Electronic and Photophysical Properties of Re I (CO) 3 Br Complexes Modulated by Pyrazolyl-Pyridazine Ligands

Marianela Saldías, Nicolás Guzmán, Franco Palominos, Catalina Sandoval-Altamirano, Germán Günther, Nancy Pizarro, Andrés Vega

Resultado de la investigación: Article

1 Cita (Scopus)

Resumen

The direct reaction of a series of substituted (1H-pyrazol-1-yl)pyridazine (L I : 6-(1H-pyrazolyl)pyridazine; L II : 3-chloro-6-(1H-pyrazole-1-yl)-pyridazine; L III : 6-(1H-3,5-dimethylpyrazolyl)pyridazine-3-carboxylic acid; L IV : 3,6-bis-N-pyrazolyl-pyridazine; and L V : 3,6-bis-N-3-methylpyrazolyl-pyridazine) with the bromotricarbonyl(tetrahydrofuran)-rhenium(I) dimer leads to the monometallic complexes [(L X )Re(CO) 3 Br] (I-V), which displays a nonregular octahedral geometry around the Re I center and a fac-isomerism for the carbonyl groups, whereas pyridazine and pyrazolyl rings remain highly coplanar after coordination to rhenium. Cyclic voltammetry shows one irreversible oxidation and one irreversible reduction for each compound as measured in N,N-dimethylformamide. Oxidation ranges from 0.94 V for III to 1.04 V for I and have been attributed to the Re I /Re II couple. In contrast, the reductions are ligand centered, ranging from -1.64 V for II to -1.90 V for III and V. Density functional theory calculations on the vertical one electron oxidized and one electron reduced species, using the gas-phase optimized geometry for the neutral complex confirm this assignment. Compounds I-V show two absorption bands, one around 410 nm (metal-to-ligand charge transfer (MLCT), Re → π∗) and the other at ∼300 nm (intraligand, π → π∗). Excitation at 400 nm at 77 K leads to unstructured and monoexponential emission with large Stokes shift, whose maxima vary between 570 (III) and 636 (II) nm. The quantum yields for these emissions in solution are intensified strongly going from air to argon equilibrated solution. Singlet oxygen quantum yields change from 0.03 (III) to 0.21 (IV). These data are consistent with emission from 3 MLCT. The emission undergoes a bathochromic shift when R 1 is a π-donating group (Cl or N-pyrazolyl) and a hypsochromic shift for a π-acceptor (COOH). The bimolecular emission quenching rate constant by triethylamine (TEA) for II, IV, and V is 1.09, 0.745, and 0.583 × 10 8 M -1 s -1 , respectively. Photolysis in dichloromethane-CO 2 saturated solution with TEA as a sacrificial electron donor leads in all cases to formic acid generation.

Idioma originalEnglish
Páginas (desde-hasta)4679-4690
Número de páginas12
PublicaciónACS Omega
Volumen4
N.º3
DOI
EstadoPublished - 4 mar 2019

Huella dactilar

Carbon Monoxide
Rhenium
Ligands
Quantum yield
Electrons
Charge transfer
Oxidation
Geometry
Formic acid
Dichloromethane
Photolysis
Dimethylformamide
formic acid
Metals
Carboxylic acids
Dimers
Cyclic voltammetry
Density functional theory
Argon
Absorption spectra

