Inorganics, Volume 10, Issue 8 (August 2022) – 19 articles

Pressure-induced amorphization (PIA) has drawn great attention since it was first observed in ice. This process depends closely on the crystal structure, the size, the morphology and the correlated pressurization environments, among which the morphology-tuned PIA remains an open question on the widely concerned mesoscale. In this work, we report the synthesis and high-pressure research of VO₂(B) nanobelts. XRD and TEM were performed to investigate the amorphization process. The amorphization pressure in VO₂(B) nanobelts(~30 GPa) is much higher than that in previous reported 2D VO₂(B) nanosheets(~21 GPa), the mechanism is the disruption of connectivity at particular relatively weaker bonds in the (010) plane. These results suggest a morphology-tuned pressure-induced amorphization, which could promote the fundamental understanding of PIA. Full article

Uranyl ions, {UO₂}ⁿ⁺ (n = 1, 2), display trans, strongly covalent, and chemically robust U-O multiple bonds, where 6d, 5f, and 6p orbitals play important roles. The synthesis of isoelectronic analogues of uranyl has been of interest for quite some time, mainly with the purpose of unveiling covalence and 5f-orbital participation in bonding. Significant advances have occurred in the last two decades, initially marked by the synthesis of uranium(VI) bis(imido) complexes, the first analogues with a {RNUNR}²⁺ core, later followed by the synthesis of unique trans-{EUO}²⁺ (E = S, Se) complexes, and recently highlighted by the synthesis of the first complexes featuring a linear {NUN} moiety. This review covers the synthesis, structure, bonding, and reactivity of uranium complexes containing a linear {EUE}ⁿ⁺ core (n = 0, 1, 2), isoelectronic to uranyl ions, {OUO}ⁿ⁺ (n = 1, 2), incorporating σ- and π-donating ligands that can engage in uranium–ligand multiple bonding, where oxygen may be replaced by heavier chalcogenido, imido, nitride, and carbene ligands, or by a transition metal. It focuses on synthetic methods of well-defined molecular uranium species in the condensed phase but also references gas-phase and low-temperature-matrix experiments, as well as computational studies that may lead to valuable insights. Full article

The structure, equation of state and transport properties of warm dense nitric oxide (NO) were investigated in wide density and temperature ranges by ab initio molecular dynamics simulations. Both the Perdew–Burke–Ernzerhof (PBE) and the strongly constrained and appropriately normed functional with revised Vydrov–van Voorhis nonlocal correlation (SCAN−rVV10) functionals were used in the simulations, and the pressures predicted by the SCAN−rVV10 functional were found to be systematically lower than those predicted using PBE and experimental data along the shock Hugoniot curve. Along the Hugoniot curve, as density increased, we found that the system transformed towards a mixture of atomic nitrogen and oxygen liquids with molecular NO that remained present up to the highest densities explored. The electrical conductivity along Hugoniot indicated that nonmetal to metal transition had taken place. We also calculated the electrical and thermal conductivities of nitric oxide in the warm dense matter regime, and used them to compute the Lorentz number. In addition, we also report the electronic density of states. Full article

C₃N₄ is an innovative material that has had huge success as a photocatalyst in recent years. More recently, it has been coupled to robust metal oxides to obtain more stable materials. This work is focused on the different synthesis techniques used to prepare bare C₃N₄ and combined C₃N₄/ZnO mixed systems. Different precursors, such as pure melamine and cyanuric acid-based supramolecular complexes, were employed for the preparation of the C₃N₄ material. Moreover, different solvents were also used, demonstrating that the use of water leads to the formation of a more stable heterojunction. Structural (XRD), morphological (FESEM) and optical (UV-vis) measurements underlined the role of the precursors used in the preparation of the materials. A clear trend can be extrapolated from this experimental approach involving different intimate contacts between the two C₃N₄ and ZnO phases, strictly connected to the particular preparation method adopted. The use of the supramolecular complexes for the preparation of C₃N₄ leads to a tighter association between the two phases at the heterojunction, resulting in much higher visible light harvesting (connected to lower band gap values). Full article

