Novel self-assembling system based on resorcinarene and cationic surfactant

Mixed association of calix[4]resorcinarene with ethyl sulfonate groups on the lower rim and dimethylaminomethyl groups on the upper rim (CR) and cationic surfactant 4-aza-1-hexadecyl-azoniabicyclo[2.2.2]octane bromide (DABCO-16) is studied by methods of tensiometry, conductometry, potentiometry and NMR spectroscopy at fixed CR concentration and varied surfactant concentration. Beyond ca. 0.4 mM of DABCO-16, mixed aggregates enriched by CR are proved to be formed due to electrostatic forces, while beyond ca. 5 mM, aggregates enriched by surfactant occur due to the hydrophobic effect. Spectrophotometry monitoring of the solubilization of a hydrophobic dye, Orange OT, demonstrated that only the second type of mixed aggregate enriched by DABCO-16 is capable of binding the organic probe, while the mixed system where the surfactant is a minor component shows no binding capacity towards Orange OT. This finding can be used for the design of nanocontainers with controllable binding/release properties.     

Fluorescent Silver Nanoclusters in Condensed DNA

We study the formation and fluorescent properties of silver nanoclusters encapsulated in condensed DNA nanoparticles. Fluorescent globular DNA nanoparticles are formed using a dsDNA–cluster complex and polyallylamine as condensing agents. The fluorescence emission spectrum of single DNA nanoparticles is obtained using tip‐enhanced fluorescence microscopy. Fluorescent clusters in condensed DNA nanoparticles appear to be more protected against destructive damage in solution compared to clusters synthesized on a linear polymer chain. The fluorescent clusters on both dsDNA and ssDNA exhibit the same emission bands (at 590 and 680 nm) and the same formation efficiency, which suggests the same binding sites. By using density functional theory, we show that the clusters may bind to the Watson–Crick guanine–cytosine base pairs and to single DNA bases with about the same affinity.     

[Pd(CH3COO)2]n from X‐ray powder diffraction data

The water‐insoluble title compound, catena‐poly­[palladium(II)‐di‐μ‐acetato‐κ⁴O:O′], [Pd(C₂H₃O₂)₂]_n, was obtained from a nitratopalladium solution and acetic acid as a pale‐pink powder. Ab initio crystal structure determination was carried out using X‐ray powder diffraction techniques. Patterson and Fourier syntheses were used for atom location and the Rietveld technique was applied for the final structure refinement. The structure consists of palladium acetate complexes connected into polymeric chains running along b, in which two Pd atoms are bridged by two acetate groups that are in a cis configuration with respect to one another. The unique Pd atom lies on a site with 2/m symmetry and the acetate moieties have imposed m symmetry; these are joined into infinite chains running along the b direction. The shortest Pd⋯Pd distance in the row is 2.9192 (1) Å. The planes of adjacent palladium complexes are inclined towards each other, the angle between the planes being approximately 30°.     

Effects of energy spread on brightness and coherence of undulator sources

The (spectral) brightness for partially transverse coherent sources such as synchrotron radiation and free‐electron laser sources can be defined as the maximum of the Wigner distribution. Then, the brightness includes information on both coherence and wavefront characteristics of the radiation field. For undulator sources, it is customary to approximate the single‐electron electric field at resonance with a Gaussian beam, leading to great simplifications. Attempts to account for the modified spatial and angular profile of the undulator radiation in the presence of detuning due to energy spread, currently build on the simplified brightness expression derived under the assumption of Gaussian beams. The influence of energy spread on undulator radiation properties is becoming important in view of diffraction‐limited rings with ultralow emittance coming on‐line. Here the effects of energy spread on the brightness of undulator radiation at resonance are discussed, as well as relevant relations with coherence properties.     

Electrocatalytic Fast and Efficient Multicomponent Approach to Medicinally Relevant (2‐Amino‐4H‐chromen‐4‐yl) phosphonate Scaffold

‘One‐pot’ electrocatalytic transformation of salicylaldehydes, malononitrile, and triethyl phosphite in an undivided cell results in the formation of diethyl (2‐amino‐3‐cyano‐4H‐chromen‐4‐yl)phosphonates in 88–93% substance yields and 880–930% current efficiency via complex multicomponent process. This novel electrocatalytic chain process opens an effective, fast, and convenient way to cyano‐functionalized (2‐amino‐4H‐chromen‐4‐yl)phosphonate systems which are promising compounds for biomedical applications. This efficient electrocatalytic approach to the (2‐amino‐4H‐chromen‐4‐yl)phosphonate scaffold represents novel synthetic concept for multicomponent reactions (MCR) strategy and allows to combine the synthetic virtues of conventional MCR with ecological benefits and convenience of facile electrocatalytic procedure.     

Induction of A549 Nonsmall-Cell Lung Cancer Cells Proliferation by Photoreleased Nicotine

Caged compounds comprise the group of artificially synthesized, light-sensitive molecules that enable in situ derivation of biologically active constituents capable of affecting cells, tissues and/or biological processes upon exposure to light. Ruthenium-bispyridine (RuBi) complexes are photolyzed by biologically harmless visible light. In the present study, we show that RuBi-caged nicotine can be used as a source of free nicotine to induce proliferation of A549 nonsmall-cell lung cancer (NSCLC) cells by acting on nicotinic acetylcholine receptors expressed in these cells. RuBi-nicotine was photolyzed using LED light source with the spectrum matching RuBi-absorption. Photorelease of free nicotine ([Nic]_p/r) was quantified by high-performance liquid chromatography (HPLC). 5-s-long light exposure of 10 μm of RuBi-nicotine generated 2 μm [Nic]_p/r which enhanced A549 cell proliferation similarly to the 2 μm of plain nicotine during 72 h of cell culturing. Both RuBi-nicotine per se and its photolysis byproduct exerted no effect on A549 cells. We conclude that RuBi-nicotine can be a good source of free nicotine for inducing short- and long-term biological effects. Photolysis of RuBi-nicotine is quite effective, and can produce biologically relevant concentrations of nicotine at acceptable concentrations of the source material with the use of simple, inexpensive, and easily accessible light sources.