Dichloridobis{N,N-diethyl-4-[(pyridin-2-yl-κN)diazen­yl]aniline}zinc

In the title complex, [ZnCl2(C15H18N4)2], the ZnII cation is coordinated by two N atoms from the pyridine rings of two unidentate N,N-diethyl-4-[(pyridin-2-yl)diazen­yl]aniline ligands and two Cl atoms, resulting in a distorted tetra­hedral geometry. The ligands are mutually transoid with respect to the metal atom. Weak inter­molecular C—H⋯Cl hydrogen bonds and π–π inter­actions, with centroid–centroid distances of 3.8452 (14) and 3.9932 (14) Å, are found in the crystal packing

Development of a Simple Reversible-Flow Method for Preparation of Micron-Size Chitosan-Cu(II) Catalyst Particles and Their Testing of Activity

A simple flow system employing a reversible-flow syringe pump was employed to synthesize uniform micron-size particles of chitosan-Cu(II) (CS-Cu(II)) catalyst. A solution of chitosan and Cu(II) salt was drawn into a holding coil via a 3-way switching valve and then slowly pumped to drip into an alkaline solution to form of hydrogel droplets. The droplets were washed and dried to obtain the catalyst particles. Manual addition into the alkaline solution or employment of flow system with a vibrating rod, through which the end of the flow line is inserted, was investigated for comparison. A sampling method was selected to obtain representative samples of the population of the synthesized particles for size measurement using optical microscopy. The mean sizes of the particles were 880 ± 70 µm, 780 ± 20 µm, and 180 ± 30 µm for the manual and flow methods, without and with the vibrating rod, respectively. Performance of the flow methods, in terms of rate of droplet production and particle size distribution, are discussed. Samples of 180 µm size CS-Cu(II) particles were tested for catalytic reduction of 0.5 mM p-nitrophenol to p-aminophenol by 100-fold excess borohydride. The conversion was 98% after 20 min, whereas without the catalyst there was only 14% conversion

Size-Controlled Preparation of Gold Nanoparticles Deposited on Surface-Fibrillated Cellulose obtained by Citric Acid-Modification

Cellulose-based functional materials have gained immense interest due to its low density, hydrophilicity, chirality, and degradability. So far, a facile and scalable preparation of fibrillated cellulose by treating the hydroxy groups of cellulose with citric acid (F-CAC) have been developed, and applied as a reinforcing filler for polypropylene composite. Herein, a size-selective preparation of Au nanoparticles (NPs) stabilized by F-CAC is described. By modifying the conditions of trans-deposition method, established in our group previously, a transfer of Au NPs from poly(N-vinyl-2-pyrrolidone) (PVP) to F-CAC proceeded up to 96% transfer efficiency with retaining its cluster sizes in EtOH. Meanwhile, the deposition efficiency drastically decreased in the case of non-modified cellulose, showing the significance of citric acid-modification. A shift of binding energy at Au 4f core level X-ray photoelectron microscopy (XPS) from 82.0 eV to 83.3 eV indicated that the NPs were stabilized on a F-CAC surface rather than by PVP matrix. The reproducible particle size growth was observed when 2-propanol was used as a solvent instead of EtOH, expanding the range of the available particle size with simple manipulation. The thus-obtained Au:F-CAC nanocatalysts exhibited a catalytic activity toward an aerobic oxidation of 1-indonol in toluene to yield 1-indanone quantitatively, and were recyclable at least 6 times, illustrating high tolerance against organic solvents.</p

OctaDist: a tool for calculating distortion parameters in spin crossover and coordination complexes

OctaDist is an interactive and visual program for determination of structural distortion in octahedral coordination complexes such as spin crossover complexes, single-ion magnets, perovskites or metal–organic frameworks. OctaDist computes the octahedral distortion parameters initially designed in the context of the spin-crossover phenomenon and denoted ζ, Σ, and Θ from standard structural files. The program also provides additional tools for molecular analyses and visualization. It emphasizes performance, flexibility, ease of use, application programming interface (API) consistency, and clear documentation. The modules and classes in OctaDist can be easily customized to include new algorithms or analytical tools. OctaDist is cross-platform supported for modern operating systems and is available as open-source distributed under the GNU General Public License version 3

Graphene oxide-loaded shortening as an environmentally friendly heat transfer fluid with high thermal conductivity

Graphene oxide-loaded shortening (GOS), an environmentally friendly heat transfer fluid with high thermal conductivity, was successfully prepared by mixing graphene oxide (GO) with a shortening. Scanning electron microscopy revealed that GO particles, prepared by the modified Hummer’s method, dispersed well in the shortening. In addition, the latent heat of GOS decreased while their viscosity and thermal conductivity increased with increasing the amount of loaded GO. The thermal conductivity of the GOS with 4% GO was higher than that of pure shortening of ca. three times, from 0.1751 to 0.6022 W/mK, and increased with increasing temperature. The GOS started to be degraded at ca. 360°C. After being heated and cooled at 100°C for 100 cycles, its viscosity slightly decreased and no chemical degradation was observed. Therefore, the prepared GOS is potentially used as environmentally friendly heat transfer fluid at high temperature

Oligonucleotide Hybridization Combined with Competitive Antibody Binding for the Truncation of a High-Affinity Aptamer

Truncation can enhance the affinity of aptamers for their targets by limiting nonessential segments and therefore limiting the molecular degrees of freedom that must be overcome in the binding process. This study demonstrated a truncation protocol relying on competitive antibody binding and the hybridization of complementary oligonucleotides, using platelet derived growth factor BB (PDGF-BB) as the model target. On the basis of the immunoassay results, an initial long aptamer was truncated to a number of sequences with lengths of 36–40 nucleotides (nt). These sequences showed apparent <i>K</i>_D values in the picomolar range, with the best case being a 36-nt truncated aptamer with a 150-fold increase in affinity over the full-length aptamer. The observed binding energies correlated well with relative energies calculated by molecular dynamics simulations. The effect of the truncated aptamer on PDGF-BB-stimulated fibroblasts was found to be equivalent to that of the full-length aptamer

Highly tunable catalyst supports for single-site sthylene polymerization

A new class of tunable crystalline solid supports for metal complexes has been synthesized and used for ethylene polymerization. We developed a family of high surface area, highly dispersible layered double hydroxides (AMO–LDHs) which, on treatment with alkyl aluminum activators, are able to support metallocene and nonmetallocene complexes to make active catalyst systems for the slurry polymerization of ethylene. We show that the chemical composition of the AMO–LDH support can dramatically affect catalyst activity, polymer morphology, and polymer microstructure. A Zr K-edge EXAFS study of these active catalysts has enabled us to observe a metallocene-derived single-center catalytic species in close proximity to the support