Nanostructured diamine-fullerene derivatives: computational density functional theory study and experimental evidence for their formation via gas-phase functionalization

Nanostructure derivatives of fullerene C(60) are used in emerging applications of composite matrices, including protective and decorative coating, superadsorbent material, thin films, and lightweight high-strength fiber-reinforced materials, etc. In this study, quantum chemical calculations and experimental studies were performed to analyze the derivatives of diamine-fullerene prepared by the gas-phase solvent-free functionalization technique. In particular, the aliphatic 1,8-diamino-octane and the aromatic 1,5-diaminonaphthalene, which are diamines volatile in vacuum, were studied. We addressed two alternative mechanisms of the amination reaction via polyaddition and cross-linking of C(60) with diamines, using the pure GGA BLYP, PW91, and PBE functionals; further validation calculations were performed using the semiempirical dispersion GGA B97-D functional which contains parameters that have been specially adjusted by a more realistic view on dispersion contributions. In addition, we looked for experimental evidence for the covalent functionalization by using laser desorption/ionization time-of-flight mass spectrometry, thermogravimetric analysis, and atomic force microscopy.     

Analysis of Plant–Plant Interactions Reveals the Presence of Potent Antileukemic Compounds

A method to identify anticancer compounds in plants was proposed based on the hypothesis that these compounds are primarily present in plants to provide them with an ecological advantage over neighboring plants and other competitors. According to this view, identifying plants that contain compounds that inhibit or interfere with the development of other plant species may facilitate the discovery of novel anticancer agents. The method was developed and tested using Magnolia grandiflora, Gynoxys verrucosa, Picradeniopsis oppositifolia, and Hedyosmum racemosum, which are plant species known to possess compounds with cytotoxic activities. Plant extracts were screened for growth inhibitory activity, and then a thin-layer chromatography bioautography assay was conducted. This located the major antileukemic compounds 1, 2, 4, and 5 in the extracts. Once the active compounds were located, they were extracted and purified, and their structures were determined. The growth inhibitory activity of the purified compounds showed a significant correlation with their antileukemic activity. The proposed approach is rapid, inexpensive, and can easily be implemented in areas of the world with high biodiversity but with less access to advanced facilities and biological assays.     

Preparative Mass Spectrometry Using a Rotating-Wall Mass Analyzer

The design of functional interfaces is central to both fundamental and applied research in materials science and energy technology. We introduce a new, broadly applicable technique for the precisely controlled high-throughput preparation of well-defined interfaces containing polyatomic species ranging from small ions to nanocrystals and large protein complexes. The mass-dispersive deposition of ions onto surfaces is achieved using a rotating-wall mass analyzer, a compact device which enables the separation of ions using low voltages and has a theoretically unlimited mass range. We demonstrate an efficient deposition of singly charged Au₁₄₄(SC₄H₉)₆₀ ions (33.7 kDa), which opens up exciting opportunities for the structural characterization of nanocrystals and their assemblies using transmission electron microscopy. Our approach also enables the high-throughput deposition of mass-selected ions from multicomponent mixtures, which is of interest to the controlled preparation of surface gradients and rapid screening of molecules in mixtures for a specific property.     

Allyl palladium complexes bearing carbohydrate-based N-heterocyclic carbenes: Anticancer agents for selective and potent in vitro cytotoxicity

Novel allyl palladium compounds stabilized by carbohydrate-based N-heterocyclic carbenes (NHCs) were prepared and characterized by nuclear magnetic resonance, high-resolution mass spectrometry and elemental analysis. The antiproliferative activity of the compounds was tested on a panel of different tumor lines, especially ovarian cancer and MRC-5 human lung fibroblasts (nontumor cells). These experiments showed that both mixed NHC/PPh₃ and NHC/PTA (PTA = 1,3,5-triaza-7-phosphaadamantane) allyl complexes have IC₅₀ (half maximal inhibitory concentration) values comparable and sometimes even significantly lower than cisplatin. Moreover, the mixed NHC/PTA allyl complexes exhibit good activity toward the seven tumor lines tested with a substantial inactivity against normal cells, a necessary condition to avoid the general cytotoxicity of a metallo-drug. Furthermore, this subclass of compounds proved particularly active on the A549 lung cancer tumor line (up to 100-fold more cytotoxic than cisplatin) and exhibited satisfactory cytotoxicity against KURAMOCHI and OVCAR3 cell lines, which are currently considered the best in vitro models for serous ovarian cancer, the most lethal tumor for women worldwide.     

Rhodium and iridium complexes containing the anion of 1-phenyl-3-methyl-4-benzoyl- pyrazolone-5, a sophisticated analogue of β-diketones

Several (diolefin)M(A) complexes (M = Rh, Ir) were prepared, where AH is 1-phenyl-3-methyl- 4-benzoylpyrazolone-5, a very stable asymmetric analogue of acetylacetone. In these complexes the diolefin could be replaced by one mole of (Ph₂PCH₂CH₂)₂, two of CO or of PPh₃, or three of CNBu^t, while 1,10-phenanthroline displaced the chelating ligand to yield [(cyclooctadiene)Rh(phen)]⁺ (A)^?. Some compounds X?Y (X?Y = iodine or MeI) added oxidatively yielding the corresponding trivalent species. Using ³¹P NMR spectra the presence of the expected steric isomers was detected in (Ph₃P)(CO)Rh(A) and in (Ph₃P) (CO)Rh(A)(X)(Y).     

