Mesostructured organosilica with a 9-mesityl-10-methylacridinium bridging unit: photoinduced charge separation in the organosilica framework

Polycondensation of 9-mesityl-10-methylacridinium-bridged organosilane in the presence of a nonionic surfactant yielded a mesostructured organosilica solid with a functional framework that exhibited long-lived photoinduced charge separation.     

Controlling the dissociative ionization of ethanol with 800 and 400 nm two-color femtosecond laser pulses

Ethanol molecules were irradiated with a pair of temporally overlapping ultrashort intense laser pulses (10(13)-10(14) Wcm(2)) with different colors of 400 and 800 nm, and the dissociative ionization processes have been investigated. The yield ratio of the C-O bond breaking with respect to the C-C bond breaking was varied in the range of 0.17-0.53 sensitively depending on the delay time between the two laser pulses, and the absolute value of the yield of the C-O bond breaking was found to be increased largely when the Fourier-transform limited 800 nm laser pulse overlaps the stretched 400 nm laser pulse, demonstrating an advantage of the two-color intense laser fields in controlling chemical bond breaking processes.     

Aromaticity Relocation in Perylene Derivatives upon Two‐Electron Oxidation To Form Anthracene and Phenanthrene

We prepared perylene dications 1 ²⁺ and 2 ²⁺ by using “capped” perylene derivatives, and for the first time, successfully obtained single crystals of a perylene dication 1 ²⁺ that enabled us to perform its structural analysis. We realized that the substituted aryl groups on perylene control the positions of positive charges, thus the remaining electronic system satisfies Clar's sextet rule toward the highest number of localized sextets. Experimental and theoretical evidence proved that Clar's aromatic π‐sextet rule could be applied even for the dicationic perylenes in a very simple way.     

Orientational isomerism controlled by the difference in electronic environments of a self-assembling heterodimeric capsule

Tetrakis(4-hydroxyphenyl)-cavitand 1 and tetra(4-pyridyl)-cavitand 2 self-assemble into a heterodimeric capsule 1.2 via four ArOH...pyridyl hydrogen bonds in CDCl3. The 1.2 expresses the orientational isomerism of an encapsulated unsymmetrical guest with high orientational selectivity because the electronic environment of the 1 unit is different from that of the 2 unit. For p-ethoxyiodobenzene and 2-iodo-6-methoxynaphthalene encapsulated in 1.2, the iodo group is specifically oriented to the cavity of the 2 unit. The orientational isomeric selectivity for methyl p-acetoxybenzoate and methyl p-ethoxybenzoate within 1.2 is 1:0.11 and 1:<0.05, respectively, wherein the methyl ester group is preferentially oriented to the cavity of the 2 unit. The delicate balance among electrostatic potential repulsion, CH-pi interaction, or CH-halogen (halogen-pi) interaction, in 1.2-guest assembly influences the orientational isomeric selectivity of unsymmetrical guests within 1.2.     

Tuning the effective width of the optical stop band in colloidal photonic crystals

The optical stop band in colloidal crystals is characterized by the central frequency and bandwidth. Although the former is known to be highly tunable by changing the lattice constant, the latter is basically determined by the refractive index contrast between the particles and the background medium that is intrinsic to the materials. In this study, we show that the effective bandwidth in gelled colloidal crystals can also be tuned by controlling the fabrication conditions. Single-domain gelled colloidal crystals were prepared by photopolymerization under various photoirradiation conditions. It was observed that the width of the stop band in the transmission or reflectance spectrum could be expanded by simply adjusting the irradiation time.     

Reaction of octafluorocyclopentene with various carbon nucleophiles

The treatment of octafluorocyclopentene with organolithium reagents gave the corresponding symmetrical disubstituted perfluorocyclopentenes in good to high yields. The reaction with Grignard reagents led to the monosubstituted perfluorocyclopentenes, which were subjected to the further nucleophilic substitution reaction using another Grignard or aryllithium reagents, unsymmetrical disubstituted perfluorocyclopentenes being obtained in high yields.     

Dissociation equilibrium between uncharged and charged local anesthetic lidocaine in a surface-adsorbed film

The dissociation equilibrium between uncharged local anesthetic lidocaine (LC) and charged local anesthetic LC (LCH⁺) in a surface-adsorbed film was investigated by measuring the surface tension and pH of aqueous solutions of a mixture of hydrochloric acid and LC. The surface tension values decreased slightly with increasing total molality m_t at 0X₂0.5, where X₂ is the mole fraction of LC in the mixture, while they decreased rapidly with increasing m_t at 0.5<X₂1. It was shown from the pH measurements that almost all LC molecules were changed into LCH⁺ ions by protonation at 0X₂0.5 and both forms coexisted only at 0.5<X₂1. The quantities of the respective LC and LCH⁺ transferred from the aqueous solution to the adsorbed film, i.e., their surface densities, were calculated by applying the thermodynamic equations derived to the surface tension and pH data. A greater quantity of LC than LCH⁺ existed in the adsorbed film at the coexisting composition. The partitioning behavior of LC and LCH⁺ in the adsorbed film was characterized by three composition regions: (1) slight partitioning of low surface-active LCH⁺ in the region at 0X₂0.5, (2) preferential partitioning of LC at 0.5<X₂<around 0.7, and (3) negative partitioning of LCH⁺ at around 0.7X₂1. The present results clearly indicate that uncharged local anesthetics transfer into hydrophobic environments such as cell membranes more than charged ones.     

Ionic liquid crystal as a hole transport layer of dye-sensitized solar cells

Use of a new ionic liquid crystal, 1-dodecyl-3-methylimidazolium iodide, and iodine as an electrolyte of dye-sensitized solar cells leads to a high short circuit photocurrent density and a high light-to-electricity conversion efficiency, due to a self-assembled structure of the imidazolium cations, resulting in high conductivity of the electrolyte.     

Surface structures of adsorption layers of sodium hyaluronate and bovine serum albumin complexes on poly(γ-methyl-l-glutamate) film and their surface properties

Two-dimensional structures and characteristics of the complexes between sodium hyaluronate (NaHA) and bovine serum albumin (BSA) were studied by using a quartz crystal microbalance method and an atomic force microscope (AFM). NaHA did not adsorb on poly(-methyl-l-glutamate) (PMLG) film. On the other hand, the complexes adsorbed on it and the adsorption behaviors were found to be Langmuir types. With increasing weight ratio of BSA to NaHA, W _BSA, the adsorption constants K decreased and the saturated adsorption masses increased. The adsorbed complexes were spherical particles and at saturated adsorption states they covered compactly on the PMLG film. The mean diameters d _AFM estimated from the topographic images decreased from 70 to 54 nm with increasing W _BSA. The adhesion force F _ad and the frictional force F _f between the complex layers and the AFM tip were obtained by using the contact mode of the AFM. With increasing W _BSA, the values of F _ad decreased and the values of F _f increased. Compared with the frictional coefficient of the NaHA adsorption layer on the BSA monolayer, the values for the NaHA–BSA complex layer were found to be much higher.