Research

Jump to: Review

16 pages, 3842 KiB

Open AccessArticle

Structural Investigation of Magnesium Complexes Supported by a Thiopyridyl Scorpionate Ligand

by Matthew P. Stevens, Emily Spray, Iñigo J. Vitorica-Yrezabal, Kuldip Singh, Vanessa M. Timmermann, Lia Sotorrios and Fabrizio Ortu

Molecules 2022, 27(14), 4564; https://doi.org/10.3390/molecules27144564 - 18 Jul 2022

Viewed by 1645

Abstract

Herein, we report the synthesis of a series of heteroleptic magnesium complexes stabilized with the scorpionate ligand tris(2-pyridylthio)methanide (Tptm). The compounds of the general formula [Mg(Tptm)(X)] (1-X; X = Cl, Br, I) were obtained via protonolysis reaction between the proligand and [...] Read more.

Herein, we report the synthesis of a series of heteroleptic magnesium complexes stabilized with the scorpionate ligand tris(2-pyridylthio)methanide (Tptm). The compounds of the general formula [Mg(Tptm)(X)] (1-X; X = Cl, Br, I) were obtained via protonolysis reaction between the proligand and selected Grignard reagents. Attempts to isolate the potassium derivative K(Tptm) lead to decomposition of Tptm and formation of the alkene (C₅H₄N-S)₂C=C(C₅H₄N-S)₂, and this degradation was also modelled using DFT methods. Compound 1-I was treated with K(CH₂Ph), affording the degradation product [Mg(Bptm)₂] (2; Bptm = {CH(S-C₅NH₃)₂}⁻). We analyzed and quantified the steric properties of the Tptm ligand using the structural information of the compounds obtained in this study paired with buried volume calculations, also adding the structural data of HTptm and its CF₃-substituted congener (HTptm^CF3). These studies highlight the highly flexible nature of this ligand scaffold and its ability to stabilize various coordination motifs and geometries, which is a highly desirable feature in the design of novel organometallic reagents and catalysts. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Graphical abstract

21 pages, 2492 KiB

Open AccessArticle

Metal Coordination Properties of a Chromophoric Desferrioxamine (DFO) Derivative: Insight on the Coordination Stoichiometry and Thermodynamic Stability of Zr⁴⁺ Complexes

by Matteo Savastano, Francesca Boscaro and Antonio Bianchi

Molecules 2022, 27(1), 184; https://doi.org/10.3390/molecules27010184 - 29 Dec 2021

Cited by 5 | Viewed by 1818

Abstract

Desferrioxamine (DFO) is the current “gold standard” chelator for ⁸⁹Zr⁴⁺, which is used to label monoclonal antibodies for applications in immunopositron emission tomography. Recently, controversial data have been reported regarding the speciation and the stability of the complexes formed by [...] Read more.

Desferrioxamine (DFO) is the current “gold standard” chelator for ⁸⁹Zr⁴⁺, which is used to label monoclonal antibodies for applications in immunopositron emission tomography. Recently, controversial data have been reported regarding the speciation and the stability of the complexes formed by DFO with Zr⁴⁺ in solution. To shed some light on this point, we studied the coordination properties in solution ofa chromophoric DFO derivative bearing a substituted pyrimidine residue (DFO–Pm) toward several metal ions (Zr⁴⁺, Cu²⁺, Zn²⁺, Mg²⁺, Ca²⁺, Na⁺, K⁺). Potentiometric titrations showed that DFO–Pm and pristine DFO form complexes with very similar stoichiometry and stability. DFO–Pm, which can consequently be taken as a model system for DFO, provides a photochemical response to metal coordination that can be used to further define the complexes formed. In the critical case of Zr⁴⁺, spectrophotometric measurements allowed the verification of the formation of 1:1 and 2:3 complexes that, together with 2:2 complexes form the coordination model that was obtained through the use of our potentiometric measurements. Additionally, mass spectrometry measurements verified the formation of 1:1 and 2:3 complexes and showed that 1:2 species can be easily generated through the fragmentation of the 2:3 species. In conclusion, the results obtained with DFO–Pm validate the complexation model of Zr⁴⁺/DFO composed of 1:1, 2:2, and 2:3 metal-to-ligand complexes. Convergences and conflicts with other works are addressed. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Graphical abstract

14 pages, 14829 KiB

Open AccessArticle

Dialkylboryl-Substituted Cyclic Disilenes Synthesized by Desilylation-Borylation of Trimethylsilyl-Substituted Disilenes

by Kaho Tanaka, Naohiko Akasaka, Tomoyuki Kosai, Shunya Honda, Yuya Ushijima, Shintaro Ishida and Takeaki Iwamoto

Molecules 2021, 26(6), 1632; https://doi.org/10.3390/molecules26061632 - 15 Mar 2021

Cited by 5 | Viewed by 2506

Abstract

π-Electron systems of silicon have attracted attention because of their narrow HOMO-LUMO gap and high reactivity, but the structural diversity remains limited. Herein, new dialkylboryl-substituted disilenes were synthesized by the selective desilylation-borylation of the corresponding trimethylsilyl-substituted disilenes. The dialkylboryl-substituted disilenes were fully characterized [...] Read more.

