Study of the crystal shape and its influence on the anti‐tumor activity of tumor necrosis factor‐related apoptosis‐inducing ligand (Apo2L/TRAIL)

This paper describes a method about the crystal shape control improving the anti‐tumor activity of tumor necrosis factor‐related apoptosis‐inducing ligand (Apo2L/TRAIL) in a batch cooling suspension crystallization by selecting pH values as a controllable variable. Three shaped TRAIL crystals could be obtained under different pH conditions, among which the hexagonal plate crystals had the highest specific activities against tumor cell line. The relationship among pH values, trimer contents and the specific activities of crystals and the purified TRAIL solutions were investigated. The results showed that different trimer contents resulted from pH altering in crystals and protein solutions is a main reason for their different specific activities. The studies may supply a new method to improve the bioactivity of TRAIL agent during its production and storage. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis of 3-(Bromomethylene)isobenzofuran-1(3H)-ones through regioselective 5-exo-dig bromocyclization of 2-alkynylbenzoic acids

A direct synthesis of 3-(bromomethylene)isobenzofuran-1(3H)-ones from 2-alkynylbenzoic acids is developed through a regioselective 5-exo-dig bromocyclization. The reaction proceeds smoothly with a broad substrate scope. The products can be further elaborated via a palladium-catalyze cross-coupling reaction, or can convert to other heterocycles through simple operation. Preliminary mechanistic studies reveal that this transformation undergoes a radical process.     

Regioselective α-benzylation of 3-iodoazetidine via Suzuki cross-coupling

An efficient protocol for the synthesis of α-benzyl azetidines starting from benzylboronic acid pinacol ester derivatives and 3-iodoazetidine was developed. A wide range of α-benzyl azetidine derivatives were obtained in moderate to good yields with high regioselectivity (>99%).     

Syntheses,Structures, and Magnetic Properties of Two DMTCNQ and DETCNQ Gadolinium Complexes

Two DMTCNQ (DMTCNQ = 2,5‐dimethyl‐7,7,8,8‐tetracyano‐p‐quinodimethane) and DETCNQ (DETCNQ = 2,5‐diethyl‐7,7,8,8‐tetracyano‐p‐quinodimethane) gadolinium complexes [Gd(DMTCNQ)₂(CH₃OH)(H₂O)₆][DMTCNQ] · 4H₂O ( 1 ) and [Gd(DETCNQ)(H₂O)₇][2DETCNQ] ( 2 ) were synthesized by reactions of GdCl₃ · 6H₂O with Li(DMTCNQ) or Li(DETCNQ). X‐ray diffraction analysis reveals that complexes 1 and 2 are discrete complexes. The central metal atom in 1 is coordinated by two DMTCNQ ligand radicals whereas that in 2 is coordinated by just one DETCNQ ligand radical. The adjacent molecules are connected by the intermolecular hydrogen bonds to form the two‐dimensional (2D) supramolecular layer structures, which are further packed into a three‐dimensional (3D) supramolecular architecture through the π–π interactions between ligand radicals in 1 and 2 . Magnetic investigation indicates that the antiferromagnetic interactions between spin carriers exists in 1 and 2 .     

Electrochemical Monitoring of ROS/RNS Homeostasis Within Individual Phagolysosomes Inside Single Macrophages

The existence of a homeostatic mechanism regulating reactive oxygen/nitrogen species (ROS/RNS) amounts inside phagolysosomes has been invoked to account for the efficiency of this process but could not be unambiguously documented. Now, intracellular electrochemical analysis with platinized nanowire electrodes (Pt‐NWEs) allowed monitoring ROS/RNS effluxes with sub‐millisecond resolution from individual phagolysosomes impacting onto the electrode inserted inside a living macrophage. This shows for the first time that the consumption of ROS/RNS by their oxidation at the nanoelectrode surface stimulates the production of significant ROS/RNS amounts inside phagolysosomes. These results establish the existence of the long‐postulated ROS/RNS homeostasis and allows its kinetics and efficiency to be quantified. ROS/RNS concentrations may then be maintained at sufficiently high levels for sustaining proper pathogen digestion rates without endangering the macrophage internal structures.     

