Inorganics

16 pages, 7506 KiB

Open AccessArticle

Synthesis of Anthraquinones by Iridium-Catalyzed [2 + 2 + 2] Cycloaddition of a 1,2-Bis(propiolyl)benzene Derivative with Alkynes

by Takahiro Sawano, Yuko Toyoshima and Ryo Takeuchi

Inorganics 2019, 7(11), 138; https://doi.org/10.3390/inorganics7110138 - 18 Nov 2019

Cited by 4 | Viewed by 3567

Abstract

[2 + 2 + 2] cycloaddition of a 1,2-bis(propiolyl)benzene derivative with terminal and internal alkynes takes place in the presence of [Ir(cod)Cl]₂ (cod = 1,5-cyclooctadiene) combined with bis(diphenylphosphino)ethane (DPPE) to give anthraquinones in 42% to 93% yields with a simple experimental procedure. [...] Read more.

[2 + 2 + 2] cycloaddition of a 1,2-bis(propiolyl)benzene derivative with terminal and internal alkynes takes place in the presence of [Ir(cod)Cl]₂ (cod = 1,5-cyclooctadiene) combined with bis(diphenylphosphino)ethane (DPPE) to give anthraquinones in 42% to 93% yields with a simple experimental procedure. A fluorenone derivative can also be synthesized by iridium-catalyzed [2 + 2 + 2] cycloaddition of a benzene-linked ketodiyne with an internal alkyne to give a 94% yield. Full article

(This article belongs to the Special Issue Iridium Complexes)

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11 pages, 1754 KiB

Open AccessArticle

A Zn(II) Metallocycle as Platform to Assemble a 1D + 1D → 1D Polyrotaxane via π···π Stacking of an Ancillary Ligand

by Marzio Rancan, Giada Truccolo, Alice Carlotto, Silvio Quici and Lidia Armelao

Inorganics 2019, 7(11), 137; https://doi.org/10.3390/inorganics7110137 - 15 Nov 2019

Cited by 2 | Viewed by 3047

Abstract

A new [Zn₂L₂] metallocycle bearing two metal centers that can coordinate ancillary ligands and a pocket suitable to host guest molecules is reported. These two features are exploited by reacting the metallocycle with a pyridine ligand to self-assemble in [...] Read more.

A new [Zn₂L₂] metallocycle bearing two metal centers that can coordinate ancillary ligands and a pocket suitable to host guest molecules is reported. These two features are exploited by reacting the metallocycle with a pyridine ligand to self-assemble in the solid state an extended intertwined system with the rare 1D + 1D → 1D topology. This interpenetrated architecture is supported by π···π stacking between two pyridine units of two different metallocycles in the pocket of a third metallocycle. Full article

(This article belongs to the Special Issue Recent Advances in Coordination Rings and Cages)

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9 pages, 2299 KiB

Open AccessArticle

High-Pressure Synthesis, Crystal Structure, and Photoluminescence Properties of β-Y₂B₄O₉:Eu³⁺

by Birgit Fuchs, Franziska Schröder, Gunter Heymann, Thomas Jüstel and Hubert Huppertz

Inorganics 2019, 7(11), 136; https://doi.org/10.3390/inorganics7110136 - 12 Nov 2019

Viewed by 3007

Abstract

A high-pressure/high-temperature experiment at 7.5 GPa and 1673 K led to the formation of the new compound β-Y₂B₄O₉. In contrast to the already known polymorph α-Y₂B₄O₉, which crystallizes in [...] Read more.

A high-pressure/high-temperature experiment at 7.5 GPa and 1673 K led to the formation of the new compound β-Y₂B₄O₉. In contrast to the already known polymorph α-Y₂B₄O₉, which crystallizes in the space group C2/c, the reported structure could be solved via single-crystal X-ray diffraction in the triclinic space group P

\bar{1}

(no. 2) and is isotypic to the already known lanthanide borates β-Dy₂B₄O₉ and β-Gd₂B₄O₉. Furthermore, the photoluminescence of an europium doped sample of β-Y₂B₄O₉:Eu³⁺ (8%) was investigated. Full article

(This article belongs to the Special Issue Oxido Compounds)

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13 pages, 1421 KiB

Open AccessArticle

Theoretical Insights into the Aerobic Hydrogenase Activity of Molybdenum–Copper CO Dehydrogenase

by Anna Rovaletti, Maurizio Bruschi, Giorgio Moro, Ugo Cosentino, Claudio Greco and Ulf Ryde

Inorganics 2019, 7(11), 135; https://doi.org/10.3390/inorganics7110135 - 9 Nov 2019

Cited by 7 | Viewed by 3312

Abstract

The Mo/Cu-dependent CO dehydrogenase from O. carboxidovorans is an enzyme that is able to catalyse CO oxidation to CO

_{2}

; moreover, it also expresses hydrogenase activity, as it is able to oxidize H

_{2}

. Here, we have studied the dihydrogen oxidation [...] Read more.

