Helical supramolecular assembly of N2,N2′‐bis[3‐(morpholin‐4‐yl)propyl]‐N1,N1′‐(1,2‐phenylene)dioxalamide dimethyl sulfoxide monosolvate

In the title compound, C₂₄H₃₆N₆O₆·C₂H₆OS, the carbonyl groups are in an antiperiplanar conformation, with O=C—C=O torsion angles of 178.59 (15) and −172.08 (16)°. An intramolecular hydrogen‐bonding pattern is depicted by four N—H...O interactions, which form two adjacent S(5)S(5) motifs, and an N—H...N interaction, which forms an S(6) ring motif. Intermolecular N—H...O hydrogen bonding and C—H...O soft interactions allow the formation of a meso‐helix. The title compound is the first example of a helical 1,2‐phenylenedioxalamide. The oxalamide traps one molecule of dimethyl sulfoxide through N—H...O hydrogen bonding. C—H...O soft interactions give rise to the two‐dimensional structure.     

Dibenzylammonium hydrogen maleate and a redetermination at 120 K of bis(dibenzylamino)methane

In dibenzylammonium hydrogen maleate [or dibenzylammonium (2Z)‐3‐carboxyprop‐2‐enoate], C₁₄H₁₆N⁺·C₄H₃O₄⁻, (I), the anion contains a fairly short and nearly linear O—H...O hydrogen bond, with an O...·O distance of 2.4603 (16) Å, but with the H atom clearly offset from the mid‐point of the O...O vector. The counter‐ions in (I) are linked by two N—H...O hydrogen bonds to form C₂²(6) chains and these chains are weakly linked into sheets by a C—H...O hydrogen bond. Bis(dibenzylamino)methane, C₂₉H₃₀N₂, (II), crystallizes with two independent molecules lying across twofold rotation axes in the space group C2/c, and the molecules are conformationally chiral; there are no direction‐specific intermolecular interactions in the crystal structure of (II).     

A chain of π‐stacked molecules in 4‐(2‐chlorophenyl)pyrrolo[1,2‐a]quinoxaline and a hydrogen‐bonded sheet in (4RS)‐4‐(1,3‐1,3‐benzodioxol‐6‐yl)‐4,5‐dihydropyrrolo[1,2‐a]quinoxaline

In the molecule of 4‐(2‐chlorophenyl)pyrrolo[1,2‐a]quinoxaline, C₁₇H₁₁ClN₂, (I), the bond lengths are consistent with electron delocalization in the two outer rings of the fused tricyclic system, with a localized double bond in the central ring. The molecules of (I) are linked into chains by a π–π stacking interaction. In (4RS)‐4‐(1,3‐benzodioxol‐6‐yl)‐4,5‐dihydropyrrolo[1,2‐a]quinoxaline, C₁₈H₁₄N₂O₂, (II), the central ring of the fused tricyclic system adopts a conformation intermediate between screw‐boat and half‐chair forms. A combination of N—H...O and C—H...π(arene) hydrogen bonds links the molecules of (II) into a sheet. Comparisons are made with related compounds.     

Determination of phenolic compounds and authentication of PDO Lambrusco wines by HPLC-DAD and chemometric techniques

This work proposes a fast and simple method for detection and quantification of phenolic compounds in PDO Lambrusco wines using HPLC-DAD and chemometric techniques. Samples belonging to three different varieties of Lambrusco (Grasparossa, Salamino and Sorbara) were analyzed to provide a methodology appropriate for routine analysis. Given the high complexity of the sample and the coelution among chromatographic peaks, the use of chemometric techniques to extract the information of the individual eluting compounds was needed. Multivariate curve resolution-alternating least squares (MCR-ALS) allowed the resolution of the chromatographic peaks obtained and the use of this information for the quantification of the phenolic analytes in the presence of interferences. Use of multiset analysis and local rank/selectivity information was proven to be crucial for the correct resolution and quantification of compounds. The quantitative data provided by MCR-ALS about the phenolic targets and additional compounds present in the samples analyzed provided wine composition profiles, which were afterwards used to distinguish among wine varieties. Principal component analysis applied to the wine profiles allowed characterizing the wines according to their varieties.     

