Polyphenol-Mediated Assembly of Proteins for Engineering Functional Materials

Functional materials composed of proteins have attracted much interest owing to the inherent and diverse functionality of proteins. However, establishing general techniques for assembling proteins into nanomaterials is challenging owing to the complex physicochemical nature and potential denaturation of proteins. Here, a simple, versatile strategy is introduced to fabricate functional protein assemblies through the interfacial assembly of proteins and polyphenols (e.g., tannic acid) on various substrates (organic, inorganic, and biological). The dominant interactions (hydrogen-bonding, hydrophobic, and ionic) between the proteins and tannic acid were elucidated; most proteins undergo multiple noncovalent stabilizing interactions with polyphenols, which can be used to engineer responsiveness into the assemblies. The proteins retain their structure and function within the assemblies, thereby enabling their use in various applications (e.g., catalysis, fluorescence imaging, and cell targeting).     

On the existence of hydrogen atoms in higher dimensional Euclidean spaces

The question of whether hydrogen atoms can exist or not in spaces with a number of dimensions (D) greater than 3 is revisited. The lowest quantum mechanical stable states and the corresponding wave functions are determined by applying Numerov?s method to solve Schrödinger?s equation. States for different angular momentum quantum number and dimensionality are considered. One is lead to the result that hydrogen atoms in higher dimensions could actually exist. The most probable distance between the electron and the nucleus are then computed as a function of D showing the possibility of tiny confined states.     

Rigid chain ribbon‐like metallopolymers

A set of new copolymers is here reported in which the repeating units are connected each other through Cu(II) metal centers. The coordination link is based on the bis‐chelating properties of salicylaldiminate groups of two different monomers. Due to their chemical structure, the two monomers afford, respectively, flexible and rigid repeating units in the metallocopolymers constitution upon coordination to copper centers. All the copolymers were soluble and easily processable. As shown by XRD analysis, rigid units' rich copolymers adopt a ribbon‐like structure in solid state in which highly planar strands of polymer stack thanks to π?π interactions, similarly to the polymer composed exclusively by rigid units. This behavior can be justified assuming the existence of a partial block character in copolymer constitution where long sequences of rigid units are alternated to sequences of flexible units. This assumption is supported also by DSC and UV–Vis analysis. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2412–2421     

Lewis acid-mediated azidolysis of 2,3-three membered heterocyclic amines

The Lewis acid-catalyzed regioselective azidolysis of 2,3-three membered heterocyclic amines has been investigated. The results obtained demonstrated that using TMSN₃ as a source of azide, the appropriate choice of Lewis acid allowed to obtain different regio- and stereocontrolled precursors of aminoalcoholic and triaminic sequences. Considering the occurrence of these moieties in the structure of many biologically active compounds, the present methodologies could represent a powerful tool in organic synthesis for the preparation of interesting molecules.     

Quenching vibrations of cesium dimers by He at low and ultralow temperatures: quantum dynamical calculations

This paper analyses in detail the energy redistribution from the upper vibrational levels of Cs dimers, thought to be obtained from initial recombination processes that generate excited internal states of the triplet configuration ³ Σ _u ⁺ . Their quenching is examined as they are made to further collide with ⁴He buffer gas at temperatures below and around 100 mK. The relevant cross sections are computed by using a multichannel quantum dynamical approach and employ a full, ab initio potential energy surface. Due to their smallness (see Ref. [R.B. Ross, J.M. Powers, T. Atashroo, W.C. Ermler, I.A. LaJohn, P. Christiansen, J. Chem. Phys. 93, 6654 (1999)]) the fine structure effects have not been explicitly included in this study. The final, cumulative cross-sections are discussed and analyzed in terms of the overall quenching behavior shown by different initial states of the dimer and in terms of the changing ratios between collisional cooling and vibrational quenching cross sections as a function of trap temperature. The corresponding quenching rates are also computed and analysed.     

Modular Assembly of Host–Guest Metal–Phenolic Networks Using Macrocyclic Building Blocks

The manipulation of interfacial properties has broad implications for the development of high‐performance coatings. Metal–phenolic networks (MPNs) are an emerging class of responsive, adherent materials. Herein, host–guest chemistry is integrated with MPNs to modulate their surface chemistry and interfacial properties. Macrocyclic cyclodextrins (host) are conjugated to catechol or galloyl groups and subsequently used as components for the assembly of functional MPNs. The assembled cyclodextrin‐based MPNs are highly permeable (even to high molecular weight polymers: 250–500 kDa), yet they specifically and noncovalently interact with various functional guests (including small molecules, polymers, and carbon nanomaterials), allowing for modular and reversible control over interfacial properties. Specifically, by using either hydrophobic or hydrophilic guest molecules, the wettability of the MPNs can be readily tuned between superrepellency (>150°) and superwetting (ca. 0°).     

On the influence of unsaturation on the macrolactonization of hydroxy fatty acids

Regioselectivity and yields of Yamaguchi cyclization of (15S,16S)‐15,16‐dihydroxy‐otadecyl‐(6Z,9Z,12Z)‐trienoic acid and its saturated homologue have been compared at different temperatures and concentrations. For the unsaturated species the regioselectivity of cyclization depends on temperature to such an extent that the preferred regioisomer changes as the temperature changes, whereas for the saturated homologue the even‐membered ring turns out to be always the preferred one. Molecular mechanics is used to interpret these findings. For both dihydroxyacids, there is experimental evidence that the yields of the two monocyclic regioisomers are thermodynamically controlled, unlike those of the analogue monohydroxy lactones. The higher cyclization yield of the unsaturated monohydroxyacid is interpreted in terms of conformational pre‐organization. Copyright © 2009 John Wiley & Sons, Ltd.     

The Vulcano 1994 summer campaign

Summary A set of measurements from various sources was collected for the Island of Vulcano (Aeolian Archipelago, South Tyrrhenian Sea) during summer 1994 with the scope of characterising the circulation pattern and the CO₂ natural volcanic emission of the island. Ground meteorological stations were activated, wind profiles from pilot balloons were obtained, ground temperature measurements were produced. Furthermore, temperature and humidity data from satellite (Landsat TM) were also derived. A critical analysis of the data on the gathered information was performed to quantify the volcanic risk related to the toxic-volcanic-gas release in foreseeable paroxysmal events.