The Mo/Cu-dependent CO dehydrogenase from O. carboxidovorans is an enzyme that is able to catalyse CO oxidation to CO

_{2}

; moreover, it also expresses hydrogenase activity, as it is able to oxidize H

_{2}

. Here, we have studied the dihydrogen oxidation catalysis by this enzyme using QM/MM calculations. Our results indicate that the equatorial oxo ligand of Mo is the best suited base for catalysis. Moreover, extraction of the first proton from H

_{2}

by means of this basic centre leads to the formation of a Mo–OH–Cu

^{I}

H hydride that allows for the stabilization of the copper hydride, otherwise known to be very unstable. In light of our results, two mechanisms for the hydrogenase activity of the enzyme are proposed. The first reactive channel depends on protonation of the sulphur atom of a Cu-bound cysteine residues, which appears to favour the binding and activation of the substrate. The second reactive channel involves a frustrated Lewis pair, formed by the equatorial oxo group bound to Mo and by the copper centre. In this case, no binding of the hydrogen molecule to the Cu center is observed but once H

_{2}

enters into the active site, it can be split following a low-energy path. Full article

(This article belongs to the Special Issue Transition Metals in Catalysis: The Functional Relationship of Fe–S Clusters and Molybdenum or Tungsten Cofactor-Containing Enzyme Systems)

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20 pages, 3437 KiB

Open AccessArticle

Towards ^99mTc- and Re-Based Multifunctional Silica Platforms for Theranostic Applications

by Michel A. Wuillemin, Michael J. Reber, Thomas Fox, Bernhard Spingler, Dominik Brühwiler, Roger Alberto and Henrik Braband

Inorganics 2019, 7(11), 134; https://doi.org/10.3390/inorganics7110134 - 9 Nov 2019

Cited by 5 | Viewed by 3272

Abstract

Taking advantage of the radiation properties of ^99mTc and ^186/188Re and the photophysical characteristics of the {M(CO)₃}⁺ moiety (M = Re), we developed a multifunctional silica platform with the theranostic pair ^99mTc/Re with high potential for (nano)medical [...] Read more.

Taking advantage of the radiation properties of ^99mTc and ^186/188Re and the photophysical characteristics of the {M(CO)₃}⁺ moiety (M = Re), we developed a multifunctional silica platform with the theranostic pair ^99mTc/Re with high potential for (nano)medical applications. Starting with a general screening to evaluate the most suitable mesoporous silica construct and the development of appropriate chelate systems, multifunctional mesoporous silica microparticles (SBA-15) were synthesized. These particles act as a model towards the synthesis of the corresponding nanoconstructs. The particles can be modified at the external surface with a targeting function and labeled with the {M(CO)₃}⁺ moiety (M = ^99mTc, Re) at the pore surface. Thus, a silica platform is realized, whose bioprofile is not altered by the loaded modalities. The described synthetic procedures can be applied to establish a target-specific theranostic nanoplatform, which enables the combination of fluorescence and radio imaging, with the possibility of radio- and chemotherapy. Full article

(This article belongs to the Special Issue Advanced Applications of Technetium Chemistry)

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14 pages, 1612 KiB

Open AccessArticle

Cysteine Derivatized ^99mTc-Labelled Fatty Acids as β-Oxidation Markers

by Theodoros Tsotakos, Charalambos Triantis, Christos Kiritsis, Aggeliki Panagiotopoulou, Dimitrios Psimadas, Patricia Kyprianidou, Maria Pelecanou, Minas Papadopoulos and Ioannis Pirmettis

Inorganics 2019, 7(11), 133; https://doi.org/10.3390/inorganics7110133 - 8 Nov 2019

Cited by 1 | Viewed by 2521

Abstract

With the aim of developing ^99mTc-labeled fatty acids intended for myocardial metabolism imaging we report herein the synthesis and characterization of two novel derivatives of undecanonoic and hexadecanonoic acid that have been functionalized at the ω-site by cysteine through the formation of [...] Read more.