The rational design of heterometallic compounds bearing s-block metal ions have been a difficult task for chemists owing to their lack of preferential geometries. However, some strategies, such as the design of coordinating pockets with different sizes and/or donor atoms, have offered great results. In this work, this strategy has been tested using Ca(II) as an s-block metal ion and a compound previously obtained by our group with the formula [Zn₃(μ-ACA)₆(4-phpy)₂], which contains tetrahedral N,O- and octahedral O-coordinating pockets as a model structure. From this work, the corresponding heterometallic compound with the formula [Zn₂Ca(μ-ACA)₆(4-phpy)₂]·EtOH (1) has been successfully synthesized, and fully characterized, and its crystal structure has been elucidated. Furthermore, we have compiled all the crystal structures containing [Zn₂M] pinwheel secondary building units (SBUs), where M stands for an s-block metal ion, and the observed tendencies, as well as the promising applications as template SBUs for the preparation of 1D–3D coordination polymers, have been discussed. Finally, solid-state UV-Vis and photoluminescence have been recorded and compared with the homometallic [Zn₃(μ-ACA)₆(4-phpy)₂] compound. Full article

A practical application composite based on mixed chelate complexes [M(S-Ala)₂(H₂O)_n]–[M(S-Phe)₂(H₂O)_n] (M = Cu(II), Zn(II); n = 0–1) as chiral selectors in enantioselective voltammetric sensors was suggested. The structures of the resulting complexes were studied by XRD, ESI-MS, and IR- and NMR-spectroscopy methods. It was determined that enantioselectivity depends on the metal nature and on the structure of the mixed complex. The mixed complexes, which were suggested to be chiral selectors, were stable under the experimental conditions and provided greater enantioselectivity in the determination of chiral analytes, such as naproxen and propranolol, in comparison with the amino acids they comprise. The best results shown by the mixed copper complex [Cu(S-Ala)₂]–[Cu(S-Phe)₂] were: i_pS/i_pR = 1.27 and ΔE_p = 30 mV for Nap; and i_pS/i_pR = 1.37 and ΔE_p = 20 mV for Prp. The electrochemical and analytical characteristics of the sensors and conditions of voltammogram recordings were studied by differential pulse voltammetry. Linear relationships between the anodic current and the concentrations of Nap and Prp enantiomers were achieved in the range of 2.5 × 10⁻⁵ to 1.0 × 10⁻³ mol L⁻¹ for GCE/PEC-[Cu(S-Ala)₂]–[Cu(S-Phe)₂] and 5.0 × 10⁻⁵ to 1.0 × 10⁻³ for GCE/PEC–[Zn(S-Ala)₂(H₂O)]–[Zn(S-Phe)₂(H₂O)], with detection limits (3 s/m) of 0.30–1.24 μM. The suggested sensor was used to analyze Nap and Prp enantiomers in urine and plasma samples. Full article

Energy levels of pentacoordinate d⁵ to d⁹ complexes were evaluated according to the generalized crystal field theory at three levels of sophistication for two limiting cases of pentacoordination: trigonal bipyramid and tetragonal pyramid. The electronic crystal field terms involve the interelectron repulsion and the crystal field potential; crystal field multiplets account for the spin–orbit interaction; and magnetic energy levels involve the orbital– and spin–Zeeman interactions with the magnetic field. The crystal field terms are labelled according to the irreducible representations of point groups D_3h and C_4v using Mulliken notation. The crystal field multiplets are labelled with the Bethe notations for the respective double groups D’₃ and C’₄. The magnetic functions, such as the temperature dependence of the effective magnetic moment and the field dependence of the magnetization, are evaluated by employing the apparatus of statistical thermodynamics as derivatives of the field-dependent partition function. When appropriate, the formalism of the spin Hamiltonian is applied, giving rise to a set of magnetic parameters, such as the zero-field splitting D and E, magnetogyric ratio tensor, and temperature-independent paramagnetism. The data calculated using GCFT were compared with the ab initio calculations at the CASSCF+NEVPT2 level and those involving the spin–orbit interaction. Full article

