Tetrazole Photoclick Chemistry: Reinvestigating Its Suitability as a Bioorthogonal Reaction and Potential Applications

The bioorthogonality of tetrazole photoclick chemistry has been reassessed. Upon photolysis of a tetrazole, the highly reactive nitrile imine formed undergoes rapid nucleophilic reaction with a variety of nucleophiles present in a biological system, along with the expected cycloaddition with alkenes. The alternative use of the tetrazole photoclick reaction was thus explored: tetrazoles were incorporated into Bodipy and Acedan dyes, providing novel photo‐crosslinkers with one‐ and two‐photon fluorescence Turn‐ON properties that may be developed into protein‐detecting biosensors. Further introduction of these photo‐activatable, fluorogenic moieties into staurosporine resulted in the corresponding probes capable of photoinduced, no‐wash imaging of endogenous kinase activities in live mammalian cells.     

Dual‐Targeting Nanovesicles for In Situ Intracellular Imaging of and Discrimination between Wild‐type and Mutant p53

p53 is a tumor‐suppressor protein related to the cell cycle and programmed cell apoptosis. Herein, dual‐targeting nanovesicles are designed for in situ imaging of intracellular wild‐type p53 (WTp53) and mutant p53 (MUp53). Nanovesicle‐encapsulated plasmonic gold nanoparticles (AuNPs) were functionalized with consensus DNA duplexes, and a fluorescein isothiocyanate (FITC)‐marked anti‐MUp53 antibody was conjugated to the nanovesicle surface. After entering the cytoplasm, the released AuNPs aggregated through recognition of WTp53 and the double‐stranded DNA. The color changes of AuNPs were observed using dark‐field microscopy, which showed the intracellular WTp53 distribution. The MUp53 location was detected though the immunological recognition between FITC‐labeled anti‐MUp53 and MUp53. Thus, a one‐step incubation method for the in situ imaging of intracellular WTp53 and MUp53 was obtained; this was used to monitor the p53 level under a drug treatment.     

Basic Physicochemical Properties of Polyethylene Glycol Coated Gold Nanoparticles that Determine Their Interaction with Cells

A homologous nanoparticle library was synthesized in which gold nanoparticles were coated with polyethylene glycol, whereby the diameter of the gold cores, as well as the thickness of the shell of polyethylene glycol, was varied. Basic physicochemical parameters of this two‐dimensional nanoparticle library, such as size, ζ‐potential, hydrophilicity, elasticity, and catalytic activity ,were determined. Cell uptake of selected nanoparticles with equal size yet varying thickness of the polymer shell and their effect on basic structural and functional cell parameters was determined. Data indicates that thinner, more hydrophilic coatings, combined with the partial functionalization with quaternary ammonium cations, result in a more efficient uptake, which relates to significant effects on structural and functional cell parameters.     

Synthesis,Crystal Structure,and Electrochemical Properties of a Simple Magnesium Electrolyte for Magnesium/Sulfur Batteries

Most simple magnesium salts tend to passivate the Mg metal surface too quickly to function as electrolytes for Mg batteries. In the present work, an electroactive salt [Mg(THF)₆][AlCl₄]₂ was synthesized and structurally characterized. The Mg electrolyte based on this simple mononuclear salt showed a high Mg cycling efficiency, good anodic stability (2.5 V vs. Mg), and high ionic conductivity (8.5 mS cm^?1). Magnesium/sulfur cells employing the as‐prepared electrolyte exhibited good cycling performance over 20 cycles in the range of 0.3–2.6 V, thus indicating an electrochemically reversible conversion of S to MgS without severe passivation of the Mg metal electrode surface.     

