrated an oteworthy logic gate responsive to pH andr edox chemistry.[15] The prototype consisted of ad imethylaniline moiety (protonr eceptor) attached to aP t II complexedt erpyridyl (by av irtual spacer) linked to af errocenyl acetylide (electron donor). From ad esign point of view,t his molecule exemplifies am olecular device with an "electron-donor-fluorophore-spacer-receptor" format. The logic gate exhibited an INHIBIT function with H + and Fe 3 + as the inputs and absorbance at 405 nm as the output. The mechanism of operation involved photoinduced electron transfer (PET) from the dimethylaniline unit and am etal-toligand charget ransfer from the ferrocenyl acetylide. Understandably,b eing ap roof-of-concept, the study wasp erformed in acetonitrile.Herein we now presente xamples of pyrazoline-ferrocene conjugates 1-3 with an ovel "electron-donor-spacer-fluorophore-receptor" format for the first time (Figure 1). In contrast to the example by Wu, we illustrate pE-pH INHIBIT logic gates with an ew structuralc onfiguration (the spaceri sl ocated between the electron donor and fluorophore rather than between the fluorophore and receptor) with fluorescencer ather than absorbance as the output and in 1:1( v/v)m ethanol/water rather than in acetonitrile.At the 5-position of the pyrazoline ring, 1-3 have aferrocene (electro...

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Section: Figurementioning

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Redox‐Enabled, pH‐Disabled Pyrazoline–Ferrocene INHIBIT Logic Gates

et al. 2017

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“…In recent years there has been a tremendous effort focused exclusively on pH sensing [5], notably for intracellular fluorescence imaging applications [6]. In contrast, the field of luminescent redox indicators has not received as much attention and offers much opportunity for future development [7]. Indeed, de spite there being numerous molecular probes for specifically mon itoring the pH or the redox environment in living cells, there are no commercially available probes that simultaneously probe pH and pE in living cells [8].…”

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confidence: 99%

A fluorescent AND logic gate based on a ferrocene-naphthalimide-piperazine format responsive to acidity and oxidizability

et al. 2018

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A novel fluorescent molecular logic gate 1 is demonstrated as a two-input AND logic gate for the detection of acidity and oxidizability. Designed according to an electron-donor-spacer-fluorophore-spacer-receptor' format, the modules are represented by ferrocene as the electron donor, 1,8-naphthalimide as the fluorophore and piperazine as the proton receptor. In the presence of elevated concentrations of H + and Fe 3+ , the molecule switches 'on' emitting at λ max = 530 nm with Φ f = 0.060 at 10 −4 M H + and 50 μM Fe 3+. The H + binding and apparent Fe 3+ binding constants determined by fluorimetric titrations in 1:1 (v/v) methanol/water are log β H+ = 8.1 and log β Fe3+ = 4.7. Modulation of the fluorescence output results from controlling competing photoinduced electron transfer (PET) at the ferrocene end and internal charge transfer (ICT) at the piperazine end. Time-resolved fluorescence spectroscopy reveals a single fluorescent lifetime of 5.8 ns, while from absorption transient spectroscopy a remarkable fast decay signal < 2 ps is observed. Comparison is made with methylpiperazine 2 and piperazine fluorescent pH indicator 3 as model compounds.

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“…Researchers within the chemosensor community with an interest in the design, synthesis, and function of molecular sensors and molecular logic gates are the target audience. Previous articles have highlighted aspects of design concepts, the mechanisms of operation (photoinduced electron transfer (PET) and internal charge transfer (ICT)) [16][17][18] and some envisioned applications of this new class of chemosensor [19,20]. Pourbaix sensors could, in principle, have applications in various disciplines from living cell imaging, corrosion detection, water quality, medical diagnostics, and environmental analysis.…”

Section: Introductionmentioning

confidence: 99%

Recent Progress on the Evolution of Pourbaix Sensors: Molecular Logic Gates for Protons and Oxidants

Magri

2018

Chemosensors

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Recent progress in the area of molecular logic, in particular molecules capable of sensing for acidity and oxidizability, are gathered together in this short review. Originally proposed as AND logic gates that provide a high fluorescence output when simultaneously protonated and oxidized, the concept has been extended from two-input to three-input variants and to include molecules that function as INHIBIT logic gates. Photochemical concepts such as photoinduced electron transfer (PET) and internal charge transfer (ICT) are exploited as favorite design concepts. This review highlights the evolution of Pourbaix sensors with anthracene, pyrazoline, and naphthalimide fluorophores. Future applications abound in various disciplines from corrosion science, material science, geochemistry to cell imaging.

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Photoinduced electron transfer as a design concept for luminescent redox indicators

Cited by 30 publications

References 70 publications

Redox‐Enabled, pH‐Disabled Pyrazoline–Ferrocene INHIBIT Logic Gates

Redox‐Enabled, pH‐Disabled Pyrazoline–Ferrocene INHIBIT Logic Gates

A fluorescent AND logic gate based on a ferrocene-naphthalimide-piperazine format responsive to acidity and oxidizability

Recent Progress on the Evolution of Pourbaix Sensors: Molecular Logic Gates for Protons and Oxidants

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