Dalton technical issue “Lanthanide and transition metal complexes as molecular magnets Single-molecule magnets within polyoxometalate-based frameworks

2021 ◽  
Author(s):  
Malihe Babaei Zarch ◽  
Masoud Mirzaei ◽  
Maryam Bazargan ◽  
Sandeep K Gupta ◽  
Franc Meyer ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Single Molecule ◽  
Molecular Magnets ◽  
Technical Issue ◽  
Hydrothermal Conditions ◽  
Single Molecule Magnets ◽  
Design And Synthesis

As an extension of our interest in polyoxometalates (POMs) and lanthanoids, we report the design and synthesis of two polyoxometalate-based frameworks under hydrothermal conditions; [Ho4(PDA)4(H2O)11][(SiO4)@W12O36]·8H2O (1) and [Tb4(PDA)4(H2O)12][(SiO4)@W12O36]·4H2O (2) (H2PDA...

scholarly journals High-Spin Cobalt(II) Complex with Record-Breaking Anisotropy of the Magnetic Susceptibility According to Paramagnetic NMR Spectroscopy Data

2021 ◽  
Vol 47 (1) ◽  
pp. 10-16
Author(s):  
Ya. A. Pankratova ◽  
Yu. V. Nelyubina ◽  
V. V. Novikov ◽  
A. A. Pavlov
Keyword(s):  
Magnetic Susceptibility ◽  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Single Molecule ◽  
Functional Materials ◽  
Medical Diagnostics ◽  
Paramagnetic Nmr ◽  
Single Molecule Magnets

Abstract The tetrahedral cobalt(II) complex [CoL2](HNEt3)2 (I), where L is 1,2-bis(methanesulfonamido)benzene, exhibiting the properties of a single-molecule magnet is synthesized and characterized. The electronic structure parameters of complex I are determined by paramagnetic NMR spectroscopy. They completely reproduce the results of less available methods of studying single-molecule magnets. The value of axial anisotropy of the magnetic susceptibility estimated for complex I (Δχax = 34.5 × 10–32 m3 at 20°C) is record-breaking among all transition metal complexes studied by the NMR method, which provides wide possibilities for the use of complex I as a paramagnetic label for structural biology or as a contrast agent and even a temperature sensor for medical diagnostics. The data obtained indicate the advantages of paramagnetic NMR spectroscopy as a method of investigation of the magnetic properties and electronic structures of highly anisotropic transition metal complexes, which are precursors of many functional materials.

scholarly journals The Underexplored Field of Lanthanide Complexes with Helicene Ligands: Towards Chiral Lanthanide Single Molecule Magnets

2021 ◽  
Vol 7 (10) ◽  
pp. 138
Author(s):  
Gabriela Handzlik ◽  
Katarzyna Rzepka ◽  
Dawid Pinkowicz
Keyword(s):  
Transition Metal Complexes ◽  
Single Molecule ◽  
Specific Rotation ◽  
Crystalline Material ◽  
Lanthanide Ions ◽  
Single Molecule Magnets ◽  
Design And Synthesis ◽  
Chiral Carbon ◽  
Effective Combination ◽  
Recent Developments

The effective combination of chirality and magnetism in a single crystalline material can lead to fascinating cross-effects, such as magneto–chiral dichroism. Among a large variety of chiral ligands utilized in the design and synthesis of chiral magnetic materials, helicenes seem to be the most appealing ones, due to the exceptionally high specific rotation values that reach thousands of deg×cm3×g−1×dm−1, which is two orders of magnitude higher than for compounds with chiral carbon atoms. Despite the sizeable family of transition metal complexes with helicene-type ligands, there are only a few examples of such complexes with lanthanide ions. In this mini-review, we describe the most recent developments in the field of lanthanide-based complexes with helicene-type ligands and summarize insights regarding the further exploration of this family of compounds towards multifunctional chiral lanthanide single molecule magnets (Ln-SMMs).

