Color Bricks: Building Highly Organized and Strongly Absorbing Multicomponent Arrays of Terpyridyl Perylenes on Metal Oxide Surfaces

Terpyridine‐substituted perylenes containing cyclic anhydrides in the peri position were synthesized. The anhydride group served as an anchor for assembly of the terpyridyl‐crowned chromophores as monomolecular layers on metal oxide surfaces. Further coordination with Zn²⁺ ions allowed for layer‐by‐layer formation of supramolecular assemblies of perylene imides on the solid substrates. With properly selected anchor and linker molecules it was possible to build high quality structures of greater than ten successive layers by a simple and straightforward procedure. The prepared films were stable and had a broad spectral coverage and high absorbance. To demonstrate their potential use, the synthesized dyes were employed in solid‐state dye‐sensitized solar cells, and electron injection from the perylene antennas to titanium dioxide was observed.     

Synthesis of 3-substituted indazoles and benzoisoxazoles via Pd-catalyzed cyclization reactions: application to the synthesis of nigellicine

Syntheses of 3-substituted indazoles and benzoisoxazoles were efficiently accomplished with the aid of Pd-catalyzed intramolecular carbon-nitrogen and carbon-oxygen bond formations. The catalyst system described herein allows the cyclization to proceed under very mild conditions and thus could be applied to a wide range of substrates with acid- or base-sensitive functional groups. A total synthesis for the indazole ring-containing natural product nigellicine is also described.     

Surface modification with well-defined biocompatible triblock copolymers Improvement of biointerfacial phenomena on a poly(dimethylsiloxane) surface

To improve interfacial phenomena of poly(dimethylsiloxane) (PDMS) as biomaterials, well-defined triblock copolymers were prepared as coating materials by reversible addition-fragmentation chain transfer (RAFT) controlled polymerization. Hydroxy-terminated poly(vinylmethylsiloxane-co-dimethylsiloxane) (HO–PV_lD_mMS–OH) was synthesized by ring-opening polymerization. The copolymerization ratio of vinylmethylsiloxane to dimethylsiloxane was 1/9. The molecular weight of HO–PV_lD_mMS–OH ranged from (1.43 to 4.44) × 10⁴, and their molecular weight distribution (M_w/M_n) as determined by size-exclusion chromatography equipped with multiangle laser light scattering (SEC-MALS) was 1.16. 4-Cyanopentanoic acid dithiobenzoate was reacted with HO–PV_lD_mMS–OH to obtain macromolecular chain transfer agents (macro-CTA). 2-Methacryloyloxyethyl phosphorylcholine (MPC) was polymerized with macro-CTAs. The gel-permeation chromatography (GPC) chart of synthesized polymers was a single peak and M_w/M_n was relatively narrow (1.3–1.6). Then the poly(MPC) (PMPC)–PV_lD_mMS–PMPC triblock copolymers were synthesized. The molecular weight of PMPC in a triblock copolymer was easily controllable by changing the polymerization time or the composition of the macro-CTA to a monomer in the feed. The synthesized block copolymers were slightly soluble in water and extremely soluble in ethanol and 2-propanol.

Surface modification was performed via hydrosilylation. The block copolymer was coated on the PDMS film whose surface was pretreated with poly(hydromethylsiloxane). The surface wettability and lubrication of the PDMS film were effectively improved by immobilization with the block copolymers. In addition, the number of adherent platelets from human platelet-rich plasma (PRP) was dramatically reduced by surface modification. Particularly, the triblock copolymer having a high composition ratio of MPC units to silicone units was effective in improving the surface properties of PDMS.

By selective decomposition of the Si–H bond at the surface of the PDMS substrate by irradiation with UV light, the coating region of the triblock copolymer was easily controlled, resulting in the fabrication of micropatterns. On the surface, albumin adsorption was well manipulated.     

Molecular aggregates of partially fluorinated quaternary ammonium salt gemini surfactants

The size and shape of novel partially fluorinated gemini surfactant 1,2-bis[dimethyl-(3-perfluoroalkyl-2-hydroxypropyl)ammonium]ethane bromide (CnFC3-2-C3CnF, where n=4, 6, and 8) were investigated in aqueous solution by means of light scattering and transmission electron microscopy (TEM). The sizes of these molecular aggregates changed with increasing carbon number of the alkyl chain and concentration. For example, the apparent hydrodynamic radius by dynamic light scattering was 18 nm at a concentration of cmcx5 for n=4, 115 nm at the cmcx15 for n=6, and 62 nm at the cmcx30 for n=8, at 298.2 K. The shapes of CnFC3-2-C3CnF aggregates drastically changed with the alkyl chain length; the aggregates were mainly in the form of large or irregular small aggregates (n=4), string-like aggregates (n=6), and vesicles (n=8). The bromide-ion activity was measured using a bromide-ion-selective electrode to determine the degree of counterion binding to the aggregates. The degree of counterion binding to aggregate was very small compared with that in the typical hydrogenated gemini surfactants. These results indicated that the small curvature of large aggregates was not influenced by an electrostatic repulsion between the cationic head groups in the case of the bulky molecular volume of fluorinated gemini surfactants.     

Metachromins R--T, new sesquiterpenoids from marine sponge Spongia sp

Three new sesquiterpenoids, metachromins R--T (1--3), have been isolated from an Okinawan marine sponge Spongia sp. The structures and stereochemistry of 1--3 were elucidated on the basis of the spectroscopic data. Metachromins S (2) and T (3) showed modest cytotoxicity.     

Thermoluminescence study of persistent luminescence materials: Eu2+- and R3+-doped calcium aluminates, CaAl2O4:Eu2+,R3+

Thermoluminescence properties of the Eu2+-, R3+-doped calcium aluminate materials, CaAl2O4:Eu2+,R3+, were studied above room temperature. The trap depths were estimated with the aid of the preheating and initial rise methods. The seemingly simple glow curve of CaAl2O4:Eu2+ peaking at ca. 80 degrees C was found to correspond to several traps. The Nd3+ and Tm3+ ions, which enhance most the intensity of the high-temperature TL peaks, form the most suitable traps for intense and long-lasting persistent luminescence, too. The location of the 4f and 5d ground levels of the R3+ and R2+ ions were deduced in relation to the band structure of CaAl2O4. No clear correlation was found between the trap depths and the R3+ or R2+ level locations. The traps may thus involve more complex mechanisms than the simple charge transfer to (or from) the R3+ ions. A new persistent luminescence mechanism presented is based on the photoionization of the electrons from Eu2+ to the conduction band followed by the electron trapping to an oxygen vacancy, which is aggregated with a calcium vacancy and a R3+ ion. The migration of the electron from one trap to another and also to the aggregated R3+ ion forming R2+ (or R3+-e-) is then occurring. The reverse process of a release of the electron from traps to Eu2+ will produce the persistent luminescence. The ability of the R3+ ions to trap electrons is probably based on the different reduction potentials and size of the R3+ ions. Hole trapping to a calcium vacancy and/or the R3+ ion may also occur. The mechanism presented can also explain why Na+, Sm3+, and Yb3+ suppress the persistent luminescence.     

Iron(II)‐ and Cobalt(II) Complexes with Tridentate Bis(imino)pyridine Nitrogen Ligands Bearing Chiral Bulky Aliphatic and Aromatic Substituents: Crystal Structure of [CoCl2{2, 6‐bis[R‐(+)‐(bornylimino)methyl]pyridine}]

Iron(II) and cobalt(II) complexes ( 7 ‐ 15 ) based on new aldimine 2, 6‐bis[(imino)methyl]pyridine ( 1 , 2 , 4 , 6 ) and ketimine (2, 6‐bis[(imino)ethyl]pyridine ( 3 , 5 ) ligands with bulky chiral aliphatic or aromatic terminal groups have been prepared and characterized by ¹H NMR, ¹³C NMR, IR‐, mass spectroscopy (EI), and elemental analysis. The complex [CoCl₂(BBoMP)]·¹/₂ CHCl₃ ( 13 ) (BBoMP: 2, 6‐bis{(R‐(+)‐(bornylimino)‐methyl}pyridine) crystallizes in monoclinic space group P2₁ with cell dimensions: a = 7.6603(11) Å, b = 28.3153(14) Å, c = 13.537(2) Å, V = 2908.1(6) ų, Z = 4. The coordination sphere around Co is distorted trigonal bipyramidal.     

Effect of compression on interaction between 1,4-dihydropyridine compounds and lactose monohydrate

Manidipine dihydrochloride or benidipine hydrochloride will change to hydrate form in part, when differential scanning calorimetric (DSC) measurement is carried out together with lactose monohydrate. This interaction was accelerated by compressing their mixture. It can be suggested that the interaction may cause by the disruption of crystal structure of lactose monohydrate due to compression to set free of water molecules. A new DSC peak at 170 degrees C, which was not observed in each component, appeared in DSC measurement of a mixture. This will be based on hydrate formed by the interaction, i.e., movement of water molecules. The profile of the plotting of the DSC peak area ratio before and after compression against the compression force changed by the molar ratio of lactose monohydrate in a mixture. In the case of low molar ratio of lactose monohydrate, profiles for manidipine dihydrochloride and benidipine hydrochloride differed from each other. This will be because manidipine dihydrochloride is stickier than benidipine hydrochloride. The profile for manidipine dihydrochloride became more gradual and showed lag compression force region when the amount of addition of the lubricant, magnesium stearate in a mixture increased. The endothermic peak area at 170 degrees C for manidipine dihydrochloride was larger than that for benidipine hydrochloride. It should be suggested that benidipine hydrochloride is easier to be transformed to its hydrate than manidipine dihydrochloride.     

Atomic layer deposition in nanometer-level replication of cellulosic substances and preparation of photocatalytic TiO2/cellulose composites

TiO2 replicas of filter paper with nanometer-level accuracy were prepared by atomic layer deposition of thin conformal TiO2 coating, followed by a removal of the paper by air-anneal at 450 degrees C. Photocatalytic anatase TiO2/cellulose composites were also made by leaving the paper intact. The TiO2 films were deposited from Ti(OMe)4 and H2O at 150-250 degrees C. The photocatalytic activity of the TiO2/cellulose composite was verified by photocatalytic reduction of Ag(I) from an aqueous solution to Ag nanoparticles on the TiO2 surface. The TiO2/cellulose composites are mechanically more stable than the free-standing TiO2 replicas and are therefore potentially suitable as lightweight, high surface area photocatalysts.     

Harmonic analysis from quasi-periodic domains

Harmonic analysis is applied in a quasi-periodic context to get rigidity results in orbit equivalence theory. This paper has been written while the author was visiting the University of Tokyo under a JSPS Fellowship for European researchers.