NMR for Single Ion Magnets

Abstract

Nuclear Magnetic Resonance is particularly sensitive to the electronic structure of matter and is thus a powerful tool to characterize in-depth the magnetic properties of a system. NMR is indeed increasingly recognized as an ideal tool to add precious structural information for the development of Single Ion Magnets, small complexes that are recently gaining much popularity due to their quantum computing and spintronics applications. In this review, we recall the theoretical principles of paramagnetic NMR, with particular attention to lanthanoids, and we give an overview of the recent advances in this field.

A dysprosium single molecule magnet outperforming current pseudocontact shift agents

“…electron density distribution. 27,28 Finally, the O1-Dy-O1 i angle in 1, 167.19 (15) , is by far the closest to linear among the three complexes (154.3(2) and 158.07 (11) for 2 and 3, respectively).…”

“…On these grounds, it is possible to expect that good SMMs also make excellent PCS tags for structural analysis of, e.g., biologically relevant molecules. 11,12 Despite the similar requirements and the increased number of solution NMR studies of SMMs, [13][14][15][16] a factor that slowed down the cross-communication across these elds is chemical compatibility. To date, the best mononuclear SMMs consist of dysprosium(III) ions (4f 9 , L ¼ 5, S ¼ 5/2, and J ¼ 15/2) in a highly axial crystal eld (CF) generated by low coordination numbers or cyclic polyhapto ligands in a sandwich arrangement, 5,6 most of them characterized by relatively low stability towards air and common solvents.…”

The evolution of paramagnetic NMR as a tool in structural biology

“…(6) When discussing the use of high fields, it is mandatory to mention the use of solid-state NMR, where the absence/reduction of incoherent molecular tumbling yields an effective reduction of the Curie-spin relaxation 146,147 and, in parallel, the appearance of a “powder pattern” reflects the geometry and the anisotropy of the interaction of the nuclear spin with the “Curie Spin”, and encodes highly relevant structural/dynamical information. 11,127,148–150…”

“…Efforts are currently being devoted to the development of pulses that can efficiently cover the full spectral width, 144 as well as for methods that allow for reducing the massive phase distortion that occurs as a result of pulse imperfections and dead time. 145 (6) When discussing the use of high fields, it is mandatory to mention the use of solid-state NMR, where the absence/ reduction of incoherent molecular tumbling yields an effective reduction of the Curie-spin relaxation 146,147 and, in parallel, the appearance of a ''powder pattern'' reflects the geometry and the anisotropy of the interaction of the nuclear spin with the ''Curie Spin'', and encodes highly relevant structural/dynamical information. 11,127,[148][149][150] The possibility of providing structural information in solution with an increasing level of detail, in conjunction with the possibility of characterizing biomolecular dynamics, is expected to further increase the number of users and applications of paramagnetic NMR, and to foster the development of computational tools and automated protocols for integrated data analysis.…”

Observability of Paramagnetic NMR Signals at over 10 000 ppm Chemical Shifts

“…[3,4] At the same time, there is a growing interest in the detection and analysis of paramagnetic intermediates in catalytic reaction cycles, particularly for the first-row transition metals, where the reactive molecular fragments tend to be either directly bonded, or otherwise in close proximity to the metal. [5][6][7][8][9][10][11] Other areas of current interest are singlemolecule magnets (SMMs), [12][13][14][15] contrast agents in magnetic resonance imaging (MRI), [16][17][18] and pseudocontact shift (PCS) probes in structural biology. [19][20][21][22] Several recent studies used magneto-structural correlations derived by multireference ab initio methods to refine chemical structures using paramagnetic NMR shifts.…”