Anthracene-Fused Oligo-BODIPYs: A New Class of π-Extended NIR-Absorbing Materials

Large π-conjugated systems are key in the area of molecular materials. Herein, we prepare via Au^I-catalyzed cyclization a series of fully π-conjugated anthracene-fused oligo-BODIPYs. Their structural and optoelectronic properties were studied by several techniques, ranging from X-ray, UV/Vis, and cyclic voltammetry to transient absorption spectroscopy. As a complement, their electronic structures were explored by means of Density Functional Theory (DFT) calculations. Depending on the size and shape of the π-conjugated skeleton, unique features—such as face-to-face supramolecular organization, NIR absorption and fluorescence as well as strong electron accepting character—were noted. All in all, the aforementioned features render them valuable for technological applications.     

Elusive Double Perovskite Iodides: Structural,Optical, and Magnetic Properties

Halide double perovskites [A₂M^IM^IIIX₆] are an important class of materials that have garnered substantial interest as non-toxic alternatives to conventional lead iodide perovskites for optoelectronic applications. While numerous studies have examined chloride and bromide double perovskites, reports of iodide double perovskites are rare, and their definitive structural characterization has not been reported. Predictive models have aided us here in the synthesis and characterization of five iodide double perovskites of general formula Cs₂NaLnI₆ (Ln=Ce, Nd, Gd, Tb, Dy). The complete crystal structures, structural phase transitions, optical, photoluminescent, and magnetic properties of these compounds are reported.     

甘油的催化选择氧化

综述了近年来生物柴油主要副产物甘油的催化选择氧化的研究进展。分析了甘油的化学催化选择氧化的反应网络;介绍了催化甘油选择氧化反应主要的催化剂如负载型金属催化剂、多孔催化剂以及有机酰基-TEMPO催化剂的催化性能及其催化机理;评述了甘油催化氧化过程中各反应条件等对产物选择性和反应物转化率的影响;概括了甘油的电催化氧化、甘油催化氧化聚合生成新型聚合物-聚丙酮二酸盐（Polyketomalonate）等新催化反应及其机理,总结了甘油生物催化氧化的产物二羟基丙酮（DHA）的新进展。最后提出了甘油的催化氧化存在的一些问题,并展望了甘油催化氧化的研究和发展方向。     

Three-dimensional concentration mapping of gases using a portable mass spectrometer system

The visualization of hazardous gaseous emissions at volcanoes using in-situ mass spectrometry (MS) is a key step towards a better comprehension of the geophysical phenomena surrounding eruptive activity. In-situ data consisting of helium, carbon dioxide, sulfur dioxide, and other gas species, were acquired with a quadrupole based MS system. Global position systems (GPS) and MS data were plotted on ground imagery, topography, and remote sensing data collected by a host of instruments during the second Costa Rica Airborne Research and Technology Applications (CARTA) mission. This combination of gas and imaging data allowed three-dimensional (3D) visualization of the volcanic plume and the mapping of gas concentration at several volcanic structures and urban areas. This combined set of data has demonstrated a better tool to assess hazardous conditions by visualizing and modeling of possible scenarios of volcanic activity. The MS system is used for in-situ measurement of 3D gas concentrations at different volcanic locations with three different transportation platforms: aircraft, auto, and hand-carried. The demonstration for urban contamination mapping is also presented as another possible use for the MS system.     

Determination of gas-phase acidities of dimethylphenols: Combined experimental and theoretical study

The gas-phase acidities of the six dimethylphenol isomers were determined experimentally, by using the kinetic method, and theoretically, through quantum chemistry calculations. The experimental values, relative to the gas-phase acidity of phenol, are (in kJ mol⁻¹): −1.76 ± 0.76 (2,3-Me₂C₆H₃OH), 1.78 ± 0.29 (2,4-Me₂C₆H₃OH), 0.83 ± 0.58 (2,5-Me₂C₆H₃OH), −4.39 ± 0.89 (2,6-Me₂C₆H₃OH), 5.38 ± 1.08 (3,4-Me₂C₆H₃OH), and 1.88 ± 0.08 (3,5-Me₂C₆H₃OH). This trend was discussed by considering the substituent effects on the thermodynamic stabilities both of the parent phenols and the corresponding phenoxide ions. The above acidity data, the literature values for 2-, 3-, and 4-methylphenol, and the substituent effects analysis allowed to develop a simple empirical method to estimate the acidity of any methyl-substituted phenol.     