With the aim of developing ^99mTc-labeled fatty acids intended for myocardial metabolism imaging we report herein the synthesis and characterization of two novel derivatives of undecanonoic and hexadecanonoic acid that have been functionalized at the ω-site by cysteine through the formation of a thioether bond (Cys–FA11 and Cys–FA16). Equimolar amounts of each ligand and the [NEt₄]₂[Re(CO)₃Br₃] precursor generated the respective hexacoordinated neutral complexes in which the ligand coordinated to the metal through the SNO donor system of cysteine. The rhenium complexes were characterized by elemental analysis, IR and NMR spectroscopies. The analogous technetium-99m complexes, ^99mTc–Cys–FA11 and ^99mTc–Cys–FA16 were prepared by incubation of the ligand with the precursor [^99mTc(CO)₃(H₂O)₃]⁺ (radiochemical yield ≥98%). Their structure was established by comparative HPLC techniques. In vivo studies in mice showed high initial heart uptake for both ^99mTc complexes (7.4 ± 0.53 and 7.07 ± 0.73 percentage of injected dose (%ID)/g at 1 min post injection. Rapid clearance (0.60 ± 0.02 %ID/g) was observed for ^99mTc–Cys–FA11 while the clearance of the longer fatty acid ^99mTc–Cys–FA16 was slower (2.31 ± 0.09 %ID/g at 15 min p.i.). Metabolite analysis study indicated that complexes were catabolized through the β-oxidation process. Full article

(This article belongs to the Special Issue Advanced Applications of Technetium Chemistry)

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12 pages, 2450 KiB

Open AccessArticle

Syntheses and Structures of Novel λ³,λ³-Phosphanylalumanes Fully Bearing Carbon Substituents and Their Substituent Effects

by Tatsuya Yanagisawa, Yoshiyuki Mizuhata and Norihiro Tokitoh

Inorganics 2019, 7(11), 132; https://doi.org/10.3390/inorganics7110132 - 7 Nov 2019

Cited by 7 | Viewed by 2993

Abstract

The novel phosphanylalumanes, Al–P single-bond species, fully bearing carbon protecting groups on aluminum and phosphorus atoms, are synthesized by the reactions of aluminum monohalides [(t-Bu)₂AlBr and (C₆F₅)₂AlCl·0.5(toluene)] with Mes₂PLi. Regarding the [...] Read more.

The novel phosphanylalumanes, Al–P single-bond species, fully bearing carbon protecting groups on aluminum and phosphorus atoms, are synthesized by the reactions of aluminum monohalides [(t-Bu)₂AlBr and (C₆F₅)₂AlCl·0.5(toluene)] with Mes₂PLi. Regarding the t-Bu system, λ³,λ³-phosphanylalumane is obtained. Concerning the C₆F₅ system, on the other hand, the corresponding LiCl complex, λ⁴,λ⁴-phosphanylalumane, is obtained. The Al–P bond lengths of C₆F₅-substituted λ³,λ⁴-, and λ⁴,λ⁴-derivatives are much shorter than those of the reported λ³,λ⁴-phosphanylalumane derivatives and comparable to that observed for the previously reported λ³,λ³-phosphanylalumanes. Theoretical calculations reveal that the binding of the C₆F₅ groups to Al results in a large contribution of Al and a large s-character in the Al–P bond of phosphanylalumanes. Considering t-Bu-substituted phosphanylalumanes, the Al–P bond lengths reflect the coordination number of Al, showing a longer Al–P bond length in the case of λ⁴-Al as compared with that of λ³-Al. Combining the structural, spectroscopic, and theoretical results, the t-Bu-substituted λ³,λ³-phosphanylalumane has well separated vacant p orbital and lone pairs, which is suitable for reactivity studies. Full article

(This article belongs to the Special Issue Organoaluminum Compounds)

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2 pages, 159 KiB

Open AccessEditorial

Bioinorganic Chemistry of Nickel

by Michael J. Maroney and Stefano Ciurli

Inorganics 2019, 7(11), 131; https://doi.org/10.3390/inorganics7110131 - 30 Oct 2019

