Record high magnetic exchange and magnetization blockade in Ln<sub>2</sub>@C<sub>79</sub>N (Ln = Gd(<scp>iii</scp>) and Dy(<scp>iii</scp>)) molecules: a theoretical perspective

Singh, Mukesh Kumar; Yadav, Neeraj; Rajaraman, Gopalan

doi:10.1039/c5cc06642e

Cited by 77 publications

(78 citation statements)

References 40 publications

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“…This methodology has a proven track record to rationalize, and also predict at times, a reliable mechanism of magnetic relaxation. 12,13,19,20 The eight Kramers Doublets (KDs), corresponding to the 6 H 15/2 state, span within energy ranges of 882.1 cm À1 and 919.0 cm À1 , respectively for complexes 1 and 2. For both complexes, m J = AE15/2 is the ground state with m J = AE13/2 as the first excited state and m J = AE1/2 as the second-excited state.…”

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confidence: 99%

Chemical andin silicotuning of the magnetisation reversal barrier in pentagonal bipyramidal Dy(iii) single-ion magnets

et al. 2018

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Two new air-stable axial Dy(iii) single-ion magnets, [Dy(H2O)5(HMPA)2]Cl3·HMPA·H2O (1) and [Dy(H2O)5(HMPA)2]I3·2HMPA (2) (HMPA = hexamethylphosphoramide), exhibit magnetic hysteresis which remains open up to 9 K for 1@Y and 10 K for 2@Y, respectively. Ab initio calculations, using step-by-step elimination of fragments to generate a series of model complexes, reveal that the secondary coordination sphere plays a key role in controlling the magnetisation reversal barrier and predict that the removal of outer-sphere molecules and anions will enhance the barrier further.

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confidence: 99%

Chemical andin silicotuning of the magnetisation reversal barrier in pentagonal bipyramidal Dy(iii) single-ion magnets

et al. 2018

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“…Severalm odelsw ere taken into accounta sD y-rad,D yi nside non-radicalf ullerene, Dy-Dy full fullerenea nd av ariousr ange of U cal 134 cm À1 to 713 cm À1 has been obtained which confirms as the exchange between the Dy and radical increases the U cal effectively (Table 3). [42] After this Popov and co-workers synthesised analogues complex Dy 2 @C 80 (CH 2 Ph) with ar adical trapped in between the two Dy centres showing the blocking temperature of 18 Ka nd U eff value of 613 K( 426 cm À1 )a greeing quite close to theoretical predictions. [43] In the next phase of the fullerene type SMMs,o ther models focusingo nt he Dy III ion within C 72 (9c), C 76 (9d)a nd C 82 (9e) cages where the Dy-C distance estimated in the range of 2.4 to 2.6 A o and the Dy III ion is bridgedt ot he Sc III ion via an oxo bridge inside the fullerenec ages have been explored.…”

Section: Endohedral Lanthanofullerenes As Smmsmentioning

confidence: 60%

“…The Dy 2 @C 79 N (complex 9 b ) taken into the CASSCF+RASSI‐SO/SINGLE‐ANISO/POLY‐ANISO module to calculate the energy blockade for magnetic reversal and it shows an energy barrier of 837.6 and 785.7 cm −1 at individual Dy centres with Ising type anisotropy at the ground state which is of pure 15/2 type (see Table also). Several models were taken into account as Dy‐rad, Dy inside non‐radical fullerene, Dy‐Dy full fullerene and a various range of U cal 134 cm −1 to 713 cm −1 has been obtained which confirms as the exchange between the Dy and radical increases the U cal effectively (Table ) …”

Section: Introductionmentioning

confidence: 60%

Role of Ab Initio Calculations in the Design and Development of Organometallic Lanthanide‐Based Single‐Molecule Magnets

Swain

Sarkar

Rajaraman

2019

Chemistry An Asian Journal

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Single‐molecule magnets based on lanthanides are very attractive due to their potential applications proposed in the area of microelectronic devices. Very recent advances in this area are due to the blend of conventional lanthanide chemistry with organometallic ligands, and several breakthrough achievements are attained with this combination. Ab initio methods based on multi‐reference CASSCF calculations are playing a vital role in the design and development of such molecules. In this minireview, we aim to appraise various contributions in the area of organometallic lanthanide complexes (those containing lanthanide‐carbon bonds) and describe how these robust wavefunction‐based methods have played a constructive role not only in rationalizing the observed magnetic properties but also proven to be a potential predictive tool with some selected examples.

