A redox-active ionic liquid manifesting charge-transfer interaction between a viologen and carbazole and its effect on the viscosity,ionic conductivity,and redox process of the viologen

Redox-active ionic liquids (RAILs) are gaining attention as a material that can create a wide range of functions. We herein propose a charge-transfer (CT) RAIL by mixing two RAILs, specifically a carbazole-based ionic liquid ([CzC₄ImC₁][TFSI]) as a donor and a viologen-based ionic liquid ([C₄VC₇][TFSI]₂) as an acceptor. We investigated the effect of CT interaction on the physicochemical properties of the CT ionic liquid (CT-IL) using the results of temperature-dependent measurements of UV-vis absorption, viscosity, and ionic conductivity as well as cyclic voltammograms. We employed the Walden analysis and the Grunberg–Nissan model to elucidate the effect of the CT interaction on the viscosity and ionic conductivity. The CT interaction reduces the viscosity by reducing the electrostatic attraction between the dicationic viologen and TFSI anion. It also reduces the ionic conductivity by the CT association of the dicationic viologen and carbazole. The electrochemically reversible responses of the viologens in [C₄VC₇][TFSI]₂ and CT-IL are consistent with the Nernstian and the interacting two-redox site models. Notably, the transport and electrochemical properties are modulated by CT interaction, leading to unique features that are not present in individual component ILs. The inclusion of CT interaction in RAILs thus provides a powerful means to expand the scope of functionalized ionic liquids.

A redox-active ionic liquid (RAIL) consisting of a carbazole and viologen shows charge transfer (CT) interaction. The physicochemical properties are modulated by the CT interaction by comparison with the individual RAILs.     

Quantitative estimation of NH3 partial pressure in H2 desorbed from the Li-N-H system by Raman spectroscopy

The partial pressure of NH3 gas estimated by Raman spectroscopy indicates that approximately 0.1% NH3 inevitably contaminates the H2 desorbed from a hydrogen storage material composed of LiH and LiNH2 at any temperature up to 400 degrees C in a closed system.     

Seven novel seco-prezizaane-type sesquiterpenes from the pericarps of Illicium merrillianum

Seven new seco-prezizaane-type sesquiterpenes were isolated from the methanol extract of the pericarps of Illicium merrillianum. Their structures were elucidated as 3-deoxypseudoanisatin (1), 2beta-hydroxy-3,6-dedioxypseudoanisatin (2), 8alpha-hydroxy-10-deoxycyclomerrillianolide (3), 10beta-hydroxypseudoanisatin (4), 10beta-hydroxycyclopseudoanisatin (5), 1,6-dihydroxy-3-deoxyminwanensin (6), and 8-deoxymerrilliortholactone (7) by analyses of their spectroscopic data and chemical transformation. Compounds 4 and 5 as well as 6 and 7 coexist as a keto/acetal equilibrated mixture in methanol solution.     

Antibacterial metal implant with a TiO2‐conferred photocatalytic bactericidal effect against Staphylococcus aureus

Photocatalysis with anatase Titanium dioxide (TiO₂) under ultraviolet A (UVA) has a well recognized bactericidal effect. There have been a few reports, however, on the effects of photocatalysis on bio‐implant‐related infections. The purpose of present study was to evaluate the photocatalytic bactericidal effects of anatase TiO₂ on Staphylococcus aureus (S. aureus) associated with surgical site infections. TiO₂ films were synthesized on commercially pure titanium substrates and SUS316 stainless steel using a plasma source ion implantation method followed by annealing. The chemical composition of the surface layers was determined using GXRD and XPS. The disks were seeded with cultured S. aureus and exposed to UVA illumination from black light. The bactericidal effect of the TiO₂ films was evaluated by counting the survived colonies statistically. A structural gradient anatase type TiO₂ layer formed on all substrates. The viability of the bacteria on the photocatalytic TiO₂ film coated on titanium was suppressed to 7.0% at 30 minutes and 5.5% at 45 minutes, whereas that on a similarly coated stainless steel was suppressed to 45.8% at 30 minute and 28.6% at 45 minutes (ANOVA: p < 0.05). Complete bacterial inactivation was achieved after 90 minutes on titanium and after 60 minutes on stainless steel. The photocatalytic bactericidal effect of TiO₂ is useful for sterilizing the contaminated surfaces of bioimplants. Copyright © 2008 John Wiley & Sons, Ltd.     