α-Pyridinyl Alcohols, α,α’-Pyridine Diols, α-Bipyridinyl Alcohols, and α,α’-Bipyridine Diols as Structure Motifs Towards Important Organic Molecules and Transition Metal Complexes

2020 ◽  
Vol 17 (5) ◽  
pp. 344-366
Author(s):  
Tegene T. Tole ◽  
Johannes H.L. Jordaan ◽  
Hermanus C.M. Vosloo
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Single Molecule ◽  
Organic Molecules ◽  
Metal Cluster ◽  
Metal Center ◽  
Phosphine Ligands ◽  
High Ability ◽  
Metal Centers

Background: The preparation and use of pyridinyl alcohols as ligands showed incredible increment in the past three decades. Important property of pyridinyl alcoholato ligands is their strong basicity, which is mainly due to the lack of resonance stabilization of the corresponding anion. This strongly basic anionic nature gives them high ability to make bridges between metal centers rather than to bind to only one metal center in a terminal fashion. They are needed as ligands due to their ability to interact with transition metals both covalently (with oxygen) and hemilabile coordination (through nitrogen). Objective: The review focuses on the wide application of α-pyridinyl alcohols, α,α’-pyridine diols, α- bipyridinyl alcohols, and α,α’-bipyridine diols as structure motifs in the preparation of important organic molecules which is due to their strongly basic anionic nature. Conclusion: It is clear from the review that in addition to their synthetic utility in the homogeneous and asymmetric catalytic reactions, the preparation of the crown ethers, cyclic and acyclic ethers, coordinated borates (boronic esters), pyridinyl-phosphine ligands, pyridinyl-phosphite ligands, and pyridinyl-phosphinite ligands is the other broad area of application of pyridinyl alcohols. In addition to the aforementioned applications they are used for modeling mode of action of enzymes and some therapeutic agents. Their strongly basic anionic nature gives them high ability to make bridges between metal centers rather than to bind to only one metal center in a terminal fashion in the synthesis of transition metal cluster complexes. Not least numbers of single molecule magnets that can be used as storage of high density information were the result of transition metal complexes of pyridinyl alcoholato ligands.

Chelating agents in high temperature aqueous chemistry. 2. The thermal decomposition of some transition metal complexes of nitrilotriacetate (NTA)

1977 ◽  
Vol 55 (10) ◽  
pp. 1770-1776 ◽  
Author(s):  
Meindert Booy ◽  
Thomas Wilson Swaddle
Keyword(s):  
Thermal Decomposition ◽  
High Temperature ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Half Life ◽  
Chelating Agents ◽  
Nuclear Reactors ◽  
Hydrothermal Conditions ◽  
Mechanism Of Decomposition

The kinetics and mechanism of decomposition of NTA complexes of FeIII, FeII, CoII, NiII, and CuII under hydrothermal conditions (425–573 K) have been examined. The relative rates at 573 K are CoIINTA− < NTA3−[Formula: see text] < NiIINTA− < FeIIINTA0 < H3NTA0 < CuIINTA− < H4NTA+. Aqueous CoIINTA− and FeIINTA−, like NTA3−, decomposed at 573 K by decarboxylation, precipitating Co(OH)2 and Fe3O4 respectively; NiIINTA− precipitated Ni(OH)2 initially but subsequently Ni metal. At 530 K, FeIIINTA0 solutions precipitated FeII3(NTA)2•H2O, but at higher temperatures Fe3O4 formed, the NTA ligand being reduced to HCHO and iminodiacetate (IDA) rather than decarboxylated. Similarly, CuIINTA−gave IDA and HCHO at temperatures as low as 425 K, forming first CuI (which precipitated as CuCl in the presence of Cl−) and then metallic Cu. The applicability of NTA to corrosion control in boilers and to 60Co removal from water-cooled nuclear reactors is briefly considered. The half-life of FeIIINTA in the hydrosphere is estimated at 80 years (cf. 8 × 106 years for free NTA), in the absence of photolysis or biodégradation.

Synthesis, Crystal Structures and Properties of Two Transition Metal Complexes Based on 4, 4'-{[2, 2'-(ethane-1, 2-bicarboxymethyl)] amino-bis(acetyl)} Dibenzoic Acid

2014 ◽  
Vol 997 ◽  
pp. 255-259
Author(s):  
Ying Ying Bing ◽  
Hong Gao ◽  
Ming Hu
Keyword(s):  
Thermal Stability ◽  
Thermogravimetric Analysis ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
High Thermal Stability ◽  
Two Dimensional ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Structures And Properties

Two isostructural transition metal complexes based on the 4,4'-{[2,2'-(ethane-1,2-bicarboxymethyl)] amino-bis (acetyl)} dibenzoic acid (H4L) were synthesized under hydrothermal conditions, namely, [M(H2L)(H2O)]·3H2O (M=Ni, 1 ; Co, 2). The two compounds were structurally characterized by infrared spectra, thermogravimetric analysis and single crystal X-ray diffractions. Compounds 1-2 are mononuclear units and further extended to generate the two dimensional structures by hydrogen-bonds and π-π interactions. Compounds 1 exhibit the high thermal stability.