π-Electron systems of silicon have attracted attention because of their narrow HOMO-LUMO gap and high reactivity, but the structural diversity remains limited. Herein, new dialkylboryl-substituted disilenes were synthesized by the selective desilylation-borylation of the corresponding trimethylsilyl-substituted disilenes. The dialkylboryl-substituted disilenes were fully characterized by a combination of NMR spectroscopy, MS spectrometry, single-crystal X-ray diffraction analysis, and theoretical calculations. The longest-wavelength absorption bands of boryldisilenes were bathochromically shifted compared to the corresponding silyl-substituted disilenes, indicating a substantial conjugation between π(Si=Si) and vacant 2p(B) orbitals. In the presence of 4-(dimethylamino)pyridine (DMAP), the dialkylboryl groups in the boryl-substituted disilenes were easily converted to trimethylsilyl groups, suggesting the dialkylboryl-substituted disilenes in the presence of a base serve as the surrogates of disilenyl anions (disilenides). Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Figure 1

16 pages, 4027 KiB

Open AccessFeature PaperArticle

Switching-On Fluorescence by Copper (II) and Basic Anions: A Case Study with a Pyrene-Functionalized Squaramide

by Giacomo Picci, Jessica Milia, Maria Carla Aragoni, Massimiliano Arca, Simon J. Coles, Alessandra Garau, Vito Lippolis, Riccardo Montis, James B. Orton and Claudia Caltagirone

Molecules 2021, 26(5), 1301; https://doi.org/10.3390/molecules26051301 - 28 Feb 2021

Cited by 11 | Viewed by 2948

Abstract

The new symmetric acyclic N,N’-bis(1-pyrenyl) squaramide (H₂L) functionalized with the pyrene moiety as a fluorogenic fragment has been designed and its ability to selectively detect specific anions and metals investigated. H₂L selectively binds Cl⁻ both [...] Read more.

The new symmetric acyclic N,N’-bis(1-pyrenyl) squaramide (H₂L) functionalized with the pyrene moiety as a fluorogenic fragment has been designed and its ability to selectively detect specific anions and metals investigated. H₂L selectively binds Cl⁻ both in solution (DMSO 0.5% H₂O and MeCN) and in the solid state, and allows to selectively detect Cu²⁺ in MeCN with the formation of a 2:1 metal-receptor complex, with a green intense emission appreciable by naked eye under the UV lamp. The H₂L copper complex preserves its emission properties in the presence of Cl⁻. The addition of basic anions (OH⁻, CN⁻, and F⁻) up to 10 equivalents caused the deprotonation of the squaramide NHs and a dramatic change of the emission properties of the H₂L copper complex. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Figure 1

25 pages, 4086 KiB

Open AccessFeature PaperArticle

Can Serendipity Still Hold Any Surprises in the Coordination Chemistry of Mixed-Donor Macrocyclic ligands? The Case Study of Pyridine-Containing 12-Membered Macrocycles and Platinum Group Metal ions Pd^II, Pt^II, and Rh^III

by Alessandra Garau, Giacomo Picci, Massimiliano Arca, Alexander J. Blake, Claudia Caltagirone, Greta De Filippo, Francesco Demartin, Francesco Isaia, Vito Lippolis, Anna Pintus, M. Andrea Scorciapino and M. Carla Aragoni

Molecules 2021, 26(5), 1286; https://doi.org/10.3390/molecules26051286 - 27 Feb 2021

Cited by 3 | Viewed by 1846

Abstract

This study investigates the coordination chemistry of the tetradentate pyridine-containing 12-membered macrocycles L¹-L³ towards Platinum Group metal ions Pd^II, Pt^II, and Rh^III. The reactions between the chloride salts of these metal ions and [...] Read more.

