Inorganics

8 pages, 1787 KiB

Open AccessEditor’s ChoiceArticle

A Partial Anion Disorder in SrVO₂H Induced by Biaxial Tensile Strain

by Morito Namba, Hiroshi Takatsu, Wataru Yoshimune, Aurélien Daniel, Shoichi Itoh, Takahito Terashima and Hiroshi Kageyama

Inorganics 2020, 8(4), 26; https://doi.org/10.3390/inorganics8040026 - 8 Apr 2020

Cited by 13 | Viewed by 6125

Abstract

SrVO₂H, obtained by a topochemical reaction of SrVO₃ perovskite using CaH₂, is an anion-ordered phase with hydride anions exclusively at the apical site. In this study, we conducted a CaH₂ reduction of SrVO₃ thin films epitaxially [...] Read more.

SrVO₂H, obtained by a topochemical reaction of SrVO₃ perovskite using CaH₂, is an anion-ordered phase with hydride anions exclusively at the apical site. In this study, we conducted a CaH₂ reduction of SrVO₃ thin films epitaxially grown on KTaO₃ (KTO) substrates. When reacted at 530 °C for 12 h, we observed an intermediate phase characterized by a smaller tetragonality of c/a = 0.96 (vs. c/a = 0.93 for SrVO₂H), while a longer reaction of 24 h resulted in the known phase of SrVO₂H. This fact suggests that the intermediate phase is a metastable state stabilized by applying tensile strain from the KTO substrate (1.4%). In addition, secondary ion mass spectrometry (SIMS) revealed that the intermediate phase has a hydrogen content close to that of SrVO₂H, suggesting a partially disordered anion arrangement. Such kinetic trapping of an intermediate state by biaxial epitaxial strain not only helps to acquire a new state of matter but also advances our understanding of topochemical reaction processes in extended solids. Full article

(This article belongs to the Section Inorganic Solid-State Chemistry)

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11 pages, 5648 KiB

Open AccessEditor’s ChoiceCommunication

Magnetic Composite Submicron Carriers with Structure-Dependent MRI Contrast

by Anastasiia A. Kozlova, Sergey V. German, Vsevolod S. Atkin, Victor V. Zyev, Maxwell A. Astle, Daniil N. Bratashov, Yulia I. Svenskaya and Dmitry A. Gorin

Inorganics 2020, 8(2), 11; https://doi.org/10.3390/inorganics8020011 - 30 Jan 2020

Cited by 19 | Viewed by 4370

Abstract

Magnetic contrast agents are widely used in magnetic resonance imaging in order to significantly change the signals from the regions of interest in comparison with the surrounding tissue. Despite a high variety of single-mode T₁ or T₂ contrast agents, there is [...] Read more.

Magnetic contrast agents are widely used in magnetic resonance imaging in order to significantly change the signals from the regions of interest in comparison with the surrounding tissue. Despite a high variety of single-mode T₁ or T₂ contrast agents, there is a need for dual-mode contrast from the one agent. Here, we report on the synthesis of magnetic submicron carriers, containing Fe₃O₄ nanoparticles in their structure. We show the ability to control magnetic resonance contrast by changing not only the number of magnetite nanoparticles in one carrier or the concentration of magnetite in the suspension but also the structure of the core–shell itself. The obtained data open up the prospects for dual-mode T₁/T₂ magnetic contrast formation, as well as provides the basis for future investigations in this direction. Full article

(This article belongs to the Special Issue Smart Tools for Smart Applications: New Insights into Inorganic Magnetic Systems and Materials)

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59 pages, 11275 KiB

Open AccessEditor’s ChoiceReview

Magnetic Materials and Systems: Domain Structure Visualization and Other Characterization Techniques for the Application in the Materials Science and Biomedicine

by Roberto Nisticò, Federico Cesano and Francesca Garello

Inorganics 2020, 8(1), 6; https://doi.org/10.3390/inorganics8010006 - 17 Jan 2020

Cited by 63 | Viewed by 18825

Abstract

Magnetic structures have attracted a great interest due to their multiple applications, from physics to biomedicine. Several techniques are currently employed to investigate magnetic characteristics and other physicochemical properties of magnetic structures. The major objective of this review is to summarize the current [...] Read more.

