Fluorescence properties of novel 6-butyl-2,3-dicyano-7-methyl-6H-1,4-diazepine styryl dyes containing ethyleneglycol units

The fluorescence properties of novel 6-butyl-2,3-dicyano-7-methyl-6H-1,4-diazepine styryl dyes having mono-, di-, tri-, and tetra(ethyleneglycol) units were examined. The mono(ethylenglycol) derivative was solid at room temperature, whereas the di-, tri-, and tetra(ethylenglycol) derivatives were oily. The monoethyleneglycol derivative showed weak aggregation-induced emission enhancement with fluorescence maximum at 649 nm, which comes from J-aggregates. The fluorescence of oily di-, tri-, and tetra(ethyleneglycol) derivatives in neat form was very weak. No aggregation-induced emission enhancement was observed for the oily derivatives.     

Synthesis of lipophilic bisanthracene fluorophores: versatile building blocks toward the synthesis of new light-harvesting dendrimers

Lipophilic bisanthracene-based fluorophore and its derivatives were synthesized by the Suzuki-Miyaura cross-coupling reaction of 9-anthrylboronic acid with a substituted dibromobenzene. In addition to desirable fluorescent properties, these molecular systems were demonstrated to serve as versatile building blocks toward the synthesis of two types of new light-harvesting dendrimers due to their chemical stability.     

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Diffusion and solution behavior of methanol vapor in two diblock copolymers, poly(2-vinylpyridine)—block—polyisoprene [P(2VPbI)] and poly(2-vinylpyridine)—block—polystyrene [P(2VPbS)], was studied by the weighing method at 25°C. The domain structure of films of both copolymers showed an alternating lamellar arrangement. Methanol is a good solvent for P2VP, but a nonsolvent for PI and PS. Methanol dissolved exclusively in the P2VP phase of the copolymers. For both copolymer systems, absorption and desorption processes of non-Fickian type were observed as characterized by a thickness anomaly. However, the magnitude of the deviations from purely Fickian behavior was small, and the integral diffusion coefficient, D?, was obtainable with reasonable accuracy. At low and medium concentrations, D? for P(2VPbI) was greater, by about one order of magnitude, than that for P2VP, while D? for P(2VPbS) was lower than that for P2VP. A similar trend was observed in plots of the permeability coefficient against the vapor pressure of methanol. The results indicate that the rubbery PI phase may facilitate the transport of penetrant molecules in the P(2VPbI) film. On the other hand, the glassy PS phase in the P(2VPbS) film merely interferes with the transport of methanol molecules.     

A novel synthesis of α-methylene-γ-butyrolactones from 1-(N,N-dimethylaminomethyl)cyclopropanecarboxylate esters

A new method is reported for constructing α-methylene-γ-butyrolactone moiety under neutral, anhydrous conditions. Olefin-dibromocarbene adducts are transformed to methyl 1-(N,N-dimethylaminomethyl)cyclopropanecarboxylates which in turn are treated with trimethylsilyl iodide and the crude products distilled to give the title compounds with high regio- and stereoselectivity.     

Estimation of monomer reactivity ratios by nonlinear least-squares procedure with consideration of the weight of experimental data

To obtain the optimum values of the monomer reactivity ratios for the copolymerization systems with largely different reactivities between both monomers, a nonlinear least-squares procedure which took into account the weights of experimental data, was proposed and discussed. The weights of the data were treated for the errors arisen from the amounts of monomers charged, the densities of monomers, the weights of copolymer formed, and the composition of copolymer. The least-squares procedure with the consideration of the weights was applicable to both differentiated equation and integrated equation derived by Lewis and Mayo. This procedure was applied to radical copolymerizations of α-substituted crotonic esters with styrene, and reasonable monomer reactivity ratios were obtained. It was noted that errors from the copolymer composition were more important than those from the other factors and that the use of the integrated equation was recommended even when the copolymers were isolated at low conversions.     

Pentagonal-Dodecahedral La2 Charge Density in [80-Ih]Fullerene: La2@C80

No Abstract     

First-Known High-Nuclearity Copper–Nickel Carbonyl Cluster: [CuxNi35−x(CO)40]5− (with x=3 or 5) Containing an Unprecedented 35-Atom Three-Layer hcp Triangular Stacking Metal-Core Geometry

Reactions of [Ni₆(CO)₁₂]^2- (1) with CuBr₂ have given rise in small yields (10%) to the first example of a close-packed copper-nickel carbonyl cluster; its formulation as [Cu_xNi_35-x(CO)₄₀]^5- (with x=3 or 5) is based upon a low-temperature CCD X-ray crystallographic determination coupled with an elemental analysis and X-ray fluorescence measurements. This air-unstable black pentaanion (2) together with one co-crystallized bromide anion, six [NMe₄]⁺ counterions, and one solvated acetone molecule comprise the crystallographic independent part in a monoclinic unit cell of P2₁/n symmetry (with Z=4). The geometrically unprecedented 35-atom hcp M(A)₂M(B)₃Ni₃₀ polyhedron of pseudo-D_3h symmetry consists of a central 15-atom equilateral ₄M(B)₃Ni₁₂ triangle that is capped on both sides by two symmetry-related 10-atom equilateral ₃M(A)Ni₉ triangles. The 35-atom M(A)₂M(B)₃Ni₃₀ core is encapsulated by 40 COs, whose connectivities, due to an extra CO ligand on one of the three triangular sides, reduce the pseudo D_3h symmetry of the metal core to C_s. An elemental analysis via AA and X-ray fluorescence measurements resulted in Cu/Ni ratios of 3.2/31.8 and 3.7/31.3, respectively, that are consistent with the metal core being either Cu₅Ni₃₀ (i.e., M(A)=M(B)=Cu) or Cu₃Ni₃₂ (i.e., M(A)=Ni; M(B)=Cu). Several attempts to determine the actual stoichiometry of the metal core by use of electrospray FT/MS/ICR measurements were unsuccessful. The maximum metal-core diameter of 2 is ca. 0.41 nm parallel and 0.85 nm perpendicular to the principal 3-fold axis.