Hydrogen Storage and Selective,Reversible O2 Adsorption in a Metal–Organic Framework with Open Chromium(II) Sites

A chromium(II)‐based metal–organic framework Cr₃[(Cr₄Cl)₃(BTT)₈]₂ (Cr‐BTT; BTT^3?=1,3,5‐benzenetristetrazolate), featuring coordinatively unsaturated, redox‐active Cr²⁺ cation sites, was synthesized and investigated for potential applications in H₂ storage and O₂ production. Low‐pressure H₂ adsorption and neutron powder diffraction experiments reveal moderately strong Cr–H₂ interactions, in line with results from previously reported M‐BTT frameworks. Notably, gas adsorption measurements also reveal excellent O₂/N₂ selectivity with substantial O₂ reversibility at room temperature, based on selective electron transfer to form Cr^III superoxide moieties. Infrared spectroscopy and powder neutron diffraction experiments were used to confirm this mechanism of selective O₂ binding.     

Imino‐Bridged Bisphosphaalkenes (2,4‐Diphospha‐3‐azapentadienes)

Deprotonation of aminophosphaalkenes (RMe₂Si)₂C?PN(H)(R′) (R=Me, iPr; R′=tBu, 1‐adamantyl (1‐Ada), 2,4,6‐tBu₃C₆H₂ (Mes*)) followed by reactions of the corresponding Li salts Li[(RMe₂Si)₂C?P(M)(R′)] with one equivalent of the corresponding P‐chlorophosphaalkenes (RMe₂Si)₂C?PCl provides bisphosphaalkenes (2,4‐diphospha‐3‐azapentadienes) [(RMe₂Si)₂C?P]₂NR′. The thermally unstable tert‐butyliminobisphosphaalkene [(Me₃Si)₂C?P]₂NtBu ( 4 a ) undergoes isomerisation reactions by Me₃Si‐group migration that lead to mixtures of four‐membered heterocyles, but in the presence of an excess amount of (Me₃Si)₂C?PCl, 4 a furnishes an azatriphosphabicyclohexene C₃(SiMe₃)₅P₃NtBu ( 5 ) that gave red single crystals. Compound 5 contains a diphosphirane ring condensed with an azatriphospholene system that exhibits an endocylic P?C double bond and an exocyclic ylidic P⁽⁺⁾? C^(?)(SiMe₃)₂ unit. Using the bulkier iPrMe₂Si substituents at three‐coordinated carbon leads to slightly enhanced thermal stability of 2,4‐diphospha‐3‐azapentadienes [(iPrMe₂Si)₂C?P]₂NR′ (R′=tBu: 4 b ; R′=1‐Ada: 8 ). According to a low‐temperature crystal‐structure determination, 8 adopts a non‐planar structure with two distinctly differently oriented P?C sites, but ³¹P NMR spectra in solution exhibit singlet signals. ³¹P NMR spectra also reveal that bulky Mes* groups (Mes*=2,4,6‐tBu₃C₆H₂) at the central imino function lead to mixtures of symmetric and unsymmetric rotamers, thus implying hindered rotation around the P? N bonds in persistent compounds [(RMe₂Si)₂C?P]₂NMes* ( 11 a , 11 b ). DFT calculations for the parent molecule [(H₃Si)₂C?P]₂NCH₃ suggest that the non‐planar distortion of compound 8 will have steric grounds.     

Multielemental characterization of honey using inductively coupled plasma mass spectrometry fused with chemometrics

