This special issue of Inorganics features a Forum for novel materials and approaches for electrochemical energy storage and conversion. Diminishing non-renewable fossil fuels and the resulting unattainability of environment have made us search new sustainable energy resources and develop technology for efficient utilization of such resources. Green energy sources, such as solar, hydroelectric, thermal and wind energy are partially replacing fossil fuels as means to generate power. Inorganic (solid state) materials are key in the development of advanced devices for the efficient storage and conversion of energy. The grand challenge facing the inorganic chemist is to discover, design rationally and utilize advanced technological materials made from earth-abound elements for these energy storage and conversion processes. Recent spectacular progress in inorganic materials synthesis, characterization, and computational screening has greatly advanced this field, which drove us to edit this issue to provide a window to view the development of this field for the community. This special issue comprises research articles, which highlights some of the most recent advances in new materials for energy storage and conversion. [...] Full article

This manuscript summarizes the failure mechanisms found in inorganic fullerene-type tungsten disulfide (IF-WS₂) nanoparticles treated with diverse pressure loading methods. The approaches utilized to induce failure included: the use of an ultrasonic horn, the buildup of high pressures inside a shock tube which created a shock wave that propagated and impinged in the sample, and impact with military rounds. After treatment, samples were characterized using electron microscopy, powder X-ray diffraction, energy dispersive X-ray spectroscopy, and surface area analysis. The microstructural changes observed in the IF-WS₂ particulates as a consequence of the treatments could be categorized in two distinct fracture modes. The most commonly observed was the formation of a crack at the particles surface followed by a phase transformation from the 3D cage-like structures into the 2D layered polymorphs, with subsequent agglomeration of the plate-like sheets to produce larger particle sizes. The secondary mechanism identified was the incipient delamination of IF-WS₂. We encountered evidence that the IF-WS₂ structure collapse initiated in all cases at the edges and vertices of the polyhedral particles, which acted as stress concentrators, independent of the load application mode or its duration. Full article

Innovative synthetic approaches should be simple and environmentally friendly. Here, we present the surface modification of inorganic submicrometer particles with long alkyl chain organophosphorus coupling agents without the need of a solvent, which makes the technique environmentally friendly. In addition, it is of great benefit to realize two goals in one step: size reduction and, simultaneously, surface functionalization. A top-down approach for the synthesis of metal oxide particles with in situ surface functionalization is used to modify titania with long alkyl chain organophosphorus coupling agents. A high energy planetary ball mill was used to perform reactive milling using titania as inorganic pigment and long alkyl chain organophosphorus coupling agents like dodecyl and octadecyl phosphonic acid. The final products were characterized by IR, NMR and X-ray fluorescence spectroscopy, thermal and elemental analysis as well as by X-ray powder diffraction and scanning electron microscopy. The process entailed a tribochemical phase transformation from the starting material anatase to a high-pressure modification of titania and the thermodynamically more stable rutile depending on the process parameters. Furthermore, the particles show sizes between 100 nm and 300 nm and a degree of surface coverage up to 0.8 mmol phosphonate per gram. Full article

The reaction of the ligand Et₄todit (4,5,6,7-Tetrathiocino-[1,2-b:3,4-b']-diimidazolyl-1,3,8,10-tetraethyl-2,9-dithione) with gold complexes leads to the dinuclear gold(I) complexes [{Au(C₆F₅)}₂(Et₄todit)] and [Au(Et₄todit)]₂(OTf)₂, which do not contain any gold-gold interactions, or to the gold(III) derivative [{Au(C₆F₅)₃}₂(Et₄todit)]. The crystal structures have been established by X-ray diffraction studies and show that the gold centers coordinate to the sulfur atoms of the imidazoline-2-thione groups. Full article

Design of experiments (DOE) methodology was used to identify and optimize factors that influence the degree of functionalization (polycarboxylation) of WS₂ INTs via a modified acidic Vilsmeier–Haack reagent. The six factors investigated were reaction time, temperature and the concentrations of 2-bromoacetic acid, WS₂ INTs, silver acetate and DMF. The significance of each factor and the associated interactive effects were evaluated using a two-level factorial statistical design in conjunction with statistical software (MiniTab^® 16) based on quadratic programming. Although statistical analysis indicated that no factors were statistically significant, time, temperature and concentration of silver acetate were found to be the most important contributors to obtaining maximum functionalization/carboxylation. By examining contour plots and interaction plots, it was determined that optimal functionalization is obtained in a temperature range of 115–120 °C with a reaction time of 54 h using a mixture of 6 mL DMF, 200 mg INTs, 800 mg 2-bromoacetic acid and 60 mg silver acetate. Full article

