Transition metal dichalcogenides (TMDs) of molybdenum and tungsten are layered van der Waals materials that exhibit a rich array of polytypes. The different possible arrangements of the constituents of the “two-dimensional” MX2 sheets (where M = group 4–10 elements, X = chalcogen) give rise to a host of interesting and tunable phenomena. Molybdenite, or molybdenum disulfide (MoS2) in its most abundant and thermodynamically stable form, 2H-MoS2, is perhaps the most widely used TMD, though the potential applications of its metastable polytypes have been recognized only recently. From among the polytypes, the 3R-MoS2 (rhombohedral) phase has attracted the most interest because of its thermodynamic stability, ABC stacking (as opposed to the AA′ of the more common 2H-MoS2), and lack of inversion symmetry. These properties make it an excellent candidate for photonics, optoelectronics, and catalysis. Because the literature on this material is rapidly expanding, this review seeks to summarize the history, known and predicted characteristics, syntheses, and applications, as well as common misconceptions of, and surrounding, 3R-MoS2. Although the review is chemically focused, it includes suggested reading to cover a broader scope.

To be able to correlate the catalytic properties of nanoparticles with their structure, detailed knowledge about their make-up on the atomic level is required. Herein, we demonstrate how atom-probe tomography (APT) can be used to quantitatively determine the three-dimensional distribution of atoms within a Au@Ag nanoparticle with near-atomic resolution. We reveal that the elements are not evenly distributed across the surface and that this distribution is related to the surface morphology and residues from the particle synthesis.

The need for greener compounds able to replace conventional ones with similar reactivity is crucial for the development of sustainable chemistry. Isopropenyl esters (iPEs) represent one eco-friendly alternative to acyl halides and anhydrides. This review provides a comprehensive overview of the preparation methodologies and reported synthetic applications of iPEs and, in particular, of isopropenyl acetate (iPAc). Intriguingly, the presence of a C=C double bond adjacent to the ester functionality makes iPEs appealing in different chemoselective organic synthesis transformations. For instance, the acyl moiety is suitable for transesterification reactions in presence of different heteroatom-based nucleo-philes (CÀ , OÀ , NÀ , SÀ , SeÀ ); these reactions are irreversible thanks to the formation of acetone, obtained upon keto-enol tautomerization of the prop-1-en-2-ol (isopropenyl) leaving group. Similarly, the unsaturation contained in the isopropenyl synthon could be selectively exploited in organic synthesis for electrophilic and/or radical additions as well as in metal-catalyzed cross-coupling reactions. To conclude, iPEs recently found major interest in the direct modification of biomass (i.e. lignin or cellulose) and in the implementation of tandem reactions of esterification-acetalization by exploiting the co-formation of acetone during the reaction.

Durch Immobilisierung des Cobaltkomplexes 1 in den mit Glycinresten funktionalisierten Kanälen des mesoporösen Silicats MCM 41 entsteht ein effizienter Heterogenkatalysator für die selektive Oxidation von Cyclohexan zu Cyclohexanon mit tert‐Butylhydroperoxid. Die atomare Struktur der aktiven Zentren wahrend der Katalyse konnte durch In‐situ‐Röntgenabsorptionsspektroskopie bestimmt werden. Die Befunde sind wichtig für das Design neuer effizienter Oxidationskatalysatoren.

Bioadsorption is a promising technology to sequester heavy metal ions from water, and brown seaweed has been identified as one of the most appropriate adsorbents as it is abundant, low cost, and efficient at removing various metal ion contaminations. The ability to remove heavy metals from water arises from the high concentration of polysaccharides and phlorotannins in brown seaweed; however, remediation can be hampered by the salinity, location, and coexistence of pollutants in the contaminated water. Maintaining the adsorbent properties of brown seaweed while avoiding the fragility of living organisms could allow for the development of better adsorbents. Herein, we demonstrate that polymerized phlorotannin particles, synthesized from phlorotannins extracted from a species of brown seaweed (Carpophyllum f lexuosum), were able to remove 460 mg of Pb 2+ from water per gram of adsorbent. Scanning electron microscopy (SEM), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), and thermogravimetric analysis (TGA) were used to characterize the polymerization process and the polymerized phlorotannin particles. Importantly, there was no direct correlation between the Pb 2+ removal capacity and the phlorotannin content of various algal derivatives of three species of brown seaweed, C. flexuosum, Carpophyllum plumosum, and Ecklonia radiata, as all three had similar adsorption capacities despite differences in phlorotannin content. This work shows that naturally abundant, "green" materials can be used to help remediate the environment.