Magnetic structures have attracted a great interest due to their multiple applications, from physics to biomedicine. Several techniques are currently employed to investigate magnetic characteristics and other physicochemical properties of magnetic structures. The major objective of this review is to summarize the current knowledge on the usage, advances, advantages, and disadvantages of a large number of techniques that are currently available to characterize magnetic systems. The present review, aiming at helping in the choice of the most suitable method as appropriate, is divided into three sections dedicated to characterization techniques. Firstly, the magnetism and magnetization (hysteresis) techniques are introduced. Secondly, the visualization methods of the domain structures by means of different probes are illustrated. Lastly, the characterization of magnetic nanosystems in view of possible biomedical applications is discussed, including the exploitation of magnetism in imaging for cell tracking/visualization of pathological alterations in living systems (mainly by magnetic resonance imaging, MRI). Full article

(This article belongs to the Special Issue Smart Tools for Smart Applications: New Insights into Inorganic Magnetic Systems and Materials)

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63 pages, 14258 KiB

Open AccessEditor’s ChoiceReview

Halogen Bonding: A Halogen-Centered Noncovalent Interaction Yet to Be Understood

by Pradeep R. Varadwaj, Arpita Varadwaj and Helder M. Marques

Inorganics 2019, 7(3), 40; https://doi.org/10.3390/inorganics7030040 - 12 Mar 2019

Cited by 135 | Viewed by 11060

Abstract

In addition to the underlying basic concepts and early recognition of halogen bonding, this paper reviews the conflicting views that consistently appear in the area of noncovalent interactions and the ability of covalently bonded halogen atoms in molecules to participate in noncovalent interactions [...] Read more.

In addition to the underlying basic concepts and early recognition of halogen bonding, this paper reviews the conflicting views that consistently appear in the area of noncovalent interactions and the ability of covalently bonded halogen atoms in molecules to participate in noncovalent interactions that contribute to packing in the solid-state. It may be relatively straightforward to identify Type-II halogen bonding between atoms using the conceptual framework of σ-hole theory, especially when the interaction is linear and is formed between the axial positive region (σ-hole) on the halogen in one monomer and a negative site on a second interacting monomer. A σ-hole is an electron density deficient region on the halogen atom X opposite to the R–X covalent bond, where R is the remainder part of the molecule. However, it is not trivial to do so when secondary interactions are involved as the directionality of the interaction is significantly affected. We show, by providing some specific examples, that halogen bonds do not always follow the strict Type-II topology, and the occurrence of Type-I and -III halogen-centered contacts in crystals is very difficult to predict. In many instances, Type-I halogen-centered contacts appear simultaneously with Type-II halogen bonds. We employed the Independent Gradient Model, a recently proposed electron density approach for probing strong and weak interactions in molecular domains, to show that this is a very useful tool in unraveling the chemistry of halogen-assisted noncovalent interactions, especially in the weak bonding regime. Wherever possible, we have attempted to connect some of these results with those reported previously. Though useful for studying interactions of reasonable strength, IUPAC’s proposed “less than the sum of the van der Waals radii” criterion should not always be assumed as a necessary and sufficient feature to reveal weakly bound interactions, since in many crystals the attractive interaction happens to occur between the midpoint of a bond, or the junction region, and a positive or negative site. Full article

(This article belongs to the Special Issue Halogen Bonding: Fundamentals and Applications)

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15 pages, 591 KiB

Open AccessEditor’s ChoiceReview

Designing Ruthenium Anticancer Drugs: What Have We Learnt from the Key Drug Candidates?

by James P. C. Coverdale, Thaisa Laroiya-McCarron and Isolda Romero-Canelón

Inorganics 2019, 7(3), 31; https://doi.org/10.3390/inorganics7030031 - 1 Mar 2019

Cited by 144 | Viewed by 10698

Abstract

After nearly 20 years of research on the use of ruthenium in the fight against cancer, only two Ru(III) coordination complexes have advanced to clinical trials. During this time, the field has produced excellent candidate drugs with outstanding in vivo and in vitro [...] Read more.

After nearly 20 years of research on the use of ruthenium in the fight against cancer, only two Ru(III) coordination complexes have advanced to clinical trials. During this time, the field has produced excellent candidate drugs with outstanding in vivo and in vitro activity; however, we have yet to find a ruthenium complex that would be a viable alternative to platinum drugs currently used in the clinic. We aimed to explore what we have learned from the most prominent complexes in the area, and to challenge new concepts in chemical design. Particularly relevant are studies involving NKP1339, NAMI-A, RM175, and RAPTA-C, which have paved the way for current research. We explored the development of the ruthenium anticancer field considering that the mechanism of action of complexes no longer focuses solely on DNA interactions, but explores a diverse range of cellular targets involving multiple chemical strategies. Full article

(This article belongs to the Special Issue Unconventional Anticancer Metallodrugs and Strategies to Improve their Pharmacological Profile)

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14 pages, 7701 KiB

Open AccessEditor’s ChoiceArticle

Development and Validation of Liquid Chromatography-Based Methods to Assess the Lipophilicity of Cytotoxic Platinum(IV) Complexes

by Matthias H. M. Klose, Sarah Theiner, Hristo P. Varbanov, Doris Hoefer, Verena Pichler, Mathea Sophia Galanski, Samuel M. Meier-Menches and Bernhard K. Keppler

Inorganics 2018, 6(4), 130; https://doi.org/10.3390/inorganics6040130 - 4 Dec 2018

Cited by 30 | Viewed by 7683

Abstract

Lipophilicity is a crucial parameter for drug discovery, usually determined by the logarithmic partition coefficient (Log P) between octanol and water. However, the available detection methods have restricted the widespread use of the partition coefficient in inorganic medicinal chemistry, and recent investigations have [...] Read more.