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

Citar esto

Saldías, Marianela ; Guzmán, Nicolás ; Palominos, Franco ; Sandoval-Altamirano, Catalina ; Günther, Germán ; Pizarro, Nancy ; Vega, Andrés. / Electronic and Photophysical Properties of Re I (CO) 3 Br Complexes Modulated by Pyrazolyl-Pyridazine Ligands. En: ACS Omega. 2019 ; Vol. 4, N.º 3. pp. 4679-4690.
@article{fba3ca0cd1d24d2cb7f75b41d0d6fc37,
title = "Electronic and Photophysical Properties of Re I (CO) 3 Br Complexes Modulated by Pyrazolyl-Pyridazine Ligands",
abstract = "The direct reaction of a series of substituted (1H-pyrazol-1-yl)pyridazine (L I : 6-(1H-pyrazolyl)pyridazine; L II : 3-chloro-6-(1H-pyrazole-1-yl)-pyridazine; L III : 6-(1H-3,5-dimethylpyrazolyl)pyridazine-3-carboxylic acid; L IV : 3,6-bis-N-pyrazolyl-pyridazine; and L V : 3,6-bis-N-3-methylpyrazolyl-pyridazine) with the bromotricarbonyl(tetrahydrofuran)-rhenium(I) dimer leads to the monometallic complexes [(L X )Re(CO) 3 Br] (I-V), which displays a nonregular octahedral geometry around the Re I center and a fac-isomerism for the carbonyl groups, whereas pyridazine and pyrazolyl rings remain highly coplanar after coordination to rhenium. Cyclic voltammetry shows one irreversible oxidation and one irreversible reduction for each compound as measured in N,N-dimethylformamide. Oxidation ranges from 0.94 V for III to 1.04 V for I and have been attributed to the Re I /Re II couple. In contrast, the reductions are ligand centered, ranging from -1.64 V for II to -1.90 V for III and V. Density functional theory calculations on the vertical one electron oxidized and one electron reduced species, using the gas-phase optimized geometry for the neutral complex confirm this assignment. Compounds I-V show two absorption bands, one around 410 nm (metal-to-ligand charge transfer (MLCT), Re dπ → π∗) and the other at ∼300 nm (intraligand, π → π∗). Excitation at 400 nm at 77 K leads to unstructured and monoexponential emission with large Stokes shift, whose maxima vary between 570 (III) and 636 (II) nm. The quantum yields for these emissions in solution are intensified strongly going from air to argon equilibrated solution. Singlet oxygen quantum yields change from 0.03 (III) to 0.21 (IV). These data are consistent with emission from 3 MLCT. The emission undergoes a bathochromic shift when R 1 is a π-donating group (Cl or N-pyrazolyl) and a hypsochromic shift for a π-acceptor (COOH). The bimolecular emission quenching rate constant by triethylamine (TEA) for II, IV, and V is 1.09, 0.745, and 0.583 × 10 8 M -1 s -1 , respectively. Photolysis in dichloromethane-CO 2 saturated solution with TEA as a sacrificial electron donor leads in all cases to formic acid generation.",
author = "Marianela Sald{\'i}as and Nicol{\'a}s Guzm{\'a}n and Franco Palominos and Catalina Sandoval-Altamirano and Germ{\'a}n G{\"u}nther and Nancy Pizarro and Andr{\'e}s Vega",
year = "2019",
month = "3",
day = "4",
doi = "10.1021/acsomega.8b03306",
language = "English",
volume = "4",
pages = "4679--4690",
journal = "ACS Omega",
issn = "2470-1343",
publisher = "American Chemical Society",
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Electronic and Photophysical Properties of Re I (CO) 3 Br Complexes Modulated by Pyrazolyl-Pyridazine Ligands. / Saldías, Marianela; Guzmán, Nicolás; Palominos, Franco; Sandoval-Altamirano, Catalina; Günther, Germán; Pizarro, Nancy; Vega, Andrés.

En: ACS Omega, Vol. 4, N.º 3, 04.03.2019, p. 4679-4690.

Resultado de la investigación: Article

TY - JOUR

T1 - Electronic and Photophysical Properties of Re I (CO) 3 Br Complexes Modulated by Pyrazolyl-Pyridazine Ligands