Cited by 7 | Viewed by 3163

Abstract

Following the discovery of the first specific and essential role of nickel in biology in 1975 (the dinuclear active site of the enzyme urease) [...] Full article

(This article belongs to the Special Issue Bioinorganic Chemistry of Nickel)

2 pages, 180 KiB

Open AccessCorrection

Correction: Michaels, H.; et al. Copper Complexes with Tetradentate Ligands for Enhanced Charge Transport in Dye-Sensitized Solar Cells. Inorganics 2018, 6, 53

by Hannes Michaels, Iacopo Benesperi, Tomas Edvinsson, Ana Belén Muñoz-Garcia, Michele Pavone, Gerrit Boschloo and Marina Freitag

Inorganics 2019, 7(11), 130; https://doi.org/10.3390/inorganics7110130 - 29 Oct 2019

Viewed by 2900

Abstract

The authors express their sincere apologies to all readers of abovementioned article as mistakes were found upon discussion of the article with colleagues [...] Full article

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

13 pages, 2919 KiB

Open AccessArticle

Reaction of Dialumane Incorporating Bulky Eind Groups with Pyridines

by Takahiro Murosaki, Ryoma Ohno, Tomohiro Agou, Daisuke Hashizume and Tsukasa Matsuo

Inorganics 2019, 7(11), 129; https://doi.org/10.3390/inorganics7110129 - 25 Oct 2019

Cited by 3 | Viewed by 2952

Abstract

The reaction of the bulky Eind-based dialumane, (Eind)HAl(μ-H)₂AlH(Eind) (1) (Eind = 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl), with pyridines is described. When 1 was treated with pyridine (Py) in toluene, the Py adduct of aryldihydroalumane, Py→AlH₂(Eind) (2 [...] Read more.

The reaction of the bulky Eind-based dialumane, (Eind)HAl(μ-H)₂AlH(Eind) (1) (Eind = 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl), with pyridines is described. When 1 was treated with pyridine (Py) in toluene, the Py adduct of aryldihydroalumane, Py→AlH₂(Eind) (2), was initially formed. Then, the hydroalumination of Py took place to yield the Py-bound aryl(1,4-dihydropyrid-1-yl)hydroalumane, Py→AlH(1,4-dihydropyrid-1-yl)(Eind) (3). A similar reaction with a stronger Lewis base, 4-pyrrolidinopyridine (PPy), produced the stable PPy adduct, PPy→AlH₂(Eind) (4). The resulting organoaluminum compounds have been fully characterized by NMR spectroscopy as well as X-ray crystallography. The reaction mechanism from 1 to 3 via 2 has been examined by deuterium labeling experiments using (Eind)DAl(μ-D)₂AlD(Eind) (1-d₄). Full article

(This article belongs to the Special Issue Organoaluminum Compounds)

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16 pages, 1455 KiB

Open AccessReview

^99mTc Labelling Strategies for the Development of Potential Nitroimidazolic Hypoxia Imaging Agents

by Javier Giglio and Ana Rey

Inorganics 2019, 7(11), 128; https://doi.org/10.3390/inorganics7110128 - 23 Oct 2019

Cited by 14 | Viewed by 3471

Abstract

Technetium-99m has a rich coordination chemistry that offers many possibilities in terms of oxidation states and donor atom sets. Modifications in the structure of the technetium complexes could be very useful for fine tuning the physicochemical and biological properties of potential ^99mTc [...] Read more.

Technetium-99m has a rich coordination chemistry that offers many possibilities in terms of oxidation states and donor atom sets. Modifications in the structure of the technetium complexes could be very useful for fine tuning the physicochemical and biological properties of potential ^99mTc radiopharmaceuticals. However, systematic study of the influence of the labelling strategy on the “in vitro” and “in vivo” behaviour is necessary for a rational design of radiopharmaceuticals. Herein we present a review of the influence of the Tc complexes’ molecular structure on the biodistribution and the interaction with the biological target of potential nitroimidazolic hypoxia imaging radiopharmaceuticals presented in the literature from 2010 to the present. Comparison with the gold standard [¹⁸F]Fluoromisonidazole (FMISO) is also presented. Full article

(This article belongs to the Special Issue Advanced Applications of Technetium Chemistry)

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Inorganics, Volume 7, Issue 11 (November 2019) – 11 articles

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