Synthesis, characterization, self-assembly, and physical properties of 11-methylbenzo[d]pyreno[4,5-b]furan

Synthesis, structure, and physical properties of a novel 11-methylbenzo[d]pyreno[4,5-b]furan (BPF) and its self-assembly in water have been reported. The performance of nanowire-based films in organic light-emitting diodes is much better than that of the thin film deposited by directly drop-coating BPF molecules in THF solution. SEM study indicates that the well-organized structure (nanowires) is an important factor in enhancing the performance of OLED devices.     

On the effects of a varied diffusion time in vivo: is the diffusion in white matter restricted?

The aim of this work was to study the diffusion-related signal attenuation curves (signal-vs.-b curves) measured perpendicular and parallel to the neuronal fibers of the corticospinal tract in vivo and to determine whether effects of restricted diffusion could be observed when varying the diffusion time (T_D). A biexponential model and a two-compartment model including exchange according to the Kärger formalism were employed to analyze the signal-vs.-b curves. To validate the two-compartment model, restricted diffusion with exchange was simulated for uniformly sized cylinders, using different diameters and exchange times. The model was shown to retrieve the simulated parameters well, also when the short gradient pulse approximation was not met. The in vivo measurements performed perpendicular to the tracts, using b values up to 28000 s/mm² and T_D values between 64 and 256 ms, did not show the effects of restricted diffusion as expected from previous ex vivo studies. The applied two-compartment model yielded an average axonal diameter of about 4 μm and an intracellular exchange time of about 300 ms, but did not fit statistically well to the data. In conclusion, this study indicates that if the diffusion is modeled as two compartments, of which one is restricted, exchange must be included in the model.     

Deformation of Curved BPS Domain Walls and Supersymmetric Flows on 2<Emphasis Type="Italic">d</Emphasis> Kähler-Ricci Soliton

We consider some aspects of the curved BPS domain walls and their supersymmetric Lorentz invariant vacua of the four dimensional N = 1 supergravity coupled to a chiral multiplet. In particular, the scalar manifold can be viewed as a two dimensional Kähler-Ricci soliton generating a one-parameter family of Kähler manifolds evolved with respect to a real parameter, τ. This implies that all quantities describing the walls and their vacua indeed evolve with respect to τ. Then, the analysis on the eigenvalues of the first order expansion of BPS equations shows that in general the vacua related to the field theory on a curved background do not always exist. In order to verify their existence in the ultraviolet or infrared regions one has to perform the renormalization group analysis. Finally, we discuss in detail a simple model with a linear superpotential and the Kähler-Ricci soliton considered as the Rosenau solution.     

Quantitative Structure–Activity Relationships of Natural-Product-Inspired,Aminoalkyl-Substituted 1-Benzopyrans as Novel Antiplasmodial Agents

On the basis of the finding that various aminoalkyl-substituted chromene and chromane derivatives possess strong and highly selective in vitro bioactivity against Plasmodium falciparum, the pathogen responsible for tropical malaria, we performed a structure–activity relationship study for such compounds. With structures and activity data of 52 congeneric compounds from our recent studies, we performed a three-dimensional quantitative structure–activity relationship (3D-QSAR) study using the comparative molecular field analysis (CoMFA) approach as implemented in the Open3DQSAR software. The resulting model displayed excellent internal and good external predictive power as well as good robustness. Besides insights into the molecular interactions and structural features influencing the antiplasmodial activity, this model now provides the possibility to predict the activity of further untested compounds to guide our further synthetic efforts to develop even more potent antiplasmodial chromenes/chromanes.     

Insights into the interaction and binding mode of a set of antifungal azoles as inhibitors of potential fungal enzyme-based targets

Azole-containing compounds are a kind of chemical entities of natural and synthetic origin having a wide-range of activities. They are therefore considered as important moieties for fungicide development, mostly due to the possible action on several enzyme-based targets. As part of our research on fungicidal agents, the relationship between the ligand-enzyme affinities of several synthetic azole-containing compounds against a set of fungal enzyme-based targets was in silico evaluated through molecular docking. The affinity values of the test compounds were mostly higher than those of the respective test controls. Binding modes between enzymes and test compounds were firstly investigated through Vina scores and ligand–residue interactions. Furthermore, statistically relationships among docking scores were successfully found by multivariate analysis. They were mostly correlated with reported MIC₈₀ values, so it denoted an evident discrimination of the test compounds. Strong electron withdrawing groups on phenylacrylamide moiety were responsible for establishing stronger complexes with the enzyme targets, being trichodiene synthase and α-l-fucosidase the most important ones. Moreover, stability of a set of representative protein/ligand complexes was also analyzed by 10 ns molecular dynamics simulations (MD). Significant differences into the MD runs were detected and directly correlated to docking performances. Finally, docking affinity scores and HOMO–LUMO energy gaps resulted well predicted by comparative molecular field analysis (CoMFA) models, demonstrating the structure type is particularly associated with those calculated properties and these results were thus consistent with the respective validation parameters.     

Evaluation of the analytical performance of flow injection—Flame atomic absorption spectrometry

Analytical performance of flow injection—flame atomic absorption spectrometry was evaluated in terms of precision and sensitivity. For direct aqueous-solution introduction and alcoholic-eluate introduction after on-line sorbent extraction, the influence of the interfacing parameters was investigated, including the nebulizer uptake rate, sample-introduced flow rate and coupling tube length. High sensitivity could be achieved by the exploitation of the synergetic effect of both sample pumping and aspirating processes. A low nebulizer uptake rate combined with a high flow rate of the introduced sample zone produced the optimum precision better than 2% for peak-height measurements, the optimum rates being dependent on the nebulization characteristics of the solvent used. Precision and sensitivity deteriorate with increasing length of the coupling tube.     

Nucleophilic aromatic substitution of methyl 3‐nitropyridine‐4‐carboxylate

The nitro group of methyl 3‐nitropyridine‐4‐carboxylate ( 1 ) has successfully been replaced by nitrogen, oxygen and sulphur nucleophiles by nucleophilic aromatic substitution to give the 3‐azido, 3‐methoxy, 3‐phenoxy and 3‐thiophenoxypyridine‐4‐carboxylates ( 2a — d ).