Honey is considered a desirable ingredient in a range of different foodstuffs because of its nutrient and therapeutic effect. The honey characteristics mainly depend on the type of vegetation visited by the bees and the climatic conditions in which the plants are growing. Therefore, the purity, floral and geographical origin and authenticity are important factors influencing the overall perception of honey and honey‐based products in terms of quality and price. An important parameter in this picture is the elemental composition of honey because it can be linked with the floral type of honey, floral plant density and the botanical origin of nectar and pollens. In this work, the concentration range variation of 18 elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Mg, Mn, Na, Ni, K, Pb, Sr, Ti, V and Zn) was investigated in four varieties of honey (linden, acacia, rape, and sunflower) originating from Romania, because the elemental profile of honey may give important information to differentiate its geographical and varietal origin for authenticity purpose. All the determinations were carried out by inductively coupled plasma quadrupole mass spectrometry (ICP‐Q‐MS). The most abundant minerals decreased in the following order: K > Ca > Mg > Na, having the mean values of 248.70, 59.97, 20.54 and 11.92 mg kg^?1, respectively. The mineral content marks the differences in honey samples from different botanical origin and can be used as a tool for authentication purposes and also extends its applicability to assess the traceability of honey. Analysis of variance showed the preliminary relationships between the elements and samples. Further, the discrimination between different studied honey samples was achieved by principal component analysis (PCA). The multivariate analysis of the data allowed us to separate the honey samples into distinct groups according to their macroelement and microelement composition, emphasizing the origin of variation of element concentrations by honey type. Therefore, this approach might be potentially useful for the control of honey quality, origin or authenticity, and even to use the honey as environmental tracer.     

Investigation of thermal behaviour of hybrid nanostructures based on Fe2O3 and PAMAM dendrimers

Dendrimers or biofunctionalized dendrimers can be assembled onto magnetic iron oxide nanoparticles to stabilize or functionalize inorganic nanoparticles. Carboxylated poly(amidoamine) PAMAM dendrimers (generation 4.5) have been used for the synthesis of iron oxide nanoparticles, resulting nanocomposites with potential biomedical applications. The present paper aims to systematically investigate the thermal behaviour of nanostructured hybrids based on ferric oxide and PAMAM dendrimers, by differential scanning calorimetry (DSC) technique. The novelty consists both in synthesis procedure of hybrid nanostructures as well as in DSC approach of these nanocomposites. For the first time, we propose a new method to prepare Fe₂O₃??dendrimer nanocomposite, using soft chemical process at high pressure. Commercial PAMAM dendrimers with carboxylic groups on its surface were used. When high pressure is applied, polymeric structures suffer morphological changes leading to hybrid nanostructures' formation. In the same time, crystallinity of inorganic nanoparticles is provided. DSC results showed an increase in thermal stability of composites as compared to commercial dendrimers. This could be due to the formation of strong interactions between ferric oxide and carboxyl groups, as confirmed by Fourier transform infrared spectroscopy. Electron microscopy analysis (SEM/EDX) and size measurements were performed to demonstrate the existence of nanosized particles.     

Incorporation and exclusion of long chain alkyl halides in fatty acid monolayers at the air-water interface

Mixed monolayers of deuterated palmitic acid C(15)D(31)COOH (dPA) and deuterated stearic acid C(17)D(35)COOH (dSA) with 1-bromoalkanes of different alkyl chain length (C(4) to C(16)) at the air-water interface were investigated. Alkanes and 1-chlorohexadecane ClC(16)H(33) (ClHex) were also studied to compare the effects of the halogen on the mixed monolayers. Surface pressure-area isotherms and Brewster angle microscopy (BAM) were used to obtain the organization and phase behavior, providing a macroscopic view of the mixed monolayers. A molecular-level understanding of the interfacial molecular organization and intermolecular interactions was obtained by using vibrational sum frequency generation (SFG) spectroscopy and infrared reflection-absorption spectroscopy (IRRAS). It was found that from the alkyl halide molecules investigated 1-bromopentadecane, BrC(15)H(31) (BrPent), 1-bromohexadecane, BrC(16)H(33) (BrHex), and ClHex incorporate into the fatty acid monolayers. Alkanes of 15- and 16-carbon chain length do not incorporate into the fatty acid monolayer, which suggests that the halogen is needed for incorporation. Isotherms and spectra suggest that BrHex molecules are squeezed out, or excluded, from the fatty acid monolayer as the surface pressure is increased, while BAM images confirm this. Additionally, SFG spectra reveal that the alkyl chains of both fatty acids (dPA and dSA) retain an all-trans conformation after the incorporation of alkyl halide molecules. BAM images show that at low surface pressures BrHex does not affect the two-dimensional morphology of the dPA and dSA domains and that BrHex is miscible with dPA and dSA. We also present for the first time BAM images of BrHex deposited on a water surface, which reveal the formation of aggregates while the surface pressure remains unchanged from that of neat water.     

