Inorganics

N,O-chelating dicarbonylhydrazido-palladium complexes were synthesized by treatment of 1,2-bis(trifluoroacetyl)hydrazine with a mixture of a Pd(0) source, [Pd(dba)₂] (DBA = dibenzylideneacetone), and four-electron donors including 1,3-bis(diphenylphosphino)propane (DPPP), N,N,N’,N’-tetramethylethylenediamine (TMEDA), and two equivalents of triphenylphosphine. The same products from DPPP and TMEDA could be obtained alternatively by using Pd(OAc)₂ through deprotonation of the diacylhydrazine. The five-membered chelate structure was confirmed by NMR spectra and X-ray crystal structure determination. The X-ray structures indicate that the products are formally considered as Pd(II) complexes with a hydrazido(2–) ligand. In the case of the triphenylphosphine-coordinated complex, a fluxional behavior in dichloromethane-d₂ was observed by variable temperature NMR experiments, possibly due to structural changes between the square planar and pseudo-tetrahedral geometries. Full article

A spirogermabifluorene that bears sterically demanding 3,3′,5,5′-tetra(t-butyl)-2,2′-biphenylene groups (1) was obtained from the reaction of in-situ-generated 2,2′-dilithiobiphenylene with GeCl₂·(dioxane). The solid-state structure and the redox behavior of 1 were examined by single-crystal X-ray diffraction analysis and electrochemical measurements, respectively. The sterically hindered biphenyl ligands endow 1 with high redox stability and increased electron affinity. The experimental observations were corroborated by theoretical DFT calculations. Full article

Ten mononuclear rare earth complexes of formula [La(btfa)₃(H₂O)₂] (1), [La(btfa)₃(4,4′-Mt₂bipy)] (2), [La(btfa)₃(4,4′-Me₂bipy)₂] (3), [La(btfa)₃(5,5′-Me₂bipy)₂] (4), [La(btfa)₃(terpy)] (5), [La(btfa)₃(phen)(EtOH)] (6), [La(btfa)₃(4,4′-Me₂bipy)(EtOH)] (7), [La(btfa)₃(2-benzpy)(MeOH)] (8), [Tb(btfa)₃(4,4′-Me₂bipy)] (9) and (Hpy)[Eu(btfa)₄] (10), where btfa = 4,4,4-trifuoro-1-phenylbutane-1,3-dionato anion, 4,4′-Mt₂bipy = 4,4′-dimethoxy-2,2′-bipyridine, 4,4′-Me₂bipy = 4,4′-dimethyl-2,2′-bipyridine, 5,5′-Me₂bipy = 5,5′-dimethyl-2,2′-bipyridine, terpy = 2,2′:6′,2′-terpyridine, phen = 1,10-phenathroline, 2-benzpy = 2-(2-pyridyl)benzimidazole, Hpy = pyridiniumH⁺ cation) have been synthesized and structurally characterized. The complexes display coordination numbers (CN) eight for 1, 2, 9, 10, nine for 5, 6, 7, 8 and ten for 3 and 4. The solid-state luminescence spectra of Tb-9 and Eu-10 complexes showed the same characteristic bands predicted from the Tb(III) and Eu(III) ions. The Overall Quantum Yield measured (ϕ_TOT) at the excitation wavelength of 371 nm for both compounds yielded 1.04% for 9 and up to 34.56% for 10. Full article

Novel vitamin E chelate siderophore derivatives and their V^V and Fe^III complexes have been synthesised and the chemical and biological properties have been evaluated. In particular, the α- and δ-tocopherol derivatives with bis-methyldroxylamino triazine (α-tocTHMA) and (δ-tocDPA) as well their V^V complexes, [V₂^VO₃(α-tocTHMA)₂] and [V₂^IVO₃(δ-tocTHMA)₂], have been synthesised and characterised by infrared (IR), nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR) and ultra violet-visible (UV-Vis) spectroscopies. The dimeric vanadium complexes in solution are in equilibrium with their respefrctive monomers, H₂O + [V₂^VO₂(μ-O)]⁴⁺ = 2 [V^VO(OH)]²⁺. The two amphiphilic vanadium complexes exhibit enhanced hydrolytic stability. EPR shows that the complexes in lipophilic matrix are mild radical initiators. Evaluation of their biological activity shows that the compounds do not exhibit any significant cytotoxicity to cells. Full article

