Single Crystalline,Non-stoichiometric Cocrystals of Hydrogen-Bonded Organic Frameworks

Porous frameworks composed of non-stoichiometrically mixed multicomponent molecules attract much attention from a functional viewpoint. However, their designed preparation and precise structural characterization remain challenging. Herein, we demonstrate that cocrystallization of tetrakis(4-carboxyphenyl)hexahydropyrene and pyrene derivatives ( CP-Hp and CP-Py , respectively) yields non-stoichiometric mixed frameworks through networking via hydrogen bonding. The composition ratio of CP-Hp and CP-Py in the framework was determined by single crystalline X-ray crystallographic analysis, indicating that the mixed frameworks were formed over a wide range of composition ratios. Furthermore, microscopic Raman spectroscopy on the single crystal indicates that the components are not uniformly distributed such as ideal solid solution, but are done gradationally or inhomogeneously.     

Vinyl polymerization. 432. Initiation mechanism of uncatalyzed polymerization in the presence of copper(II) ion

The initiation mechanisms of the uncatalyzed polymerization of methyl acrylate and methyl methacrylate by the system of starch, α-amylase or water-soluble nylon 3/copper(II) ion/H₂O were investigated by spin trapping techniques. Using 2,4-dimethyl-3-nitrosobenzene sulfonate d₈ and 5,5-dimethyl-1-pyrroline-N-oxide as the water-soluble spin trapping agents, the simultaneous generation of both monomer and hydroxyl radicals has been observed, and the propriety of the initiation mechanism proposed previously was confirmed. Thus, the initiation of polymerization in the presence of copper(II) ion was concluded to take place through a hydrogen atom transfer from the complexed water to the β-carbon of the complexed monomer.     

Deracemization in a Complex Quaternary System with a Second-Order Asymmetric Transformation by Using Phase Diagram Studies

A productive deracemization process based on a quaternary phase diagram study of a naphthamide derivative is reported. New racemic compounds of an atropisomeric naphthamide derivative have been discovered, and a quaternary phase diagram has been constructed that indicated that four solids are stable in a methanol/H₂O solution. Based on the results of a heterogeneous equilibria study showing the stable domain of the conglomerate, a second-order asymmetric transformation was achieved with up to 97 % ee. Furthermore, this methodology showcases the chiral separation of a stable racemic compound forming system and does not suffer from any of the typical limitations of deracemization, although application is still limited to conglomerate-forming systems. We anticipate that this present study will serve as a fundamental model for the design of sophisticated chiral separation processes.     

Neutral transport code for rovibrational population calculation of molecular hydrogen in large helical device plasmas

An rovibrationally resolved collisional-radiative model of molecular hydrogen (K. Sawada and M. Goto, Atoms 4: 29, 2016) is included in the authors' neutral transport code for large helical device (LHD) plasmas. The spatial distributions of the electron temperature and density, including the divertor and divertor leg regions, are given to the code. The molecules released from the graphite divertor target are tracked. The initial rotational and vibrational states of the released molecules are provided by simulation using a molecular dynamics model. The rovibrational population produced in an LHD plasma is evaluated.     

Geometrically Mismatched Hydrogen-bonded Framework Composed of Tetratopic Carboxylic Acid

Porous organic frameworks possessing interactive free sites in the pore have attracted much attention due to their potential to show the site-originated specific functionalities. Herein, we demonstrate that such a framework could be constructed using a concept of geometrically mismatched frameworks composed of phenanthroline-based tetratopic carboxylic acid CP-Phen . Simple recrystallization of CP-Phen yielded a solvent included porous framework CP-Phen-1 , in which three of four carboxy groups form hydrogen-bonded dimer to form a ladder-shaped framework, while the remained one does not participate in framework formation due to geometrical mismatch and interacts with solvent molecules through weak hydrogen-bonding. This result implies that our proposed strategy is effective to provide free interactive sites in porous frameworks. Although CP-Phen-1 undergoes two-step structural transformation presumably accompanied by hydrogen-bond rearrangements upon loss of solvent molecules, the activate framework shows good thermal stability up to 360 °C and selective CO₂ adsorption.     

Thermodynamic quantities of surface formation of aqueous electrolyte solutions X. Aqueous solution of 2:1 valence-type salts

The behaviors of a series of calcium halides and of alkali earth metal chlorides in the air/water surface region were studied in comparison with those of alkali metal halides by measuring the surface tension increments of solutions. The effect of salts with divalent cations on the surface tension increments is more pronounced than that of uni-univalent salts, but there are some similarities between these two types. It seems that the anions cause a marked effect on surface tension which is proportional to the magnitude of hydration in the bulk water. We also observed a decrease in the entropy change of surface formation with increasing concentration. The importance of an electrical double layer at the surface is discussed in relation to these surface tension increments.     

