Theoretical and Experimental Evaluation of the Reduction Potential of Straight-Chain Alcohols for the Designed Synthesis of Bimetallic Nanostructures.

Recently, the development of bimetallic nanoparticles with functional properties has been attempted extensively but with limited control over their morphological and structural properties. The reason was the inability to control the kinetics of the reduction reaction in most liquid-phase syntheses. However, the alcohol reduction technique has demonstrated the possibility of controlling the reduction reaction and facilitating the incorporation of other phenomena such as diffusion, etching, and galvanic replacement during nanostructure synthesis. In this study, the reduction potential of straight-chain alcohols has been investigated using molecular orbital calculations and experimentally verified by reducing transition metals. The alcohols with a longer chain exhibited higher reduction potential, and 1-octanol was found to be the strongest among alcohols considered. Furthermore, the experimental evaluation carried out via the synthesis of metallic Cu, Ni, and Co particles was consistent with the theoretical predictions. The reaction mechanism of metallic particle formation was also studied in detail in the Ni-1-octanol system, and the metal ions were confirmed to be reduced via the formation of nickel alkoxide. The results of this investigation were successfully implemented to synthesize Cu-Ni bimetallic nanostructures (core-shell, wire, and tube) via the incorporation of diffusion and etching besides the reduction reaction. These results suggest that the designed synthesis of a wide range of bimetallic nanostructures with more refined control has become possible.

Selection Criteria for Metal Precursors and Solvents for Targeted Synthesis of Metallic Nanostructures Via Kinetic Control in the Polyol Process.

Development of a technology for the synthesis of monometallic or multimetallic nanoparticles is exceptionally vital for the preparation of novel magnetic, optical. and catalytic functional materials. In this context, the polyol process is a safe and scalable method for preparation of metal nanoparticles with controlled sizes and shapes in large scales. However, there is no systematic investigation that discusses the criteria for the selection of metal salt and solvent type that determine the kinetics of reduction reaction that influences the morphology of the particles. Consequently, the design of metallic nanoparticles, which is controlled by the kinetics and thermodynamics of the reduction reaction, has become difficult. In this paper, the selection criterion for metal salt precursor is established based on the presumption that the ligand of the metal precursor promotes the formation of active species of the solvent, and the criterion for the selection of the solvent type is based on the highest occupied molecular orbital (HOMO) energy value estimated using molecular orbital theory. The results suggested that the dissociation constants of metal salt precursors and HOMO energy of the polyol solvent can be tuned to control the kinetics of the reduction reaction. The reduction potential of polyol depends on the number of carbon atoms and the location of hydroxyl ligands within the molecule. Among the polyols considered in this study, 1,4-butanediol had the highest reduction potential. The predictions have been experimentally verified by synthesizing metallic Co and Fe nanoparticles. The findings could be extended to other techniques such as thermal decomposition and alcohol reduction for the synthesis of noble metal-transition metal magnetic and catalytic nanoparticles with novel properties.

Separation of halogenated benzenes enabled by investigation of halogen-π interactions with carbon materials.

The halogen-π (X-π) interaction is an intermolecular interaction between the electron-poor region of bonded halogen atoms and aromatic rings. We report an experimental evaluation of the halogen-π (X-π) interaction using liquid chromatography with carbon-material coated columns providing strong π interactions in the normal phase mode. A C70-fullerene (C70)-coated column showed higher retentions for halogenated benzenes as the number of halogen substitutions increased as a result of X-π interactions. In addition, the strength of the X-π interaction increased in the order of F < Cl < Br < I. Changes to the UV absorption of C70 and the brominated benzenes suggested that the intermolecular interaction changed from the π-π interaction to X-π interaction as the number of bromo substitutions increased. Computer simulations also showed that the difference in dipole moments among structural isomers affected the strength of the π-π interaction. Furthermore, we concluded from small peak shifts in 1H NMR and from computer simulations that the orbital interaction contributes to the X-π interactions. Finally, we succeeded in the one-pot separation of all isomers of brominated benzenes using the C70-coated column by optimizing the mobile phase conditions.

UV-visible spectral analysis for the characterization of the titanium(iv)-4-(2-pyridylazo)resorcinol complex as a reagent for determining hydrogen peroxide.

Titanium(iv)-4-(2-pyridylazo)resorcinol (Ti-PAR) has been effectively used for the determination of hydrogen peroxide. In 1985, Takamura et al. proposed its molecular structure showing the absorption peak at 508 nm. However the results obtained from computational calculations showed the absorption peak at 472 nm. Based on the UV-visible spectral simulations and crystal structures of metal-PAR registered in the Cambridge Structural Database (CSD), the structure of Ti-PAR-H2O2 showing the absorption peak at 508 nm was determined. Then the reaction profiles and the reaction mechanism were clarified.

