Inorganics — Open Access Journal

Ferromagnetic cluster spin wave theory (FCSWT) provides an exact and concise description of the low-energy excitations from the ferromagnetic ground state in finite magnetic systems, such as bounded magnetic molecules. In particular, this theory is applicable to the description of experimental inelastic neutron scattering (INS) spectra at low temperatures. We provide a detailed conceptual overview of the FCSWT. Additionally, we introduce a pictorial representation of calculated wavefunctions, similar to the usual depiction of vibrational normal modes in molecules. We argue that this representation leads to a better intuitive understanding of the excitations, their symmetry properties, and has links to the energy and wavevector dependence of intensity in the neutron scattering experiments. We apply FCSWT and illustrate the results on a series of examples with available low-temperature INS data, ranging from the Mn₁₀ supertetrahedron, the Mn₇ disk to the Mn₆ single molecule magnet. Full article

o-Quinones are both well-studied and promising redox-active chelating ligands. There are plenty of interesting effects to be found on o-quinone-derived metallocomplexes, such as photo-thermo mechanical effect in solid phase and in solution, luminescence, SMM properties and so on. A combination o-quinone function with an additional coordination site or redox active fragment in the same molecule might sufficiently extend an assembling as well as functional capability of such ligand in complexes. In this paper, the authors focus on o-quinones decorated with additional non-dioxolene chelating coordination site or with electron donor redox active annelated fragments. Full article

Treatment of N,N′-diisopropylcarbodiimide with sodium cyclopentadienide (NaCp) in a molar ratio of 1:1 in THF solution resulted in formation of the unexpected dinuclear sodium half-sandwich complex [NaC₅H₃{C(NHⁱPr)(=NⁱPr)}₂-1,2]₂ (1) as colorless crystals in low yield. The newly formed ligand, which belongs to the group of 6-aminofulvene-2-aldiminate ligands, coordinates to sodium in an η⁵-coordination mode via the cyclopentadienyl ring. Dimerization occurs through additional chelating κN,N′-coordination of the amidine substituents. The NMR data of 1 indicated a slow dimer/monomer equilibrium in solution. A serendipitously isolated hydrolysis product, {µ-(ⁱPrNH)₂C=O}₂[NaC₅H₃{C(NHⁱPr)(=NⁱPr)}₂-1,2]₂ (2), contains the new 6-aminofulvene-2-aldiminate ligand in the N,N′-chelating coordination mode with the cyclopentadiene ring being uncoordinated. In this case, dimerization occurs through the presence of two bridging neutral N,N′-diisopropylurea ligands. Both compounds have been structurally characterized by single-crystal X-ray diffraction. Full article

Lithium fluoride is an important material for ultraviolet optical systems, possessing among the largest optical bandgaps of dielectric materials. We report on the development of an atomic layer deposition (ALD) process for lithium fluoride that is capable of depositing thin films in a self-limiting manner, with an approximate deposition rate of approximately 0.15 Å per ALD cycle at a substrate temperature of 150 °C. Films are characterized by spectroscopic ellipsometry, atomic force microscopy, X-ray photoelectron spectroscopy, and far ultraviolet reflectometry. For substrate temperatures of 150 °C and greater, films showed significant microroughness with a correlated reduction in effective refractive index. This behavior was mitigated by a reduction in substrate temperature to as low as 100 °C. Films deposited on silicon substrates were subjected to long-term storage testing to evaluate the environmental sensitivity of the deposited layers. Protected aluminum mirrors were also fabricated with ALD LiF overcoats, yielding a reflectance of 84% at a wavelength of 125 nm. The performance relative to state-of-the-art LiF thin films deposited by physical vapor deposition methods is discussed, along with the prospects for future optimization. Full article

The reaction between the 2,2′-benzene-1,4-diylbis(6-hydroxy-4,7-di-tert-butyl-1,3-benzodithiol-2-ylium-5-olate biradical triad (L) and the metallo-precursor [Dy(hfac)₃]·2H₂O leads to the formation of a one-dimensional coordination polymer with the formula {[Dy(hfac)₃(L)]·2C₆H₁₄}_n (1). The X-ray structure reveals that the polymeric structure is formed by the bridging of the Dy(hfac)₃ units with the multi-redox triad L. Single-crystal X-ray diffraction and UltraViolet-visible absorption spectroscopy confirm that the triad L in 1 is bound as a direduced, diprotonated form of o-quinone-extended tetrathiafulvalene-o-quinone (Q-exTTF-Q). Alternate Current (AC) measurements highlight a field-induced single-molecule magnet (SMM) behavior with an energy barrier of 20 K, and thus 1 can be described as a one-dimensional assembly of mononuclear SMMs bridged by the L triad. Full article