Synthesis of highly thermostable norbornene‐isoprene‐1‐octene terpolymer with titanium catalyst

Terpolymerization of norbornene (NB), isoprene (IP), and 1‐octene was achieved by using fluorenylamido‐ligated titanium catalyst, which showed very high activity for the copolymerization of NB and various α‐olefins. The content of IP in the terpolymer was controlled by the feed ratio and reaction temperature up to 7 mol %. The incorporated IP was mainly inserted in 1,4‐addition. The polymer was dissolved into common solvents such as toluene and chloroform, which enabled the preparation of a transparent film by solution casting process. The degradation temperature of the terpolymer was comparable with other cyclic olefin copolymers and the glass transition temperature (T_g) was higher than that of NB‐1‐octene copolymer with almost the same NB content. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2136–2140     

Electrochemical Condensation of Methylviologen on Specifically‐adsorbed Anion Layers

The adsorption of methylviologen dications (MV²⁺) on single‐crystalline Au electrodes in both H₂SO₄ and HClO₄ was examined. MV²⁺ strongly interacted with sulfate and bisulfate anions adsorbed on the Au(111) electrode surface in 0.05 M H₂SO₄ under a controlled potential of 1.25 V vs. the reversible hydrogen electrode (RHE). A characteristic non‐Faradaic current was observed at 1.10 V vs. RHE. When adsorption of MV²⁺ was carried out in 0.1 M HClO₄, the electrochemical response of MV²⁺ was less than that obtained in H₂SO₄. The results show that the formation of a highly ordered sulfate/bisulfate adlayer plays an important role in the formation of condensed MV²⁺ layers. Examination of polycrystalline Au and Au(100) electrodes revealed a poor electrochemical response due to the surface roughness of the Au substrate, but the electrochemical detection was applicable to polycrystalline Au electrodes. A systematic investigation of the structural dependency of viologen derivatives showed that molecular size is important for electrostatic interactions with a highly ordered sulfate/bisulfate adlayer. The findings of the present study demonstrate successful detection of MV²⁺ at a concentration of ≤1 pM with a non‐Faradaic current.     

Structure Controlling Factors of Oxido-Bridged Dinuclear Iron(III) Complexes

Oxido bridges commonly form between iron(III) ions, but their bond angles and symmetry vary with the circumstances. A large number of oxido-bridged dinuclear iron(III) complexes have been structurally characterized. Some of them belong to the C₂ point group, possessing bent Fe–O–Fe bonds, while some others belong to the C_i symmetry, possessing the linear Fe–O–Fe bonds. The question in this study is what determines the structures and symmetry of oxido-bridged dinuclear iron(III) complexes. In order to gain further insights, three oxido-bridged dinuclear iron(III) complexes were newly prepared with 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) ligands: [Fe₂OCl₂(bpy)₄][PF₆]₂ (1), [Fe₂O(NO₃)₂(bpy)₄][PF₆]₂·0.6MeCN·0.2(2-PrOH) (2), and [Fe₂OCl₂(phen)₄][PF₆]₂·MeCN·0.5H₂O (3). The crystal structures of 1, 2, and 3 were determined by the single-crystal X-ray diffraction method, and all of them were found to have the bent Fe–O–Fe bonds. Judging from the crystal structure, some intramolecular interligand hydrogen bonds were found to play an important role in fixing the structures. Additional density functional theory (DFT) calculations were conducted, also for a related oxido-bridged dinuclear iron(III) complex with a linear Fe–O–Fe bond. We conclude that the Fe–O–Fe bridge tends to bend like a water molecule, but is often stretched by interligand steric repulsion, and that the structures are mainly controlled by the intramolecular interligand interactions.     

Retro-Friedel-Crafts-Type Acidic Ring-Opening of Triptycenes: A New Synthetic Approach to Acenes

The triptycene scaffold has been ring-opened by using a retro-Friedel-Crafts-type reaction under acidic conditions to give its corresponding anthrone product. 9-Hydroxytriptycenes and unsubstituted triptycene undergo ring-opening reaction under strongly acidic conditions, such as with TfOH. An investigation of the substitution effect has revealed that the electron-donating group on the arene moiety allows the reaction to proceed in the presence of a weaker acid, such as TFA. In addition, the reaction has been successfully applied toward the synthesis of tetracene.