The hydrophilization of polystyrene substrates by 172-nm vacuum ultraviolet light

This paper describes the photochemical surface modification of polystyrene (PS) substrates using vacuum ultraviolet (VUV) light 172 nm in wavelength. We have particularly focused on the effects of atmospheric pressure during VUV irradiation on the obtained surface's wettability and the stability of the wettability, in addition to its chemical structure, morphology, and photooxidation rate. Samples were photoirradiated with VUV light under pressures of 10, 10(3), or 10(5) Pa. Although, in each case, the originally hydrophobic PS surface became highly hydrophilic, the final water-contact angle and photooxidation rate depended on the atmospheric pressure. The samples treated at 10 Pa were less wettable than those prepared at 10(3) and 10(5) Pa due to the shortage of oxygen molecules in the atmosphere. The minimum water-contact angles of the samples treated at 10, 10(3), and 10(5) Pa were about 8 degrees, 0 degrees, and 0 degrees, respectively. With the samples prepared at 10 and 10(3) Pa, photooxidation reactions proceeded in the topmost region closest to the surface, while at 10(5) Pa photooxidation was found to be greatly enhanced in the deeper regions, as evidenced by angle-resolved X-ray photoelectron spectroscopy. Photoetching rates were determined through atomic force microscope observation of microstructured PS samples prepared by a simple mesh-contact method. As estimated from AFM images of the latticed microstructures obtained, the rates of samples prepared at 10(3) and 10(5) Pa were about 1.5 and 1.3 nm/min, respectively. However, no photoetched features were observable on the sample surface prepared at 10 Pa. Hydrophilic stability also varied greatly depending on atmospheric pressure. The hydrophilicity of samples treated at 10 and 10(3) Pa gradually decreased as they were exposed to air. On the other hand, the sample surface prepared at 10(5) Pa showed excellent hydrophilicity even after being left in air for 30 days.     

Tetrabenzoperipentacene: Stable Five‐Electron Donating Ability and a Discrete Triple‐Layered β‐Graphite Form in the Solid State

An oxidative ring‐closure reaction of a tetranaphthylpyrene derivative led to the synthesis of a 56 all‐carbon conjugated tetrabenzoperipentacene. In the single‐crystal X‐ray structure, three molecules make a triple‐layered cluster by π‐stacking, wherein each layer rotates by 120°, and is thus considered a petit β‐graphite. As for the optical properties, the Stokes shift is extremely small (10 cm^?1), thus indicating its remarkably rigid framework. The tetrabenzoperipentacene exhibits reversible five‐electron oxidation waves in cyclic voltammetry, and is regarded as a counterpart to the fullerene C₆₀ in terms of stable multicharge‐storage nanocarbon materials.     

meso‐3,5‐Bis(trifluoromethyl)phenyl‐Substituted Expanded Porphyrins: Synthesis,Characterization, and Optical,Electrochemical, and Photophysical Properties

Trifluoroacetic acid‐catalyzed condensation of pyrrole with electron‐deficient and sterically hindered 3,5‐bis(trifluoromethyl)benzaldehyde results in the unexpected production of a series of meso‐3,5‐bis(trifluoromethyl)phenyl‐substituted expanded porphyrins including [22]sapphyrin 2 , N‐fused [22]pentaphyrin 3 , [26]hexaphyrin 4 , and intact [32]heptaphyrin 5 together with the conventional 5,10,15,20‐tetrakis(3,5‐bis(trifluoromethyl)phenyl)porphyrin 1 . These expanded porphyrins are characterized by mass spectrometry, ¹H NMR spectroscopy, UV/Vis/NIR absorption spectroscopy, and fluorescence spectroscopy. The optical and electrochemical measurements reveal a decrease in the HOMO–LUMO gap with increasing size of the conjugated macrocycles, and in accordance with the trend, the deactivation of the excited singlet state to the ground state is enhanced.     

Simultaneous determination of beta-blockers in human plasma using liquid chromatography-tandem mass spectrometry

A detailed procedure for the analysis of four beta-blockers, acebutolol, labetalol, metoprolol and propranolol, in human plasma by high-performance liquid chromatography (LC)-tandem mass spectrometry (MS-MS) using an MSpak GF column, which enables direct injection of crude plasma samples, is presented. Protein and/or macromolecule matrix compounds were eluted first from the column, while the drugs were retained on the polymer stationary phase of the MSpak GF column. The analytes retained on the column were then eluted into an acetonitrile-rich mobile phase using a gradient separation technique. All drugs showed base peak ions due to [M + H]+ ions by LC-MS with positive ion electrospray ionization, and the product ions were produced from each [M + H]+ ion by LC-MS-MS. Quantification was performed by selected reaction monitoring. The recoveries of the four beta-blockers spiked into plasma were 73.5-89.9%. The regression equations for all compounds showed excellent linearity in the range 10-1000 ng/mL of plasma, with the exception of propranolol (10-800 ng/mL). The limits of detection and quantification for each drug were 1-3 and 10 ng/mL, respectively, of plasma. The intra- and inter-day coefficients of variation for all drugs in plasma were not greater than 10.9%.