A Combined Immunofluorescence and Fluorescent Viability Cocktail Staining Procedure for Rapid Microscopic Detection and Enumeration of Live Legionella pneumophila

Journal of Fluorescence - This report describes a combined immunofluorescence and fluorescence viability stain applied as one staining solution for rapid detection of live Legionella...     

The Key Role of U28 in the Aqueous Self‐Assembly of Uranyl Peroxide Nanocages

For 11 years now, the structural diversity and aesthetic beauty of uranyl–peroxide capsules have fascinated researchers from the diverse fields of mineralogy, polyoxometalate chemistry, and nuclear fuel technologies. There is still much to be learned about the mechanisms of the self‐assembly process, and the role of solution parameters including pH, alkali template, temperature, time, and others. Here we have exploited the high solubility of the UO₂²⁺/H₂O₂/LiOH aqueous system to address the effect of the hydroxide concentration. Important techniques of this study are single‐crystal X‐ray diffraction, small‐angle X‐ray scattering, and Raman spectroscopy. Three key phases dominate the solution speciation as a function of time and the LiOH/UO₂²⁺ ratio: the uranyl–triperoxide monomer [UO₂(O₂)₃]^4?and the two capsules [(UO₂)(O₂)(OH)]₂₄^24?(U₂₄) and [(UO₂)(O₂)_1.5]₂₈^28?(U₂₈). When the LiOH/U ratio is around three, U₂₈ forms rapidly and this cluster can be isolated in high yield and purity. This result was most surprising and challenges the hypothesis that alkali templating is the most important determinant in the cluster geometry. Moreover, analogous experiments with KOH, NH₄OH, and TEAOH (TEA=tetraethylammonium) also rapidly yield U₂₈, which suggests that U₂₈ is the kinetically favored species. Complete mapping of the pH–time phase space reveals only a narrow window of the U₂₈ dominance, which is why it was previously overlooked as an important kinetic species in this chemical system, as well as others with different counterions.     

Self‐Assembly of Uranyl–Peroxide Nanocapsules in Basic Peroxidic Environments

A wide range of uranyl–peroxide nanocapsules have been synthesized using very simple reactants in basic media; however, little is known about the process to form these species. We have performed a density functional theory study of the speciation of the uranyl ions under different experimental conditions and explored the formation of dimeric species via a ligand exchange mechanism. We shed some light onto the importance of the excess of peroxide and alkali counterions as a thermodynamic driving force towards the formation of larger uranyl–peroxide species.     

Reversible M−M Bonding by Alkaline Earth Metals (Mg,Ca, Sr,Ba) in Graphite Intercalation Compounds

The alkaline earth metals (M=Mg, Ca, Sr, and Ba) exhibit a +2 oxidation state in nearly all known stable compounds, but M^I dimeric complexes with M−M bonding, [M₂(en)₂]²⁺, (en=ethylenediamine) of all these metals can be stabilized within the galleries of donor-type graphite intercalation compounds (GICs). These metals can also form GICs with more conventional metal (II) ion complexes, [M(en)₂]²⁺. Here, the facile interconversion between dimeric-M^I and monomeric-M^II intercalates upon the addition/removal of en are reported. Thermogravimetry, powder X-ray diffraction, and pair distribution function analysis of total scattering data support the presence of either [M₂(en)₂]²⁺ or [M(en)₂]²⁺ guests. This phase conversion requires coupling graphene and metal redox centers, with associated reversible M−M bond formation within graphene galleries. This chemistry allows the facile isolation of unusual oxidation states, reveals M⁰→M²⁺ reaction pathways, and present new opportunities in the design of hybrid conversion/intercalation materials for applications such as charge storage.     

Lewis Acid Catalyzed Condensation–Cyclization Cascade: Direct Synthesis of Di/Trifluoromethyl‐1,2,3,4‐tetrahydroquinazolines

Condensed heterocycles such as quinazolines constitute the framework of many promising drugs. The great impact of the dramatic fluorine effect in pharmaceuticals prompted a great surge in the quest for fluorinated drug design resulting in over 20 % fluorine‐containing drugs in the market today. Therefore, finding an efficient and cost‐effective method for the direct synthesis of fluorine‐tagged quinazoline systems is of great significance in the pharmaceutical arena. For the first time, a one‐pot sequential condensation–cyclization reaction to form selectively the difluoro/trifluoromethylated tetrahydroquinazolines from simple components difluoro/trifluoroacetaldehyde hemiacetal and aromatic amines is reported. Our recent studies using difluoro/trifluoroacetaldehyde hemiacetal as simple and elegant difluoro/trifluoromethyl synthons and metal triflates such as gallium triflate as safe and stable Lewis acid catalysts led us to this direct synthesis protocol for the expedient and convenient synthesis of fluorinated quinazolines. DFT calculations at PCM/B3LYP/6‐31++G** were carried out for evaluating a possible reaction mechanism for this cyclization. According to the DFT calculations, product stereochemistry is thermodynamically driven, favoring the cis isomer as the major product, which is also confirmed experimentally.     

Organocatalyzed Asymmetric Conjugate Addition of Heteroaryl and Aryl Trifluoroborates: a Synthetic Strategy for Discoipyrrole D

Bis‐heteroaryl or bis‐aryl stereocenters were formed by an organocatalytic enantioselective conjugate addition using the respective trifluoroborate salts as nucleophiles. Control studies suggested that fluoride dissociation is necessary in the anhydrous conditions. This strategy is applicable to the synthesis of discoipyrrole D, an inhibitor of BR5 fibroblast migration.     

Morphology transformation of thermosensitive metronidazol by spray freeze-drying

Journal of Thermal Analysis and Calorimetry - Spray freeze-drying (SFD) is an effective method for reducing the size of thermosensitive organic substances that are sparingly soluble in water....     

Ternary and binary copper(II) complexes: synthesis,characterization, ROS-inductive,proteasome inhibitory,and anticancer properties

Three ternary copper(II) complexes, [Cu(phen)(L-phe)Cl]·2H₂O, [Cu(phen)(L-leu)Cl]·4½H₂O, and [Cu(phen)(L-tyr)Cl]·3H₂O, and four binary copper(II) complexes, [Cu(phen)Cl₂]_, Cu(L-phe)₂·½H₂O, Cu(L-leu)₂·½H₂O, and Cu(L-tyr)₂·H₂O (where phen = 110-phenanthroline, L-phe = L-phenylalanine, L-tyr = L-tyrosine, L-leu = L-leucine and Cl^- = chloride), were synthesized and characterized by elemental analysis, spectroscopic techniques (FTIR, UV–visible, fluorescence spectroscopy), magnetic susceptibility, molar conductivity, and lipophilicity measurement. X-ray diffraction determination of a single crystal of [Cu(phen)(L-tyr)Cl] showed two independent molecules in the asymmetric unit, each with the same distorted square pyramidal geometry about copper(II). p-Nitrosodimethylaniline assay revealed that the three ternary complexes were better inducers of reactive oxygen species over time than binary complexes, CuCl₂, and free ligands. All the copper(II) complexes in this series inhibited the three proteolytic activities in the order Trypsin-like > Caspase-like > Chymotrypsin-like. In terms of anticancer properties, the copper(II)-phen complexes had GI50 values of less than 4 μM against MCF-7, HepG2, CNE1 and A549 cancer cell lines, more potent than cisplatin.