Some correspondence between classes of incidence structures with tolerance

Summary We consider structures (G,T,J) whereT is a tolerance (i.e. a reflexive and symmetric binary relation) on the setG (whose elements are called lines) andJ is 0271 0247 V 3 a family of sets of mutuallyT-related lines, called incidence structures with tolerance (briefly: ISTs). We study certain operators between the tolerances on a setG and certain classes of ISTs defined onG.

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Riassunto Una struttura d'incidenza con tolleranza (brevemente IST) è una terna (G,T,J) doveT è una tolleranza (cioè una relazione binaria che sia riflessiva e simmetrica) su un insieme non vuotoG (i cui elementi sono detti rette) eJ è una famiglia di insiemi 0271 0247 V 3 di rette in mutua relazioneT. In questa nota noi studiamo certi operatori tra le tolleranze su un insiemeJ e 0271 0247 V 2 certe classi di ISTs definite suG.

     

Studies on immobilizd lipase in hydrophobic sol-gel

The hydrolysis of tetraethoxysilane using the sol-gel process was used to produce silica matrices, and these were tested for the immobilization of lipase from Candida rugosa by three methods: physical adsorption, covalent binding, and gel entrapment in the presence and absence of polyethylene glycol (PEG-1450). The silica matrices and their derivatives were characterized regarding particle size distribution, specific surface area, pore size distribution (Brunauer, Emmett, and Teller [B.E.T.] method), yield of grafting (thermogravimetric analyzer [TGA]), and chemical composition (Fourier transform infrared). Immobilization yields based on recovered lipase activity varied from 3.0 to 32.0%, and the highest efficiency was attained when lipase was encapsulated in the presence of PEG.     

Fuel‐Selective Transient Activation of Nanosystems for Signal Generation

The transient activation of function using chemical fuels is common in nature, but much less in synthetic systems. Progress towards the development of systems with a complexity similar to that of natural ones requires chemical fuel selectivity. Here, we show that a self‐assembled nanosystem, composed of monolayer‐protected gold nanoparticles and a fluorogenic peptide, is activated for transient signal generation only in case the chemical fuel matches the recognition site present at the nanoparticle surface. A modification of the recognition site in the nanosystem completely changes the chemical fuel selectivity. When two nanosystems are simultaneously present, the selectivity expressed by the system depends on the concentration of nucleotide added.     

Understanding and controlling the efficiency of Au24M(SR)18 nanoclusters as singlet-oxygen photosensitizers

Singlet oxygen, ¹O₂, can be generated by molecules that upon photoexcitation enable the ³O₂ → ¹O₂ transition. We used a series of atomically precise Au₂₄M(SR)₁₈ clusters, with different R groups and doping metal atoms M. Upon nanosecond photoexcitation of the cluster, ¹O₂ was efficiently generated. Detection was carried out by time-resolved electron paramagnetic resonance (TREPR) spectroscopy. The resulting TREPR transient yielded the ¹O₂ lifetime as a function of the nature of the cluster. We found that: these clusters indeed generate ¹O₂ by forming a triplet state; a more positive oxidation potential of the molecular cluster corresponds to a longer ¹O₂ lifetime; proper design of the cluster yields results analogous to those of a well-known reference photosensitizer, although more effectively. Comprehensive kinetic analysis provided important insights into the mechanism and driving-force dependence of the quenching of ¹O₂ by gold nanoclusters. Understanding on a molecular basis why these molecules may perform so well in ¹O₂ photosensitization is instrumental to controlling their performance.

Atomically precise Au₂₄M(SR)₁₈ clusters were used as singlet-oxygen photosensitizers. Comprehensive kinetic analysis provided insights into the mechanism and driving-force dependence of the quenching of ¹O₂ by gold nanoclusters.     

Grafting of cyclodextrins onto filter paper

Grafting of cyclodextrins and cyclodextrins derivatives on cellulosic surface, such as paper or filter paper, provides hosting cavities that can include a large variety of chemicals for specific cellulose finishing. In this study grafting of monocholorotriazinyl-β-cyclodextrin (MCT-β-CD) and β-cyclodextrin (β-CD) to filter paper has been performed. β-cyclodextrin has been bonded to filter paper using 1,4-butanediol diglycidyl ether as the crosslinking agent. The untreated and treated filter papers were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), demonstrating the covalent binding of cyclodextrins to filter paper. The quantification of β-CD and MCT-β-CD grafted to filter paper was determined by the dye extinction method with the inclusion of phenolphthalein. The final β-CD content amounted to 15.9 μmol per gram of support (1.8% by weight), and 72.8 μmol per gram of support (11.3% by weight) for MCT-β-CD.