Sterically bulky β-diketiminate (or Nacnac) ligand systems have recently shown the ability to kinetically stabilize highly reactive low-oxidation state main group complexes. Metal halide precursors to such systems can be formed via salt metathesis reactions involving alkali metal complexes of these large ligand frameworks. Herein, we report the synthesis and characterization of lithium and potassium complexes of the super bulky anionic β-diketiminate ligands, known [^TCHPNacnac]⁻ and new [^TCHP/DipNacnac]⁻ (^ArNacnac = [(ArNCMe)₂CH]⁻) (Ar = 2,4,6-tricyclohexylphenyl (TCHP) or 2,6-diisopropylphenyl (Dip)). The reaction of the proteo-ligands, ^ArNacnacH, with nBuLi give the lithium etherate compounds, [(^TCHPNacnac)Li(OEt₂)] and [(^TCHP/DipNacnac)Li(OEt₂)], which were isolated and characterized by multinuclear NMR spectroscopy and X-ray crystallography. The unsolvated potassium salts, [{K(^TCHPNacnac)}₂] and [{K(^TCHP/DipNacnac)}_∞], were also synthesized and characterized in solution by NMR spectroscopy. In the solid state, these highly reactive potassium complexes exhibit differing alkali metal coordination modes, depending on the ligand involved. These group 1 complexes have potential as reagents for the transfer of the bulky ligand fragments to metal halides, and for the subsequent stabilization of low-oxidation state metal complexes. Full article

A review of the coordination chemistry along with the structural features of heavy element complexes of dithiocarbimate di-anions in the form of [(R)C=NCS₂]²⁻ for R = CN, alkyl, and aryl are described. This class of compound is far less studied compared with the well-explored dithiocarbamate mono-anions formulated as [R(R’)NCS₂]⁻ for R/R’ = H, alkyl, and aryl. The coordination chemistry of dithiocarbimate di-anions is dominated by a S,S-chelating mode; rare examples of alternative modes of coordination are evident. When comparisons are available, the structural motifs adopted by metal dithiocarbimate complexes match those found for their dithiocarbamate analogs, with only small, non-systematic variations in the M–S bond lengths. Full article

Copper dithiocarbamate complexes have been known for ca. 120 years and find relevance in biology and medicine, especially as anticancer agents and applications in materials science as a single-source precursor (SSPs) to nanoscale copper sulfides. Dithiocarbamates support Cu(I), Cu(II) and Cu(III) and show a rich and diverse coordination chemistry. Homoleptic [Cu(S₂CNR₂)₂] are most common, being known for hundreds of substituents. All contain a Cu(II) centre, being either monomeric (distorted square planar) or dimeric (distorted trigonal bipyramidal) in the solid state, the latter being held together by intermolecular C···S interactions. Their d⁹ electronic configuration renders them paramagnetic and thus readily detected by electron paramagnetic resonance (EPR) spectroscopy. Reaction with a range of oxidants affords d⁸ Cu(III) complexes, [Cu(S₂CNR₂)₂][X], in which copper remains in a square-planar geometry, but Cu–S bonds shorten by ca. 0.1 Å. These show a wide range of different structural motifs in the solid-state, varying with changes in anion and dithiocarbamate substituents. Cu(I) complexes, [Cu(S₂CNR₂)₂]⁻, are (briefly) accessible in an electrochemical cell, and the only stable example is recently reported [Cu(S₂CNH₂)₂][NH₄]·H₂O. Others readily lose a dithiocarbamate and the d¹⁰ centres can either be trapped with other coordinating ligands, especially phosphines, or form clusters with tetrahedral [Cu(μ₃-S₂CNR₂)]₄ being most common. Over the past decade, a wide range of Cu(I) dithiocarbamate clusters have been prepared and structurally characterised with nuclearities of 3–28, especially exciting being those with interstitial hydride and/or acetylide co-ligands. A range of mixed-valence Cu(I)–Cu(II) and Cu(II)–Cu(III) complexes are known, many of which show novel physical properties, and one Cu(I)–Cu(II)–Cu(III) species has been reported. Copper dithiocarbamates have been widely used as SSPs to nanoscale copper sulfides, allowing control over the phase, particle size and morphology of nanomaterials, and thus giving access to materials with tuneable physical properties. The identification of copper in a range of neurological diseases and the use of disulfiram as a drug for over 50 years makes understanding of the biological formation and action of [Cu(S₂CNEt₂)₂] especially important. Furthermore, the finding that it and related Cu(II) dithiocarbamates are active anticancer agents has pushed them to the fore in studies of metal-based biomedicines. Full article