Differentiating π Interactions by Constructing Concave/Convex Surfaces Using a Bucky Bowl Molecule, Corannulene in Liquid Chromatography.

Convex-concave π conjugated surfaces in hemispherical bucky bowl such as corannulene (Crn) have shown increasing utility in constructing self-assembled new functional materials owing to its unique π electrons and strong dipole. Here, we investigate these specific molecular recognitions on Crn by developing new silica-monolithic capillary columns modified with Crn and evaluating their performance in the separation of different aromatic compounds by liquid chromatography (LC). We synthesized two Crn derivatives and conjugated them onto the surface of a silica monolith. The first Crn derivative was edge functionalized, which can undergo free inversion of a convex-concave surface. The second Crn derivative was synthesized by modifying the spoke of Crn, which suppresses the convex-concave inversion. Results of LC suggest that each surface showed different shape recognition based on π interaction. Furthermore, the concave surface of Crn showed strong CH-π interaction with a planar molecule, coronene, demonstrated by the shifts of the 1H NMR signals of both Crn and coronene resulting from the multiple interactions between Crn and π electrons in coronene. These results clearly demonstrated the presence of CH-π interactions at multiple points, and the role of shape recognition.

Design of monoalcohol - Copolymer system for high quality silver nanowires.

Research to improve the dimensional properties of silver nanowires (Ag NWs) for transparent conductive film (TCF) applications are being carried out intensively. However, the protocol for the designed synthesis of high-quality Ag NWs is yet to be developed due to the inadequacy of knowledge on the role of parameters. Here, we attempt to elucidate the role played by the parameters and propose a monoalcohol-copolymer based system for the designed synthesis of Ag NWs superior in quality to the one synthesized using conventional ethylene glycol (EG)-polyvinylpyrrolidone (PVP) system. The key findings of the study are as follows: (1) the solubility of Ag source and the partially formed AgCl particles in monoalcohols was found to play an important role not only in the reduction to metallic Ag but also on the uniaxial growth, (2) the adsorption of capping agents on Ag NWs was carried through O and N atoms in the base molecule and their binding energies indicated that the strength is the key parameter to obtain Ag NWs with high aspect ratio, (3) the properties of nanowire could be enhanced through copolymerization of VP and base molecules that have O- and N-based ligands, and (4) the influence of copolymerization on the physical and chemical properties of the surface active agent has been theoretically and experimentally verified. Consequently, we succeeded in the development of a new technique to synthesize high yield of Ag NWs with improved aspect ratio than EG-PVP system by using benzyl alcohol as reducing solvent and N-vinylpyrrolidone/N,N-diethylaminoethyl metacrylate copolymer as a capping agent. The optical transmittance and electrical resistivity of TCFs prepared using the Ag NWs with an average diameter of 43 nm, and an average length of 13 µm were 98.6% and R: 49.1 Ω/□, respectively.

YACHIYO HOSPITAL; Center of SUPER CARE MIX--Comprehensive Care from Emergency to Home for the community.

Anjo City has two general hospitals. Kosei Hospital, a central medical center for advanced care, and our Yachiyo Hospital for regional care. Recently, Kosei Hospital faced over-capacity problem because of overflow in emergency visits and congested wards due to shortage of post-acute beds. We planned a project to ease the congestion of the central hospital and manage post-acute patients.

Effect of photo-oxidation of on the determination of and using the - reagent.

The Ti-TPyP reagent, i.e. an acidic aqueous solution of oxo[5,10,15,20-tetra(4-pyridyl)-porphyrinato]titanium(iv) complex, denoted as TiO(tpyp), was developed as a highly sensitive reagent for determining hydrogen peroxide. The Ti-TPyP reagent exhibits a sharp absorption peak at 432 nm. Following the addition of hydrogen peroxide to the reagent, a new absorption peak appeared at 450 nm. Its absorbance was proportional to the hydrogen peroxide concentration with an apparent molar absorptivity of 1.1 × 105 L mol-1 cm-1. In the determination of hydrogen peroxide using the Ti-TPyP reagent, ascorbic acid concurrently present in the samples caused a positive error in the analytical results. In the present paper, the source of the error was revealed to be due to the production of hydrogen peroxide through the oxidation of ascorbic acid by singlet oxygen arising from the energy transfer between the dissolved oxygen molecule and the photo-excited porphyrin moiety of the TiO(tpyp) complex. The reaction mechanism was proposed for the photo-oxidation of ascorbic acid caused by the TiO(tpyp) complex to produce dehydroascorbic acid and hydrogen peroxide. The effect of ascorbic acid is really a serious problem in the practical uses of the Ti-TPyP reagent in food and biochemical analysis. However, use of ascorbic acid oxidase as a scavenger for ascorbic acid was found to be quite effective to remove its effect in the flow injection analysis of 3-hydroxybutyric acid in human serum.