Iridium Oxide (IrO₂) is a metal oxide with a rutile crystalline structure, analogous to the TiO₂ rutile polymorph. Unlike other oxides of transition metals, IrO₂ shows a metallic type conductivity and displays a low surface work function. IrO₂ is also characterized by a high chemical stability. These highly desirable properties make IrO₂ a rightful candidate for specific applications. Furthermore, IrO₂ can be synthesized in the form of a wide variety of nanostructures ranging from nanopowder, nanosheets, nanotubes, nanorods, nanowires, and nanoporous thin films. IrO₂ nanostructuration, which allows its attractive intrinsic properties to be enhanced, can therefore be exploited according to the pursued application. Indeed, IrO₂ nanostructures have shown utility in fields that span from electrocatalysis, electrochromic devices, sensors, fuel cell and supercapacitors. After a brief description of the IrO₂ structure and properties, the present review will describe the main employed synthetic methodologies that are followed to prepare selectively the various types of nanostructures, highlighting in each case the advantages brought by the nanostructuration illustrating their performances and applications. Full article

The quality and the performance of hybrid perovskite (HP)’s films strongly depend on the complete conversion into MAPbI₃ of a spin-coated solution of methylammonium iodide (MAI) and PbI₂. Highly crystalline PbI₂ on a substrate limits such a conversion and, consequently, the HP’s solar cell performances. We investigate for the first time the use of short-chain organic acids as additives in a non-complexing solvent like γ-butyrolactone (GBL), that can retard retard the crystallization of PbI₂. Based on XRD analyses of the spin coated films, the acetic acid is the most effective additive in retarding the PbI₂ crystallization, making Pb²⁺ available for a subsequent reaction with MAI. These results open a new experimental path for fabricating perovskite films by single or sequential step methods involving acid additives. Full article

Nonessential heavy metals are toxic to human health. In this study, mercury, a hazardous metal, was detected by colorimetric analysis using Artemisia vulgaris-mediated silver nanoparticles (AgNP) without any modification in an aqueous solution. The UV–vis spectroscopy showed a characteristic SPR band of Ag⁰ at 418 nm, indicating the formation of AgNPs. The AgNPs were crystalline, with an average size of 7 nm, as calculated from the XRD data. The SEM images revealed the spherical and polycrystalline AgNPs within the agglomerated form. The FTIR spectra elucidated the functional group of the extract attached with the Ag⁰. The broad, strong peak at 3632 cm⁻¹ indicated the involvement of the -OH group of compounds of extract in reducing silver ions. The peak of EDX spectra around 3 keV confirmed the silver in the nanostructure. A colorimetric method was employed for the heavy metal sensing in the aqueous medium without modification of AgNPs suspension. The obtained AgNPs were found to be selective and highly sensitive toward Hg²⁺ ions. The AgNPs suspension turned colorless after adding 380 µL of 1 mM Hg²⁺. The synthesized AgNPs showed the catalytic activity on reduction of 4-nitrophenol in the presence of NaBH₄ within 8 min with a rate constant of 1.21 × 10⁻² s⁻¹. The outcome of these findings suggests that the application of Artemisia vulgaris influenced AgNPs for metal sensing and green catalysis. Full article

The structural stability of layered LiNi_1-x-yCo_xMn_yO₂ cathode materials is critical for guaranteeing their excellent electrochemical cycling performance, particularly at elevated temperatures. However, the notorious H₂–H₃ phase transition along with associated large changes in the c-axis or (003) facet is the fundamental origin of the anisotropic and abrupt change in the unit cell and the degradation of the cycling performance. In this study, we coat micron-sized LiNi_0.6Co_0.2Mn_0.2O₂ (NCM) with tungsten oxide via atomic layer deposition and investigate the atomic-to-microscopic structures in detail via advanced characterization techniques, such as Cs-corrected scanning transmission electron microscopy. The results reveal that coated tungsten oxide is predominately accumulated on the (003) facet of NCM, with the migration of a small amount of W⁶⁺ into this facet, resulting in a reduction of Ni³⁺ to Ni²⁺ and the formation of a rock-salt-like structure on the surface. The electrochemical cycling performance of tungsten-oxide-coated NCM is significantly improved, showing a capacity retention of 86.8% after 300 cycles at 55 °C, compared to only 69.4% for the bare NCM. Through further structural analysis, it is found that the initial tungsten-oxide-coating-induced (003) facet distortion effectively mitigates the expansion of the c-lattice during charge, as well as oxygen release from the lattice, resulting in a lowered strain in the cathode lattices and a crack in the cathode particles after prolonged cycling. Full article

