Structural and thermodynamic aspects of hydration of Gd(<scp>iii</scp>) systems

Janicki, Rafał; Mondry, Anna

doi:10.1039/c8dt04869j

Cited by 32 publications

(30 citation statements)

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“…Later EXAFS studies however provided results in contradiction with the early work, proposing that the aqua-ions are nona-coordinated throughout the series. 33 The more recent results based on EXAFS, 44 Raman spectroscopy, 45,46 optical spectroscopy 47 and theoretical studies 48,49 support that the light lanthanide(III) aqua ions are nine-coordinated, while the heaviest lanthanide(III) ions are octa-coordinated in aqueous solutions. In this study, we aim to use high-resolution optical spectroscopy and state-of-the-art computational chemistry to determine the coordination number and structure of four Yb 3+ solvates in order to -hopefully -close this discussion.…”

Section: Introductionmentioning

confidence: 93%

Electronic Structure of Ytterbium(III) Solvates – A Combined Spectro-scopic and Theoretical Study

Kofod¹,

Nawrocki²,

Platas‐Iglesias³

et al. 2021

Preprint

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The wide range of optical and magnetic properties of the lanthanide(III) ions is associated to their intricate electronic structures, which in contrast to lighter elements is characterized by strong relativistic effects and spin-orbit coupling. Nevertheless, computational methods are now capable of describing the ladder of electronic energy levels of the simpler trivalent lanthanide ions, as well as the lowest energy term of most of the series. The electronic energy levels result from electron configurations that are first split by spin-orbit coupling into groups of energy levels denoted by the corresponding Russel-Saunders terms. Each of these groups are then split by the ligand field into the actual electronic energy levels known as microstates or sometimes mJ levels. The ligand field splitting directly informs on coordination geometry, and is a valuable tool for determining structure and thus correlating the structure and properties of metal complexes in solution. The issue with lanthanide complexes is that the determination of complex structures from ligand field splitting remains a very challenging task. In this manuscript, the optical spectra – absorption, luminescence excitation and luminescence emission – of ytterbium(III) solvates were rec-orded in water, methanol, dimethyl sulfoxide and N,N-dimethylformamide. The electronic energy levels, that is the microstates, were resolved experimentally. Subsequently, density functional theory (DFT) calculations were used to model the structures of the solvates and ab initio relativistic complete active space self-consistent field (CASSCF) calculations were employed to obtain the microstates of the possible structures of each solvate. By comparing experimental and theoretical data, it was possible to determine both the coordination number and solution structure of each solvate. In water, methanol and N,N-dimethylformamide the solvates were found to be eight-coordinated and to have a square anti-prismatic coordination geometry. In DMSO the speciation was found to be more complicated. The robust methodology developed for comparing experimental spectra and computational results allows the solution structures of lanthanide complexes to be determined, paving the way for the design of complexes with predetermined properties. <br>

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Section: Introductionmentioning

confidence: 93%

Electronic Structure of Ytterbium(III) Solvates – A Combined Spectro-scopic and Theoretical Study

Kofod¹,

Nawrocki²,

Platas‐Iglesias³

et al. 2021

Preprint

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“…Such interactions may be responsible e.g. for slightly negative ÁH of the dehydration reaction of the [Gd(H 2 O) 9 ] 3+ ion (Janicki & Mondry, 2019).…”

Section: Electronic Structure Of [Gd(h 2 O) 9 ] 3+mentioning

confidence: 99%

“…It is however difficult to quantify the covalent interactions in the case of Ln III systems. There are a variety of different criteria that can be employed to probe the covalency contribution to Ln-L bonds: for example, the nephelauxetic effect observed for the f-f bands (Jørgensen, 1962;Frey & Horrocks, 1995;Janicki & Mondry, 2019), bond lengths (Minasian et al, 2011) and bond order (Trzesowska et al, ISSN 2052-5206 # 2020 International Union of Crystallography 2006), paramagnetic shifts in NMR spectra (Autillo et al, 2019), ligand field parameters [within the crystal field (Alessandri et al, 2018) and ab initio ligand field theories (Jung et al, 2017(Jung et al, , 2019], analysis of electron localization function (ELF) and Laplacian bond order (LBO; Lu & Chen, 2013), as well as examination of natural bond order (NBO) (Janicki et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Interestingly, this effect is usually analysed in the context of the 4f and ligand orbital mixing; thus it is thought that the covalency is reflected in the electronic spectra of f-f transitions (Janicki & Mondry, 2019). On the other hand, it is well known that 4f electrons are substantially core orbitals, which are screened by the closed 5s and 5p subshells, in this way being unable to participate significantly in the covalent bonding.…”

