Sensitive and Selective PET-Based Diimidazole Luminophore for Zn<sup>II</sup> Ions:  A Structure−Activity Correlation

Salman, Husein; Tal, Shay; Chuvilov, Yulia; Solovey, Olga; Abraham, Yael; Kapon, Moshe; Suwińska, Kinga; Eichen, Yoav

doi:10.1021/ic051897+

Cited by 32 publications

(16 citation statements)

References 39 publications

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“…The interaction of the sensor with the target analyte reduces the energy of the HOMO of the donor, and thus PET is prevented and fluorescence enhanced. [45] The analysis of the frontier molecular orbitals in the GdHL2 + and GdZnL2 2+ systems confirms that a PET process is responsible for the quenching of the ligand-centred luminescence in the absence of Zn 2+ . Indeed, the HOMO of GdHL2 + is mainly centred on the TACN moiety and contains an important contribution of the lone pairs of the amine nitrogen atoms ( Figure 5, right panel).…”

Section: Dft Calculationsmentioning

confidence: 68%

Lanthanide Complexes with Heteroditopic Ligands as Fluorescent Zinc Sensors

et al. 2014

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International audienceWe report the synthesis of two ligands containing a DO3A unit (H3DO3A = 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid) linked to a triazacyclononane (TACN) moiety by a 2,6-dimethylpyridine spacer designed to form stable Ln3+ complexes in solution that respond to the presence of Zn2+ ions. The Eu3+ and Gd3+ complexes have been characterized by using a combination of experimental and theoretical techniques that include absorption and emission electronic spectroscopy, NMR spectroscopy, 1H relaxometry, and DFT calculations. The Ln3+ ions are eight-coordinated by the ligand, which binds to the metal ion through the seven donor atoms of the DO3A unit and the nitrogen atom of the pyridyl linker. Luminescence lifetime measurements recorded from solutions of the Eu3+ complexes in H2O and D2O and relaxometric measurements point to the absence of inner-sphere water molecules. The addition of Zn2+ causes important changes in the absorption spectra of the complexes that evidence the formation of both 1:1 and 2:1 (Ln3+/Zn2+) complex species. However, the emission lifetimes of the Eu3+ complexes and relaxivity experience weak changes, thus indicating that Zn2+ addition does not significantly affect the number of coordinated water molecules. The Gd3+ complexes show a weak emission band at 325 nm, the intensity of which dramatically increases in the presence of Zn2+. However, the “turn-on” behaviour induced by Zn2+ is not observed for other metal cations such as Ca2+, Mg2+ or Cu2+. DFT calculations indicate that a photoinduced electron-transfer (PET) process is responsible for the quenching of the luminescence in the absence of Zn2+

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Section: Dft Calculationsmentioning

confidence: 68%

Lanthanide Complexes with Heteroditopic Ligands as Fluorescent Zinc Sensors

et al. 2014

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“…A number of groups have studied the PET in fluorescent probes using Kohn-Sham density functional theory (DFT) and time dependent density functional theory (TDDFT). 10,[20][21][22][23] The most common approach is to construct a molecular orbital diagram for the frontier molecular orbitals based upon the Kohn-Sham orbitals and their associated energies to determine whether PET and the associated fluorescence quenching or enhancement should occur. [20][21][22] This can often provide a picture that is consistent with the experimental observations, and can be used to rationalise the observed fluorescent properties of a chemical sensor.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Based Analysis of Photoinduced Electron Transfer in a Triazacryptand Based K⁺ Sensor

Briggs

Besley

2015

J. Phys. Chem. A

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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. The electronic structure and photoinduced electron transfer processes in a K + fluorescent sensor that comprises a 4-amino-naphthalimide derived fluorophore with a triazacryptand ligand is investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT) in order to rationalise the function of the sensor. The absorption and emission energies of the intense electronic excitation localised on the fluorophore are accurately described using a ∆SCF Kohn-Sham DFT approach, which gives excitation energies closer to experiment than TDDFT. Analysis of the molecular orbital diagram arising from DFT calculations for the isolated molecule or with implicit solvent cannot account for the function of the sensor and it is necessary to consider the relative energies of the electronic states formed from the local excitation on the fluorophore and the lowest fluorophore→chelator charge transfer state. The inclusion of solvent in these calculations is critical since the strong interaction of the charge transfer state with the solvent lowers it energy below the local fluorophore excited state making a reductive photoinduced electron transfer possible in the absence of K + , while no such process is possible when the sensor is bound to K + . The rate of electron transfer is quantified using Marcus theory, which gives a rate of electron transfer of k ET =5.98 x 10 6 s −1 .