Four new symmetrical Schiff bases derived from 2,2′-diamino-6,6′-dibromo-4,4′-dimethyl-1,1′-biphenyl or 2,2′-diamino-4,4′-dimethyl-1,1′-biphenyl, and 3,5-dichloro- or 5-nitro-salicylaldehyde, were synthesized and reacted with copper-, iron- and zinc-acetate, producing the corresponding complexes. The Schiff bases and their metal complexes were characterized by ¹H-, ¹³C-NMR, IR and UV-Vis spectroscopy and elemental analysis. The structures of one Schiff base and the two zinc complexes were resolved by X-ray structure determination. Density functional theory (DFT) calculations at the B3LYP/6-31G(d) level of the latter compounds were carried out to optimize and examine their molecular geometries. The biomedical applications of the Schiff bases and their complexes were investigated as anticancer or antimicrobial agents. Full article

In a previous publication, a tribute to Michel Armand was provided, which highlighted his outstanding contribution to all aspects of research and development of lithium-metal and lithium-ion batteries. This area is in constant progress and rather than an overview of the work of Armand et al. since the seventies, we mainly restrict this review to his contribution to advances in solid polymer electrolytes (SPEs) and their performance in all-solid-state lithium-metal batteries in recent years. Full article

Two phosphonite ligands bearing the highly sterically demanding 2,6-bis (2,6-dimethylphenyl)phenyl group (Ar^Xyl₂), PAr^Xyl₂(OPh^NO₂)₂ and PAr^Xyl₂(OPh^NO₂,Me)₂, were prepared from the parent dihalophosphines PAr^Xyl₂X₂ (X = Cl, Br) and the corresponding phenols, 4-nitrophenol and 4-nitro-2,6-dimethylphenol, respectively. DFT methods were used to examine their structural features and to determine three steric descriptors, namely the Tolman cone angle, the percentage of buried volume, and the percentage of the coordination sphere protected by the ligand. A comparison with the related terphenyl phosphines is also provided. Reactions of PAr^Xyl₂(OPh^NO₂)₂ and PAr^Xyl₂(OPh^NO₂,Me)₂ with several Pt(II) precursors were investigated, revealing a high tendency of both phosphonites to undergo C-H activation processes and generate five- or six-membered cyclometalated structures. The coordination chemistry of the new ligands was explored with isolation, among others, of three carbonyl complexes, 1-3∙CO, and the triphenylphosphine adduct 3∙PPh₃. X-ray diffraction methods permitted the determination of the solid-state structures of the mononuclear methyl carbonyl complex 1∙CO, the dinuclear chloride-bridged complex 2 and the doubly cyclometalated complex 3∙SMe₂, including the conformations adopted by the ligands upon coordination. All of the new compounds were characterized by multinuclear NMR spectroscopy in solution. Full article

The reaction of [GeF₄L₂], L = dmso (Me₂SO), dmf (Me₂NCHO), py (pyridine), pyNO (pyridine-N-oxide), OPPh₃, OPMe₃, with Me₃SiO₃SCF₃ (TMSOTf) and monodentate ligands, L, in a 1:1:1 molar ratio in anhydrous CH₂Cl₂ formed the monocations [GeF₃L₃][OTf]. These rare trifluoro-germanium (IV) cations were characterised by microanalysis, IR, ¹H, ¹⁹F{¹H} and, where appropriate, ³¹P{¹H} NMR spectroscopy. The ¹⁹F{¹H} NMR data show that in CH₃NO₂ solution the complexes exist as a mixture of mer and fac isomers, with the mer isomer invariably having the higher abundance. The X-ray structure of mer-[GeF₃(OPPh₃)₃][OTf] is also reported. The attempts to remove a second fluoride using a further equivalent of TMSOTf and L were mostly unsuccessful, although a mixture of [GeF₂(OAsPh₃)₄][OTf]₂ and [GeF₃(OAsPh₃)₃][OTf] was obtained using excess TMSOTf and OAsPh₃. The reaction of [GeF₄(MeCN)₂] with TMSOTf in CH₂Cl₂ solution, followed by the addition of 2,2′:6′,2”-terpyridine (terpy) formed mer-[GeF₃(terpy)][OTf], whilst a similar reaction with 1,4,7-trimethyl-1,4,7-triazacyclononane (Me₃-tacn) in MeCN solution produced fac-[GeF₃(Me₃-tacn)][OTf]. Dicationic complexes bearing the GeF₂²⁺ fragment were isolated using the tetra-aza macrocycles, 1,4,7,10-tetramethyl-1,4,7,10-tetra-azacyclododecane (Me₄-cyclen) and 1,4,8,11-tetramethyl-1,4,8,11-tetra-azacyclotetradecane (Me₄-cyclam), which reacted with [GeF₄(MeCN)₂] and two equivalents of TMSOTf to cleanly form the dicationic difluoride salts, cis-[GeF₂(Me₄-cyclen)][OTf]₂ and trans-[GeF₂(Me₄-cyclam)][OTf]₂. The ¹⁹F{¹H} NMR spectroscopy shows that in CH₃NO₂ solution there are four stereoisomers present for trans-[GeF₂(Me₄-cyclam)][OTf]₂, whereas the smaller ring-size of Me₄-cyclen accounts for the formation of only cis-[GeF₂(Me₄-cyclen)][OTf], and is confirmed crystallographically. New spectroscopic data are also reported for [GeF₄(L)₂] (L = dmso, dmf and pyNO). Density functional theory calculations were used to probe the effect on the bonding as fluoride ligands were sequentially removed from the germanium centre in the OPMe₃ complexes. Full article