Bowl Inversion in an Exo‐type Supramolecule in the Solid State

Bowl inversion is a unique property of buckybowls. The polarity and assembly configuration of buckybowls are reversed after bowl inversion. So far, this unique phenomenon has been studied in solution and on surface, but not in solid state due to spatial constraint. Now a series of exo‐type supramolecular assemblies of trithiasumanene and nanographene are investigated. Tuning the electron density of the nanogaphene component was found to directly affect the binding constant of the complex. Reversible bowl inversion in the solid state was then successfully achieved by subjecting the trithiasumanene–nanographene assembly with the weakest binding strength to repeated heating–cooling cycles, which was unambiguously observed by single crystal X‐ray diffraction.     

Encapsulation of a Phase‐Change Material in Nanocapsules with a Well‐Defined Hole in the Wall for the Controlled Release of Drugs

As a class of biocompatible and biodegradable phase‐change materials, natural fatty acids have received considerable interest in recent years for temperature‐controlled release of drugs. However, the poor dispersibility and colloidal stability of their nanoparticles under physiological conditions place a major limitation on their applications in biomedicine. Herein, we report a facile method for encapsulating a mixture of two natural fatty acids (with a eutectic melting point at 39 °C) in a biocompatible, silica‐based nanocapsule to achieve both stable dispersion and controllable release of drugs. The nanocapsules have a well‐defined hole in the wall to ensure easy loading of fatty acids, together with multiple types of functional components such as therapeutics and near‐infrared dyes. The payloads can be released through the hole when the fatty acids are melted upon photothermal heating. The release profile can be controlled by varying the size of the hole and/or the duration of laser irradiation.     

Strain‐Induced Isomerization in One‐Dimensional Metal–Organic Chains

The ability to use mechanical strain to steer chemical reactions creates completely new opportunities for solution‐ and solid‐phase synthesis of functional molecules and materials. However, this strategy is not readily applied in the bottom‐up on‐surface synthesis of well‐defined nanostructures. We report an internal strain‐induced skeletal rearrangement of one‐dimensional (1D) metal–organic chains (MOCs) via a concurrent atom shift and bond cleavage on Cu(111) at room temperature. The process involves Cu‐catalyzed debromination of organic monomers to generate 1,5‐dimethylnaphthalene diradicals that coordinate to Cu adatoms, forming MOCs with both homochiral and heterochiral naphthalene backbone arrangements. Bond‐resolved non‐contact atomic force microscopy imaging combined with density functional theory calculations showed that the relief of substrate‐induced internal strain drives the skeletal rearrangement of MOCs via 1,3‐H shifts and shift of Cu adatoms that enable migration of the monomer backbone toward an energetically favorable registry with the Cu(111) substrate. Our findings on this strain‐induced structural rearrangement in 1D systems will enrich the toolbox for on‐surface synthesis of novel functional materials and quantum nanostructures.     

Finite-Temperature Dimer Method for Finding Saddle Points on Free Energy Surfaces

The dimer method and its variants have been shown to be efficient in finding saddle points on potential surfaces. In the dimer method, the most unstable direction is approximately obtained by minimizing the total potential energy of the dimer. Then, the force in this direction is reversed to move the dimer toward saddle points. When the finite-temperature effect is important for a high-dimensional system, one usually needs to describe the dynamics in a low-dimensional space of reaction coordinates. In this case, transition states are collected as saddle points on the free energy surface. The traditional dimer method cannot be directly employed to find saddle points on a free energy surface since the surface is not known a priori. Here, we develop a finite-temperature dimer method for searching saddle points on the free energy surface. In this method, a constrained rotation dynamics of the dimer system is used to sample dimer directions and an efficient average method is used to obtain a good approximation of the most unstable direction. This approximated direction is then used in reversing the force component and evolving the dimer toward saddle points. Our numerical results suggest that the new method is efficient in finding saddle points on free energy surfaces. © 2019 Wiley Periodicals, Inc.