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“…These lanthanide endohedral metallofullerenes (EMFs) are fullerenes that have metal ions, dinuclear fragments, trinuclear or mixed systems encapsulated in various C n cages exhibiting fascinating magnetic properties . If doped fullerene cages such as C 79 N are utilised, this leads to extremely strong magnetic coupling between the Ln III and the radical centres, again predicted by theory and verified lately by experiments . Lanthanide ions are known to be anisotropic in nature because of the deeply buried degenerate 4f orbitals and by virtue of this property, they are found to be the most promising tool to build an SMM with high energy barrier for spin reversal …”

Section: Introductionmentioning

confidence: 98%

A Design Criteria to Achieve Giant Ising‐Type Anisotropy in Co^II‐Encapsulated Metallofullerenes

Singh

Shukla

Khatua

et al. 2019

Chemistry A European J

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Discovery of permanent magnetisation in molecules just like in hard magnets decades ago led to the proposal of utilising these molecules for information storage devices and also as Q‐bits in quantum computing. A significant breakthrough with a blocking temperature as high as 80 K has been recently reported for lanthanocene complexes. While enhancing the blocking temperature further remains one of the primary challenges, obtaining molecules that are suitable for the fabrication of the devices sets the bar very high in this area. Encouraged by the fact that our earlier predictions of potential single‐molecule magnets (SMMs) in lanthanide‐containing endohedral fullerenes have been verified, here we set out to undertake a comprehensive study on CoII‐ion‐encapsulated fullerene as potential SMMs. To study this class of molecules, we have utilised an array of theoretical methods ranging from density functional to ab initio CASSCF/NEVPT2 methods for obtaining reliable estimate of zero‐field splitting parameters D and E. Additionally, we have also employed, for the first time a combination of molecular dynamics based on DFT methods coupled with CASSCF/NEVPT2 methods to seek the role of conformational isomers in the relaxation of magnetisation. Particularly, we have studied, Co@C28, Co@C38 and Co@C48 cages and their isomers as potential target molecules that could yield substantial magnetic anisotropy. Our calculations categorically reveal a very large Ising anisotropy in this class of molecules, with Co@C48 cages predicted to yield D values as high as −127 cm−1. Our calculations on the smaller cages reveal the free movement of CoII ion inside the cage, leading to the likely scenario of faster relaxation of magnetisation. However, larger fullerene cages were found to solve this issue. Further models with incorporating units such as {CoOZn}, {CoScZnN} inside larger fullerenes yield axial zero‐field splitting values as high as −200 cm−1 with negligible E/D values. As these units represent a strong axiality coupled with a viable way to obtain air‐stable low‐coordinate CoII complexes, this opens up a new paradigm in the search of SMMs in this class of molecules.

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Record high magnetic exchange and magnetization blockade in Ln₂@C₇₉N (Ln = Gd(iii) and Dy(iii)) molecules: a theoretical perspective

Cited by 77 publications

References 40 publications

Chemical andin silicotuning of the magnetisation reversal barrier in pentagonal bipyramidal Dy(iii) single-ion magnets

Chemical andin silicotuning of the magnetisation reversal barrier in pentagonal bipyramidal Dy(iii) single-ion magnets

Role of Ab Initio Calculations in the Design and Development of Organometallic Lanthanide‐Based Single‐Molecule Magnets

A Design Criteria to Achieve Giant Ising‐Type Anisotropy in Co^II‐Encapsulated Metallofullerenes

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Record high magnetic exchange and magnetization blockade in Ln2@C79N (Ln = Gd(iii) and Dy(iii)) molecules: a theoretical perspective

Cited by 77 publications

References 40 publications

Chemical andin silicotuning of the magnetisation reversal barrier in pentagonal bipyramidal Dy(iii) single-ion magnets

Chemical andin silicotuning of the magnetisation reversal barrier in pentagonal bipyramidal Dy(iii) single-ion magnets

Role of Ab Initio Calculations in the Design and Development of Organometallic Lanthanide‐Based Single‐Molecule Magnets

A Design Criteria to Achieve Giant Ising‐Type Anisotropy in CoII‐Encapsulated Metallofullerenes

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Record high magnetic exchange and magnetization blockade in Ln₂@C₇₉N (Ln = Gd(iii) and Dy(iii)) molecules: a theoretical perspective

A Design Criteria to Achieve Giant Ising‐Type Anisotropy in Co^II‐Encapsulated Metallofullerenes