How the Ligand Field in Lanthanide Coordination Complexes Determines Magnetic Susceptibility Anisotropy, Paramagnetic NMR Shift, and Relaxation Behavior
| العنوان: | How the Ligand Field in Lanthanide Coordination Complexes Determines Magnetic Susceptibility Anisotropy, Paramagnetic NMR Shift, and Relaxation Behavior |
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| المؤلفون: | Elizaveta A. Suturina, Nicholas F. Chilton, David Parker, Ilya Kuprov |
| المصدر: | Accounts of Chemical Research |
| بيانات النشر: | American Chemical Society (ACS), 2020. |
| سنة النشر: | 2020 |
| مصطلحات موضوعية: | Lanthanide, Ligand field theory, Materials science, 010405 organic chemistry, Relaxation (NMR), Energy level splitting, General Medicine, General Chemistry, equipment and supplies, 010402 general chemistry, 01 natural sciences, Magnetic susceptibility, Article, 0104 chemical sciences, Paramagnetism, Magnetic anisotropy, Chemical physics, Anisotropy, human activities |
| الوصف: | ConspectusComplexes of lanthanide(III) ions are being actively studied because of their unique ground and excited state properties and the associated optical and magnetic behavior. In particular, they are used as emissive probes in optical spectroscopy and microscopy and as contrast agents in magnetic resonance imaging (MRI). However, the design of new complexes with specific optical and magnetic properties requires a thorough understanding of the correlation between molecular structure and electric and magnetic susceptibilities, as well as their anisotropies. The traditional Judd-Ofelt-Mason theory has failed to offer useful guidelines for systematic design of emissive lanthanide optical probes. Similarly, Bleaney's theory of magnetic anisotropy and its modifications fail to provide accurate detail that permits new paramagnetic shift reagents to be designed rather than discovered.A key determinant of optical and magnetic behavior in f-element compounds is the ligand field, often considered as an electrostatic field at the lanthanide created by the ligands. The resulting energy level splitting is a sensitive function of several factors: The nature and polarizability of the whole ligand and its donor atoms; the geometric details of the coordination polyhedron; the presence and extent of solvent interactions; specific hydrogen bonding effects on donor atoms and the degree of supramolecular order in the system. The relative importance of these factors can vary widely for different lanthanide ions and ligands. For nuclear magnetic properties, it is both the ligand field splitting and the magnetic susceptibility tensor, notably its anisotropy, that determine paramagnetic shifts and nuclear relaxation enhancement.We review the factors that control the ligand field in lanthanide complexes and link these to aspects of their utility in magnetic resonance and optical emission spectroscopy and imaging. We examine recent progress in this area particularly in the theory of paramagnetic chemical shift and relaxation enhancement, where some long-neglected effects of zero-field splitting, magnetic susceptibility anisotropy, and spatial distribution of lanthanide tags have been accommodated in an elegant way. |
| وصف الملف: | text |
| تدمد: | 1520-4898 0001-4842 |
| DOI: | 10.1021/acs.accounts.0c00275 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::70daa84a6bbab4bbfd237b34c3e22171 https://doi.org/10.1021/acs.accounts.0c00275 |
| Rights: | OPEN |
| رقم الانضمام: | edsair.doi.dedup.....70daa84a6bbab4bbfd237b34c3e22171 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 15204898 00014842 |
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| DOI: | 10.1021/acs.accounts.0c00275 |