The divalent complex [{Pt(bzq)(μ-L)}₂] (1) [Hbzq = benzo[h]quinolone, HL = CF₃C₄H₂N₂SH: 4-(trifluoromethyl)pyrimidine-2-thiol] was obtained from equimolar amounts of [Pt(bzq)(NCMe)₂]ClO₄ and 4-(trifluoromethyl)pyrimidine-2-thiol with an excess of NEt₃. The presence of a low intensity absorption band at 486 nm (CH₂Cl₂), assignable to a metal-metal-to-ligand charge transfer transition (¹MMLCT) [dσ*(Pt)₂→π*(bzq)], is indicative of the existence of two platinum centers located in close proximity because the rigidity of the half-lantern structure allows the preservation of these interactions in solution. Compound 1 undergoes two-electron oxidation upon treatment with halogens X₂ (X₂: Cl₂, Br₂ or I₂) to give the corresponding dihalodiplatinum (III) complexes [{Pt(bzq)(μ-L)X}₂] (L = CF₃C₄H₂N₂S-κN,S; X: Cl 2, Br 3, I 4). Complexes 2–4 were also obtained by reaction of 1 with HX (molar ratio 1:2, 10% excess of HX) in THF with yields of about 80% and compound 2 was also obtained by reaction of [{Pt(bzq)(μ-Cl)}₂] with HL (4-(trifluoromethyl)pyrimidine-2-thiol) in molar ratio 1:2 in THF, although in small yield. The X-ray structures of 2 and 3 confirmed the half-lantern structure and the anti configuration of the molecules. Both of them show Pt–Pt distances (2.61188(15) Å 2, 2.61767(16) Å 3) in the low range of those observed in Pt₂(III,III)X₂ half-lantern complexes. Full article

New bromidotetracarboxylatodiruthenium(II,III) compounds of the type [Ru₂Br(μ-O₂CC₆H₄–R)₄]_n [R = o-Me (1), m-Me (2), p-Me (3)] have been prepared using microwave-assisted methods. Syntheses by means of solvothermal and conventional activations have also been carried out to compare different preparation methods. The crystal structure determination of complexes 1–3 is also described. All compounds display a typical carboxylate-bridged paddlewheel-type structure with the metal atoms connected by four bridging carboxylate ligands. The axial bromide ligands connect the dimetallic units giving one-dimensional zigzag chains. The magnetic properties of all compounds have also been analyzed. Weak antiferromagnetic intermolecular interactions mediated by the bromide ligands and an appreciable zero field splitting are calculated in the fits of the magnetic data of these complexes. Full article

The spray-pyrolysis of borazine at 1400 °C under nitrogen generates boron nitride (BN) nanoparticles (NPs). The as-prepared samples form elementary blocks containing slightly agglomerated NPs with sizes ranging from 55 to 120 nm, a Brunauer-Emmett-Teller (BET)-specific surface area of 34.6 m² g⁻¹ and a helium density of 1.95 g cm⁻³. They are relatively stable in air below 850 °C in which only oxidation of the NP surface proceeds, whereas under nitrogen, their lower size affects their high temperature thermal behavior in the temperature range of 1450–2000 °C. Nitrogen heat-treated nanostructures have been carefully analyzed using X-ray diffraction, electron microscopy and energy-dispersive X-ray spectroscopy. The high temperature treatment (2000 °C) gives hollow-cored BN-NPs that are strongly facetted, and after ball-milling, hollow core-mesoporous shell NPs displaying a BET-specific surface area of 200.5 m²·g⁻¹ and a total pore volume of 0.287 cm³·g⁻¹ were produced. They have been used as host material to confine, then destabilize ammonia borane (AB), thus improving its dehydrogenation properties. The as-formed AB@BN nanocomposites liberated H₂ at 40 °C, and H₂ is pure in the temperature range 40–80 °C, leading to a safe and practical hydrogen storage composite material. Full article

Since the first gold liquid crystal was described in 1986, much effort has been done to prepare new compounds bearing this property. The review deals with the last results obtained in this new century. Gold(I) has a strong affinity to give linear co-ordination and metal-metal interactions, which produce a rich supramolecular chemistry, and can promote the behavior as liquid crystal. Therefore, most liquid crystals are based on rod-like gold(I) compounds, while gold(III) liquid crystals are scarce. Calamitic and discotic mesogens have been reported, as well as chiral liquid crystals. Weak interactions such as H-bonds have also been used to obtain gold mesogens. Some of them exhibit additional properties, such as color, luminescence, and chirality. Luminescence has been reported, not only in the solid state or in solution, but also in the mesophase. This is relevant for applications in LEDs (Light Emitting Diodes), information storage, and sensors. Full article

In this review, microwave plasma gas-phase synthesis of inorganic materials and material groups is discussed from the application-oriented perspective of a materials scientist: why and how microwave plasmas are applied for the synthesis of materials? First, key players in this research field will be identified, and a brief overview on publication history on this topic is given. The fundamental basics, necessary to understand the processes ongoing in particle synthesis—one of the main applications of microwave plasma processes—and the influence of the relevant experimental parameters on the resulting particles and their properties will be addressed. The benefit of using microwave plasma instead of conventional gas phase processes with respect to chemical reactivity and crystallite nucleation will be reviewed. The criteria, how to choose an appropriate precursor to synthesize a specific material with an intended application is discussed. A tabular overview on all type of materials synthesized in microwave plasmas and other plasma methods will be given, including relevant citations. Finally, property examples of three groups of nanomaterials synthesized with microwave plasma methods, bare Fe₂O₃ nanoparticles, different core/shell ceramic/organic shell nanoparticles, and Sn-based nanocomposites, will be described exemplarily, comprising perspectives of applications. Full article