Section: Introductionmentioning

confidence: 99%

“…We have chosen the Gd III compound because this element (as well as lanthanum and lutetium) is perhaps the best choice for such studies due to its half-filled 4f subshell (the ground state is 8 S 7/2 ): these electrons form in principle a spherical cloud and no multipolar terms are needed to model it. Additionally the nature and strength of the Gd III -OH 2 (Janicki & Mondry, 2019) interactions are some of the most crucial factors that shape the inner-sphere spin relaxation processes, which in turn determine these processes in order to assess the efficiency of Gd III -based MRI contrast agents (Peters, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Analysis of charge density in nonaaquagadolinium(III) trifluoromethanesulfonate – insight into Gd^III—OH₂ bonding

Janicki¹,

Starynowicz²

2020

Acta Crystallogr Sect B

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The experimental charge-density distribution in [Gd(H2O)9](CF3SO3)3 has been analysed and compared with the theoretical density functional theory calculations. Although the Gd—OH2 bonds are mainly ionic, a covalent contribution is detectable when inspecting both the topological parameters of these bonds and the natural bond orbital results. This contribution originates from small electron transfer from the lone pairs of oxygen atoms to empty 5d and 6s spin orbitals of Gd3+.

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Surprising Impact of Donor Charge on the Water Exchange Rates of Gd(III) AAZTA Derivatives

Tei,

Leone,

Lalli

et al. 2024

Eur J Inorg Chem

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We report the synthesis of three new heptadentate ligands derived from H4AAZTA (6‐amino‐6‐methylperhydro‐1,4‐diazepinetetraacetic acid) that contain a dimethyl‐amide group (AAZTA‐MA)3‐, two dimethyl‐amide groups (AAZTA‐BMA)2‐ or two acetylglycine groups (AAZTA(Gly)2)4‐. The corresponding Gd(III) complexes were investigated using 1H NMR relaxometry and 17O NMR chemical shifts and transverse relaxation rates. A computational DFT study was also performed to aid the analysis of the NMR data. The Gd(III) complexes contain two water molecules coordinated to the metal ion. In contrast to the prevailing trend, the amide derivatives discussed in this context exhibit comparatively rapid water exchange rates that do not align with the changes in the overall electric charge of the complexes: kex298 = 14.4 × 106 s‐1, 14.5 × 106 s‐1 and 9.56 × 106 s‐1 for [Gd(AAZTA‐MA)(H2O)2], [Gd(AAZTA‐BMA)(H2O)2]+ and [Gd(AAZTA(Gly)2(H2O)2]‐, respectively. The analysis of the data and the computational work suggest that the relatively fast water exchange rates could be linked to the occurrence of associatively activated mechanisms, which is somewhat unexpected for nine‐coordinated complexes.

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Structural and thermodynamic aspects of hydration of Gd(iii) systems

Abstract: A first systematic experimental study on the thermodynamic description of the hydration equilibrium of Gd(iii) compounds is presented.

Cited by 32 publications

References 85 publications

Electronic Structure of Ytterbium(III) Solvates – A Combined Spectro-scopic and Theoretical Study

Electronic Structure of Ytterbium(III) Solvates – A Combined Spectro-scopic and Theoretical Study

Analysis of charge density in nonaaquagadolinium(III) trifluoromethanesulfonate – insight into Gd^III—OH₂ bonding

Surprising Impact of Donor Charge on the Water Exchange Rates of Gd(III) AAZTA Derivatives

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Structural and thermodynamic aspects of hydration of Gd(iii) systems

Abstract: A first systematic experimental study on the thermodynamic description of the hydration equilibrium of Gd(iii) compounds is presented.

Cited by 32 publications

References 85 publications

Electronic Structure of Ytterbium(III) Solvates – A Combined Spectro-scopic and Theoretical Study

Electronic Structure of Ytterbium(III) Solvates – A Combined Spectro-scopic and Theoretical Study

Analysis of charge density in nonaaquagadolinium(III) trifluoromethanesulfonate – insight into GdIII—OH2 bonding

Surprising Impact of Donor Charge on the Water Exchange Rates of Gd(III) AAZTA Derivatives

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Analysis of charge density in nonaaquagadolinium(III) trifluoromethanesulfonate – insight into Gd^III—OH₂ bonding