This study investigates the coordination chemistry of the tetradentate pyridine-containing 12-membered macrocycles L¹-L³ towards Platinum Group metal ions Pd^II, Pt^II, and Rh^III. The reactions between the chloride salts of these metal ions and the three ligands in MeCN/H₂O or MeOH/H₂O (1:1 v/v) are shown, and the isolated solid compounds are characterized, where possible, by mass spectroscopy and ¹H- and ¹³C-NMR spectroscopic measurements. Structural characterization of the 1:1 metal-to-ligand complexes [Pd(L¹)Cl]₂[Pd₂Cl₆], [Pt(L¹)Cl](BF₄), [Rh(L¹)Cl₂](PF₆), and [Rh(L³)Cl₂](BF₄)·MeCN shows the coordinated macrocyclic ligands adopting a folded conformation, and occupying four coordination sites of a distorted square-based pyramidal and octahedral coordination environment for the Pd^II/Pt^II, and Rh^III complexes, respectively. The remaining coordination site(s) are occupied by chlorido ligands. The reaction of L₃ with PtCl₂ in MeCN/H₂O gave by serendipity the complex [Pt(L³)(μ-1,3-MeCONH)PtCl(MeCN)](BF₄)₂·H₂O, in which two metal centers are bridged by an amidate ligand at a Pt1-Pt2 distance of 2.5798(3) Å and feature one square-planar and one octahedral coordination environment. Density Functional Theory (DFT) calculations, which utilize the broken symmetry approach (DFT-BS), indicate a singlet d⁸-d⁸ Pt^II-Pt^II ground-state nature for this compound, rather than the alleged d⁹-d⁷ Pt^I-Pt^III mixed-valence character reported for related dinuclear Pt-complexes. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Figure 1

16 pages, 3517 KiB

Open AccessArticle

A Mixed Valence Co^IICo^III₂ Field-Supported Single Molecule Magnet: Solvent-Dependent Structural Variation

by Susanta Hazra, Cyril Rajnák, Ján Titiš, M. Fátima C. Guedes da Silva, Roman Boča and Armando J. L. Pombeiro

Molecules 2021, 26(4), 1060; https://doi.org/10.3390/molecules26041060 - 18 Feb 2021

Cited by 4 | Viewed by 1733

Abstract

One-pot reaction of the Schiff base N,N’-ethylene bis(salicylaldimine) (H₂L), CoCl₂.6H₂O, and [Ph₂SnCl₂] in acetone produces the mixed valence Co^IICo^III₂ compound [Co^IICo^III₂(μ-L) [...] Read more.

One-pot reaction of the Schiff base N,N’-ethylene bis(salicylaldimine) (H₂L), CoCl₂.6H₂O, and [Ph₂SnCl₂] in acetone produces the mixed valence Co^IICo^III₂ compound [Co^IICo^III₂(μ-L)₂(Ph)₂(μ-Cl)₂]·(CH₃)₂CO·H₂O (1). Our recent study already revealed that the same reaction mixtures in methanol or ethanol produced a heterometallic Sn^IVCo^III (2) or monometallic Co^III complex (3), respectively. Comparison of these organometallic systems shows that the 2,1-intermetallic Ph shift occurs in any of those solvents, but their relevant structural features (mononuclear, dinuclear-heterometallic, and trinuclear mixed valence) are solvent dependent. Geometrical structural rotation is also discussed among the related organometallic Co^IICo^III₂ systems. The AC magnetic susceptibility measurements indicate that 1 is a single molecule magnet (SMM), exhibiting a field-induced slow magnetic relaxation with two modes. The relaxation time for the low-frequency channel is as slow as τ~0.6 s at T = 2.0 K and B_DC = 1.0 T. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Graphical abstract

15 pages, 2296 KiB

Open AccessFeature PaperArticle

A New Photoactivatable Ruthenium(II) Complex with an Asymmetric Bis-Thiocarbohydrazone: Chemical and Biological Investigations

by Marianna Pioli, Nicolò Orsoni, Mirco Scaccaglia, Rossella Alinovi, Silvana Pinelli, Giorgio Pelosi and Franco Bisceglie

Molecules 2021, 26(4), 939; https://doi.org/10.3390/molecules26040939 - 10 Feb 2021

Cited by 5 | Viewed by 2507

Abstract

The synthesis, photoactivation and biological activity of a new piano-stool Ru(II) complex is herein reported. The peculiarity of this complex is that its monodentate ligand which undergoes the photodissociation is an asymmetric bis-thiocarbohydrazone ligand that possesses a pyridine moiety binding to Ru(II) and [...] Read more.

The synthesis, photoactivation and biological activity of a new piano-stool Ru(II) complex is herein reported. The peculiarity of this complex is that its monodentate ligand which undergoes the photodissociation is an asymmetric bis-thiocarbohydrazone ligand that possesses a pyridine moiety binding to Ru(II) and the other moiety contains a quinoline that endows the ligand with the capacity of chelating other metal ions. In this way, upon dissociation, the ligand can be released in the form of a metal complex. In this article, the double ability of this new Ru(II) complex to photorelease the ligand and to chelate copper and nickel is explored and confirmed. The biological activity of this compound is studied in cell line A549 revealing that, after irradiation, proliferation inhibition is reached at very low half maximal inhibitory concentration (IC₅₀) values. Further, biological assays reveal that the dinuclear complex containing Ni is internalized in cells. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Figure 1

12 pages, 2039 KiB

Open AccessArticle

Exploring the Ability of Luminescent Metal Assemblies to Bind and Sense Anionic or Ionizable Analytes A Ru(phen)₂bipy-Based Dizinc Complex for Bisphenol A (BPA) Recognition

by Luca Conti, Liviana Mummolo, Giammarco Maria Romano, Claudia Giorgi, Gina Elena Giacomazzo, Luca Prodi and Andrea Bencini

Molecules 2021, 26(3), 527; https://doi.org/10.3390/molecules26030527 - 20 Jan 2021

Cited by 6 | Viewed by 2399

Abstract

The synthesis of a new Ru^II complex, in which the metal is coordinated by two 1,10-phenanthroline ligands and a 2,2′-bipyridyl unit linked, via methylene bridges in its 4 and 4′ positions, to two 1,4,7,10-tetraazacyclododecane (cyclen) macrocycles ([Ru(phen)₂L]²⁺) [...] Read more.

