Photo-Absorption and photochemical decomposition of copper and alkaline-earth ß-diketonates as source gases of high-Tc superconducting films

For low-temperature deposition of oxide films relating to Bi-Sr-Ca-Cu-O superconductors, photo-absorption and -decomposition properties were examined with respect to copper and alkaline-earth ß-diketonates. It was confirmed that all ß-diketonates examined were promising as source materials for photochemical vapour deposition (photo-CVD) using a low-pressure mercury lamp, in view of their large light absorption coefficients at wavelength 254 nm. The light irradiation was effective for the formation of highly crystalline oxide films at temperatures below 600 °C. By combining two sources, Ca₂CuO₃ and SrCuO₂ films were prepared. Photo-CVD of c-axis oriented Bi₂Sr₂CuO_x film was achieved by the irradiation of ternary sources of Bi(C₆H₅)₃ and strontium and copper ß-diketonates at 500 °C.     

FLUORESCENCE OF 1-DIMETHYLAMINONAPHTHALENE-5-SULFONATE AND PYRENE-1-SULFONATE CONJUGATED TO BACTERIORHODOPSIN

Abstract— Two fluorescence probes, 1-dimethylaminonaphthalene-5-sulfonylchloride and pyrene-1-sulfonylchloride, were conjugated to the protein in purple membrane and fluorescence intensity and anisotropy were measured as a function of temperature. The anisotropy of the 1-dimethyl-aminonaphthalene-5-sulfonate conjugate showed a characteristic temperature dependence, in which, the anisotropy is constant at 0.22 ± 0.01 until 25-30°C and decreases above 30°C. The fluorescence intensity, however, varies linearly with temperature. These results imply that the transition is due to bacteriorhodopsin in the trimer.     

Porous silicon-based ferroelectric nanostructures

A procedure is suggested for the preparation of porous silicon-based ferroelectric nanostructures. It is demonstrated that the method of chemical deposition from solutions provides for the penetration of the initial components of the solution into the matrix pores, and subsequent annealing leads to the crystallization of the ferroelectric phase. The diagnostics of the ferroelectric properties is performed using the method of generation of second optical harmonic. The spectral characteristics of the prepared ferroelectric nanostructures are investigated.     

Systematic Tuning and Switching of Neutral and Ionic Phases in a Donor–Acceptor Chain Compound by Doping with Less‐Active Donors and by Pressure Application

The temperature‐induced stepwise neutral–ionic (N–I) phase transition in the covalently bonded donor–acceptor chain compound [Ru₂(2,3,5,6‐F₄PhCO₂)₄DMDCNQI] ? 2(p‐xylene) (2,3,5,6‐F₄PhCO₂^?=2,3,5,6‐tetrafluorobenzoate; DMDCNQI=2,5‐dimethyl‐N,N′‐dicyanoquinodiimine) was systematically tuned over a wide temperature range using two techniques: 1) A chemical technique based on doping with a less‐active donor unit [Ru₂^II,II(F₅PhCO₂)₄] (F₅PhCO₂^?=pentafluorobenzoate), thereby providing an isostructural doped series [{Ru₂^II,II(2,3,5,6‐F₄PhCO₂)₄}_1?x{Ru₂^II,II(F₅PhCO₂)₄}_xDMDCNQI] ? 2(p‐xylene), with x=0.06, 0.10, 0.21, and 0.24; and 2) a physical technique, which was the application of hydrostatic pressure to the doped compounds. The stepwise N–I transition observed in the original compound was systematically varied in terms of the viewpoints of both transition temperature and transition features (stepwise or monotonic) dependent on the amount of dopants x. Application of pressure efficiently tuned the N–I transitions, with the oxidation phases being dramatically modified by applying only weak pressure up to 4 kbar. Even in cases that led to N–I transitions in small domains of the chains at ambient pressure, the application of pressure caused an expansion of the domains that enabled N–I transitions, finally leading to a complete change in the oxidation state of the chains, from neutral to ionic, accompanied by a change from a paramagnetic state to a ferrimagnetically ordered state.     

Octacyanidorhenate(V) Ion as an Efficient Linker for Hysteretic Two-Step Iron(II) Spin Crossover Switchable by Temperature,Light, and Pressure

A two-step hysteretic Fe^II spin crossover (SCO) effect was achieved in programmed layered Cs{[Fe(3-CNpy)₂][Re(CN)₈]}⋅H₂O ( 1 ) (3-CNpy=3-cyanopyridine) assembly consisting of cyanido-bridged Fe^II-Re^V square grid sheets bonded by Cs⁺ ions. The presence of two non-equivalent Fe^II sites and the conjunction of 2D bimetallic coordination network with non-covalent interlayer interactions involving Cs⁺, [Re^V(CN)₈]³⁻ ions, and 3-CNpy ligands, leads to the occurrence of two steps of thermal SCO with strong cooperativity giving a double thermal hysteresis loop. The resulting spin-transition phenomenon could be tuned by an external pressure giving the room-temperature range of SCO, as well as by visible-light irradiation, inducing an efficient recovery of the high-spin Fe^II state at low temperatures. We prove that octacyanidorhenate(V) ion is an outstanding metalloligand for induction of a cooperative multistep, multiswitchable Fe^II SCO effect.     

Coupling of chromatographic ion-exchange reaction with change-partner reaction. Presumed mechanism on the ion-ion interaction of inorganic ions in Sephadex G-15 columns

A sample solution containing sodium or potassium dihydrogenphosphate or disodium or dipotassium hydrogenphosphate was eluted from a Sephadex G-15 column with either sodium or potassium chloride solution in various sample-eluent systems, and every one of the four kinds of ions employed was determined in the eluate. Then, the elution profiles showed the phenomenon that a negative peak of chloride ion coexisted in the fractions of a positive peak of phosphate ion, in all sample-eluent systems employed. This phenomenon was assumed to occur by the coupled reaction of change-partner and ion-exchange reactions including ion exclusion.     