Silica nanoparticle supported molecularly imprinted polymer layers with varied degrees of crosslinking for lysozyme recognition

Surface imprinting over nanosized support materials is particularly suitable for protein templates, considering the problems with mass transfer limitation and low binding capacity. Previously we have demonstrated a strategy for surface protein imprinting over vinyl-modified silica nanopartiles with lysozyme as a model template by polymerization in high-dilution monomer solution to prevent macrogelation. Herein, the synthesis process was further studied toward enhancement of the imprinting performance by examining the effect of several synthesis conditions. Interestingly, the feed crosslinking degree was found to have a great impact on the thickness of the formed imprinting polymer layers and the recognition properties of the resulting imprinted materials. The imprinted particles with a crosslinking degree up to 50% showed the best imprinting effect. The imprinting factor achieved 2.89 and the specific binding reached 23.3 mg g⁻¹, which are greatly increased compared to those of the lowly crosslinked imprinted materials reported previously. Moreover, the relatively high crosslinking degree led to no significant retarding of the binding kinetics to the imprinted particles, and the saturated adsorption was reached within 10 min. Therefore, this may be a promising method for protein imprinting.     

AIPO4 Supported Zinc Borohydride as a Novel Reagent for the Hydration of Aromatic Alkenes and Alkynes

Hydration of aromatic alkenes (styrene, α-methylstyrene and E-stilbene) and alkynes (phenyl and diphenylacetylene) has been achieved by the reaction of the corresponding alkenes or alkynes on zinc borohydride combined with AIPO₄ in DME. Except in the case of α-methylstyrene, Zn(BH₄)₂/AIPO₄ provides a more efficient and selective catalytic system than the combination with SiO₂ or Al₂O₃.     

Synthesis of Novel Pyrrolo[1′,5′‐a]‐1,8‐naphthyridine Derivatives through a Facile One‐Pot Process

Novel pyrrolo[1′,5′‐a]‐1,8‐naphthyridine compounds have been synthesized through a facile one‐pot process by the reaction of the corresponding 1,8‐naphthyridines with aliphatic anhydride. The structures were established by spectroscopic data. Further X‐ray crystal analysis of 4′‐acetyl‐7‐methyl‐pyrrolo[1′,5′‐a]‐1,8‐naphthyridine (1) identifies its intriguing molecular structure and reveals the strong π‐π stacking.     

Synthesis of Some C‐3,4,5‐Substituted 2,6‐Dimethyl‐1,4‐dihydropyridines (4‐DHPs)

A series of C‐3,4,5‐substituted 2,6‐dimethyl‐1,4‐dihydropyridines (1,4‐DHPs) with pharmacological properties were prepared by a variation from the classical Hantzsch synthesis. The procedure involves treatment of the respective aldehyde with either ethyl‐3‐aminocrotonate or 3‐aminocrotonitrile in anhydrous acetic acid at temperatures not exceeding 60°C, thus minimizing by‐product formation. The structures of title compounds were elucidated by ¹H NMR, ¹³C NMR, FTIR, and elemental analysis.     

Density Functional Theory Calculations on Rhodamine B and Pinacyanol Chloride. Optimized Ground State,Dipole Moment,Vertical Ionization Potential,Adiabatic Electron Affinity and Lowest Excited Triplet State

The ground state configuration of the gas phase cationic dyes pinacyanol chloride and rhodamine B are optimized with HF/6–311 + G(2d,2p) method and basis set. B3PW91/6–311 + G(2df,2p) functional and basis set is used to calculate the Mulliken atom charge distribution, total molecular energy, the dipole moment, the vertical ionization potential, the adiabatic electron affinity and the lowest excited triplet state, the last three as an energy difference between separately calculated open shell and ground states. The triplet and extra electron states are optimized to find the relaxation energy. In the ground state optimization of both dyes the chloride anion migrates to a position near the center of the chromophore. For rhodamine B the benzoidal group turns perpendicular to the chromophore plane. For both dyes, the LUMO is mostly of π character associated with the aromatic part of the molecule containing the chromophore. The highest occupied MOs consist of three almost degenerate eigenvectors involving the chloride anion coordinated with σ electrons in the molecular framework. The fourth highest MO is of π character. For both molecules in the gas phase ionization process the chloride anion loses the significant fraction of electric charge. In electron capture, the excess charge goes mainly on the dye cation.     

Impact of Dye‐Protein Interaction and Silver Nanoparticles on Rose Bengal Photophysical Behavior and Protein Photocrosslinking

The role of recombinant Type‐I human collagen in the free form or forming AgNP@collagen on the photophysical and photochemical behavior of rose Bengal was analyzed. The formation of dye aggregates on the protein surface was experimentally observed and corroborated by docking calculations. The formation of such aggregates is believed to change the main oxidative mechanism from Type‐II (singlet oxygen) to Type‐I (free radical) photosensitization. Remarkably, the presence of AgNP in the form of AgNP@collagen altered the dynamics of dye triplet deactivation, effectively preventing the dye degradation and reducing the extent of protein crosslinked. Both crosslinked rHC and AgNP@collagen were able to support fibroblasts proliferation, but only the material containing silver was resistant to S. epidermidis infection.