Syntheses and electrochemical properties of three supramolecular architectures based on Keggin silicontungstates and different metal-organic units

Three new compounds [Mn(H₂O)₂(bimb)₂(H₃SiW₁₂O₄₀)₂](bimb)₄ (1), [Zn₂(bimb)₄(H₂O)₄][SiW₁₂O₄₀] (2), and [Ni₂(bimb)₄(H₂O)₄][SiW₁₂O₄₀] (3) (bimb = 1,3-bis(1-imidazoly)benzene) have been synthesized under the same hydrothermal reaction except for tuning the metal cations (Mn²⁺, Zn²⁺, and Ni²⁺). Structural characterizations show that the three compounds possess distinct structural motives. Compound 1 displays a supramolecular one-dimensional (1 D) chain formed by π···π interactions that occur among the almost parallel bimb ligands from adjacent [Mn(H₂O)₂(bimb)₂(SiW₁₂O₄₀)₂] dimers. Compound 2 shows a supramolecular two-dimensional (2D) layer achieved by intermolecular (C–H···O) hydrogen bondings between the Zn₂(bimb)₄ molecular loops and the SiW₁₂ anions. Compound 3 also exhibits a supramolecular 2D layer, but it is different from 2, which is generated by the π···π interactions among adjacent 1D polymeric chains. The distinct structural features of the three compounds suggest that the metal cations should play a significant role in the process of assembly. Additionally, the electrochemical properties of compounds 1–3 have been investigated, and the results indicate that compounds 1–3 possess excellent electrocatalytic activity toward reduction of both iodated and nitrite molecules.     

Electrochemical C−H/N−H Functionalization for the Synthesis of Highly Functionalized (Aza)indoles

Indoles and azaindoles are among the most important heterocycles because of their prevalence in nature and their broad utility in pharmaceutical industry. Reported herein is an unprecedented noble‐metal‐ and oxidant‐free electrochemical method for the coupling of (hetero)arylamines with tethered alkynes to synthesize highly functionalized indoles, as well as the more challenging azaindoles.     

Mechanistic Studies on the Stereoselectivity of the Serotonin 5‐HT1A Receptor

G‐protein‐coupled receptors (GPCRs) are involved in a wide range of physiological processes, and they have attracted considerable attention as important targets for developing new medicines. A central and largely unresolved question in drug discovery, which is especially relevant to GPCRs, concerns ligand selectivity: Why do certain molecules act as activators (agonists) whereas others, with nearly identical structures, act as blockers (antagonists) of GPCRs? To address this question, we employed all‐atom, long‐timescale molecular dynamics simulations to investigate how two diastereomers (epimers) of dihydrofuroaporphine bind to the serotonin 5‐HT_1A receptor and exert opposite effects. By using molecular interaction fingerprints, we discovered that the agonist could mobilize nearby amino acid residues to act as molecular switches for the formation of a continuous water channel. In contrast, the antagonist epimer remained firmly stabilized in the binding pocket.     

Constructing Interfacial Energy Transfer for Photon Up‐ and Down‐Conversion from Lanthanides in a Core–Shell Nanostructure

We report a new mechanistic strategy for controlling and modifying the photon emission of lanthanides in a core–shell nanostructure by using interfacial energy transfer. By taking advantage of this mechanism with Gd³⁺ as the energy donor, we have realized efficient up‐ and down‐converted emissions from a series of lanthanide emitters (Eu³⁺, Tb³⁺, Dy³⁺, and Sm³⁺) in these core–shell nanoparticles, which do not need a migratory host sublattice. Moreover, we have demonstrated that the Gd³⁺‐mediated interfacial energy transfer, in contrast to energy migration, is the leading process contributing to the photon emission of lanthanide dopants for the NaGdF₄@NaGdF₄ core–shell system. Our finding suggests a new direction for research into better control of energy transfer at the nanometer length scale, which would help to stimulate new concepts for designing and improving photon emission of the lanthanide‐based luminescent materials.     

Efficient Synthesis of Dimethyl Ether from Methanol in a Bifunctional Zeolite Membrane Reactor

A sandwich FAU–LTA zeolite dual‐layer membrane has been developed and used as a catalytic membrane reactor for the synthesis of dimethyl ether (DME). In the top H‐FAU layer with mild acidity, methanol is dehydrated to DME. The other reaction product, water, is removed in situ through a hydrophilic Na‐LTA layer, which is located between the porous alumina support and the H‐FAU top layer. The combination of mild acidity with the continuous removal of water results in high methanol conversion (90.9 % at 310 °C) and essentially 100 % DME selectivity. Furthermore, owing to the selective and continuous removal of water through the Na‐LTA membrane, catalyst deactivation can be effectively suppressed.