The synthesis of a new Ru^II complex, in which the metal is coordinated by two 1,10-phenanthroline ligands and a 2,2′-bipyridyl unit linked, via methylene bridges in its 4 and 4′ positions, to two 1,4,7,10-tetraazacyclododecane (cyclen) macrocycles ([Ru(phen)₂L]²⁺) is reported. Protonation and Zn^II binding by [Ru(phen)₂L]²⁺ have been analyzed by potentiometric titration, evidencing the formation of mixed hetero-binuclear and hetero-trinuclear Zn^II/Ru^II complexes. These complexes were tested as bis-phenol A (BPA) binders. Only the dizinc complex with [Ru(phen)₂L]²⁺ is able to bind BPA in aqueous solution, affording a remarkably stable {Zn₂[Ru(phen)₂L]BPA(H₋₂)}⁴⁺ adduct at neutral pH, in which BPA is bound in its doubly deprotonated form to the two Zn^II ions. BPA binding was found to quench the luminescence emission of the Ru^II(phen)₂bipy core. Although the quenching effect is modest, this study demonstrates that appropriately designed dizinc complexes can be used for binding and optical sensing of BPA in water. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Graphical abstract

16 pages, 2967 KiB

Open AccessArticle

Zn^II and Cu^II-Based Coordination Polymers and Metal Organic Frameworks by the of Use of 2-Pyridyl Oximes and 1,3,5-Benzenetricarboxylic Acid

by Ioannis Mylonas-Margaritis, Julia Mayans, Patrick McArdle and Constantina Papatriantafyllopoulou

Molecules 2021, 26(2), 491; https://doi.org/10.3390/molecules26020491 - 18 Jan 2021

Cited by 11 | Viewed by 3222

Abstract

The simultaneous use of 2-pyridyl oximes (pyridine-2 amidoxime, H₂pyaox; 2-methyl pyridyl ketoxime, Hmpko) and 1,3,5-benzenetricarboxylic acid (H₃btc) provided access to five new compounds, namely [Zn(H₂btc)₂(H₂pyaox)₂]•2H₂O (1•2H₂ [...] Read more.

The simultaneous use of 2-pyridyl oximes (pyridine-2 amidoxime, H₂pyaox; 2-methyl pyridyl ketoxime, Hmpko) and 1,3,5-benzenetricarboxylic acid (H₃btc) provided access to five new compounds, namely [Zn(H₂btc)₂(H₂pyaox)₂]•2H₂O (1•2H₂O), [Zn(Hbtc)(H₂pyaox)₂]_n (2), [Cu(Hbtc)(H₂pyaox)]_n (3), [Cu(Hbtc)(HmpKo)]_n (4) and [Cu₂(Hbtc)₂(Hmpko)₂(H₂O)₂]•4H₂O (5•4H₂O). Among them, 3 is the first example of a metal-organic framework (MOF) containing H₂pyaox. Its framework can be described as a 3-c uninodal net of hcb topology with the layers being parallel to the (1,0,1) plane. Furthermore, 3 is the third reported MOF based on a 2-pyridyl oxime in general. 2 and 4 are new members of a small family of coordination polymers containing an oximic ligand. 1–5 form 3D networks through strong intermolecular interactions. Dc magnetic susceptibility studies were carried out in a crystalline sample of 3 and revealed the presence of weak exchange interactions between the metal centres; the experimental data were fitted to a theoretical model with the fitting parameters being J = −0.16(1) cm⁻¹ and g = 2.085(1). The isotropic g value was also confirmed by electronic paramagnetic resonance (EPR) spectroscopy. Reactivity studies were performed for 3 in the presence of metal ions; the reaction progress was studied and discussed for Fe(NO₃)₃ by the use of several characterization techniques, including single crystal X-ray crystallography and IR spectroscopy. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Figure 1

12 pages, 1967 KiB

Open AccessArticle

Generation of Bis(ferrocenyl)silylenes from Siliranes

by Yang Pan, Shogo Morisako, Shinobu Aoyagi and Takahiro Sasamori

Molecules 2020, 25(24), 5917; https://doi.org/10.3390/molecules25245917 - 14 Dec 2020

Cited by 3 | Viewed by 2790

Abstract

Divalent silicon species, the so-called silylenes, represent attractive organosilicon building blocks. Isolable stable silylenes remain scarce, and in most hitherto reported examples, the silicon center is stabilized by electron-donating substituents (e.g., heteroatoms such as nitrogen), which results in electronic perturbation. In order to [...] Read more.

