Creation of a mixed-valence state from one-dimensionally aligned TTF utilizing the self-assembling nature of a low molecular-weight gel

One-dimensional TTF assemblies have been obtained through the design of low molecular-weight gels, which show a characteristic absorption band at around 1750 nm upon I2 doping, assignable to a mixed-valence state of the TTF assemblies.     

Molecular design and biological potential of galacto-type trehalose as a nonnatural ligand of shiga toxins

Galacto-type trehalose, a "C-4 epimer of trehalose", possesses a stereochemical structure around the alpha(1-1)-linkage analogous to that of the globobiosyl alpha(1-4)-linkage in Gb(2) and Gb(3) ceramides, which are known as the ligands of Shiga toxins produced by pathogenic E. coli. This paper presents evidence supporting the new idea of using a trehalosyl alpha(1-1)-linkage as a substitute for the galactobiosyl alpha(1-4)-linkage.     

Synthesis of isomeric coumarin-fluorene hybrids by photocyclization and the photophysical features

We prepared isomeric compounds 2a and 2b having fused skeletons of coumarin and fluorene by photochemical cyclization of olefin 1. They were successfully separated by chromatography, and characterized by NMR spectroscopic and X-ray crystallographic analyses. The molecular structure of 2a was nonplanar due to the repulsion between the carbonyl group of the coumarin moiety and the methylene group at 9-position on the fluorene skeleton whilst that of 2b was planar. They showed different absorption and fluorescence features in solution whereas their spectral profiles of triplet–triplet absorption and phosphorescence were similar to each other.     

Dehydrogenation of Ethanol Over Cu/ZnO Catalysts Prepared from Various Coprecipitated Precursors

For the title reaction, Cu/ZnO catalysts prepared from aurichalcite were more active than those prepared from other precursors. Selectivity to ethyl acetate over Cu/ZnO was much higher than that over Cu/SiO₂ This revised version was published online in June 2006 with corrections to the Cover Date.     

Novel 2,1,3-benzothiadiazole-based red-fluorescent dyes with enhanced two-photon absorption cross-sections

This paper reports the two-photon absorbing and orange-red fluorescence emitting properties of a series of new 2,1,3-benzothiadiazole (BTD)-based D-pi-A-pi-D-type and star-burst-type fluorescent dyes. In the D-pi-A-pi-D-type dyes 1-6, a central BTD core was connected with two terminal N,N-disubstituted amino groups via various pi-conjugated spacers. The star-burst-type dyes 8 and 10 have a three-branched structure composed of a central core (benzene core in 8 and triphenylamine core in 10) and three triphenylamine-containing BTD branches. All the BTD-based dyes displayed intense orange-red color fluorescence in a region of 550-689 nm, which was obtained by single-photon excitation with good fluorescent quantum yield up to 0.98 as well as by two-photon excitation. Large two-photon absorption (TPA) cross-sections (110-800 GM) of these BTD dyes were evaluated by open aperture Z-scan technique with a femtosecond Ti/sapphire laser. The TPA cross-sections of D-pi-A-pi-D-type dyes 2-6 with a benzene, thiophene, ethene, ethyne, and styrene moiety, respectively, as an additional pi-conjugated spacer are about 1.5-2.5 times larger than that of 1c with only a benzene spacer. The TPA cross-sections significantly increased in three-branched star-burst-type BTDs 8 (780 GM) with a benzene core and 10 (800 GM) with a triphenylamine core, which are about 3-5 times larger than those of the corresponding one-dimensional sub-units 9 (170 GM) and 11 (230 GM), respectively. The ratios of sigma/e(pi) between three-branched and one-dimensional dyes were 6.5:3.8 (for 8 and 9) and 6.0:4.0 (for 10 and 11), which are larger than those predicted simply on the basis of the chromophore number density (1:1), according to a cooperative enhancement of the two-photon absorbing nature in the three-branched system.     

Low-dose radiation response of the p21WAF1/CIP1 gene promoter transduced by adeno-associated virus vector

In cancer gene therapy, restriction of antitumor transgene expression in a radiation field by use of ionizing radiation-inducible promoters is one of the promising approaches for tumor-specific gene delivery. Although tumor suppressor protein p53 is induced by low doses (< 1 Gy) of radiation, there have been only a few reports indicating potential utilization of a p53-target gene promoter, such as that of the p21 gene. This is mainly because the transiently transfected promoter of p53-target genes is not much sensitive to radiation. We examined the response of the p21 gene promoter to low-dose radiation when transduced into a human breast cancer cell line MCF-7 by use of recombinant adeno-associated virus (rAAV) vectors. It was shown that the p21 gene promoter transduced by rAAV vectors was more highly radiation-responsive than that transiently transfected by electroporation. A significant induction of the p21 gene promoter by radiation of low doses down to 0.2 Gy was observed. When cells were transduced with the p21 gene promoter-driven HSVtk gene by rAAV vector, they were significantly sensitized to repetitive treatment with low dose radiation (1 Gy) in the presence of the prodrug ganciclovir. It was therefore considered that the p21 gene promoter in combination with a rAAV vector is potentially usable for the development of a low-dose radiation-inducible vector for cancer gene therapy.     

