Luminescence and charge transfer. Part 4. ‘On–off’ fluorescent PET (photoinduced electron transfer) sensors with pyridine receptors: 1,3-diaryl-5-pyridyl-4,5-dihydropyrazoles

Silva, A. Prasanna de; Gunaratne, H. Q. Nimal; Lynch, P. L. Mark

doi:10.1039/p29950000685

Cited by 95 publications

(56 citation statements)

References 48 publications

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“…A frontier orbital energy picture applicable to the present cases is available in ref. 8. The receptor orbitals decrease in energy upon protonation resulting in PET becoming able to compete with fluorescence emission.…”

Section: Resultsmentioning

confidence: 99%

“…12 Such states generate substantial charge separation which may influence the rate of PET processes. One system based on 1,3-diaryl-∆ 2 -pyrazoline ICT fluorophores has been reported by us 8 before, but in this instance the pyridyl group was positioned almost along the bisector of the transition dipole of the ICT state so that no electric field effects were expected or seen. The previous examination of ICT fluorophores such as 4-amino-1,8-naphthalimides with aminoalkyl side-chains revealed strong regiochemical dependence of the pH-switching efficiency, 13,14 which suggested unidirectional PET processes.…”

Section: Introductionmentioning

confidence: 99%

“…7 In contrast, there are only a few examples which employ pyridine as the basic moiety. [8][9][10][11] These show a sharp 'on-off' switching of fluorescence upon protonation. Most of these cases however, employ aromatic hydrocarbons as fluorophores.…”

Section: Introductionmentioning

confidence: 99%

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The pH-dependent fluorescence of pyridylmethyl-4-amino-1,8-naphthalimides

Silva¹,

Goligher²,

Gunaratne³

et al. 2003

Arkivoc

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Regioselective photoinduced electron transfer (PET) has been previously observed in aminoalkyl-4-amino-1,8-naphthalimide 'fluorophore-spacer-receptor' systems. PET from the amine to the fluorophore was only observed when the electron entered the fluorophore in the region of its 4-NH group. This has received two related but distinct explanations. The first is a directing effect of the molecular-scale electric field of internal charge transfer (ICT) excited state of the fluorophore. The second is a peculiarity of 4-amino-1,8-naphthalimides in possessing a node at the imide nitrogen in its frontier orbitals. The six isomeric pyridylmethyl-4-amino-1,8-naphthalimides 1-3 and 4-6 are configured as 'fluorophore-spacer-receptor' systems in order to test the relative importance of these two explanations. The two regioisomeric sets are designed such that PET is thermodynamically feasible when they are protonated, which should lead to fluorescence quenching by protons. In practice, the proton-induced fluorescence quenching is moderate and more clearly observed in the set 1-3. This evidence points to the PET-accelerating effect of the molecular-scale electric field being mitigated by the presence of the node at the imide nitrogen in the frontier orbitals. Compound 4 also shows this proton-induced fluorescence quenching effect but to a still smaller extent. In this instance, the PET is hampered by the electric field alone. Compounds 5 and 6 show an excited state intramolecular proton transfer (ESIPT) involving water-mediated hydrogen-bonded rings, which dominates over any residual PET to produce proton-induced fluorescence enhancement. Again, the effect is moderate. The two mechanisms of PET regioselectivity can now be understood to operate additively in the aminoalkyl-4-amino-1,8-naphthalimides and subtractively in the protonated pyridylmethyl-4-amino-1,8-naphthalimides.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The pH-dependent fluorescence of pyridylmethyl-4-amino-1,8-naphthalimides

Silva¹,

Goligher²,

Gunaratne³

et al. 2003

Arkivoc

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“…[12] A pH sensor operating through both absorption and emission and based on 1,3-diaryl-5-pyridyl-4,5-dihydropyrazole has been reported by de Silva. [13] However, as far we know, chemosensors operating through three different channels (colour, fluorescence and redox) are very rare and are not common in the literature. [14] We report here the synthesis and characterisation of a family of multichannel receptors containing different crown cation binding sites anchored to a 1-aminophenyl-1,2,2-tricyanoethylene group, which is simultaneously a redox-active group (showing reduction processes at moderately modest potentials) and an acceptor moiety in the 1-aminophenyl-1,2,2-tricyanoethylene chromophore.…”

Section: Introductionmentioning

confidence: 99%

Multi‐Channel Receptors and Their Relation to Guest Chemosensing and Reconfigurable Molecular Logic Gates

et al. 2005

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The synthesis and characterisation of a family of multi-channel receptors containing crown-cation binding sites anchored to a 1-aminophenyl-1,2,2-tricyanoethylene group is reported. The ligands L 1 -L 6 bear a 1-aminophenyl-1,2,2-tricyanoethylene scaffolding which is simultaneously a redox-active group (showing reduction processes at moderately modest potentials) and an acceptor moiety in the 1-aminophenyl-1,2,2-tricyanoethylene chromophore.