Synthesis and nanoimprinting of high refractive index and highly transparent polythioethers based on thiol-ene click chemistry

This work demonstrates the UV nanoimprinting lithography (UV-NIL) of high refractive index and highly transparent polythioethers based on thiol-ene click chemistry. Herein, 9,9-bis(3-mercaptopropylphenylether)fluorene (BMPF) is designed as a new thiol monomer with a high refractive index, high transparency, and good processability for UV-NIL. Colorless polythioethers are synthesized from BMPF and ene monomers under mild thiol-ene click reaction conditions. Excellent transmittance (96%) of 400 nm light is observed in all the polymer films and high refractive index values of 1.5972–1.6382 are attained. UV-NIL using thiol-ene photopolymerization affords polymer nanoimprinting patterns with various features on the order of 100–500 nm without any fractures. To the best of our knowledge, this is the first report on UV-NIL of high refractive index and highly transparent polymers. Through proper monomer and polymer design, novel polythioethers with suitable glass transition temperature (T _g) values are developed with high refractive index, high transparency, and good UV-NIL processability. Furthermore, UV-NIL based on thiol-ene click chemistry is accomplished at the nanoscale. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2175–2182     

Reactivity of the indole ring in palladium(II) complexes of 2N1O-donor ligands: cyclopalladation and pi-cation radical formation

The Pd(II) complexes of new 2N1O-donor ligands containing a pendent indole, 3-[N-2-pyridylmethyl-N-2-hydroxy-3,5-di(tert-butyl)benzylamino]ethylindole (Htbu-iepp), 1-methyl-3-[N-2-pyridylmethyl-N-2-hydroxy-3,5-di(tert-butyl)benzylamino]ethylindole (Htbu-miepp), 3-[N-2-pyridylmethyl-N-2-hydroxy-3,5-di(tert-butyl)benzylamino]methylindole (Htbu-impp), and 3-(N-2-pyridylmethyl-N-4-hydroxybenzylamino)ethylindole (Hp-iepp) (H denotes a dissociable proton), were synthesized, and the structures of [Pd(tbu-iepp)Cl] (1a), [Pd(tbu-iepp-c)Cl] (1b), [Pd(tbu-miepp)Cl] (3), and [Pd(p-iepp-c)Cl] (4) (tbu-iepp-c and p-iepp-c denote tbu-iepp and p-iepp bound to Pd(II) through a carbon atom, respectively) were determined by X-ray analysis. Complexes 1a prepared in CH(2)Cl(2)/CH(3)CN and 3 prepared in CH(3)CN have a pyridine nitrogen, an amine nitrogen, a phenolate oxygen, and a chloride ion in the coordination plane. Complex 1b prepared in CH(3)CN has the same composition as 1a and was revealed to have the C2 atom of the indole ring bound to Pd(II) with the Pd(II)-C2 distance of 1.973(2) A. The same Pd(II)-indole C2 bonding was revealed for 4. Interconversion between 1a and 1b was observed for their solutions, the equilibrium being dependent on the solvent used. Reaction of 1b and 4 with 1 equiv of Ce(IV) in DMF gave the corresponding one-electron-oxidized species, which exhibited an ESR signal at g = 2.004 and an absorption peak at approximately 550 nm, indicating the formation of the Pd(II)-indole pi-cation radical species. The half-life, t(1/2), of the indole radical species at room temperature was calculated to be 20 s (k(obs) = 3.5 x 10(-)(2) s(-)(1)) for 1b. The cyclic voltammogram for 1b in DMF gave two irreversible oxidation peaks at E(pa) = 0.68 and 0.80 V (vs Ag/AgCl), which were ascribed to the oxidation processes of the coordinated indole and phenolate moieties, respectively.     

Photoinduced graft polymerization of 2-methacryloyloxyethyl phosphorylcholine on polyethylene membrane surface for obtaining blood cell adhesion resistance

Phospholipid polymer, poly[2-methacryloyloxyethyl phosphorylcholine (MPC)], was grafted with polyethylene (PE) membrane using photoinduced polymerization technique to make the membrane resistant to cell adhesion. The water contact angle on the PE membrane grafted with poly(MPC) decreased with an increase in the photopolymerization time. This decrease corresponded to the increase in the amount of poly(MPC) grafted on the PE surface. The same graft polymerization procedure was applied using other hydrophilic monomers, such as acrylamide (AAm), N-vinylpyrrolidone (VPy) and methacryloyl poly(ethylene glycol) (MPEG). These monomers were also polymerized to form grafted chains on the PE membrane, and the grafting was confirmed with X-ray photoelectron spectroscopy. Analysis of amount and distribution of plasma proteins at the plasma-contacting surface of the original and the modified PE membranes were analyzed using immunogold assay. The grafting of poly(MPC) and poly(VPy) on PE membrane reduced the plasma protein adsorption significantly compared with that on the original PE membrane. However, the PE membranes grafted with poly(AAm) or poly(MPEG) did not show any effects on protein adsorption. Platelet adhesion on the original and modified PE membranes from platelet-rich plasma was also examined. A large number of platelets adhered and activated on the original PE membrane. Grafting with poly(AAm) did not suppress platelet adhesion, but grafting with poly(MPC) or poly(VPy) on the PE membrane was effective in preventing platelet adhesion. It is concluded that the introduction of the phosphorylcholine group on the surface could decrease the cell adhesion to substrate polymer.