scholarly journals Spin–Phonon Coupling and Dynamic Zero-Field Splitting Contributions to Spin Conversion Processes in Iron(II) Complexes

2020 ◽  
Author(s):  
Nicholas Higdon ◽  
Alexandra Barth ◽  
Patryk Kozlowski ◽  
Ryan Hadt
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Single Molecule ◽  
Ligand Field ◽  
Zero Field ◽  
Phonon Coupling ◽  
Zero Field Splitting ◽  
Spin Conversion ◽  
Coupling Terms

Magnetization dynamics of transition metal complexes manifest in properties and phenomena of fundamental and applied interest (e.g., slow magnetic relaxation in single molecule magnets (SMMs), quantum coherence in quantum bits (qubits), and intersystem crossing (ISC) rates in photophysics). While spin–phonon coupling is recognized as an important determinant of these dynamics, additional fundamental studies are required to unravel the nature of the coupling and thus leverage it in molecular engineering approaches. To this end, we describe here a combined ligand field theory and multireference <i>ab initio</i> model to define spin–phonon coupling terms in S = 2 transition metal complexes and demonstrate how couplings originate from both the static and dynamic properties of ground and excited states. By extending concepts to spin conversion processes, ligand field dynamics manifest in the evolution of the excited state origins of zero-field splitting (ZFS) along specific normal mode potential energy surfaces. Dynamic ZFSs provide a powerful means to independently evaluate contributions from spin-allowed and/or -forbidden excited states to spin–phonon coupling terms. Furthermore, ratios between various intramolecular coupling terms for a given mode drive spin conversion processes in transition metal complexes and can be used to analyze mechanisms of ISC. Variations in geometric structure strongly influence the relative intramolecular linear spin–phonon coupling terms and will thus define the overall spin state dynamics. While of general importance for understanding magnetization dynamics, this study links the phenomenon of spin–phonon coupling across fields of single molecule magnetism, quantum materials/qubits, and transition metal photophysics.

scholarly journals Spin–Phonon Coupling and Dynamic Zero-Field Splitting Contributions to Spin Conversion Processes in Iron(II) Complexes

2020 ◽  
Author(s):  
Nicholas Higdon ◽  
Alexandra Barth ◽  
Patryk Kozlowski ◽  
Ryan Hadt
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Single Molecule ◽  
Ligand Field ◽  
Zero Field ◽  
Phonon Coupling ◽  
Zero Field Splitting ◽  
Spin Conversion ◽  
Coupling Terms

Magnetization dynamics of transition metal complexes manifest in properties and phenomena of fundamental and applied interest (e.g., slow magnetic relaxation in single molecule magnets (SMMs), quantum coherence in quantum bits (qubits), and intersystem crossing (ISC) rates in photophysics). While spin–phonon coupling is recognized as an important determinant of these dynamics, additional fundamental studies are required to unravel the nature of the coupling and thus leverage it in molecular engineering approaches. To this end, we describe here a combined ligand field theory and multireference <i>ab initio</i> model to define spin–phonon coupling terms in S = 2 transition metal complexes and demonstrate how couplings originate from both the static and dynamic properties of ground and excited states. By extending concepts to spin conversion processes, ligand field dynamics manifest in the evolution of the excited state origins of zero-field splitting (ZFS) along specific normal mode potential energy surfaces. Dynamic ZFSs provide a powerful means to independently evaluate contributions from spin-allowed and/or -forbidden excited states to spin–phonon coupling terms. Furthermore, ratios between various intramolecular coupling terms for a given mode drive spin conversion processes in transition metal complexes and can be used to analyze mechanisms of ISC. Variations in geometric structure strongly influence the relative intramolecular linear spin–phonon coupling terms and will thus define the overall spin state dynamics. While of general importance for understanding magnetization dynamics, this study links the phenomenon of spin–phonon coupling across fields of single molecule magnetism, quantum materials/qubits, and transition metal photophysics.

Mechanochemical changes on cyclometalated Ir(iii) acyclic carbene complexes – design and tuning of luminescent mechanochromic transition metal complexes

2020 ◽  
Vol 7 (3) ◽  
pp. 786-794 ◽  
Author(s):  
Jingqi Han ◽  
Kin-Man Tang ◽  
Shun-Cheung Cheng ◽  
Chi-On Ng ◽  
Yuen-Kiu Chun ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Carbene Complexes ◽  
New Class

A new class of luminescent cyclometalated Ir(iii) complexes with readily tunable mechanochromic properties derived from the mechanically induced trans-to-cis isomerization have been developed.

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