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“…1 Hence the development of selective zinc chemosensors is of great importance for tracking the Zn 2+ status in biological systems. 2 Fluorescence chemosensors based on photoinduced electron transfer (PET), 3 intramolecular charge transfer (ICT), 4 excited-state intramolecular proton transfer (ESIPT), 5 and fluorescence resonance energy transfer (FRET) mechanisms have been developed for this purpose in the past years. 2,[6][7][8][9][10] Nevertheless, none of them completely satisfies the criteria for a biosystemoriented chemosensor.…”

Section: Introductionmentioning

confidence: 99%

A phenol-based compartmental ligand as a potential chemosensor for zinc(ii) cations

Chen¹,

Cao²,

Wang³

et al. 2009

J. Braz. Chem. Soc.

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O ligante compartimental 2,6-bis(2-hidroxibenzil-2-hidroxietilamino) metil-4-metilfenol (L) foi sintetizado como um sensor químico em potencial para íons Zn 2+ . A base L coordena dois cátions Zn 2+ em metanol-água, formando um complexo dinuclear cuja formulação foi confirmada por espectrometria de massas com ionização por "electrospray" (ESI-MS) e pelo gráfico de Job. A fluorescência de L é notavelmente aumentada por Zn 2+ em comparação com os íons K + , Ca 2+ , Mg 2+ , Cu 2+ , Pb 2+ , Mn 2+ , Fe 3+ , Fe 2+ , Co 2+ , Cd 2+ e Ni 2+ . Isto se deve ao fato de que a complexação do íon Zn 2+ a L interrompe o processo de transferência eletrônica fotoinduzida e aumenta a rigidez do esqueleto molecular de L. Observou-se ainda que a fluorescência de L é fortemente dependente da acidez e da polaridade dos solventes. Este composto poderá ser utilizado como uma sonda sensível a íons Zn 2+ em solventes polares próticos, após uma modificação estrutural adequada.An "end-off"-type compartmental Lewis base, 2,6-bis(2-hydroxybenzyl-2-hydroxyethylamino) methyl-4-methylphenol (L), was synthesized as a potential chemosensor for Zn 2+ ions. L coordinates two Zn 2+ cations in methanol-water solution, forming a dinuclear complex whose formulation was confirmed by ESI-MS spectroscopy and Job's plot. The fluorescence of L is remarkably enhanced by Zn 2+ as compared with K + , Ca 2+ , Mg 2+ , Cu 2+ , Pb 2+ , Mn 2+ , Fe 3+ , Fe 2+ , Co 2+ , Cd 2+ and Ni 2+ ions. The fluorescence enhancement is attributed to the complexation of Zn 2+ with L, which interrupts the photoinduced electron transfer process and rigidifies the molecular skeleton of L. The fluorescence of L is greatly dependent on the acidity and polarity of the solvents. This compound may be used as a probe to sense Zn 2+ ion in polar protic solvents after proper modification.Keywords: chemosensor, fluorescence mechanism, phenol derivative, solvent effects, zinc(II) IntroductionZinc(II) ions play vital roles in a wide range of physiological processes. Deficiency or imbalance of Zn 2+ within the human body can lead to a variety of diseases. 1 Hence the development of selective zinc chemosensors is of great importance for tracking the Zn 2+ status in biological systems. 2 Fluorescence chemosensors based on photoinduced electron transfer (PET), 3 intramolecular charge transfer (ICT), 4 excited-state intramolecular proton transfer (ESIPT), 5 and fluorescence resonance energy transfer (FRET) mechanisms have been developed for this purpose in the past years. 2,6-10 Nevertheless, none of them completely satisfies the criteria for a biosystemoriented chemosensor. Therefore, efforts to design novel zinc probes are still needed.Structural factors, such as molecular rigidity, could produce significant influence on the fluorescence efficiency of a chemosensor. An increase in planarity and a decrease in torsion may benefit the chemosensor to enhance its fluorescence. 11 As a metal ion binds to a chemosensor, the molecular rigidity is enhanced and the above mentioned transfer processes are poss...

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Sensitive and Selective PET-Based Diimidazole Luminophore for Zn^II Ions: A Structure−Activity Correlation

Cited by 32 publications

References 39 publications

Lanthanide Complexes with Heteroditopic Ligands as Fluorescent Zinc Sensors

Lanthanide Complexes with Heteroditopic Ligands as Fluorescent Zinc Sensors

Density Functional Theory Based Analysis of Photoinduced Electron Transfer in a Triazacryptand Based K⁺ Sensor

A phenol-based compartmental ligand as a potential chemosensor for zinc(ii) cations

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Sensitive and Selective PET-Based Diimidazole Luminophore for ZnII Ions: A Structure−Activity Correlation

Cited by 32 publications

References 39 publications

Lanthanide Complexes with Heteroditopic Ligands as Fluorescent Zinc Sensors

Lanthanide Complexes with Heteroditopic Ligands as Fluorescent Zinc Sensors

Density Functional Theory Based Analysis of Photoinduced Electron Transfer in a Triazacryptand Based K+ Sensor

A phenol-based compartmental ligand as a potential chemosensor for zinc(ii) cations

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Product

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Sensitive and Selective PET-Based Diimidazole Luminophore for Zn^II Ions: A Structure−Activity Correlation

Density Functional Theory Based Analysis of Photoinduced Electron Transfer in a Triazacryptand Based K⁺ Sensor