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We report the absorption spectra and photophysical properties of homo and hetero‐aggregate assemblies of a strongly emissive N‐annulated perylene dye (P) and of a dyad made of P and a methyl viologen derivative (P‐MV), in ethanol‐water solutions. In homo‐aggregate assemblies of P, the π‐π* fluorescence of the isolated chromophore is replaced by excimer emission at lower energy, with a lifetime of 900 ps, due to excimer formation from the initially prepared excitons. In homo‐aggregate assemblies of P‐MV, photoinduced charge separation, with formation of P+‐MV− species, occurs in 3 ps with a charge recombination of 20 ps. In hetero‐aggregate P/P‐MV systems, the light energy absorbed by the P components delocalizes over various P subunits, and when a P‐MV unit is reached, charge separation occurs; however, excimer emission is present for P/P‐MV ratio larger than 3 : 1, indicating that delocalized excitons within the hetero‐aggregate systems extend over a limited number of P chromophores. [ABSTRACT FROM AUTHOR]

The structure of a decanuclear photo‐ and redox‐active dendrimer based on Ru(II) polypyridine subunits, suitable as a light‐harvesting multicomponent species for artificial photosynthesis, has been investigated by means of computer modelling. The compound has the general formula [Ru{(μ‐dpp)Ru[(μ‐dpp)Ru(bpy)2]2}3](PF6)20 (Ru10; bpy=2,2′‐bipyridine; dpp=2,3‐bis(2′‐pyridyl)pyrazine). The stability of possible isomers of each monomer was investigated by performing classical molecular dynamics (MD) and quantum mechanics (QM) simulations on each monomer and comparing the results. The number of stable isomers is reduced to 36 with a prevalence of MER isomerism in the central core, as previously observed by NMR experiments. The simulations on decanuclear dendrimers suggest that the stability of the dendrimer is not linked to the stability of the individual monomers composing the dendrimer but rather governed by the steric constrains originated by the multimetallic assembly. Finally, the self‐aggregation of Ru10 and the distribution of the counterions around the complexes is investigated using Molecular Dynamics both in implicit and explicit acetonitrile solution. In representative examples, with nine and four dendrimers, the calculated pair distribution function for the ruthenium centers suggests a self‐aggregation mechanism in which the dendrimers are approaching in small blocks and then aggregate all together. Scanning transmission electron microscopy complements the investigation, supporting the formation of different aggregates at various concentrations. [ABSTRACT FROM AUTHOR]

The luminophore Ru(bpy)2(dcbpy)2+ (bpy=2,2'‐bipyridine; dcbpy=4,4'‐dicarboxy‐2,2'‐bipyridine) is covalently linked to a chitosan polymer; crosslinking by tripolyphosphate produced Ru‐decorated chitosan fibers (NS‐RuCh), with a 20 : 1 ratio between chitosan repeating units and RuII chromophores. The properties of the RuII compound are unperturbed by the chitosan structure, with NS‐RuCh exhibiting the typical metal‐to‐ligand charge‐transfer (MLCT) absorption and emission bands of RuII complexes. When crosslinks are made in the presence of IrO2 nanoparticles, such species are encapsulated within the nanofibers, thus generating the IrO2⊂NS‐RuCh system, in which both RuII photosensitizers and IrO2 water oxidation catalysts are within the nanofiber structures. NS‐RuCh and IrO2⊂NS‐RuCh have been characterized by dynamic light scattering, scanning electronic microscopy, and energy‐dispersive X‐ray analysis, which indicated a 2 : 1 ratio between RuII chromophores and IrO2 species. Photochemical water oxidation has been investigated by using IrO2⊂NS‐RuCh as the chromophore/catalyst assembly and persulfate anions as the sacrificial species: photochemical water oxidation yields O2 with a quantum yield (Φ) of 0.21, definitely higher than the Φ obtained with a similar solution containing separated Ru(bpy)32+ and IrO2 nanoparticles (0.05) or with respect to that obtained when using NS‐RuCh and "free" IrO2 nanoparticles (0.10). A fast hole‐scavenging process (rate constant, 7×104 s−1) involving the oxidized photosensitizer and the IrO2 catalyst within the IrO2⊂NS‐RuCh system is behind the improved photochemical quantum yield of IrO2⊂NS‐RuCh. [ABSTRACT FROM AUTHOR]

Abstract: Self‐supporting paper‐like membranes consisting of carbon/germanium dioxide (C/GeO2) fibers are prepared via electrospinning of solutions with different germanium load (2.50−4.25 wt%), followed by carbonization at 550−700 °C, and are evaluated as anode materials in lithium ion batteries. The investigation of the physicochemical properties of the membranes by several characterization techniques shows that, as expected, with increasing carbonization temperature better graphitized and less nitrogen‐rich C fibers are obtained, containing Ge0 and/or reduced oxide phases along with GeO2 nanoparticles. These characteristics, combined with the cold pressing of the as‐spun membrane that noticeably reduces the hollow space within the fibres giving rise to a more compact and tight structure, lead to initial discharge volumetric capacities (≈1390–3580 mAh cm−3) much higher than commercial graphite anodes. In particular, the membrane prepared from solution with 4.25 wt% Ge‐load by cold‐pressing and carbonization at 700 °C, is able to deliver ≈1500 mAh cm−3 after 50 cycles at 50 mA g−1 with a Coulombic efficiency close to 100%. Nevertheless, the anodes exhibit poor rate capability. This is because the carbonization at high temperature promotes outward diffusion and subsequent coalescence of Ge‐clusters in larger particles, with the structure of the fibers made fragile by the formation of voids within them. [ABSTRACT FROM AUTHOR]

TiO2 is frequently combined with carbon materials, such as reduced graphene oxide (RGO), to produce composites with improved properties, for example for photocatalytic applications. It is shown that heating conditions significantly affect the interface and photocatalytic properties of TiO2@C, and that microwave irradiation can be advantageous for the synthesis of carbon-based materials. Composites of TiO2 with RGO or amorphous carbon were prepared from reaction of titanium isopropoxide with benzyl alcohol. During the synthesis of the TiO2 nanoparticles, the carbon is involved in reactions that lead to the covalent attachment of the oxide, the extent of which depends on the carbon characteristics, heating rate, and mechanism. TiO2 is more efficiently stabilized at the surface of RGO than amorphous carbon. Rapid heating of the reaction mixture results in a stronger coupling between the nanoparticles and carbon, more uniform coatings, and smaller particles with narrower size distributions. The more efficient attachment of the oxide leads to better photocatalytic performance. [ABSTRACT FROM AUTHOR]

4-Carboxyphenyl groups are covalently grafted onto graphene oxide via diazonium chemistry for studying their role on the adsorption of iron oxide nanoparticles. The nanoparticles are deposited via a novel phase-transfer approach involving specific interactions at the interface between two immiscible solvents. The increased density and the homogeneous distribution of surface carboxyl moieties enable the preparation of a nanocomposite with improved iron oxide distribution and loading. Structure-properties relationships are investigated by analysing the electrochemical properties of the nanocomposites, which are regarded as promising active materials for application in supercapacitors. It is demonstrated that the nature of the interactions between the components similarly affects the overall electrochemical performances of the nanocomposites and the structure of the materials. [ABSTRACT FROM AUTHOR]

The article discusses the characteristics of Zantedeschia aethiopica that cause allergic contact dermatitis. A report involving a 30-year-old woman that indicated itching, redness and swelling on the hands after cutting Zantedeschia in the garden was examined. When ingested or touched it could cause severe burning and edema of the lips, tongue, oral mucosa, pharynx, gastrointestinal irritation, conjunctivitis or dermatitis.