Oxidation of unsaturated carboxylic acids under hydrothermal conditions.

Hydrothermal oxidation pathways of high molecular weight unsaturated carboxylic acids were investigated for the potential use of chemoselectivity to improve the efficiency of the desired products from biomasses directly containing or easily producing unsaturated carboxylic acids. Hock cleavage, which frequently occur at general chemical, was observed in the absence of any acid catalyst and may be a potential major oxidation cleavage mechanism, which leads to the cleavage at both the carbon-carbon double bond and the single bond near a double bond. The addition of a peroxyl radical to the double bond may be also a potential major oxidation mechanism, which leads to the oxidation cleavage mainly at the carbon-carbon double bond. Cleavage at the carbon-carbon bond near the double bond by the addition of a peroxyl radical to the double bond may also occur. However, oxidation at either alpha-, beta-, or gamma-carbon to the -COOH group hardly occurred. These results may help to selectively produce desired products from biomasses, such as lignin and oils.

(R)-2-Benzyl-4-methyl-pentyl (R)-2-meth-oxy-2-(1-naphth-yl)propionate.

The relative configuration of the alcohol component in the title ester, C(27)H(32)O(3), has been assigned as (R) from the known configuration of (R)-(-)-2-meth-oxy-2-(1-naphth-yl)propionic acid [(R)-MαNP acid]. In the crystal structure, the C atom of the methyl group of the MαNP acid lies in the extended plane of the naphthyl ring system [methyl C atom deviates from plane by 0.211 (2) Å; r.m.s. deviation of fitted atoms = 0.0187 Å] and a weak intra-molecular C-H⋯O hydrogen bond links the naphthyl ring system and the meth-oxy group. These structural properties are similar to those of most MαNP acid esters.

Conformation and absolute configuration of (1S,2S)-2-(phenyl-selan-yl)cyclo-hexyl (R)-2-meth-oxy-2-(1-naphth-yl)propionate.

The relative and absolute configurations of the title compound, C(26)H(28)O(3)Se, were assigned from the known configuration of (R)-(-)-2-meth-oxy-2-(1-naphth-yl)propionic acid used as starting material, and by examination of the Bijvoet (Friedel) pairs, using the anomalous dispersion data collected with Mo Kα radiation at low temperature. The geometry around the carbonyl group exists in the syn conformation, as reflected in torsion angles involving this group, and the stability of the structure is affected by weak bifurcated intra-molecular C-H⋯O hydrogen bonds.

Ultraviolet-visible spectral analysis for the reaction of hydrogen peroxide with a titanium(IV)-porphyrin reagent.

A Ti-TPyP reagent, i.e., an acidic aqueous solution of oxo[5,10,15,20-tetra(4-pyridyl)porphyrinato]titanium(IV) complex, TiO(tpyp), was developed as a highly sensitive and selective spectrophotometric reagent for the determination of traces of hydrogen peroxide. The reagent exhibited a single absorption peak at 432 nm, and the addition of hydrogen peroxide to the reagent gave rise to a new peak at 450 nm, with height being proportional to the added hydrogen peroxide concentration. Recently we succeeded in clarifying the reaction specificity of the TiO(tpyp) complex to hydrogen peroxide from the viewpoint of the reaction mechanisms and molecular orbitals based on ab initio calculations. In the present study, we performed ultraviolet-visible (UV-Vis) spectral simulations for individual species in the proposed reaction mechanisms based on the theoretical calculations carried out using the Zerner's intermediate neglect of differential overlap (ZINDO) method, since the assignment of the observed absorption peaks to the respective reaction species is important to confirm the reliability of the analysis of hydrogen peroxide using the Ti-TPyP reagent. The absorption peaks at 432 nm and 450 nm were assigned to a H(2)O-adduct structure of the protonated TiO(tpyp) complex and the important structure corresponding to the monoperoxo TiO(tpyp) complex, respectively, under acidic conditions. Particularly, it should be noted that the addition of water molecules to the protonated TiO(tpyp) complex affects the maximum absorption wavelength appreciably. Taking the addition of water molecules to the complex into consideration, the reaction mechanism proposed previously was revised in this study. The results should contribute to providing a new way to evaluate analytical reagents.