The reaction in the system Cu^II/sacNa(H)/NCNR₂ (sacNa(H) = sodium saccharinate (saccharin); R = Me, Et) results in the formation of the complexes [Cu(sac)₂(NCNR₂)(H₂O)₂] (R = Me 1, Et 2) instead of the expected products derived from the saccharin–cyanamide coupling. Complexes 1, 2, and hydrate 1·2H₂O were characterized by IR, AAS (Cu%), TGA, and also by single-crystal X-ray diffraction for 1 and 1·2H₂O. An integrated computational study of model structure 1 in the gas phase demonstrates that the Cu–N_cyanamide and Cu–N_sac coordination bonds exhibited a single bond character, polarized toward the N atom and almost purely electrostatic, with the calculated vertical total energies for the Cu–N_cyanamide and Cu–N_sac of 43.6 and 156.4 kcal/mol, respectively. These data confirmed that the copper(II) completely blocks the nucleophilic centers of ligands via coordination, thus preventing the saccharin–cyanamide coupling. Full article

Several oxidoborates, self-assembled from B(OH)₃ and templated by cationic Ni^(II) coordination compounds, were synthesized by crystallization from aqueous solution. These include the ionic compounds trans-[Ni(NH₃)₄(H₂O)₂][B₄O₅(OH)₄]^.H₂O (1), s-[Ni(dien)₂][B₅O₆(OH)₄]₂ (dien = N-(2-aminoethyl)-1,2-ethanediamine (2), trans-[Ni(dmen)₂(H₂O)₂] [B₅O₆(OH)₄]₂^.2H₂O (dmen = N,N-dimethyl-1,2-diaminoethane) (3), [Ni(HEen)₂][B₅O₆(OH)₄]₂ (HEen = N-(2-hydroxyethyl)-1,2-diaminoethane) (4), [Ni(AEN)][B₅O₆(OH)₄]^.H₂O (AEN = 1-(3-azapropyl) -2,4-dimethyl-1,5,8-triazaocta-2,4-dienato(1-)) (5), trans-[Ni(dach)₂(H₂O)₂][Ni(dach)₂] [B₇O₉(OH)₅]₂^.4H₂O (dach = 1,2-diaminocyclohexane) (6), and the neutral species trans-[Ni(en)(H₂O)₂{B₆O₇(OH)₆}]^.H₂O (7) (en = 1,2-diaminoethane), and [Ni(dmen)(H₂O){B₆O₇(OH)₆}]^.5H₂O (8). Compounds 1–8 were characterized by single-crystal XRD studies and by IR spectroscopy and 2, 4–7 were also characterized by thermal (TGA/DSC) methods and powder XDR studies. The solid-state structures of all compounds show extensive stabilizing H-bond interactions, important for their formation, and also display a range of gross structural features: 1 has an insular tetraborate(2-) anion, 2–5 have insular pentaborate(1-) anions, 6 has an insular heptaborate(2-) anion (‘O⁺’ isomer), whilst 7 and 8 have hexaborate(2-) anions directly coordinated to their Ni^(II) centers, as bidentate or tridentate ligands, respectively. The Ni^(II) centers are either octahedral (1–4, 7, 8) or square-planar (5), and compound 6 has both octahedral and square-planar metal geometries present within the structure as a double salt. Magnetic susceptibility measurements were undertaken on all compounds. Full article

The interest in decavanadate anions has increased in recent decades, since these clusters show interesting applications as varied as sensors, batteries, catalysts, or new drugs in medicine. Due to the capacity of the interaction of decavanadate with a variety of biological molecules because of its high negative charge and oxygen-rich surface, this cluster is being widely studied both in vitro and in vivo as a treatment for several global health problems such as diabetes mellitus, cancer, and Alzheimer’s disease. Here, we report a new decavanadate compound with organic molecules synthesized in an aqueous solution and structurally characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. The decavanadate anion was combined with 2-aminopyrimidine to form the compound [2-ampymH]6[V10O28]·5H2O (1). In the crystal lattice, organic molecules are stacked by π–π interactions, with a centroid-to-centroid distance similar to that shown in DNA or RNA molecules. Furthermore, computational DFT calculations of Compound 1 corroborate the hydrogen bond interaction between pyrimidine molecules and decavanadate anions, as well as the π–π stacking interactions between the central pyrimidine molecules. Finally, docking studies with test RNA molecules indicate that they could serve as other potential targets for the anticancer activity of decavanadate anion. Full article