Divalent silicon species, the so-called silylenes, represent attractive organosilicon building blocks. Isolable stable silylenes remain scarce, and in most hitherto reported examples, the silicon center is stabilized by electron-donating substituents (e.g., heteroatoms such as nitrogen), which results in electronic perturbation. In order to avoid such electronic perturbation, we have been interested in the chemistry of reactive silylenes with carbon-based substituents such as ferrocenyl groups. Due to the presence of a divalent silicon center and the redox-active transition metal iron, ferrocenylsilylenes can be expected to exhibit interesting redox behavior. Herein, we report the design and synthesis of a bis(ferrocenyl)silirane as a precursor for a bis(ferrocenyl)silylene, which could potentially be used as a building block for redox-active organosilicon compounds. It was found that the isolated bis(ferrocenyl)siliranes could be a bottleable precursor for the bis(ferrocenyl)silylene under mild conditions. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Graphical abstract

17 pages, 2073 KiB

Open AccessArticle

On the Different Mode of Action of Au(I)/Ag(I)-NHC Bis-Anthracenyl Complexes Towards Selected Target Biomolecules

by Francesca Binacchi, Federica Guarra, Damiano Cirri, Tiziano Marzo, Alessandro Pratesi, Luigi Messori, Chiara Gabbiani and Tarita Biver

Molecules 2020, 25(22), 5446; https://doi.org/10.3390/molecules25225446 - 20 Nov 2020

Cited by 12 | Viewed by 2546

Abstract

Gold and silver N-heterocyclic carbenes (NHCs) are emerging for therapeutic applications. Multiple techniques are here used to unveil the mechanistic details of the binding to different biosubstrates of bis(1-(anthracen-9-ylmethyl)-3-ethylimidazol-2-ylidene) silver chloride [Ag(EIA)₂]Cl and bis(1-(anthracen-9-ylmethyl)-3-ethylimidazol-2-ylidene) gold chloride [Au(EIA)₂]Cl. As the [...] Read more.

Gold and silver N-heterocyclic carbenes (NHCs) are emerging for therapeutic applications. Multiple techniques are here used to unveil the mechanistic details of the binding to different biosubstrates of bis(1-(anthracen-9-ylmethyl)-3-ethylimidazol-2-ylidene) silver chloride [Ag(EIA)₂]Cl and bis(1-(anthracen-9-ylmethyl)-3-ethylimidazol-2-ylidene) gold chloride [Au(EIA)₂]Cl. As the biosubstrates, we tested natural double-stranded DNA, synthetic RNA polynucleotides (single-poly(A), double-poly(A)poly(U) and triple-stranded poly(A)2poly(U)), DNA G-quadruplex structures (G4s), and bovine serum albumin (BSA) protein. Absorbance and fluorescence titrations, mass spectrometry together with melting and viscometry tests show significant differences in the binding features between silver and gold compounds. [Au(EIA)₂]Cl covalently binds BSA. It is here evidenced that the selectivity is high: low affinity and external binding for all polynucleotides and G4s are found. Conversely, in the case of [Ag(EIA)₂]Cl, the binding to BSA is weak and relies on electrostatic interactions. [Ag(EIA)₂]Cl strongly/selectively interacts only with double strands by a mechanism where intercalation plays the major role, but groove binding is also operative. The absence of an interaction with triplexes indicates the major role played by the geometrical constraints to drive the binding mode. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Graphical abstract

11 pages, 4858 KiB

Open AccessFeature PaperArticle

Systematics of Atomic Orbital Hybridization of Coordination Polyhedra: Role of f Orbitals

by R. Bruce King

Molecules 2020, 25(14), 3113; https://doi.org/10.3390/molecules25143113 - 08 Jul 2020

Cited by 5 | Viewed by 5934

Abstract

The combination of atomic orbitals to form hybrid orbitals of special symmetries can be related to the individual orbital polynomials. Using this approach, 8-orbital cubic hybridization can be shown to be sp³d³f requiring an f orbital, and 12-orbital hexagonal [...] Read more.

