1IL and 3MLCT excited states modulated by H+: the structure and photophysical properties of [(2-bromo-5-(1H-pyrazol-1-yl)pyrazine)Re(CO)3Br]

Pizarro, Nancy; Saldías, Marianela; Guzmán, Nicolás; Sandoval-Altamirano, Catalina; Kahlal, Samia; Saillard, Jean Yves; Hamon, Jean‐René; Vega, Andrés

doi:10.1039/c8nj04196b

Cited by 7 publications

(4 citation statements)

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“…Additionally, complex III shows a second reduction wave at −1.90 V, consistent with a Re I /Re 0 couple. This has been previously described for tricarbonyl Re I complexes with different diimine derivates. , …”

Section: Results and Discussionsupporting

confidence: 65%

“…This has been previously described for tricarbonyl Re I complexes with different diimine derivates. 27,64 The values for the reduction potential show to be increasingly more negative going from II to V. This means R 1 : = H (I) to N-methylpyrazolyl (V) (Scheme 1). To define the influence of these substituents, we have compared the difference between E p,c and E p,a with the HOMO−LUMO gap as determined from DFT modeling (Figure 3).…”

Section: Resultsmentioning

confidence: 99%

“…Similar transient absorption shape has been reported for a parent complex with the pyrazolyl-pyrazine ligand, which exhibited a mixture of 3 IL and 3 MLCT excited state, displaying biexponential transient decays. 64 In contrast, we discard the participation of transitions centered onto the ligands, 66 based on the single exponential decays, and the transient lifetimes and the transient absorption maxima wavelengths were determined.…”

Section: Resultsmentioning

confidence: 99%

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

et al. 2019

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The direct reaction of a series of substituted (1H-pyrazol-1yl)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-3methylpyrazolyl-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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Section: Results and Discussionsupporting

confidence: 65%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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

et al. 2019

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“…Pyrazolyl derivatives are appealing candidates to be explored, mainly due to their planarity and limited conformational flexibility that will diminish non-radiative deactivation paths [27,28]. We have recently shown that substitution modifications over this skeleton would modulate the electronic structure and in consequence, the compound properties [29,30]. Thus, this kind of compounds provides unique opportunities to rationally address their properties by finely tuning through modification of the ligands.…”

Section: Introductionmentioning

confidence: 99%

STRUCTURE OF fac-[(ppyEt)Re(CO)3Br], A MONONUCLEAR ReI COMPLEX DERIVED FROM PYRROLINE-PYRAZOLYL-PYRIDAZINE

Saldías

Palominos

Pizarro

et al. 2020

J. Chil. Chem. Soc.

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The reaction of 6-(1H-3,5-dimethylpyrazolyl)pyridazine-3-carboxylic acid with oxalyl chloride and then 2,4-dimethyl-3-ethylpyrrole leads to [6-(3,5-dimethyl-1Hpyrazol-1-yl)pyridazin-3-yl](4-ethyl-3,5-dimethyl-1H-pyrrol-2-yl)methanone (ppyEt). The reaction of ppyEt with bromotricarbonyl(tetrahydrofuran)-rhenium(I) dimer leads to [(ppyEt)Re(CO)3Br] compound. The molecule of [(ppyEt)Re(CO)3Br] displays a non-regular octahedron around the rhenium(I) center with a bromide. The molecule defines an intramolecular hydrogen bond between the 4-ethyl-3,5-dimethyl-1H-pyrrol-2-yl hydrogen atom and one nitrogen from the pyridazin-3-yl fragment with D•••A 2.833(17) Å. The coplanarity of the 4-ethyl-3,5-dimethyl-1H-pyrrol-2-yl-carbonyl is attributed to this intramolecular bond, in addition to C-H•••O≡C and N-H•••O≡C interactions as suggested by NCI calculations.

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Electronic Properties of Rhenium(I) Carbonyl Complexes Bearing Strongly Donating Hexahydro‐Pyrimidopyrimidine Based Ligands

2021

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Re(I) tricarbonyl complexes have been synthesized using biand tridentate ligands equipped with one or two hexahydropyrimidopyrimidine (hpp) units attached to either a pyridine or a pyrazine ring. These complexes have been characterized by NMR, ESI-MS, vibrational and optical spectroscopies as well as electrochemistry. Their structures were determined via singlecrystal X-ray crystallography and modelled using both DFT and TD-DFT methods. The complexes are non-emissive in solution at room temperature but display emission with mixed intra ligand (major) and metal-ligand (minor) charge transfer characters at 77 K. Additionally, both pyrazine-based complexes appear to be emissive in the solid state, presumably due to the presence of intermolecular interactions, as observed in the crystal structure.

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¹IL and ³MLCT excited states modulated by H⁺: the structure and photophysical properties of [(2-bromo-5-(1H-pyrazol-1-yl)pyrazine)Re(CO)₃Br]

Cited by 7 publications

References 56 publications

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

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

STRUCTURE OF fac-[(ppyEt)Re(CO)3Br], A MONONUCLEAR ReI COMPLEX DERIVED FROM PYRROLINE-PYRAZOLYL-PYRIDAZINE

Electronic Properties of Rhenium(I) Carbonyl Complexes Bearing Strongly Donating Hexahydro‐Pyrimidopyrimidine Based Ligands

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1IL and 3MLCT excited states modulated by H+: the structure and photophysical properties of [(2-bromo-5-(1H-pyrazol-1-yl)pyrazine)Re(CO)3Br]

Cited by 7 publications

References 56 publications

Electronic and Photophysical Properties of ReI(CO)3Br Complexes Modulated by Pyrazolyl–Pyridazine Ligands

Electronic and Photophysical Properties of ReI(CO)3Br Complexes Modulated by Pyrazolyl–Pyridazine Ligands

STRUCTURE OF fac-[(ppyEt)Re(CO)3Br], A MONONUCLEAR ReI COMPLEX DERIVED FROM PYRROLINE-PYRAZOLYL-PYRIDAZINE

Electronic Properties of Rhenium(I) Carbonyl Complexes Bearing Strongly Donating Hexahydro‐Pyrimidopyrimidine Based Ligands

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¹IL and ³MLCT excited states modulated by H⁺: the structure and photophysical properties of [(2-bromo-5-(1H-pyrazol-1-yl)pyrazine)Re(CO)₃Br]

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

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