Large solutions to the p-Laplacian for large p

In this work we consider the behaviour for large values of p of the unique positive weak solution u _p to Δ _p u = u ^q in Ω, u = +∞ on , where q > p − 1. We take q = q(p) and analyze the limit of u _p as p → ∞. We find that when q(p)/p → Q the behaviour strongly depends on Q. If 1 < Q < ∞ then solutions converge uniformly in compacts to a viscosity solution of with u = +∞ on . If Q = 1 then solutions go to ∞ in the whole Ω and when Q = ∞ solutions converge to 1 uniformly in compact subsets of Ω, hence the boundary blow-up is lost in the limit.     

Supramolecular Subphthalocyanine Cage as Catalytic Container for the Functionalization of Fullerenes in Water

Herein we report the first example of a supramolecular cage that works as a catalytic molecular reactor to perform transformations over fullerenes in aqueous medium. Taking advantage of the ability of metallo–organic Pd(II)-subphthalocyanine (SubPc) capsules to form stable host:guest complexes with C₆₀, we have prepared a water-soluble cage that provides a hydrophobic environment for conducting cycloadditions over encapsulated C₆₀, namely, Diels–Alder reactions with anthracene. Indeed, the presence of catalytic amounts of SubPc cage dissolved in water promotes co-encapsulation of insoluble C₆₀ and anthracene substrates, allowing the reaction to occur inside the cavity under mild conditions. The lower stability of the host:guest complex with the resulting C₆₀ cycloadduct facilitates its displacement by pristine C₆₀, which grants catalytic turnover. Moreover, bis-addition compounds are regioselectively formed inside the cage when using excess anthracene.     

Regio- and Z-Selective Alkyne Hydroamination and Hydrophenoxylation using Tetrafluoro-λ6-Sulfanyl Alkynes under Superbasic,Naked Anion Conditions

Alkyne hydroamination is an effective approach for the production of enamines and enamine-containing N-heterocycles. However, stereoselectivity control is a considerable challenge in this reaction because of the electronic repulsion between an incoming nitrogen lone pair and the alkyne π-system. Herein, we propose a methodology involving β-regio- and Z-selective alkyne hydroamination by using tetrafluoro-λ⁶-sulfanyl (SF₄) alkynes under superbasic, naked anion conditions. The reaction is compatible with a wide variety of N-heterocycles, including indoles, carbazoles, pyrazoles, and imidazoles, and selectively furnishes SF₄-linked Z-vinyl enamines with β-regioselectively. Moreover, the method can be extended to the β- and Z-controlled, base-mediated alkyne hydrophenoxylation with phenols to provide SF₄-linked Z-vinyl ethers in high yields. As the SF₄ unit has attracted attention as a bioisostere for alkynes, p-benzenes, bicyclo[1.1.1]pentyl (BCP) groups, and cubanes in medicinal chemistry, this chemistry represents an effective approach to creating novel drug candidates incorporating SF₄-containing molecules.     

Shape control in gold nanoparticle synthesis

In this tutorial review, we summarise recent research into the controlled growth of gold nanoparticles of different morphologies and discuss the various chemical mechanisms that have been proposed to explain anisotropic growth. With the overview and discussion, we intended to select those published procedures that we consider more reliable and promising for synthesis of morphologies of interest. We expect this to be interesting to researchers in the wide variety of fields that can make use of metal nanoparticles.     

Films based on chitosan polyelectrolyte complexes for skin drug delivery: Development and characterization

Novel chitosan based polyelectrolyte complexes (PEC) were developed and optimized in order to obtain films possessing the optimal functional properties (flexibility, resistance, water vapour transmission rate and bioadhesion) to be applied on skin. The development was based on the combination of chitosan and two polyacrylic acid (PAA) polymers with different crosslinkers and crosslinking densities. The interaction between the polymers was maximized controlling the pH, and by forming the films at a pH value close to the pK_a of the respective components as identified by potentiometric and turbidimetric titrations. The action of glycerol, PEG200, Hydrovance and trehalose upon the functional properties of the films was also evaluated. Glycerol was found to improve the film properties in terms of flexibility, resistance and water vapour transmission rate (WVTR) with a maximum effect at 30%. The application of a pressure sensitive adhesive (PSA) significantly improved bioadhesion with a negligible influence in the resistance and flexibility of the films.The optimized film, including adhesive, has shown very good properties for application in the skin and represents a very promising formulation for further incorporation of drugs for topical and transdermal administration.