The combination of atomic orbitals to form hybrid orbitals of special symmetries can be related to the individual orbital polynomials. Using this approach, 8-orbital cubic hybridization can be shown to be sp³d³f requiring an f orbital, and 12-orbital hexagonal prismatic hybridization can be shown to be sp³d⁵f²g requiring a g orbital. The twists to convert a cube to a square antiprism and a hexagonal prism to a hexagonal antiprism eliminate the need for the highest nodality orbitals in the resulting hybrids. A trigonal twist of an O_h octahedron into a D_3h trigonal prism can involve a gradual change of the pair of d orbitals in the corresponding sp³d² hybrids. A similar trigonal twist of an O_h cuboctahedron into a D_3h anticuboctahedron can likewise involve a gradual change in the three f orbitals in the corresponding sp³d⁵f³ hybrids. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Graphical abstract

18 pages, 2878 KiB

Open AccessFeature PaperArticle

Antibacterial Activity of Amidodithiophosphonato Nickel(II) Complexes: An Experimental and Theoretical Approach

by Enrico Podda, Massimiliano Arca, Giulia Atzeni, Simon J. Coles, Antonella Ibba, Francesco Isaia, Vito Lippolis, Germano Orrù, James B. Orton, Anna Pintus, Enrica Tuveri and M. Carla Aragoni

Molecules 2020, 25(9), 2052; https://doi.org/10.3390/molecules25092052 - 28 Apr 2020

Cited by 6 | Viewed by 3071

Abstract

The reactions of 2,4-bis(4-methoxyphenyl)-1,3-dithio-2,4-diphosphetane-2,4-disulfide (Lawesson’s Reagent, LR) with benzylamine (BzNH₂) and 4-phenylbutylamine (PhBuNH₂) yield benzylammonium P-(4-methoxyphenyl)-N-benzyl-amidodithiophosphonate (BzNH₃)(BzNH-adtp) and 4-phenylbutylammonium P-(4-methoxyphenyl)-N-(4-phenylbutyl)-amidodithiophosphonate (PhBuNH₃)(PhBuNH-adtp). The relevant nickel complexes [Ni(BzNH-adtp)₂] and [...] Read more.

The reactions of 2,4-bis(4-methoxyphenyl)-1,3-dithio-2,4-diphosphetane-2,4-disulfide (Lawesson’s Reagent, LR) with benzylamine (BzNH₂) and 4-phenylbutylamine (PhBuNH₂) yield benzylammonium P-(4-methoxyphenyl)-N-benzyl-amidodithiophosphonate (BzNH₃)(BzNH-adtp) and 4-phenylbutylammonium P-(4-methoxyphenyl)-N-(4-phenylbutyl)-amidodithiophosphonate (PhBuNH₃)(PhBuNH-adtp). The relevant nickel complexes [Ni(BzNH-adtp)₂] and [Ni(PhBuNH-adtp)₂] and the corresponding hydrolysed derivatives (BzNH₃)₂[Ni(dtp)₂] and (PhBuNH₃)₂[Ni(dtp)₂] were prepared and fully characterized. The antimicrobial activity of the aforementioned amidodithiophosphonates against a set of Gram-positive and Gram-negative pathogen bacteria was evaluated, and [Ni(BzNH-adtp)₂] and [Ni(PhBuNH-adtp)₂] showed antiproliferative activity towards Staphylococcus aureus and Staphylococcus haemolyticus strains. density functional theory (DFT) calculations were performed to shed some light on the activity of reported compounds related to their tendency towards P–N bond cleavage. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Graphical abstract

31 pages, 5085 KiB

Open AccessFeature PaperArticle

Synthesis, Characterization and Biological Activity of Novel Cu(II) Complexes of 6-Methyl-2-Oxo-1,2-Dihydroquinoline-3-Carbaldehyde-4n-Substituted Thiosemicarbazones

by Eswaran Ramachandran, Valentina Gandin, Roberta Bertani, Paolo Sgarbossa, Karuppannan Natarajan, Nattamai S. P. Bhuvanesh, Alfonso Venzo, Alfonso Zoleo, Mirto Mozzon, Alessandro Dolmella, Alberto Albinati, Carlo Castellano, Nuno Reis Conceição, M. Fátima C. Guedes da Silva and Cristina Marzano

Molecules 2020, 25(8), 1868; https://doi.org/10.3390/molecules25081868 - 17 Apr 2020

Cited by 19 | Viewed by 4621

Abstract

Three new 6-methyl-2-oxo-1,2-dihydroquinoline-3-carbaldehyde-thiosemicarbazones-N-4-substituted pro-ligands and their Cu(II) complexes (1, -NH₂; 2, -NHMe; 3, -NHEt) have been prepared and characterized. In both the X-ray structures of 1 and 3, two crystallographically independent complex molecules were found that [...] Read more.

