Templated nucleation of hybrid iron oxide nanoparticles on polysaccharide nanogels

Novel organic–inorganic hybrid nanoparticles consisting of polymer–hydrogel nanoparticles (nanogels) and iron oxide were developed for potential biomedical applications. Hybrid nanoparticles were prepared by a simple procedure using polysaccharide nanogels as a reactive site for iron oxide formation. The hybrid nanoparticles have a narrow size distribution with a diameter of approximately 30 nm and show high colloidal stability. These nanohybrid particles could be used as a contrast medium for magnetic resonance imaging or for magnetic hyperthermia therapy.     

A Selective Synthesis of 3,3-Di-C-(hydroxymethyl)-3-deoxy-furanorono-1,4-lactone in the Formose Reaction

Abstract

The formose reaction, by which a complex mixture of sugars and sugar alcohols (the so-called formose) are produced by the base-catalyzed condensation of formaldehyde, has received much attention in connection with the prebiotic synthesis of carbohydrates² and the microbial utilization of formose.^3–5 Formose, however, has not been useful yet, because of the complexity of this product mixture (Fig. 1a). Therefore, it seemed desirable to make the reaction more selective.     

First Synthesis of DL-2-C-Hydroxymethyl-3-Pentulose in the Formose Reaction

Abstract

The formose reactions² in N,N-dimethylformamide (DMF) catalyzed by 2-(dimethylamino)ethanol and thiamine hydrochloride, have been found to give rise to dihydroxyacetone and DL-glycero-tetrulose selectively at 1.1 M and 3.0 M of formaldehyde concentration, respectively. In our consecutive study on the formose reaction in DMF, it has been fortunately found that the distribution of products is able to be controlled by the amount of water added to the reaction mixture. We describe herein the first example of the favored formation of DL-2-C-hydroxymethyl-3-pentu-lose (GP-19¹) in the formose reaction using DMF-H₂O solvent, and it's isolation and structure elucidation.     

Selective hydrogen peroxide oxidation of sulfides to sulfoxides or sulfones with MWW-type titanosilicate zeolite catalyst under organic solvent-free conditions

Selective oxidation of sulfides to sulfoxides and sulfones with hydrogen peroxide under organic solvent-free conditions was demonstrated by the MWW-type titanosilicate zeolite catalyst. Sulfides were oxidized smoothly to give sulfoxides with good selectivities at ambient temperature using 1.0–1.2 equiv of hydrogen peroxide with the MWW-type titanosilicate zeolite catalyst. Especially, the Ti-MWW with an interlayer-expanded structure (Ti-IEZ-MWW) catalyst showed high activity with good chemoselectivity for the oxidation of various sulfides. The catalyst is recyclable for at least five cycles, and the only byproduct is water. Sulfides were directly oxidized to give sulfones in high yields by 2.5 equiv of hydrogen peroxide with the MWW-type titanosilicate zeolite catalyst under organic solvent-free conditions.     

Laser-induced breakdown spectroscopy in Asia

Laser-induced breakdown spectroscopy (LIBS) is an analytical detection technique based on atomic emission spectroscopy to measure the elemental composition. LIBS has been extensively studied and developed due to the non-contact, fast response, high sensitivity, real-time and multi-elemental detection features. The development and applications of LIBS technique in Asia are summarized and discussed in this review paper. The researchers in Asia work on different aspects of the LIBS study in fundamentals, data processing and modeling, applications and instrumentations. According to the current research status, the challenges, opportunities and further development of LIBS technique in Asia are also evaluated to promote LIBS research and its applications.     

Rhodium(I)‐Catalyzed Cyclization of Allenynes with a Carbonyl Group through Unusual Insertion of a CO Bond into a Rhodacycle Intermediate

Rhodium(I)‐catalyzed cyclization of allenynes with a tethered carbonyl group was investigated. An unusual insertion of a C?O bond into the C(sp²)–rhodium bond of a rhodacycle intermediate occurs via a highly strained transition state. Direct reductive elimination from the obtained rhodacyle intermediate proceeds to give a tricyclic product containing an 8‐oxabicyclo[3.2.1]octane skeleton, while β‐hydride elimination from the same intermediate gives products that contain fused five‐ and seven‐membered rings in high yields.     