Lipophilicity is a crucial parameter for drug discovery, usually determined by the logarithmic partition coefficient (Log P) between octanol and water. However, the available detection methods have restricted the widespread use of the partition coefficient in inorganic medicinal chemistry, and recent investigations have shifted towards chromatographic lipophilicity parameters, frequently without a conversion to derive Log P. As high-performance liquid chromatography (HPLC) instruments are readily available to research groups, a HPLC-based method is presented and validated to derive the partition coefficient of a set of 19 structurally diverse and cytotoxic platinum(IV) complexes exhibiting a dynamic range of at least four orders of magnitude. The chromatographic lipophilicity parameters φ₀ and Log k_w were experimentally determined for the same set of compounds, and a correlation was obtained that allows interconversion between the two lipophilicity scales, which was applied to an additional set of 34 platinum(IV) drug candidates. Thereby, a φ₀ = 58 corresponds to Log P = 0. The same approaches were successfully evaluated to determine the distribution coefficient (Log D) of five ionisable platinum(IV) compounds to sample pH-dependent effects on the lipophilicity. This study provides straight-forward HPLC-based methods to determine the lipophilicity of cytotoxic platinum(IV) complexes in the form of Log P and φ₀ that can be interconverted and easily expanded to other metal-based compound classes. Full article

(This article belongs to the Special Issue Unconventional Anticancer Metallodrugs and Strategies to Improve their Pharmacological Profile)

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14 pages, 1967 KiB

Open AccessEditor’s ChoiceArticle

S–H Bond Activation in Hydrogen Sulfide by NHC-Stabilized Silyliumylidene Ions

by Amelie Porzelt, Julia I. Schweizer, Ramona Baierl, Philipp J. Altmann, Max C. Holthausen and Shigeyoshi Inoue

Inorganics 2018, 6(2), 54; https://doi.org/10.3390/inorganics6020054 - 24 May 2018

Cited by 16 | Viewed by 6492

Abstract

Reactivity studies of silyliumylidenes remain scarce with only a handful of publications to date. Herein we report the activation of S–H bonds in hydrogen sulfide by mTer-silyliumylidene ion A (mTer = 2,6-Mes₂-C₆H₃, Mes = [...] Read more.

Reactivity studies of silyliumylidenes remain scarce with only a handful of publications to date. Herein we report the activation of S–H bonds in hydrogen sulfide by mTer-silyliumylidene ion A (mTer = 2,6-Mes₂-C₆H₃, Mes = 2,4,6-Me₃-C₆H₂) to yield an NHC-stabilized thiosilaaldehyde B. The results of NBO and QTAIM analyses suggest a zwitterionic formulation of the product B as the most appropriate. Detailed mechanistic investigations are performed at the M06-L/6-311+G(d,p)(SMD: acetonitrile/benzene)//M06-L/6-311+G(d,p) level of density functional theory. Several pathways for the formation of thiosilaaldehyde B are examined. The energetically preferred route commences with a stepwise addition of H₂S to the nucleophilic silicon center. Subsequent NHC dissociation and proton abstraction yields the thiosilaaldehyde in a strongly exergonic reaction. Intermediacy of a chlorosilylene or a thiosilylene is kinetically precluded. With an overall activation barrier of 15 kcal/mol, the resulting mechanistic picture is fully in line with the experimental observation of an instantaneous reaction at sub-zero temperatures. Full article

(This article belongs to the Special Issue Coordination Chemistry of Silicon)

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34 pages, 10625 KiB

Open AccessEditor’s ChoiceReview

Ruthenium Complexes as Sensitizers in Dye-Sensitized Solar Cells

by Sadig Aghazada and Mohammad Khaja Nazeeruddin

Inorganics 2018, 6(2), 52; https://doi.org/10.3390/inorganics6020052 - 21 May 2018

Cited by 117 | Viewed by 12520

Abstract

In this review, we discuss the main directions in which ruthenium complexes for dye-sensitized solar cells (DSCs) were developed. We critically discuss the implemented design principles. This review might be helpful at this moment when a breakthrough is needed for DSC technology to [...] Read more.

In this review, we discuss the main directions in which ruthenium complexes for dye-sensitized solar cells (DSCs) were developed. We critically discuss the implemented design principles. This review might be helpful at this moment when a breakthrough is needed for DSC technology to prove its market value. Full article

(This article belongs to the Collection Coordination Complexes for Dye-Sensitized Solar Cells (DSCs))

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