Self-assembly of a water-soluble endohedrally functionalized coordination cage including polar guests

Coordination cages containing endohedrally functionalized aromatic cavities are scarce in the literature. Herein, we report the self-assembly of a tetra-cationic super aryl-extended calix[4]pyrrole tetra-pyridyl ligand into a water-soluble Pd(ii)-cage featuring two endohedral polar binding sites. They are defined by the four pyrrole NHs of the calix[4]pyrrole unit and the four inwardly directed α-protons of the coordinated pyridyl groups. The efficient assembly of the Pd(ii)-cage requires the inclusion of mono- and ditopic pyridyl N-oxide and aliphatic formamide guests. The monotopic guests only partially fill the cage''s cavity and require the co-inclusion of a water molecule that is likely hydrogen-bonded to the endohedral α-pyridyl protons. The ditopic guests are able to completely fill the cage''s cavity and complement both binding sites. We observed high conformational selectivity in the inclusion of the isomers of α,ω-bis-formamides. We briefly investigate the uptake and release mechanism/kinetics of selected polar guests by the Pd(ii)-cage using pair-wise competition experiments.

A tetra-cationic calix[4]pyrrole tetra-pyridyl ligand self-assembles into a water-soluble Pd(ii)-cage featuring two endohedral polar binding sites. The Pd(ii)-cage encapsulates pyridyl N-oxide and aliphatic formamide guests in water.     

Loading of Amino Acids onto RNA in a Putative RNA-Peptide World

RNA is a molecule that can both store genetic information and perform catalytic reactions. This observed dualism places RNA into the limelight of concepts about the origin of life. The RNA world concept argues that life started from self-replicating RNA molecules, which evolved toward increasingly complex structures. Recently, we demonstrated that RNA, with the help of conserved non-canonical nucleosides, which are also putative relics of an early RNA world, had the ability to grow peptides covalently connected to RNA nucleobases, creating RNA-peptide chimeras. It is conceivable that such molecules, which combined the information-coding properties of RNA with the catalytic potential of amino acid side chains, were once the structures from which life emerged. Herein, we report prebiotic chemistry that enabled the loading of both nucleosides and RNAs with amino acids as the first step toward RNA-based peptide synthesis in a putative RNA-peptide world.     

Synthesis,characterization, and crystal structure of 2′,2″-dihydroxy-3,3‴-bichalcone and its related chalcone–flavanone and biflavanone analogs

The synthesis of 3,3′-diformyl-1,1′-biphenyl 1 and its reaction in basic media with 2′-hydroxyacetophenone and paeonol, respectively, are described. The products, a bichalcone 2, it’s partially cyclized analog, a flavanone–chalcone 3 and the fully cyclized biflavanone 4, are reported as products for the first reaction, while only the chalcone 5 for the second. The crystalline and molecular structure, solved by X-ray diffraction analysis, for compounds 2 and 5 are also presented in this work.     

Bioinspired Nitroalkylation for Selective Protein Modification and Peptide Stapling

Nitroalkanes react specifically with aldehydes, providing rapid, stable, and chemoselective protein bioconjugation. These nitroalkylated proteins mimic key post‐translational modifications (PTMs) of proteins and can be used to understand the role of these PTMs in cellular processes. Demonstrated here is the substrate scope of this bioconjugation by attaching a variety of tags, such as NMR tags, fluorescent tags, affinity tags, and alkyne tags, to proteins. The structure and enzymatic activity of modified proteins remain conserved after labeling. Notably, the nitroalkane group leads to easy characterization of proteins by mass spectrometry because of its distinct fingerprint pattern. Importantly, the nitro‐alkylated peptides provide a new handle for site‐selective fluorination of peptides, thus installing a specific probe to study peptide–protein interactions by ¹⁹F NMR spectroscopy. Furthermore, nitroalkane reagents can be used for the late‐stage diversification of peptides and for the synthesis of peptide staples.     

Convolution of Ultradistributions and Field Theory

A general definition of convolution between twoarbitrary tempered ultradistributions is given. When oneof the tempered ultradistributions is rapidly decreasingthis definition coincides with the definition of J. Sebastiao e Silva. The product of twoarbitrary distributions of exponential type is definedvia the convolution of its corresponding Fouriertransforms. Several examples of convolution of twotempered ultradistributions and singular products aregiven. In particular, we reproduce the results obtainedby A. Gonzales Dominguez and A. Bredimas.     

Analysis of the prediction capacity of a categorization method for urban noise assessment

A street categorization method to study urban noise was tested by comparing its results and predictive capacity with those of a reference method – the standard grid method (mentioned in the ISO 1996 standard). To this end, two independent noise surveys were carried out simultaneously in the city of Cáceres (Spain), each using one of these two methods. In a first step, the overall values of each procedure were obtained and the differences analyzed. Then, to analyze the predictive capacity of the categorization method, the two noise maps were constructed, and their predicted values (the noise levels of the squares of the grid for the grid method, and of the categories for the categorization method) were compared with the data of the other procedure used as control.It was found that the categorization method yielded similar results for the overall analysis of the city to those obtained with the value of the points of the grid method with considerably fewer sampling points.The categorization method also seems to be a more suitable predictor for new measurements, particularly for levels in the noisiest streets of the town.     

Peak demand forecasting for a seasonal product using Bayesian approach

An actual demand-forecasting problem of the US apparel dealers is studied. Demand is highly fluctuating during the peak sale season and low prior to the peak season. The model is described by the continuous time stochastic process applying the Bayesian process. The standard gamma distribution is selected for the demand process and an inverse gamma distribution is chosen as the conjugate prior for the model. The choice is supported by the maximum likelihood estimate among a number of non-negative distribution models. The proposed Bayesian models predict the probability of the future demand expressed explicitly conditional on the observed demand prior to the peak season. The data set illustrates partial demand of a seasonal product procured by the US dealers from overseas. In recent years, hazard and operational risks due to weather disasters and equipment shutdowns were felt significantly. These caused supply chain disruption and unrecorded demand. The model is extended to contribute to forecast from an unrecorded data set due to supply disruption. Forecasts are compared with real data and a widely implemented adaptive Holt-Winters (H-W) seasonal forecasting model. Results show that the forecasts calculated by the proposed methods do better than those of the adaptive H-W model.