Organic Dicarboxylate Negative Electrode Materials with Remarkably Small Strain for High‐Voltage Bipolar Batteries

As advanced negative electrodes for powerful and useful high‐voltage bipolar batteries, an intercalated metal–organic framework (iMOF), 2,6‐naphthalene dicarboxylate dilithium, is described which has an organic‐inorganic layered structure of π‐stacked naphthalene and tetrahedral LiO₄ units. The material shows a reversible two‐electron‐transfer Li intercalation at a flat potential of 0.8 V with a small polarization. Detailed crystal structure analysis during Li intercalation shows the layered framework to be maintained and its volume change is only 0.33 %. The material possesses two‐dimensional pathways for efficient electron and Li⁺ transport formed by Li‐doped naphthalene packing and tetrahedral LiO₃C network. A cell with a high potential operating LiNi_0.5Mn_1.5O₄ spinel positive and the proposed negative electrodes exhibited favorable cycle performance (96 % capacity retention after 100 cycles), high specific energy (300 Wh kg^?1), and high specific power (5 kW kg^?1). An 8 V bipolar cell was also constructed by connecting only two cells in series.     

Dehydration‐fragmentation mechanism of cathinones and their metabolites in ESI‐CID

Various cathinone‐derived designer drugs (CATs) have recently appeared on the drug market. This study examined the mechanism for the generation of dehydrated ions for CATs during electrospray ionization collision‐induced dissociation (ESI‐CID). The generation mechanism of dehydrated ions is dependent on the amine classification in the cathinone skeleton, which is used in the identification of CATs. The two hydrogen atoms eliminated during the dehydration of cathinone (primary amine) and methcathinone (secondary amine) were determined, and the reaction mechanism was elucidated through the deuterium labeling experiments. The hydrogen atom bonded to the amine nitrogen was eliminated with the proton added during ESI, in both of the tested compounds. This provided evidence that CATs with tertiary amine structures (such as dimethylcathinone and α‐pyrrolidinophenones [α‐PPs]) do not undergo dehydration. However, it was shown that the two major tertiary amine metabolites (1‐OH and 2″‐oxo) of CATs generate dehydrated ions in ESI‐CID. The dehydration mechanisms of the metabolites of α‐pyrrolidinobutiophenone (α‐PBP) belongs to α‐PPs were also investigated. Stable‐isotope labeling showed the dehydration of the 1‐OH metabolite following a simple mechanism where the hydroxy group was eliminated together with the proton added during ESI. In contrast, the dehydration mechanism of the 2″‐oxo metabolite involved hydrogen atoms in three or more locations along with the carbonyl group oxygen, indicating that dehydration occurred via multiple mechanisms likely including the rearrangement reaction of hydrogen atoms. These findings presented herein indicate that the dehydrated ions in ESI‐CID can be used for the structural identification of CATs.     

Macrocyclic Metal Complexes Bearing Rigid Polyaromatic Ligands: Synthesis and Catalytic Activity

We synthesised palladium and platinum complexes possessing cyclic and acyclic pincer‐type polyaromatic ligands and investigated their structural effect on the catalysis. The pincer‐type bis(6‐arylpyridin‐2‐yl)benzene skeleton was constructed via Kröhnke pyridine synthesis under transition metal‐free conditions on gram‐scale quantity. Ligand structure significantly influenced catalytic activity toward the platinum‐catalysed hydrosilylation of diphenyl acetylenes, despite the ligand‐independence of the conformations and electronic properties of these complexes.     

Carbometalation and Heterometalation of Carbon‐Carbon Multiple‐Bonds Using Group‐13 Heavy Metals: Carbogallation,Carboindation, Heterogallation,and Heteroindation

Organogallium and ‐indium compounds are useful reagents in organic synthesis because of their moderate stability, efficient reactivity and high chemoselectivity. Carbogallation and ‐indation of a carbon‐carbon multiple bond achieves the simultaneous formation of carbon‐carbon and carbon‐metal bonds. Heterogallation and ‐indation construct carbon‐heteroatom and carbon‐metal bonds. Therefore, these reaction systems represent a significant synthetic method for organogalliums and ‐indiums. Many chemists have attempted to apply various types of unsaturated compounds such as alkynes, alkenes, and allenes to these reaction systems. This minireview provides an overview of carboindation and ‐gallation as well as heteroindation and ‐gallation.