Reaction specificity of a titanium(IV)-porphyrin complex to hydrogen peroxide in view of an Ab initio study.

A Ti-TPyP reagent, i.e. an acidic aqueous solution of oxo[5,10,15,20-tetra(4-pyridyl)porphyrinato]titanium(IV) complex, TiO(tpyp), was previously developed as a highly sensitive and specific reagent for determining hydrogen peroxide. In the present work, the reaction specificity of the TiO(tpyp) complex to hydrogen peroxide was clarified based on ab initio calculations. The results provide a well-grounded argument for determining hydrogen peroxide using the Ti-TPyP reagent experimentally.

Characterization of a titanium(IV)-porphyrin complex as a highly sensitive and selective reagent for the determination of hydrogen peroxide: a computational chemistry approach and a critical review.

The Ti-TPyP reagent, i.e. an acidic aqueous solution of the oxo[5,10,15,20-tetra(4-pyridyl)porphyrinato] titanium(IV) complex, TiO(tpyp), was developed as a highly sensitive and selective spectrophotometric reagent for determination of traces of hydrogen peroxide. Using this reagent, determination of hydrogen peroxide was performed by flow-injection analysis with a detection limit of 0.5 pmol per test. The method was actually applied to determination of several constituents of foods, human blood, and urine mediated by appropriate oxidase enzymes. The reaction specificity of the TiO(tpyp) complex for hydrogen peroxide was clarified from the viewpoint of the reaction mechanisms and molecular orbitals based on ab initio calculations. The results provided a well-grounded argument for determination of hydrogen peroxide using the Ti-TPyP reagent experimentally. This review deals with characterization of the high sensitivity and reaction specificity of the Ti-TPyP reagent for determination of hydrogen peroxide, to prove its reliability in analytical applications.

Simple and effective 3D recognition of domoic acid using a molecularly imprinted polymer.

We have developed a simple and effective molecular imprinting technique to target compounds with flexible structure. Domoic acid (DA), an amnesic shellfish poison, was used as the target compound while many acidic compounds (mono-, di-, and tricarboxylic acids) were used as template molecules for molecularly imprinted polymers (MIPs). Evaluation of selective recognition abilities using liquid chromatography revealed that the highest selective recognition ability for DA was found when pentane-1,3,5-tricarboxylic acid (1,3,5-PeTA) was used as the template. Computer modeling studies of the DA structure suggested that the observed selective recognition depended on the structural changes in DA at the recognition site of the MIPs as well as spatial distance between the COOH groups in DA and 1,3,5-PeTA. Using the 1,3,5-PeTA-MIP, we could easily purify DA from blue mussel extracts by solid-phase extraction.

Closure of duodenocutaneous fistula due to recurrent colon cancer with a pedicled jejunal seromuscular flap.

A new approach to closing a malignant enterocutaneous fistula is reported. Transverse colon cancer recurred around the superior mesenteric vein along with a duodenocutaneous fistula, thus causing severe dermatitis. The tumor was partially resected at the fascia level and the fistula measured 2.5 cm in diameter. A left rectus abdominis musculocutaneous flap failed to close the fistula because of graft necrosis. A jejunal flap measuring 8 cm in length was prepared by sacrificing about 15 cm of adjacent jejunum to create the pedicle. The mucosal layer of the flap was removed and the fistula was closed, then the tumor surface was covered. Two weeks later, the skin defect was covered with free skin grafting. The patient died of cancer 6 months after surgery, but there was no recurrence of the fistula.

Continuous vertical hemimattress suture for biliary-enteric anastomosis.

The continuous hemivertical mattress suture technique for biliary-enteric anastomosis has not been well reported in the literature. We used the technique with a double-armed monofilament absorbable suture (Glycomer 631) for 32 anastomoses in 31 patients. There was one anastomotic leakage (3.1%). The mean follow-up period was 683 days, during which time no patient developed anastomotic stenosis or cholangitis. The technique provided satisfactory results with lower cost than one-layer interrupted sutures.

Pedicled ileal flap to repair large duodenal defect after right hemicolectomy for right colon cancer invading the duodenum.

Although right-sided colon cancer occasionally invades the second part of the duodenum, there is no standard procedure for reconstructing a large duodenal defect after resection. This report describes a new approach we recently devised. After resecting the right hemicolon and the involved duodenum, a segment of terminal ileum was isolated on the vascular pedicle, sacrificing the adjacent ileum. We created a flap by opening the segment along the antimesenteric border, and used this flap to cover the defect. This method does not create a nonanatomical bypass and fewer intestinal anastomoses are required than for Roux-en-Y reconstruction.