Two new oxidovanadium(V) complexes, (HNEt₃)[V^VO₂L] (1) and [(V^VOL)₂μ-O] (2), have been synthesized using a tridentate Schiff base ligand H₂L [where H₂L = 4-((E)-(2-hydroxy-5-nitrophenylimino)methyl)benzene-1,3-diol] and VO(acac)₂ as starting metal precursor. The ligand and corresponding metal complexes are characterized by physicochemical (elemental analysis), spectroscopic (FT-IR, UV–Vis, and NMR), and spectrometric (ESI–MS) methods. X-ray crystallographic analysis indicates the anion in salt 1 features a distorted square-pyramidal geometry for the vanadium(V) center defined by imine-N, two phenoxide-O, and two oxido-O atoms. The interaction of the compounds with CT–DNA was studied through UV–Vis absorption titration and circular dichroism methods. The results indicated that complexes showed enhanced binding affinity towards DNA compared to the ligand molecule. Finally, the in vitro cytotoxicity studies of H₂L, 1, and 2 were evaluated against colon cancer (HT-29) and mouse embryonic fibroblast (NIH-3T3) cell lines by MTT assay. The results demonstrated that the compounds manifested a cytotoxic potential comparable with clinically referred drugs and caused cell death by apoptosis. Full article

Apatite (Ap) dissolution in diluted acids is well described in the literature, but in technological processes which use more concentrated acids, the reaction is fast, and it is complicated to follow the process kinetics. The relationship between pH change and the apatite dissolution rate depending on HCl concentration was studied by thermodynamic calculations and experiments with synthetic fluorapatite (FAp). On the basis of experimental pH measurements, the kinetics of dissolution was analyzed. The solution composition (P, Ca, F) was determined by wet chemical methods and the solid part was characterized by XRD and FTIR. It was shown that the amount of HCl needed for FAp dissolution depends on acid concentration. FAp dissolution rate cannot be deduced from solubility data of P, Ca or F as the secondary reactions of CaF₂ and CaHPO₄ formation take place simultaneously. It was found that the Ap dissolution rate can be followed by pH change. Full article

A solvent effect towards the performance of two single-molecule magnets (SMMs) was observed. The tetrahydrofuran and toluene solvents can switch the equatorial coordinated 4-Phenylpyridine (4-PhPy) molecules from five to four, respectively, in [Dy(O^tBu)₂(4-PhPy)₅]BPh₄1 and Na{[Dy(O^tBu)₂(4-PhPy)₄][BPh₄]₂}∙2thf∙hex 2. This alternation significantly changes the local coordination symmetry of the Dy(III) center from D_5h to D_4h for 1 and 2, seperately. Magnetic studies show that the magnetic anisotropy energy barrier of 2 is higher than that of 1, while the relation of blocking temperature is just on the contrary due to the symmetry effect. The calculations of the electrostatic potential successfully explained the driving force of solvents for the molecular structure change, confirming the feasibility of adjusting the performance of SMMs via diverse solvents. Full article

Rare-earth doped ceria materials are amongst the top choices for use in electrolytes and composite electrodes in intermediate temperature solid oxide fuel cells. Trivalent acceptor dopants such as gadolinium, which mediate the ionic conductivity in ceria by creating oxygen vacancies, have a tendency to segregate at grain boundaries and triple points. This leads to formation of ionically resistive blocking grain boundaries and necessitates high operating temperatures to overcome this barrier. In an effort to improve the grain boundary conductivity, we studied the effect of a modified sintering cycle, where 10 mol% gadolinia doped ceria was sintered under a reducing atmosphere and subsequently reoxidized. A detailed analysis of the complex impedance, conductivity, and activation energy values was performed. The analysis shows that for samples processed thus, the ionic conductivity improves when compared with conventionally processed samples sintered in air. Equivalent circuit fitting shows that this improvement in conductivity is mainly due to a drop in the grain boundary resistance. Based on comparison of activation energy values for the conventionally processed vs. reduced-reoxidized samples, this drop can be attributed to a diminished blocking effect of defect-associates at the grain boundaries. Full article

We investigated the nitridation of reduced BaTiO₃, BaTiO_2.60H_0.08, corresponding to an oxyhydride with a large concentration of O defects (>10%). The material is readily nitrided under flowing N₂ gas at temperatures between 400 and 450 °C to yield oxynitrides BaTiO_2.6N_x (x = 0.2−0.22) with a slightly tetragonally distorted perovskite structure, a ≈ 4.01 and c ≈ 4.02 Å, and Ti partially remaining in the oxidation state III. The tetragonal structure was confirmed from Raman spectroscopy. ¹⁴N MAS NMR spectroscopy shows a single resonance at 270 ppm, which is typical for perovskite transition metal oxynitrides. However, largely different signal intensity for materials with very similar N content suggests N/O/vacancy ordering when prolonging nitridation times to hours. Diffuse reflectance UV-VIS spectroscopy shows a reduction of the intrinsic band gap to 2.4–2.45 eV compared to BaTiO₃ (~3.2 eV). Mott-Schottky measurements confirm n-type conductivity and reveal a slight negative shift of the conduction band edge from –0.59 V (BaTiO₃) to ~–0.65 eV. Full article