A redox-active M₂L₂ metalla-macrocycle is depicted, of which construction has been achieved through coordination driven self-assembly from an electron-rich 9-(1,3-dithiol-2-ylidene)fluorene bis-pyridyl ligand and a cis-blocked square planar palladium complex (Pd(dppf)OTf₂, dppf = 1,1′-Bis(diphenylphosphino)ferrocene). The resulting metalla-macrocycle has been fully characterized in solution, as well as in the solid state (X-ray crystal structure). Its electronic properties show that both constitutive ligands can be oxidized independently through a one-electron process. Full article

A series of metal (Hg, Pt, Ru) bis(alkynyl-tetrathiafulvalene) complexes have been investigated to study the electronic interplay between the metal and the tetrathiafulvalene (TTF), as well as between the two peripheral TTF electrophores along the organometallic bridge. Cyclic voltammetry experiments, together with spectro-electrochemical investigations, have shown the electronic effect of the metal center through the linker on redox properties of the TTF, as well as the influence of the length of the conjugated organic linker. These data show that the degree of coupling can be modulated from no coupling with mercury to appreciable electronic coupling between different electrophores with ruthenium. Full article

In this review we cover some aspects of metal–salophen and metal–salen complex chemistry related to their supramolecular attitude. We examined under the lens of the non-covalent interactions their potential to behave as building blocks for auto-assembled architectures, supramolecular receptors and catalysts, although this last point has been only briefly mentioned. Full article

Sillén–Aurivillius perovskite Bi₄NbO₈X (X = Cl, Br) is a promising photocatalyst for water splitting under visible light, as well as a potential ferroelectric material. In this work, we investigate the crystal growth conditions by mainly varying soak temperature, soak time and cooling rate. Under the optimal conditions, we successfully obtained yellow platelet single crystals with an in-plane distance of several hundred microns. As opposed to conventional crystal growth, a moderate cooling is essential to suppress an evaporation of the Bi–O–Cl species from a melt zone. The single crystals of Bi₄NbO₈Br were also grown using a similar condition. We suggest that the knowledge obtained in this study can be generally applied to other Sillén–Aurivillius phases and related oxyhalides. Full article

A systematic investigation of four heteroleptic bis(diimine) copper(I) dyes in n-type Dye-Sensitized Solar Cells (DSSCs) is presented. The dyes are assembled using a stepwise, on-surface assembly. The dyes contain a phosphonic acid-functionalized 2,2′-bipyridine (bpy) anchoring domain (5) and ancillary bpy ligands that bear peripheral phenyl (1), 4-methoxyphenyl (2), 3,5-dimethoxyphenyl (3), or 3,4,5-trimethoxyphenyl (4) substituents. In masked DSSCs, the best overall photoconversion efficiency was obtained with the dye [Cu(5)(4)]⁺ (1.96% versus 5.79% for N719). Values of J_SC for both [Cu(5)(2)]⁺ (in which the 4-MeO group is electron releasing) and [Cu(5)(4)]⁺ (which combines electron-releasing and electron-withdrawing effects of the 4- and 3,5-substituents) and are enhanced with respect to [Cu(5)(1)]⁺. DSSCs with [Cu(5)(3)]⁺ show the lowest J_SC. Solid-state absorption spectra and external quantum efficiency spectra reveal that [Cu(5)(4)]⁺ benefits from an extended spectral range at higher energies. Values of V_OC are in the order [Cu(5)(4)]⁺ > [Cu(5)(1)]⁺ > [Cu(5)(2)]⁺ > [Cu(5)(3)]⁺. Density functional theory calculations suggest that methoxyphenyl character in MOs within the HOMO manifold in [Cu(5)(2)]⁺ and [Cu(5)(4)]⁺ may contribute to the enhanced performances of these dyes with respect to [Cu(5)(1)]⁺. Full article