AU - Saldías, Marianela

AU - Guzmán, Nicolás

AU - Palominos, Franco

AU - Sandoval-Altamirano, Catalina

AU - Günther, Germán

AU - Pizarro, Nancy

AU - Vega, Andrés

PY - 2019/3/4

Y1 - 2019/3/4

N2 - The direct reaction of a series of substituted (1H-pyrazol-1-yl)pyridazine (L I : 6-(1H-pyrazolyl)pyridazine; L II : 3-chloro-6-(1H-pyrazole-1-yl)-pyridazine; L III : 6-(1H-3,5-dimethylpyrazolyl)pyridazine-3-carboxylic acid; L IV : 3,6-bis-N-pyrazolyl-pyridazine; and L V : 3,6-bis-N-3-methylpyrazolyl-pyridazine) with the bromotricarbonyl(tetrahydrofuran)-rhenium(I) dimer leads to the monometallic complexes [(L X )Re(CO) 3 Br] (I-V), which displays a nonregular octahedral geometry around the Re I center and a fac-isomerism for the carbonyl groups, whereas pyridazine and pyrazolyl rings remain highly coplanar after coordination to rhenium. Cyclic voltammetry shows one irreversible oxidation and one irreversible reduction for each compound as measured in N,N-dimethylformamide. Oxidation ranges from 0.94 V for III to 1.04 V for I and have been attributed to the Re I /Re II couple. In contrast, the reductions are ligand centered, ranging from -1.64 V for II to -1.90 V for III and V. Density functional theory calculations on the vertical one electron oxidized and one electron reduced species, using the gas-phase optimized geometry for the neutral complex confirm this assignment. Compounds I-V show two absorption bands, one around 410 nm (metal-to-ligand charge transfer (MLCT), Re dπ → π∗) and the other at ∼300 nm (intraligand, π → π∗). Excitation at 400 nm at 77 K leads to unstructured and monoexponential emission with large Stokes shift, whose maxima vary between 570 (III) and 636 (II) nm. The quantum yields for these emissions in solution are intensified strongly going from air to argon equilibrated solution. Singlet oxygen quantum yields change from 0.03 (III) to 0.21 (IV). These data are consistent with emission from 3 MLCT. The emission undergoes a bathochromic shift when R 1 is a π-donating group (Cl or N-pyrazolyl) and a hypsochromic shift for a π-acceptor (COOH). The bimolecular emission quenching rate constant by triethylamine (TEA) for II, IV, and V is 1.09, 0.745, and 0.583 × 10 8 M -1 s -1 , respectively. Photolysis in dichloromethane-CO 2 saturated solution with TEA as a sacrificial electron donor leads in all cases to formic acid generation.

AB - The direct reaction of a series of substituted (1H-pyrazol-1-yl)pyridazine (L I : 6-(1H-pyrazolyl)pyridazine; L II : 3-chloro-6-(1H-pyrazole-1-yl)-pyridazine; L III : 6-(1H-3,5-dimethylpyrazolyl)pyridazine-3-carboxylic acid; L IV : 3,6-bis-N-pyrazolyl-pyridazine; and L V : 3,6-bis-N-3-methylpyrazolyl-pyridazine) with the bromotricarbonyl(tetrahydrofuran)-rhenium(I) dimer leads to the monometallic complexes [(L X )Re(CO) 3 Br] (I-V), which displays a nonregular octahedral geometry around the Re I center and a fac-isomerism for the carbonyl groups, whereas pyridazine and pyrazolyl rings remain highly coplanar after coordination to rhenium. Cyclic voltammetry shows one irreversible oxidation and one irreversible reduction for each compound as measured in N,N-dimethylformamide. Oxidation ranges from 0.94 V for III to 1.04 V for I and have been attributed to the Re I /Re II couple. In contrast, the reductions are ligand centered, ranging from -1.64 V for II to -1.90 V for III and V. Density functional theory calculations on the vertical one electron oxidized and one electron reduced species, using the gas-phase optimized geometry for the neutral complex confirm this assignment. Compounds I-V show two absorption bands, one around 410 nm (metal-to-ligand charge transfer (MLCT), Re dπ → π∗) and the other at ∼300 nm (intraligand, π → π∗). Excitation at 400 nm at 77 K leads to unstructured and monoexponential emission with large Stokes shift, whose maxima vary between 570 (III) and 636 (II) nm. The quantum yields for these emissions in solution are intensified strongly going from air to argon equilibrated solution. Singlet oxygen quantum yields change from 0.03 (III) to 0.21 (IV). These data are consistent with emission from 3 MLCT. The emission undergoes a bathochromic shift when R 1 is a π-donating group (Cl or N-pyrazolyl) and a hypsochromic shift for a π-acceptor (COOH). The bimolecular emission quenching rate constant by triethylamine (TEA) for II, IV, and V is 1.09, 0.745, and 0.583 × 10 8 M -1 s -1 , respectively. Photolysis in dichloromethane-CO 2 saturated solution with TEA as a sacrificial electron donor leads in all cases to formic acid generation.

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U2 - 10.1021/acsomega.8b03306

DO - 10.1021/acsomega.8b03306

M3 - Article

VL - 4

SP - 4679

EP - 4690

JO - ACS Omega

JF - ACS Omega

SN - 2470-1343

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ER -