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Optimization of the Sensitization Process and Stability of Octadentate Eu(III) 1,2-HOPO Complexes.

D'Aléo A, Moore EG, Xu J, Daumann LJ, Raymond KN - Inorg Chem (2015)

Bottom Line: The thermodynamic stability of the europium complexes has been studied and reveals these complexes may be effective for biological measurements.The luminescence properties for [Eu(H(14O4,2)-1,2-HOPO)](-) and [Eu(H(17O5,2)-1,2-HOPO)](-) are better than that of the model bis-tetradentate [Eu(5LIN(Me)-1,2-HOPO)2](-) complex, suggesting a different geometry around the metal center despite the geometric freedom allowed by the longer central chain in the H(mOn,2) scaffold.These differences are also evidenced by examining the luminescence spectra at room temperature and at 77 K and by calculating the luminescence kinetic parameters of the europium complexes.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of California, Berkeley, California 94720-1460, United States.

ABSTRACT
The synthesis of a series of octadentate ligands containing the 1-hydroxypyridin-2-one (1,2-HOPO) group in complex with europium(III) is reported. Within this series, the central bridge connecting two diethylenetriamine units linked to two 1,2-HOPO chromophores at the extremities (5-LIN-1,2-HOPO) is varied from a short ethylene chain (H(2,2)-1,2-HOPO) to a long pentaethylene oxide chain (H(17O5,2)-1,2-HOPO). The thermodynamic stability of the europium complexes has been studied and reveals these complexes may be effective for biological measurements. Extension of the central bridge results in exclusion of the inner-sphere water molecule observed for [Eu(H(2,2)-1,2-HOPO)](-) going from a nonacoordinated to an octacoordinated Eu(III) ion. With the longer chain length ligands, the complexes display increased luminescence properties in aqueous medium with an optimum of 20% luminescence quantum yield for the [Eu(H(17O5,2)-1,2-HOPO)](-) complex. The luminescence properties for [Eu(H(14O4,2)-1,2-HOPO)](-) and [Eu(H(17O5,2)-1,2-HOPO)](-) are better than that of the model bis-tetradentate [Eu(5LIN(Me)-1,2-HOPO)2](-) complex, suggesting a different geometry around the metal center despite the geometric freedom allowed by the longer central chain in the H(mOn,2) scaffold. These differences are also evidenced by examining the luminescence spectra at room temperature and at 77 K and by calculating the luminescence kinetic parameters of the europium complexes.

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Synthesis of H(m,2)-1,2-HOPOReagents and conditions: (a) 1,2-HOPOBn-thiaz, Et3N,DCM, RT, 16 h; (b) conc HCl/glacial HOAc (1:1), 3 days, RT.
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sch1: Synthesis of H(m,2)-1,2-HOPOReagents and conditions: (a) 1,2-HOPOBn-thiaz, Et3N,DCM, RT, 16 h; (b) conc HCl/glacial HOAc (1:1), 3 days, RT.


Optimization of the Sensitization Process and Stability of Octadentate Eu(III) 1,2-HOPO Complexes.

D'Aléo A, Moore EG, Xu J, Daumann LJ, Raymond KN - Inorg Chem (2015)

Synthesis of H(m,2)-1,2-HOPOReagents and conditions: (a) 1,2-HOPOBn-thiaz, Et3N,DCM, RT, 16 h; (b) conc HCl/glacial HOAc (1:1), 3 days, RT.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556046&req=5

sch1: Synthesis of H(m,2)-1,2-HOPOReagents and conditions: (a) 1,2-HOPOBn-thiaz, Et3N,DCM, RT, 16 h; (b) conc HCl/glacial HOAc (1:1), 3 days, RT.
Bottom Line: The thermodynamic stability of the europium complexes has been studied and reveals these complexes may be effective for biological measurements.The luminescence properties for [Eu(H(14O4,2)-1,2-HOPO)](-) and [Eu(H(17O5,2)-1,2-HOPO)](-) are better than that of the model bis-tetradentate [Eu(5LIN(Me)-1,2-HOPO)2](-) complex, suggesting a different geometry around the metal center despite the geometric freedom allowed by the longer central chain in the H(mOn,2) scaffold.These differences are also evidenced by examining the luminescence spectra at room temperature and at 77 K and by calculating the luminescence kinetic parameters of the europium complexes.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of California, Berkeley, California 94720-1460, United States.

ABSTRACT
The synthesis of a series of octadentate ligands containing the 1-hydroxypyridin-2-one (1,2-HOPO) group in complex with europium(III) is reported. Within this series, the central bridge connecting two diethylenetriamine units linked to two 1,2-HOPO chromophores at the extremities (5-LIN-1,2-HOPO) is varied from a short ethylene chain (H(2,2)-1,2-HOPO) to a long pentaethylene oxide chain (H(17O5,2)-1,2-HOPO). The thermodynamic stability of the europium complexes has been studied and reveals these complexes may be effective for biological measurements. Extension of the central bridge results in exclusion of the inner-sphere water molecule observed for [Eu(H(2,2)-1,2-HOPO)](-) going from a nonacoordinated to an octacoordinated Eu(III) ion. With the longer chain length ligands, the complexes display increased luminescence properties in aqueous medium with an optimum of 20% luminescence quantum yield for the [Eu(H(17O5,2)-1,2-HOPO)](-) complex. The luminescence properties for [Eu(H(14O4,2)-1,2-HOPO)](-) and [Eu(H(17O5,2)-1,2-HOPO)](-) are better than that of the model bis-tetradentate [Eu(5LIN(Me)-1,2-HOPO)2](-) complex, suggesting a different geometry around the metal center despite the geometric freedom allowed by the longer central chain in the H(mOn,2) scaffold. These differences are also evidenced by examining the luminescence spectra at room temperature and at 77 K and by calculating the luminescence kinetic parameters of the europium complexes.

Show MeSH
Related in: MedlinePlus