The development of a sustainable economy based on the use of renewable resources and the reduction of greenhouse gases emissions is an important mandate in modern societies to minimize the global warming. The CO₂-reforming of methane through a conversion of CO₂ and CH₄ to syngas is a suitable process for this purpose and there is growing interest in the development of new catalysts for this process’ application at an industrial scale. This study is the first to investigate methane dry reforming activity of nickel supported on CeO₂ and CeO₂–ZrO₂ solid solutions doped with neodymium. The supports were synthesized using a surfactant-assisted co-precipitation method and characterized through several analytical techniques to understand the role of synthesis parameters in the distribution of the dopant as well as in the properties of the supports. Co-doping with Zr and Nd resulted in an enhancement of dry reforming activity of ceria due to a higher dispersion of Ni and changes in the strength of basic sites. It was also shown that the addition of Nd helped to mitigate coking issues by increasing the mobility of surface oxygen in ceria and ceria–zirconia oxides and, accordingly, the rate of oxidation of carbonaceous deposits. Full article

The preparation of NaLnF₄ complexes, LnF₃ (Ln = La, Ce, Y) rare earth binary fluorides, CaF₂ and SrF₂ alkali earth fluorides, as well as mixtures of these compounds from their nitrates dissolved in molten NaNO₃ has been studied in order to select the ideal solvent for fluoride synthesis by spontaneous crystallization from flux. Sodium fluoride (NaF) was used as a fluorinating agent. The results of our experiments have confirmed that NaNO₃ melt is one of the most promising media for precipitating said inorganic fluoride materials within a broad temperature range (300–500 °С). Also, in contrast with precipitation/co-precipitation from aqueous solutions, our syntheses have resulted in obtaining equilibrium phases only. Full article

Molecular orientation of dyes must be one of the important factors for designing dye-sensitized solar cells (DSSC). As model systems, we have prepared new hybrid materials composed of azobenzene (AZ) and chiral Schiff base Cu(II) complexes (pn(S)Cu and pn(R)Cu) in polymethyl methacrylate (PMMA) cast films. In addition to experimental results, in order to understand their behavior due to anisotropic alignment of them by linearly polarized UV light irradiation, the so-called Weigert effect, we treated theoretically and discussed based on computational chemistry and mathematical treatments (MD simulation and Bayesian statistics). Full article

Three isostructural cyano-bridged 3d–4f linear heterotrinuclear compounds, (H_2.5O)₄{Ln[TM(CN)₅(CNH_0.5)]₂(HMPA)₄} (Ln = Y^III, TM = [Fe^III]_LS (1); Ln = Dy^III, TM = [Fe^III]_LS (2); Ln = Dy^III, TM = Co^III (3)), have been synthesized and characterized by single-crystal X-ray diffraction. Due to the steric effect of the HMPA ligands, the central lanthanide ions in these compounds possess a low coordination number, six-coordinate, exhibiting a coordination geometry of an axially elongated octahedron with a perfect D_4h symmetry. Four HMPA ligands situate in the equatorial plane around the central lanthanide ions, and two [TM(CN)₅(CNH_0.5)]^2.5− entities occupy the apical positions to form a cyano-bridged 3d–4f linear heterotrinuclear structure. The static magnetic analysis of the three compounds indicated a paramagnetic behavior of compounds 1 and 3, and possible small magnetic interactions between the intramolecular Dy^III and [Fe^III]_LS ions in compound 2. Under zero dc field, the ac magnetic measurements on 2 and 3 revealed the in-phase component (χ′) of the ac susceptibility without frequency dependence and silent out-of-phase component (χ″), which was attributed to the QTM effect induced by the coordination geometry of an axially elongated octahedron for the Dy^III ion. Even under a 1 kOe applied dc field, the χ″ components of 2 were revealed frequency dependence without peaks above 2 K. And under a 2 kOe and 3 kOe dc field, the χ″ components of 3 exhibited weak frequency dependence below 4 K with the absence of well-shaped peaks, which confirmed the poor single-ion magnetic relaxation behavior of the six-coordinate Dy^III ion excluding any influence from the neighboring [Fe^III]_LS ions as that in the analogue 2. Full article