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“…3,4 N-(9-Anthrylmethyl)amines, which combined a fluorescent probe moiety with amines as the metal binding site, give an intense fluorescence in the visible region upon excitation at anthracene fragment. [5][6][7][8][9][10][11][12] Protonation and deprotonation of amine moiety leads to on-off switching of the fluorescence associated with photo-induced electron transfer (PET), [5][6][7][8][9][10][11][12] and this phenomenon has been applied to the fluorescent pH indicators. 13,14 Furthermore, quenching of fluorescence signal takes place upon complex formation with paramagnetic Cu(II).…”

Section: 2mentioning

confidence: 99%

Switching of PET Fluorescence Signals Induced by Ligand Exchange Reactions of N-(9-Anthrylmethyl)amine on Cu(II) Complexes and Its Application to Postcolumn Detection of Glyphosate

et al. 2005

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A light-signal switching system associated with a ligand exchange reaction between a probe molecule and analyte molecules on a metal complex provides unique sensing methods of ligating compounds. 1,2 We have fabricated the detection systems of fluoride ion and catecholamine via switching of the fluorescence signal associated by exchange of sensitizing ligand with inactive analyte molecule (vice versa) on the ternary [M(AA)EDTA] (M = Zr, Tb; AA = sensitizing probe ligand) complexes. 3,4N-(9-Anthrylmethyl)amines, which combined a fluorescent probe moiety with amines as the metal binding site, give an intense fluorescence in the visible region upon excitation at anthracene fragment. [5][6][7][8][9][10][11][12] Protonation and deprotonation of amine moiety leads to on-off switching of the fluorescence associated with photo-induced electron transfer (PET), [5][6][7][8][9][10][11][12] and this phenomenon has been applied to the fluorescent pH indicators. 13,14 Furthermore, quenching of fluorescence signal takes place upon complex formation with paramagnetic Cu(II). 5,11 Therefore, when the N-(9-anthrylmethyl)amine is liberated from its Cu(II) complex by substitution with some other competing ligand, the fluorescence signal will revive. Based on this, we have attempted to construct an indirect fluorometric detection system of the molecules capable of complexing to Cu (II).N-(phosphonomethyl)glycine (glyphosate) (Scheme 1) is the most widely used herbicide for weed control in agriculture; it works by interfering with the enzymatic activity of plants. [15][16][17] Reliable and sensitive methods for the determination of glyphosate and the related herbicides present an important topic for contemporary environmental monitoring. 15-17Analytical methods so far developed involve preconcentration, and derivertization of polar glyphosate into signaling derivatives and subsequent GC or HPLC analysis. [18][19][20] Indirect determination of phosphate and glyphosate has been proposed by monitoring the quenching of fluorescence of aluminummorin complex in ethanol-water (4:1), where the signal intensity decreases with increase of analyte concentration. Science and Technology, Nigatake, Japan **LC/MS Application Department, Hitachi Science Systems Ltd., Hitachinaka,amines which combine a fluorescent subunit and a chelate forming fragment have revealed a signal switching property in an aqueous solution upon complexation (off) with Cu(II) and liberation (on) of the probe molecule by substitution with an other ligand. The ligand exchange reaction between N-(phosphonomethyl)glycine (glyphosate), a typical herbicide, with N-(9-anthrylmethyl)amines on Cu(II) ion leads the fluorescence signal intensity to revive, providing an indirect detection system of glyphosate available in water of neutral pH region. The present system has been applied to the post column detection in the ion chromatographic separation of glyphosate and its metabolite aminomethylphosphonic acid (AMPA).

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Luminescence and charge transfer. Part 4. ‘On–off’ fluorescent PET (photoinduced electron transfer) sensors with pyridine receptors: 1,3-diaryl-5-pyridyl-4,5-dihydropyrazoles

Cited by 95 publications

References 48 publications

The pH-dependent fluorescence of pyridylmethyl-4-amino-1,8-naphthalimides

The pH-dependent fluorescence of pyridylmethyl-4-amino-1,8-naphthalimides

Multi‐Channel Receptors and Their Relation to Guest Chemosensing and Reconfigurable Molecular Logic Gates

Switching of PET Fluorescence Signals Induced by Ligand Exchange Reactions of N-(9-Anthrylmethyl)amine on Cu(II) Complexes and Its Application to Postcolumn Detection of Glyphosate

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