Thermoelectric material is a new energy material that can realize the direct conversion of thermal energy and electric energy. It has important and wide applications in the fields of the recycling of industrial waste heat and automobile exhaust, efficient refrigeration of the next generation of integrated circuits and full spectrum solar power generation. Skutterudites have attracted much attention because of their excellent electrical trGiovanna Latronicoansport performance in the medium temperature region. In order to obtain skutterudites with excellent properties, it is indispensable to choose an appropriate preparation method. This review summarizes some traditional and advanced preparation methods of skutterudites in recent years. The basic principles of these preparation methods are briefly introduced. Single-phase skutterudites can be successfully obtained by these preparation methods. The study of these preparation methods also provides technical support for the rapid, low-cost and large-scale preparation of high-performance thermoelectric materials. Full article

A mononuclear Co(II) complex of a Schiff base ligand derived from 5-Bromo-vanillin and 4-aminoantipyrine, that has a compressed tetragonal bipyramidal geometry and exhibiting field-induced slow magnetic relaxation, has been synthesized and characterized by single crystal X-ray diffraction, elemental analysis and molecular spectroscopy. In the crystal packing, a hydrogen-bonded dimer structural topology has been observed with two distinct metal centers having slightly different bond parameters. The complex has been further investigated for its magnetic nature on a SQUID magnetometer. The DC magnetic data confirm that the complex behaves as a typical S = 3/2 spin system with a sizable axial zero-field splitting parameter D/hc = 38 cm⁻¹. The AC susceptibility data reveal that the relaxation time for the single-mode relaxation process is τ = 0.16(1) ms at T = 2.0 K and B_DC = 0.12 T. Full article

Two new compounds, namely {(NMe₂H₂)}[Ln(TDA)(HCOO)] 0.5H₂O, Ln = Sm³⁺ (Sm-TDA) and Gd³⁺ (Gd-TDA), where TDA³⁻ is the anion of 1H-1,2,3-triazole-4,5-dicarboxylic acid (H₃TDA), were synthesized by the solvothermal method in a DMF:H₂O mixture. According to single-crystal X-ray diffraction data, the compounds are 3d-MOFs with an anionic lattice and dimethylammonium cations occupying part of the cavities. Based on these compounds, two series of mixed-metal complexes, [NMe₂H₂][Sm_xLn_1-x(TDA)(HCOO)], (x = 0.9 (Sm_0.9Ln_0.1-TDA), x = 0.8 (Sm_0.8-Ln_0.2-TDA)…Sm_0.02Ln_0.98-TDA, Ln = Tb, Gd), were also obtained and characterized by powder XRD. The luminescent properties of the compounds were studied and it was shown that the resulting compounds are two- or three-component emitters with the possibility of fine color tuning by changing the intensities of fluorescence and phosphorescence of the ligand, as well as the luminescence of Sm³⁺ and Tb³⁺ f-ions. Full article