Three new 6-methyl-2-oxo-1,2-dihydroquinoline-3-carbaldehyde-thiosemicarbazones-N-4-substituted pro-ligands and their Cu(II) complexes (1, -NH₂; 2, -NHMe; 3, -NHEt) have been prepared and characterized. In both the X-ray structures of 1 and 3, two crystallographically independent complex molecules were found that differ either in the nature of weakly metal-binding species (water in 1a and nitrate in 1b) or in the co-ligand (water in 3a and methanol in 3b). Electron Paramagnetic Resonance (EPR) measurements carried out on complexes 1 and 3 confirmed the presence of such different species in the solution. The electrochemical behavior of the pro-ligands and of the complexes was investigated, as well as their biological activity. Complexes 2 and 3 exhibited a high cytotoxicity against human tumor cells and 3D spheroids derived from solid tumors, related to the high cellular uptake. Complexes 2 and 3 also showed a high selectivity towards cancerous cell lines with respect to non-cancerous cell lines and were able to circumvent cisplatin resistance. Via the Transmission Electron Microscopy (TEM) imaging technique, preliminary insights into the biological activity of copper complexes were obtained. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Figure 1

21 pages, 5157 KiB

Open AccessArticle

Mono-, Di- and Tetra-iron Complexes with Selenium or Sulphur Functionalized Vinyliminium Ligands: Synthesis, Structural Characterization and Antiproliferative Activity

by Gabriele Agonigi, Lucinda K. Batchelor, Eleonora Ferretti, Silvia Schoch, Marco Bortoluzzi, Simona Braccini, Federica Chiellini, Lorenzo Biancalana, Stefano Zacchini, Guido Pampaloni, Biprajit Sarkar, Paul J. Dyson and Fabio Marchetti

Molecules 2020, 25(7), 1656; https://doi.org/10.3390/molecules25071656 - 03 Apr 2020

Cited by 21 | Viewed by 3112

Abstract

A series of diiron/tetrairon compounds containing a S- or a Se-function (2a–d, 4a–d, 5a–b, 6), and the monoiron [FeCp(CO){SeC¹(NMe₂)C²HC³(Me)}] (3) were prepared [...] Read more.

A series of diiron/tetrairon compounds containing a S- or a Se-function (2a–d, 4a–d, 5a–b, 6), and the monoiron [FeCp(CO){SeC¹(NMe₂)C²HC³(Me)}] (3) were prepared from the diiron μ-vinyliminium precursors [Fe₂Cp₂(CO)( μ-CO){μ-η¹: η³-C³(R’)C²HC¹N(Me)(R)}]CF₃SO₃ (R = R’ = Me, 1a; R = 2,6-C₆H₃Me₂ = Xyl, R’ = Ph, 1b; R = Xyl, R’ = CH₂OH, 1c), via treatment with S₈ or gray selenium. The new compounds were characterized by elemental analysis, IR and multinuclear NMR spectroscopy, and structural aspects were further elucidated by DFT calculations. The unprecedented metallacyclic structure of 3 was ascertained by single crystal X-ray diffraction. The air-stable compounds (3, 4a–d, 5a–b, 6) display fair to good stability in aqueous media, and thus were assessed for their cytotoxic activity towards A2780, A2780cisR, and HEK-293 cell lines. Cyclic voltammetry, ROS production and NADH oxidation studies were carried out on selected compounds to give insights into their mode of action. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Graphical abstract

15 pages, 4532 KiB

Open AccessFeature PaperArticle

Sensing Zn²⁺ in Aqueous Solution with a Fluorescent Scorpiand Macrocyclic Ligand Decorated with an Anthracene Bearing Tail

by Matteo Savastano, Matteo Fiaschi, Giovanni Ferraro, Paola Gratteri, Palma Mariani, Antonio Bianchi and Carla Bazzicalupi

Molecules 2020, 25(6), 1355; https://doi.org/10.3390/molecules25061355 - 17 Mar 2020

Cited by 20 | Viewed by 2976

Abstract

Synthesis of the new scorpiand ligand L composed of a [9]aneN₃ macrocyclic ring bearing a CH₂CH₂NHCH₂-anthracene tail is reported. L forms both cation (Zn²⁺) and anion (phosphate, benzoate) complexes. In addition, the zinc complexes [...] Read more.

Synthesis of the new scorpiand ligand L composed of a [9]aneN₃ macrocyclic ring bearing a CH₂CH₂NHCH₂-anthracene tail is reported. L forms both cation (Zn²⁺) and anion (phosphate, benzoate) complexes. In addition, the zinc complexes of L bind these anions. The equilibrium constants for ligand protonation and complex formation were determined in 0.1 M NaCl aqueous solution at 298.1 ± 0.1 K by means of potentiometric (pH-metric) titrations. pH Controlled coordination/detachment of the ligand tail to Zn²⁺ switch on and off the fluorescence emission from the anthracene fluorophore. Accordingly, L is able to sense Zn²⁺ in the pH range 6–10 down to nM concentrations of the metal ion. L can efficiently sense Zn²⁺ even in the presence of large excess of coordinating anions, such as cyanide, sulphide, phosphate and benzoate, despite their ability to bind the metal ion. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Graphical abstract

Review

Jump to: Research

15 pages, 3638 KiB

Open AccessReview

Gold Clusters: From the Dispute on a Gold Chair to the Golden Future of Nanostructures

by Maria Luisa Ganadu, Francesco Demartin, Angelo Panzanelli, Ennio Zangrando, Massimiliano Peana, Serenella Medici and Maria Antonietta Zoroddu

Molecules 2021, 26(16), 5014; https://doi.org/10.3390/molecules26165014 - 19 Aug 2021

Cited by 1 | Viewed by 2514

Abstract

The present work opens with an acknowledgement to the research activity performed by Luciana Naldini while affiliated at the Università degli Studi di Sassari (Italy), in particular towards gold complexes and clusters, as a tribute to her outstanding figure in a time and [...] Read more.

