Broad band infrared near-field spectroscopy at finger print region using SPring-8

The authors report infrared near-field spectroscopy using synchrotron radiation at BL43IR, SPring-8 in the finger print region. At the microspectroscopy station, the infrared synchrotron radiation beam is focused on a cantilever probe with a 3 μm square aperture. A comb-shaped Au electrode with the width of 3 μm and the distance of 3 μm is used for the reflection measurement. The Au electrodes can be resolved at 650 cm⁻¹ and the resolution is estimated to be λ/5.     

Magnetostriction of a single crystal of nickel observed with an X-ray four-circle goniometer

We proposed a technique to observe magnetostrictive coefficients of a single crystal specimen with X-ray diffraction. An angle between a direction of crystallographic orientation and a direction of magnetic field could be estimated with two kinds of diffraction peaks which were found with an X-ray four-circle goniometer. The magnetostriction was measured by a shift of Bragg angle. This technique was suitable for a case to observe the magnetostrictive coefficient which varied as a function of the magnetic field direction. We applied the technique to a single crystal specimen of nickel and showed dependences of the magnetostriction on the magnetic field strength and its direction around an axis of easy magnetization at room temperature.     

Acyclic,Linear Oligo‐meta‐phenylenes as Multipotent Base Materials for Highly Efficient Single‐layer Organic Light‐emitting Devices

Oligo‐meta‐phenylenes have been designed and synthesized as multipotent base materials of single‐layer organic light‐emitting devices. Simple molecular structures of oligo‐meta‐phenylenes composed of linear phenylene arrays benefited from the wealth of modern reactions available for biaryl couplings and were concisely synthesized in a series. Structure‐performance relationship studies with the first seven congeners revealed key features important for the multipotent materials in single‐layer devices. As a result, highly efficient phosphorescent electroluminescence was made possible in a highly simplified device architecture comprising one‐region, single‐layer configurations. Detailed investigations with hole‐only devices disclosed that the hole mobility was effectively retarded by potent materials, which should facilitate hole/electron recombination for electroluminescence.     

Evaluation of physicochemical properties on the blending process of pharmaceutical granules with magnesium stearate by thermal effusivity sensor

Magnesium Stearate (MgSt) is a widely used lubricant for preventing tablet compression trouble. It is known that the powder characteristic of MgSt is different among MgSts manufactured by different methods and conditions. These differences affect blending efficiency with pharmaceutical additives. The purpose of this study is to evaluate the physicochemical properties of MgSt by thermal effusivity sensor for in-process monitoring of powder blending. MgSts having different physicochemical properties and granulated sugar spheres were used for model excipients. V-blender was used for powder blending. Thermal effusivity values of each of the ingredients in the blend were measured using one of the sensors prior to placing the ingredient in the blender. The effect of magnesium stearate addition to uniform ingredients can be clearly identified using the sensors. Compared to effusivity data and powder density, effusivity data correlated with the powder characteristics of magnesium stearate. These results suggested that effusivity can be used for end point detection of blending process for various magnesium stearates with sugar sphere. When various magnesium stearates were added to the granule, required time for achieving homogeneous powder blend was different. Blending behavior would be affected by the physicochemical characters. Blend uniformity and blended states of granules containing magnesium stearate can be detected nondestructively without intricate sampling process. Thermal effusivity sensors are an efficient tool to monitor the real time blending behavior of pharmaceutical ingredients.     

Diels-Alder via molecular recognition in a crystalline molecular flask

In the pore of a porous coordination network, Diels-Alder reactants, a diene and a dienophile, are recognized by donor-acceptor and multiple H-bond interactions, respectively, and fixed at ideal positions for the reaction. Heating the crystals promoted the Diels-Alder reactions with enhanced reactivity and controlled regioselectivity as clearly monitored by in situ X-ray crystallography.     

Soft- and reactive-landing of Cr(aniline)2 sandwich complexes onto self-assembled monolayers: separation between functional and binding sites

Soft- and reactive-landing of gas-phase synthesized cationic Cr(aniline)(2) complexes onto self-assembled monolayers of methyl-terminated (CH(3)-SAM) and carboxyl-terminated (COOH-SAM) organothiolates coated on gold were performed at hyperthermal collision energy (5-20 eV). The properties of the Cr(aniline)(2) complexes on the SAM surfaces were characterized using infrared reflection absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD), together with theoretical calculations based on density functional theory (DFT). For the CH(3)-SAM, the Cr(aniline)(2) complexes were embedded inside the SAM matrix in a neutral charge state, keeping a sandwich structure. For the COOH-SAM, the IRAS and TPD study revealed that the amine-containing Cr(aniline)(2) complexes were bound to the SAM surface in two forms of physisorption and chemical linking through an amide bond. In the desorption, the latter form appeared as the reaction product between organothiolates and Cr(aniline)(2) above 400 K, where the organothiolate molecules, forming the SAM, were desorbed from the gold surface. The results show that the hyperthermal depositions onto a COOH-SAM bring about reactive-landing followed by covalent linking of an amide bond between the amine-containing Cr(aniline)(2) complexes to the carboxyl-terminated SAM surface, in which the binding sites can be separated from the functional sites of the d-π interaction.     

Akaike's Information Criterion for Stoichiometry Inference of Supramolecular Complexes

“How do we decide the stoichiometry of host–guest complexes?” This question has long been answered by the Job plot since its first report in 1928. However, as the Job plot was claimed to be misleading in 2016, the question became an open question again and called for renewed investigations. An information-theoretic approach, called Akaike's information criterion, is introduced in this study to select the best model of host–guest complexes, which can rank the models with weight of evidence. A few test cases with unique cylindrical hosts were examined to demonstrate the applicability of the information-theoretic method. Consequently, reasonable views over the thermodynamic behaviors of dumbbell-and-cylinder complexes were obtained. Akaike's information criterion can be a useful and superior alternative to statistical null hypothesis testing, which was proposed as a remedy in place of the Job plot.     

Formation of a charge distribution within ionic gels by immobilized enzyme reaction: experimental observations and mathematical simulations

Thermally responsive cationic gels with immobilized urease, in the shape of a small cylinder with diameter 290 - 640 μm, were prepared via gelation of an aqueous monomer solution containing the enzyme. We used N-isopropylacrylamide and N-vinylimidazole as a thermo-sensitive and a pH-sensitive monomer, respectively. Diameters at different positions of the cylinder were microscopically measured in a cell through which substrate solution (pH 4; 35°C) was passed at a constant flow rate; thus, both substrate concentration and pH at the gel surface were maintained at a constant level. It was found that the gel undergoes a shrinking change due to an enzymatically induced increase in pH within the gel phase. There was a marked position dependence of the shrinking degree; the diameter at the center of the cylinder was smaller than those at the top and at the bottom, but the diameters at the top and bottom were identical with each other. This trend was observed at immobilized enzyme concentrations < 1 mg/mL, even after the establishment of swelling equilibrium. By mathematical simulations with a reaction-diffusion model, these results were understood in connection with a charge distribution which is formed as a result of an enzymatically generated pH gradient within the gel phase.