Supramolecular assemblies and redox modulation of pyromellitic diimide-based cyclophane via noncovalent interactions with naphthol

This paper reports the electroscopic and electrochemical properties of [2 + 2] pyromellitic diimide-based cyclophane 1 as well as acyclic N,N'-bis(2-methoxybenzyl)pyromellitic diimide 2 and the clathrate compounds formed by 1. Compound 1 was synthesized by direct cyclocondensation. Its structure was determined by an X-ray crystallographic analysis of a single crystal obtained by recrystallization from DMF. The intramolecular charge-transfer interactions of 1 and 2 were characterized by UV/vis spectroscopy and MO calculations. The UV/vis spectra showed that the tail of a longer wavelength absorption of both 1 and 2 reached the visible region. MO calculations (B3LYP/6-31G*) showed that the HOMO and LUMO orbitals of 1 and 2 substantially localize in the xylyl and pyromellitic diimide moieties across the methylene linker, respectively. The X-ray crystallographic analyses demonstrated that single crystals grown from a mixture of 1 and alpha-naphthol and a mixture of 1 and beta-naphthol were the clathrate compounds with 1D and 2D supramolecular assemblies, respectively, which are formed by a combination of hydrogen-bonding and charge-transfer interactions. From the cyclic voltammetry measurements, both 1 and 2 showed reversible reduction processes, and the reduction potential observed at -1.09 V vs Ag/Ag+ for 2 split into two potentials at -1.01 and -1.14 V for 1. The addition of alpha- and beta-naphthol induced a decrease in the potentials due to the diradical anion of 1 and radical anion of 2 by about 80 mV, and their reduction processes were reversible.     

Algebraic Independence Results Related to 〈q, r〉-Number Systems

We define 〈q, r〉-linear arithmetical functions attached to the 〈q, r〉-number systems and give a necessary and sufficient condition for their generating power series to be algebraically independent over . We also deduce algebraic independence of the functions values at a nonzero algebraic number in the circle of convergence.     

Framework engineering by anions and porous functionalities of Cu(II)/4,4'-bpy coordination polymers

A combination of framework-builder (Cu(II) ion and 4,4'-bipyridine (4,4'-bpy) ligand) and framework-regulator (AF(6) type anions; A = Si, Ge, and P) provides a series of novel porous coordination polymers. The highly porous coordination polymers ([Cu(AF(6))(4,4'-bpy)(2)].8H(2)O)(n)(A = Si (1a.8H(2)O), Ge (2a.8H(2)O)) afford robust 3-dimensional (3-D), microporous networks (3-D Regular Grid) by using AF(6)(2-) anions. The channel size of these complexes is ca. 8 x 8 A(2) along the c-axis and 6 x 2 A(2) along the a- or b-axes. When compounds 1a.8H(2)O or 2a.8H(2)O were immersed in water, a conversion of 3-D networks (1a.8H(2)O or 2a.8H(2)O) to interpenetrated networks ([Cu(4,4'-bpy)(2)(H(2)O)(2)].AF(6))(n)(A = Si (1b) and Ge (2b)) (2-D Interpenetration) took place. This 2-D interpenetrated network 1b shows unique dynamic anion-exchange properties, which accompany drastic structural conversions. When a PF(6)(-) monoanion instead of AF(6)(2)(-) dianions was used as the framework-regulator with another co-counteranion (coexistent anions), porous coordination polymers with various types of frameworks, ([Cu(2)(4,4'-bpy)(5)(H(2)O)(4)].anions.2H(2)O.4EtOH)(n)(anions = 4PF(6)(-) (3.2H(2)O.4EtOH), 2PF(6)(-) + 2ClO(4)(-) (4.2H(2)O.4EtOH)) (2-D Double-Layer), ([Cu(2)(PF(6))(NO(3))(4,4'-bpy)(4)].2PF(6).2H(2)O)(n)(5.2PF(6).2H(2)O) (3-D Undulated Grid), ([Cu(PF(6))(4,4'-bpy)(2)(MeCN)].PF(6).2MeCN)(n)(6.2MeCN) (2-D Grid), and ([Cu(4,4'-bpy)(2)(H(2)O)(2)].PF(6).BF(4))(n) (7) (2-D Grid), were obtained, where the three modes of PF(6)(-) anions are observed. 5.2PF(6).2H(2)O has rare PF(6)(-) bridges. The PF(6)(-) and NO(3)(-) monoanions alternately link to the Cu(II) centers in the undulated 2-D sheets of [Cu(4,4'-bpy)(2)](n)() to form a 3-D porous network. The free PF(6)(-) anions are included in the channels. 6.2MeCN affords both free and terminal-bridged PF(6)(-) anions. 3.2H(2)O.4EtOH, 4.2H(2)O.4EtOH, and 7 bear free PF(6)(-) anions. All of the anions in 3.2H(2)O.4EtOH and 4.2H(2)O.4EtOH are freely located in the channels constructed from a host network. Interestingly, these Cu(II) frameworks are rationally controlled by counteranions and selectively converted to other frameworks.