The present work opens with an acknowledgement to the research activity performed by Luciana Naldini while affiliated at the Università degli Studi di Sassari (Italy), in particular towards gold complexes and clusters, as a tribute to her outstanding figure in a time and a society where being a woman in science was rather difficult, hoping her achievements could be of inspiration to young female chemists in pursuing their careers against the many hurdles they may encounter. Naldini’s findings will be a key to introduce the most recent results in this field, showing how the chemistry of gold compounds has changed throughout the years, to reach levels of complexity and elegance that were once unimagined. The study of gold complexes and clusters with various phosphine ligands was Naldini’s main field of research because of the potential application of these species in diverse research areas including electronics, catalysis, and medicine. As the conclusion of a vital period of study, here we report Naldini’s last results on a hexanuclear cationic gold cluster, [(PPh₃)₆Au₆(OH)₂]²⁺, having a chair conformation, and on the assumption, supported by experimental data, that it comprises two hydroxyl groups. This contribution, within the fascinating field of inorganic chemistry, provides the intuition of how a simple electron counting may lead to predictable species of yet unknown molecular architectures and formulation, nowadays suggesting interesting opportunities to tune the electronic structures of similar and higher nuclearity species thanks to new spectroscopic and analytical approaches and software facilities. After several decades since Naldini’s exceptional work, the chemistry of the gold cluster has reached a considerable degree of complexity, dealing with new, single-atom precise, materials possessing interesting physico-chemical properties, such as luminescence, chirality, or paramagnetic behavior. Here we will describe some of the most significant contributions. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Figure 1

24 pages, 5206 KiB

Open AccessReview

Rh(I) Complexes in Catalysis: A Five-Year Trend

by Serenella Medici, Massimiliano Peana, Alessio Pelucelli and Maria Antonietta Zoroddu

Molecules 2021, 26(9), 2553; https://doi.org/10.3390/molecules26092553 - 27 Apr 2021

Cited by 9 | Viewed by 3570

Abstract

Rhodium is one of the most used metals in catalysis both in laboratory reactions and industrial processes. Despite the extensive exploration on “classical” ligands carried out during the past decades in the field of rhodium-catalyzed reactions, such as phosphines, and other common types [...] Read more.

Rhodium is one of the most used metals in catalysis both in laboratory reactions and industrial processes. Despite the extensive exploration on “classical” ligands carried out during the past decades in the field of rhodium-catalyzed reactions, such as phosphines, and other common types of ligands including N-heterocyclic carbenes, ferrocenes, cyclopentadienyl anion and pentamethylcyclopentadienyl derivatives, etc., there is still lively research activity on this topic, with considerable efforts being made toward the synthesis of new preformed rhodium catalysts that can be both efficient and selective. Although the “golden age” of homogeneous catalysis might seem over, there is still plenty of room for improvement, especially from the point of view of a more sustainable chemistry. In this review, temporally restricted to the analysis of literature during the past five years (2015–2020), the latest findings and trends in the synthesis and applications of Rh(I) complexes to catalysis will be presented. From the analysis of the most recent literature, it seems clear that rhodium-catalyzed processes still represent a stimulating challenge for the metalloorganic chemist that is far from being over. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Figure 1

32 pages, 15059 KiB

Open AccessReview

Recent Bio-Advances in Metal-Organic Frameworks

by Isobel Tibbetts and George E. Kostakis

Molecules 2020, 25(6), 1291; https://doi.org/10.3390/molecules25061291 - 12 Mar 2020

Cited by 51 | Viewed by 8858

Abstract

Metal-organic frameworks (MOFs) have found uses in adsorption, catalysis, gas storage and other industrial applications. Metal Biomolecule Frameworks (bioMOFs) represent an overlap between inorganic, material and medicinal sciences, utilising the porous frameworks for biologically relevant purposes. This review details advances in bioMOFs, looking [...] Read more.

Metal-organic frameworks (MOFs) have found uses in adsorption, catalysis, gas storage and other industrial applications. Metal Biomolecule Frameworks (bioMOFs) represent an overlap between inorganic, material and medicinal sciences, utilising the porous frameworks for biologically relevant purposes. This review details advances in bioMOFs, looking at the synthesis, properties and applications of both bioinspired materials and MOFs used for bioapplications, such as drug delivery, imaging and catalysis, with a focus on examples from the last five years. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Exclusive Feature Papers in Inorganic Chemistry

Share This Special Issue

Special Issue Editors

Special Issue Information

Published Papers (19 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI