Utilizing photocurrent transients for dithiolene-based photodetection: stepwise improvements at communications relevant wavelengths

Photodetection based on bis-(4-dimethylaminodithiobenzil)-Ni(II) (BDN), a representative and well-studied metal dithiolene that shows strong absorption in the near-infrared region of the electromagnetic spectrum, has been investigated. By adopting a metal/insulator/semiconductor/metal (MISM) structure, the peak photocurrent response to an oscillating light chain is increased by up to 50 times, compared to devices without an insulating layer. The transient form of the MISM photoresponse, while unsuitable for steady-state photodetection, can be used to detect periodic light signals of frequencies up to 1 MHz, and is thus applicable for optical communication. Further improvements have been realized by nanostructuring carbon black into the dithiolene layer, improving charge collection, and yielding detectivity of up to 1.6 × 10(11) Jones at wavelengths beyond the scope of silicon photodiodes. Such an architecture may allow the favorable absorption properties of other such metal dithiolenes to be harnessed, where their low charge carrier mobilities and short excitation lifetimes have previously limited their applicability to this field.     

Equilibrium and dynamic surface tension properties of partially fluorinated quaternary ammonium salt gemini surfactants

The equilibrium and dynamic surface tension properties of a partially fluorinated quaternary ammonium salt gemini surfactant 1,2-bis[dimethyl-(3-perfluoroalkyl-2-hydroxypropyl)ammonium]ethane bromide (C(n)(F)C3-2-C3C(n)F, where n represents fluorocarbon chain lengths of 4, 6, and 8) were investigated, and the effects of the fluorocarbon chain length and the number of chains on them were discussed. The plot of the logarithm of the critical micelle concentration (cmc) against the fluorocarbon chain length for C(n)(F)C3-2-C3C(n)F showed a linear decrease with an increase in chain length. On the basis of the slope of this plot, it was found that the variation in cmc with respect to the chain length is large for fluorinated gemini surfactants. The surface tension at the cmc decreased significantly; this surface tension value is lower than that of conventional fluorinated monomeric surfactants. In particular, the lowest value was 13.7 mN m(-1) for n = 8. Furthermore, it was confirmed that the kinetics of adsorption at the interface decrease with an increase in the fluorocarbon chain length and the concentration.     

Comparison of consensus scoring strategies for evaluating computational models of protein-ligand complexes

Here, the comparisons of performance of nine consensus scoring strategies, in which multiple scoring functions were used simultaneously to evaluate candidate structures for a protein-ligand complex, in combination with nine scoring functions (FlexX score, GOLD score, PMF score, DOCK score, ChemScore, DrugScore, PLP, ScreenScore, and X-Score), were carried out. The systematic naming of consensus scoring strategies was also proposed. Our results demonstrate that choosing the most appropriate type of consensus score is essential for model selection in computational docking; although the vote-by-number strategy was an effective selection method, the number-by-number and rank-by-number strategies were more appropriate when computational tractability was taken into account. By incorporating these consensus scores into the FlexX program, reasonable complex models can be obtained more efficiently than those selected by independent FlexX scores. These strategies might also improve the scoring of other docking programs, and more-effective structure-based drug design should result from these improvements.     

Coordination bond formation at charge-transfer phase transition in (BDTA)2[Co(mnt)2

The crystal structure of a charge-transfer salt, (BDTA)2[Co(mnt)2], where BDTA is 1,3,2-benzodithiazolyl and mnt is maleonitriledithiolate, consisted of an alternating stacking column of a head-to-head BDTA+ dimer and a planar [Co(mnt)2]2- dianion at 253 K. Magnetic measurements and structural analyses revealed a phase transition at 190 K, where a partial electron transfer occurred from [Co(mnt)2]2- to one of the BDTA+ cations, forming a coordination bond between the two.     

Scavenging DPPH radicals catalyzed by binary noble metal-dendrimer nanocomposites

Catalytic activity of gold-platinum, gold-palladium, and platinum-palladium dendrimer nanocomposites for scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals was investigated. The gold-platinum and gold-palladium dendrimer nanocomposites were prepared via simultaneous reduction by sodium borohydride in the presence of poly(amidoamine) (PAMAM) dendrimers with amine or carboxyl terminal groups. The particles were not mixtures of monometallic particles but alloyed bimetallic particles. Bimetallic particles exhibited higher catalytic activity than monometallic ones.     

Phomactin I, 13-epi-Phomactin I, and Phomactin J, three novel diterpenes from a marine-derived fungus

Three novel diterpenes were isolated from cultures of an unidentified marine-derived fungus. The structures of the compounds, phomactin I (1), 13-epi-phomactin I (2), and phomactin J (3) were determined by spectroscopic and X-ray crystallographic methods.     

Convectional, sedimentary, and drying dissipative patterns of colloidal suspensions of polymer complexes of poly(acrylic acid) with poly(ethylene glycol) and poly(vinyl pyrrolidone)

Convectional, sedimentary, and drying dissipative patterns were observed at room temperature on a cover glass, a watch glass, and a Petri dish during the course of dryness of aqueous suspensions of colloidal polymer complexes of poly(acrylic acid) (HPAA) with poly(ethylene glycol) (PEG) and poly(vinyl pyrrolidone) (PVP). With increase in the molecular weight of the polymer component, the complexes showed from transparent solution stable colloidal dispersion and the sticky aggregates. HPAA25K + PVP25K complex showed bluish colors and the colloidal crystal suspension. Size of the macroscopic broad rings of HPAA25K + PEG decreased as molecular weight of PEG increased. Furthermore, the size increased sharply as the polymer concentration increased in the complex systems HPAA25K + PVP25K. Characteristic microscopic patterns appeared for HPAA + PEG and HPAA + PVP complexes.     

Surface Activities of Calix[4] resorcinarenes Bearing Four Hydrophobic Chains and Its Sol ubilization for Organic Compounds

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An overview on the development of macromolecule-metal complexes and brief sketch on their recent trends

In early 1970s, there was growing tendency that the macromolecule-metal complexes should have been understood as a molecular science among many international scientists. Y. Y. Jiang, Academia Scinica, firstly proposed an international symposium on this field and the first congress (MMC-1) was held in 1985. From the 4th one, this series has been under the auspices of IUPAC and we have reached MMC-7. The current interests in this field are, for example, photoinduced electron transfer, outer-sphere process, chemical reactions in subnano-geometrical space, multi-electron transfer reaction. They are all linked to the high performances of advanced materials. The role of macromolecules in macromolecule-metal complexes are summarized and recent topics of this area are described.