Effect of solvent evaporation on the self‐assembly of poly(3‐hexylthiophene‐2,5‐diyl) and on the film morphology during electrospray deposition

A high‐voltage rectangular pulse was applied to the electro‐spray deposition (ESD) to control the evaporation‐induced self‐assembly of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT). Two groups of P3HT thin films were deposited by a series of high‐voltage rectangular pulses. Compared with the ESD driven by a constant voltage, the pulse‐driven ESD enables to probe the effect of solvent evaporation on the self‐assembly of P3HT molecules. The droplet size and the evaporation of residual solvent in the droplet determine the film morphology. Ultraviolet–visible absorption spectroscopy was used to identify the ordering of P3HT molecules in the films. The self‐assembly of P3HT molecules took place during the solvent evaporation which can be controlled by a combination of the pulse amplitude and the pulse interval. With an appropriate combination of the amplitude and the interval, the ESD produced a P3HT thin film with high chain ordering.

     

Time-domain near-infrared spectroscopy using a wavelength-tunable narrow-linewidth source by spectral compression of ultrashort soliton pulses

Time-domain absorption spectroscopy was demonstrated using a wideband, rapid wavelength-tunable, narrow-linewidth source based on an Er-doped ultrashort pulse fiber laser system. The spectrum of the Raman-shifted ultrashort soliton pulse was compressed using a comb-profile dispersion increasing fiber. Rapid wavelength sweeping was demonstrated using an electro-optical intensity modulator. The absorption spectrum of CH(2)Cl(2) liquid at 1625-1780 nm was observed in a 10 μs time-domain measurement.     

A Basic Germanodecatungstate with a −7 Charge: Efficient Chemoselective Acylation of Primary Alcohols

The synthesis of highly negatively charged polyoxometalates with electrically and structurally controlled uniform basic sites can lead to the unique base catalysis. In this work, a γ‐Keggin germanodecatungstate, [γ‐HGeW₁₀O₃₆]^7? ( A ), having a ?7 charge was, for the first time, successfully synthesized by the reaction of [γ‐H₂GeW₁₀O₃₆]^6? with one equivalent of [(n‐C₄H₉)₄N]OH under non‐aqueous conditions. The activities of germanodecatungstates for base‐catalyzed reactions dramatically increased with increase in the number negative charges from ?6 to ?7. In the presence of A , various combinations of acylating agents and primary alcohols including those with acid‐sensitive functional groups chemoselectively gave the desired acylated products in high yields even under the stoichiometric conditions.     

Presence of rhodopsin and porphyropsin in the eyes of 164 fishes, representing marine, diadromous, coastal and freshwater species--a qualitative and comparative study

There are two types of visual pigments in fish eyes; most marine fishes have rhodopsin, while most freshwater fishes have porphyropsin. The biochemical basis for this dichotomy is the nature of the chromophores, retinal (A1) and 3-dehydroretinal (A2), each of which is bound by an opsin. In order to study the regional distribution of these visual pigments, we performed a new survey of the visual pigment chromophores in the eyes of many species of fish. Fish eyes from 164 species were used to examine their chromophores by high-performance liquid chromatography--44 species of freshwater fish, 20 of peripheral freshwater fish (coastal species), 10 of diadromous fish and 90 of seawater fish (marine species) were studied. The eyes of freshwater fish, limb freshwater fish and diadromous fish had both A1 and A2 chromophores, whereas those of marine fish possessed only A1 chromophores. Our results are similar to those of previous studies; however, we made a new finding that fish which live in freshwater possessed A1 if living near the sea and A2 if living far from the sea if they possessed only one type of chromophore.     

Spurring radical reactions of organic halides with tin hydride and TTMSS using microreactors

Tributyltin hydride-mediated radical reactions of organic halides were successfully carried out in a continuous flow system using a microreactor. The reactions proceeded within a very short period of time, coupled with quickly decomposing radical initiators such as V-65 and V-70. The continuous flow reaction system was applied to gram scale synthesis of a key intermediate for furofuran lignans.     

Self‐Sorting of Two Hydrocarbon Receptors with One Carbonaceous Ligand

Non‐directional van der Waals forces in biological and synthetic supramolecular systems play important roles in molecular assembly, particularly in determining the distances of the interacting species. The van der Waals forces are normally used in combination with other directional forces and are considered to play a secondary role in achieving specificity and fidelity in molecular recognition. Using an ideal supramolecular system consisting solely of hydrogen and carbon atoms, we found that the van der Waals interactions enable the high‐fidelity sorting of two homomeric receptors during ligand‐induced assembly. The self‐sorting occurred in a narcissistic manner by repulsion of a competing diastereoisomeric receptor from the assembly. The structure–sorting relationship study with enantiomers further revealed the dominant role of the van der Waals forces in shape recognition for high‐fidelity self‐sorting.     

Mu-eta1:eta1-peroxo-bridged dinuclear peroxotungstate catalytically active for epoxidation of olefins

The reaction of the dinuclear peroxotungstate, [(n-C4H9)4N]2[{WO(O2)2}2(mu-O)] (II), with H2O2 gives the novel mu-eta1:eta1-peroxo-bridging dinuclear tungsten species, [(n-C4H9)4N]2[{WO(O2)2}2(mu-O2)] (I), which has been characterized by X-ray crystallography, elemental analysis, IR, Raman, UV-vis, and 183W NMR. Only I is active for the epoxidation of cyclic, internal, and terminal olefins, whereas II is inactive for each. The low XSO (XSO=(nucleophilic oxidation)/(total oxidation)) value of I (0.18+/-0.02) in comparison with that of II (0.39+/-0.01) for the stoichiometric oxidation of thianthrene 5-oxide, which is a mechanistic probe for determining the electronic character of an oxidant, reveals that I is more electrophilic than II. On the basis of the kinetic and spectroscopic results, the catalytic epoxidation proceeds by the reaction of I with an olefin to form II and the corresponding epoxide followed by the regeneration of I by the reaction of II with H2O2.