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Papers by Franc Meyer

Inorganic Chemistry, Sep 28, 2020

Inorganic Chemistry, Mar 6, 2020

Angewandte Chemie, May 30, 2017

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Journal of the American Chemical Society, Nov 16, 2020

Inorganic Chemistry, Jun 27, 2017

Dalton Transactions, 2016

Inorganic Chemistry, Jan 14, 2019

Dalton Transactions, 2018

ACS Catalysis, Nov 20, 2019

Physical Review B, Jun 2, 2006

Catalysts

The massive worldwide use of antibiotics leads to water pollution and increasing microbial resist... more The massive worldwide use of antibiotics leads to water pollution and increasing microbial resistance. Hence, the removal of antibiotic residues is a key issue in water remediation. Here, we report the solar light-assisted oxidative degradation of ciprofloxacin (CPF), using H2O2 in aqueous solution, catalyzed by iron(III) chelated cross-linked chitosan (FeIII-CS-GLA) immobilized on a glass plate. The FeIII-CS-GLA catalyst was characterized by FTIR and 57Fe-Mössbauer spectroscopies as well as X-ray diffraction, revealing key structural motifs and a high-spin ferric character of the metal. Catalytic degradation of CPF was investigated as a function of solar light irradiation time, solution pH, concentration of H2O2 and CPF, as well as cross-linker dosage and iron(III) content in FeIII-CS-GLA. The system was found to serve as an efficient catalyst with maximum CPF degradation at pH 3. The specific ·OH scavenger mannitol significantly reduces the degradation rate, indicating that hydrox...

Inorganic Chemistry, 2017

ACS Catalysis, Jul 10, 2019

Inorganic Chemistry, 2021

Bis(formazanate)iron(II) complexes undergo a thermally induced S = 0 to S = 2 spin transition in ... more Bis(formazanate)iron(II) complexes undergo a thermally induced S = 0 to S = 2 spin transition in solution. Here we present a study of how steric effects and π-stacking interactions between the triarylformazanate ligands affect the spincrossover behavior, in addition to electronic substituent effects. Moreover, the effect of increasing the denticity of the formazanate ligands is explored by including additional OMe donors in the ligand (7). In total, six new compounds (2−7) have been synthesized and characterized, both in solution and in the solid state, via spectroscopic, magnetic, and structural analyses. The series spans a broad range of spin-crossover temperatures (T 1/2) for the LS ⇌ HS equilibrium in solution, with the exception of compound 6 which remains high-spin (S = 2) down to 210 K. In the solid state, 6 was shown to exist in two distinct forms: a tetrahedral high-spin complex (6a, S = 2) and a rare square-planar structure with an intermediate-spin state (6b, S = 1). SQUID measurements, 57 Fe Mossbauer spectroscopy, and differential scanning calorimetry indicate that in the solid state the square-planar form 6b undergoes an incomplete spin-change-coupled isomerization to tetrahedral 6a. The complex that contains additional OMe donors (7) results in a six-coordinate (NNO) 2 Fe coordination geometry, which shifts the spin-crossover to significantly higher temperatures (T 1/2 = 444 K). The available experimental and computational data for 7 suggest that the Fe•••OMe interaction is retained upon spin-crossover. Despite the difference in coordination environment, the weak OMe donors do not significantly alter the electronic structure or ligand-field splitting, and the occurrence of spin-crossover (similar to the compounds lacking the OMe groups) originates from a large degree of metal−ligand π-covalency.

Inorganic Chemistry, 2020

Iron centers featuring thiolates in their metal coordination sphere (as ligands or substrates) ar... more Iron centers featuring thiolates in their metal coordination sphere (as ligands or substrates) are well-known to activate dioxygen. Both heme and non-heme centers that contain iron-thiolate bonds are found in nature. Investigating the ability of iron−thiolate model complexes to activate O 2 is expected to improve the understanding of the key factors that direct reactivity to either iron or sulfur. We report here the structural and redox properties of a thiolate-based dinuclear Fe complex, [Fe II 2 (LS) 2 ] (LS 2− = 2,2′-(2,2′-bipyridine-6,6′-iyl)bis(1,1-diphenylethanethiolate)), and its reactivity with dioxygen, in comparison with its previously reported protonated counterpart, [Fe II 2 (LS)(LSH)] +. When reaction with O 2 occurs in the absence of protons or in the presence of 1 equiv of proton (i.e., from [Fe II 2 (LS)(LSH)] +), unsupported μ-oxo or μ-hydroxo Fe III dinuclear complexes ([Fe III 2 (LS) 2 O] and [Fe III 2 (LS) 2 (OH)] + , respectively) are generated. [Fe III 2 (LS) 2 O], reported previously but isolated here for the first time from O 2 activation, is characterized by single crystal X-ray diffraction and Mossbauer, resonance Raman, and NMR spectroscopies. The addition of protons leads to the release of water and the generation of a mixture of two Fe-based "oxygen-free" species. Density functional theory calculations provide insight into the formation of the μ-oxo or μ-hydroxo Fe III dimers, suggesting that a dinuclear μ-peroxo Fe III intermediate is key to reactivity, and the structure of which changes as a function of protonation state. Compared to previously reported Mn−thiolate analogues, the evolution of the peroxo intermediates to the final products is different and involves a comproportionation vs a dismutation process for the Mn and Fe derivate, respectively.

Journal of the American Chemical Society, 2019

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Zeitschrift für anorganische und allgemeine Chemie, 2019

New hybrid ligands are reported that combine two types of popular donor groups within a single li... more New hybrid ligands are reported that combine two types of popular donor groups within a single linear scaffold, viz., a central pyrazolate bridge and two appended bis(N‐heterocyclic carbene) units; the ligand strands thus provide two potentially tridentate {NCC} compartments. The pyrazole/tetraimidazolium proligands, [H5L1](PF6)4 and [H5L2](PF6)4, were synthesized via multi‐step protocols, and the NH prototropy of [H5L1](PF6)4 was examined by variable temperature (VT) NMR spectroscopy, giving solvent dependent activation parameters (ΔH‡ = 27.6 kJ·mol–1, ΔS‡ = –125 J·mol–1·K–1 in [D3]MeCN; ΔH‡ = 40.4 kJ·mol–1, ΔS‡ = –86.9 J·mol–1·K–1 in [D6]DMSO) that are in the range typical for pyrazoles. Reaction of the proligands with Ag2O gave hexametallic complexes [Ag6(L1)2](PF6)4 and [Ag6(L2)2](PF6)4 that involve all six potential donor atoms of the ligands, viz. the four CNHC and two Npz donors, in metal coordination. X‐ray crystallography revealed a chair‐like central {Ag6} deck in both com...