The antimony-iron sulfide system in general does not produce alloys below 540 °C from traditional solid-state methods. However, single source precursors have been known to produce unexpected products that arise from kinetically trapped polymorphs. In this paper, we test the efficacy of this approach toward the Fe-Sb-S system. Antimony and iron diethyldithiocarbamate complexes of the form Sb[S₂CN(Et₂)]₃ (1) and Fe[S₂CN(Et₂)]₃ (2) were synthesised, characterised, and used as single-source precursors for the preparation of Sb₂S₃, Fe_xS_y, and mixed iron antimony sulfide Sb_2(1−x)Fe_2xS₃ (0 ≥ x ≥ 1) powders using the solvent-less thermolysis method at different temperatures ranging from 300 to 475 °C. The effect of different mole fractions of the iron precursor was evaluated on morphology, shape, and optical and magnetic properties of Sb_2(1−x)Fe_2xS₃ (0 ≥ x ≥ 1). The obtained powders were characterized by X-ray diffraction (XRD), Raman spectroscopy scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, magnetometer measurement, and UV/vis/NIR spectroscopy. The results demonstrated that the crystalline structure, morphology, and elemental composition of the samples changed with the mole fraction of the precursor. There was significant phase separation between Sb and Fe sulfides noted from EDX spectroscopic mapping, yet an optoelectronic study monitoring the direct band gap energy of antimony sulfide shows that the band gap energy increases as a function of Fe content, which suggests limited alloying is possible from the single source route. Full article

The incorporation of dithiocarbamate ligands in the preparation of metal complexes is largely prompted by the versatility of this molecule. Fascinating coordination chemistry can be obtained from the study of such metal complexes ranging from their preparation, the solid-state properties, solution behavior as well as their applications as bioactive materials and luminescent compounds, to name a few. In this overview, the dithiocarbamate complexes of platinum-group elements form the focus of the discussion. The structural aspects of these complexes will be discussed based upon the intriguing findings obtained from their solid- (crystallographic) and solution-state (NMR) studies. At the end of this review, the applications of platinum-group metal complexes will be discussed. Full article

Tethering known drugs to a metalorganic moiety is an efficient approach for modulating the anticancer, antibacterial, and antiparasitic activity of organometallic complexes. This study focused on the synthesis and evaluation of new dinuclear ruthenium(II)–arene compounds linked to several antimicrobial compounds such as dapsone, sulfamethoxazole, sulfadiazine, sulfadoxine, triclosan, metronidazole, ciprofloxacin, as well as menadione (a 1,4-naphtoquinone derivative). In a primary screen, 30 compounds (17 hybrid molecules, diruthenium intermediates, and antimicrobials) were assessed for in vitro activity against transgenic T. gondii tachyzoites constitutively expressing β-galactosidase (T. gondii β-gal) at 0.1 and 1 µM. In parallel, the cytotoxicity in noninfected host cells (human foreskin fibroblasts, HFF) was determined by an alamarBlue assay. When assessed at 1 µM, five compounds strongly impaired parasite proliferation by >90%, and HFF viability was retained at 50% or more, and they were further subjected to T. gondii β-gal dose-response studies. Two compounds, notably 11 and 13, amide and ester conjugates with sulfadoxine and metronidazole, exhibited low IC₅₀ (half-maximal inhibitory concentration) values 0.063 and 0.152 µM, and low or intermediate impairment of HFF viability at 2.5 µM (83 and 64%). The nature of the anchored drug as well as that of the linking unit impacted the biological activity. Full article

Chemical routes for the synthesis of nanostructures are fundamental in nanoscience. Among the different strategies for the production of nanostructures, this article reviews the fundamentals of the bottom-up approaches, focusing on wet chemistry synthesis. It offers a general view on the synthesis of different inorganic and hybrid organic–inorganic nanostructures such as ceramics, metal, and semiconductor nanoparticles, mesoporous structures, and metal–organic frameworks. This review article is especially written for a wide audience demanding a text focused on the basic concepts and ideas of the synthesis of inorganic and hybrid nanostructures. It is styled for both early researchers who are starting to work on this topic and also non-specialist readers with a basic background on chemistry. Updated references and texts that provide a deeper discussion and describing the different synthesis strategies in detail are given, as well as a section on the current perspectives and possible future evolution. Full article