Broad-Range Spectral Analysis for Chiral Metal Coordination Compounds: (Chiro)optical Superspectrum of Cobalt(II) Complexes
| Autor: | Lorenzo Arrico, Gennaro Pescitelli, Marcin Górecki, Mohammed Enamullah, Lorenzo Di Bari, Steffen Lüdeke, Irina Gruber, Marija Marolt, Mohammad Ariful Islam, Viktor Justus, Anne-Christine Chamayou, Christoph Janiak |
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| Rok vydání: | 2018 |
| Předmět: |
chemistry.chemical_classification
Circular dichroism Schiff base Absorption spectroscopy 010405 organic chemistry Aryl Diastereomer Time-dependent density functional theory 010402 general chemistry 01 natural sciences 0104 chemical sciences Coordination complex Inorganic Chemistry chemistry.chemical_compound Crystallography chemistry Physical and Theoretical Chemistry Chirality (chemistry) |
| Zdroj: | Inorganic Chemistry. 57:13397-13408 |
| ISSN: | 1520-510X 0020-1669 |
| Popis: | Chiroptical broad-range spectral analysis extending from UV to mid-IR was employed to study a family of Co(II) N-(1-(aryl)ethyl)salicylaldiminato Schiff base complexes with pseudotetrahedral geometry associated with chirality-at-metal of the Δ/Λ type. While common chiral organic compounds have well-separated absorption and circular dichroism spectra (CD) in the UV/vis and IR regions, chiral Co(II) complexes feature an almost unique continuum of absorption and CD bands, which cover in sequence the UV, visible, near-IR (NIR), and IR regions of the electromagnetic spectrum. They can be collected in a single (chiro)optical superspectrum ranging from the UV (230 nm, 5.4 eV) to the mid-IR (1000 cm-1, 0.12 eV), which offers a fingerprint of the structure and stereochemistry of the metal complexes. Each region of the superspectrum contributes to one piece of information: the NIR-CD region, in combination with TDDFT calculations, allows a reliable assignment of the metal-centered chirality; the UV-CD region facilitates the analysis of the Δ/Λ diastereomeric equilibrium in solution; and the IR-VCD region contains a combination of low-lying metal-centered electronic states (LLES) and ligand-centered vibrations and displays characteristically enhanced and monosignate VCD bands. Circular dichroism in the NIR and IR regions is crucial to reveal the presence of d-d transitions of the Co(II) core which, due to the electric-dipole forbidden character, would be otherwise overlooked in the corresponding absorption spectra. |
| Databáze: | OpenAIRE |
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