Acylhydrazones and Their Biological Activity: A Review

Due to the structure of acylhydrazones both by the pharmacophore –CO–NH–N= group and by the different substituents present in the molecules of compounds of this class, various pharmacological activities were reported, including antitumor, antimicrobial, antiviral, antiparasitic, anti-inflammatory, immunomodulatory, antiedematous, antiglaucomatous, antidiabetic, antioxidant, and actions on the central nervous system and on the cardiovascular system. This fragment is found in the structure of several drugs used in the therapy of some diseases that are at the top of public health problems, like microbial infections and cardiovascular diseases. Moreover, the acylhydrazone moiety is present in the structure of some compounds with possible applications in the treatment of other different pathologies, such as schizophrenia, Parkinson’s disease, Alzheimer’s disease, and Huntington’s disease. Considering these aspects, we consider that a study of the literature data regarding the structural and biological properties of these compounds is useful.     

Structural Investigation of Betulinic Acid Plasma Metabolites by Tandem Mass Spectrometry

Betulinic acid (BA) has been extensively studied in recent years mainly for its antiproliferative and antitumor effect in various types of cancers. Limited data are available regarding the pharmacokinetic profile of BA, particularly its metabolic transformation in vivo. In this study, we present the screening and structural investigations by ESI Orbitrap MS in the negative ion mode and CID MS/MS of phase I and phase II metabolites detected in mouse plasma after the intraperitoneal administration of a nanoemulsion containing BA in SKH 1 female mice. Obtained results indicate that the main phase I metabolic reactions that BA undergoes are monohydroxylation, dihydroxylation, oxidation and hydrogenation, while phase II reactions involved sulfation, glucuronidation and methylation. The fragmentation pathway for BA and its plasma metabolites were elucidated by sequencing of the precursor ions by CID MS MS experiments.     

Hydrogen: a good partner for rhodium‐catalyzed hydrosilylation

The influence of hydrogen pressure on the hydrosilylation of ketones catalyzed by [((S)‐SYNPHOS)Rh(nbd)]OTf has been studied. We have notably demonstrated that hydrogen significantly affected the outcome of the reaction while not being consumed as stoichiometric reducing agent. In THF, diethyl ether or toluene, the hydrogen pressure exceedingly accelerated the hydrosilylation reaction and preserved or even improved the enantioselectivity of the process. In CH₂Cl₂, the rhodium catalyst also showed generally higher catalytic activity under hydrogen pressure. Most serendipitously, several ketones were found to give products of absolute opposite configuration upon performing the hydrosilylation under argon atmosphere or under hydrogen pressure. Copyright © 2014 John Wiley & Sons, Ltd.     

Asymmetric ABC-triblock copolymer membranes induce a directed insertion of membrane proteins

Asymmetric molecules and materials provide an important basis for the organization and function of biological systems. It is well known that, for example, the inner and outer leaflets of biological membranes are strictly asymmetric with respect to lipid composition and distribution. This plays a crucial role for many membrane-related processes like carrier-mediated transport or insertion and orientation of integral membrane proteins. Most artificial membrane systems are, however, symmetric with respect to their midplane and membrane proteins are incorporated with random orientation. Here we describe a new approach to induce a directed insertion of membrane proteins into asymmetric membranes formed by amphiphilic ABC triblock copolymers with two chemically different water-soluble blocks A and C. In a comparative study we have reconstituted His-tag labeled Aquaporin 0 in lipid, ABA block copolymer, and ABC block copolymer vesicles. Immunolabeling, colorimetric, and fluorescence studies clearly show that a preferential orientation of the protein is only observed in the asymmetric ABC triblock copolymer membranes.