We report the synthesis, structure, and magnetic properties of a new dinuclear dysprosium(III) complex based on a 3-methoxycinnamate ligand. The centrosymmetric complex exhibits a field-induced SMM behavior. In contrast to the previously reported lanthanide-based systems with cinnamate derivatives that relax through a combination of Raman and direct processes, an Orbach process is also involved in highlighting the role of the structural organization over the spin-lattice relaxations. Full article

Atomic layer deposition (ALD) offers exciting possibilities for controlling the structure and composition of surfaces on the atomic scale in heterogeneous catalysts and solid oxide fuel cell (SOFC) electrodes. However, while ALD procedures and equipment are well developed for applications involving flat surfaces, the conditions required for ALD in porous materials with a large surface area need to be very different. The materials (e.g., rare earths and other functional oxides) that are of interest for catalytic applications will also be different. For flat surfaces, rapid cycling, enabled by high carrier-gas flow rates, is necessary in order to rapidly grow thicker films. By contrast, ALD films in porous materials rarely need to be more than 1 nm thick. The elimination of diffusion gradients, efficient use of precursors, and ligand removal with less reactive precursors are the major factors that need to be controlled. In this review, criteria will be outlined for the successful use of ALD in porous materials. Examples of opportunities for using ALD to modify heterogeneous catalysts and SOFC electrodes will be given. Full article

The preparation of non-symmetric Schiff base ligands possessing one oxime function that is associated to a second function such as pyrrole or phenol function is first described. These ligands, which possess inner N4 or N3O coordination sites, allow formation of cationic or neutral non-symmetric Cu^II or Ni^II metallo-ligand complexes under their mono- or di-deprotonated forms. In presence of Lanthanide ions the neutral complexes do not coordinate to the Ln^III ions, the oxygen atom of the oxime function being only hydrogen-bonded to a water molecule that is linked to the Ln^III ion. This surprising behavior allows for the isolation of Ln^III ions by non-interacting metal complexes. Reaction of cationic Ni^II complexes possessing a protonated oxime function with Ln^III ions leads to the formation of original and dianionic (Gd(NO₃)₅)²⁻ entities that are well separated from each other. This work highlights the preparation of well isolated mononuclear Ln^III entities into a matrix of diamagnetic metal complexes. These new complexes complete our previous work dealing with the complexing ability of the oxime function toward Lanthanide ions. It could open the way to the synthesis of new entities with interesting properties, such as single-ion magnets for example. Full article

Charged and neutral silicon clusters comprising Si atoms that are exclusively connected to atoms of the same type serve as models for bulk silicon surfaces. The experimentally known nido-[Si₉]⁴⁻ Zintl cluster is investigated as a building block and allows for a theoretical prediction of novel silicon-rich oligomers and polymers by interconnection of such building units to larger aggregates. The stability and electronic properties of the polymers $\{{}_{\infty }{}^1([{\mathrm{Si}}_9]–{\left({\mathrm{SiCl}}_2\right)}_2){}_n\}$ and $\{{}_{\infty }{}^1([{\mathrm{Si}}_9]–{\left({\mathrm{SiH}}_2\right)}_2){}_n\}$, as well as of related oligomers are presented. Full article

The reactions of the fused-ring bulky Eind-substituted 1,2-dibromodisilene, (Eind)BrSi=SiBr(Eind) (1a) (Eind = 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl (a)), with N-heterocyclic carbenes (NHCs) (Im-Me₄ = 1,3,4,5-tetramethylimidazol-2-ylidene and Im-ⁱPr₂Me₂ = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) are reported. While the reaction of 1a with the sterically more demanding Im-ⁱPr₂Me₂ led to the formation of the mono-NHC adduct of arylbromosilylene, (Im-ⁱPr₂Me₂)→SiBr(Eind) (2a′), a similar reaction using the less bulky Im-Me₄ affords the bis-NHC adduct of formal arylsilyliumylidene cation, [(Im-Me₄)₂→Si(Eind)]⁺[Br⁻] (3a). The NHC adducts 2a′ and 3a can also be prepared by the dehydrobromination of Eind-substituted dibromohydrosilane, (Eind)SiHBr₂ (4a), with NHCs. The NHC-coordinated silicon compounds have been characterized by spectroscopic methods. The molecular structures of bis-NHC adduct, [(Im-ⁱPr₂Me₂)₂→Si(Eind)]⁺[Br⁻] (3a′), and 4a have been determined by X-ray crystallography. Full article