86,534 research outputs found
Organische Chemie 2004
No full textBruckner R, Wurthner F, Tschierske C, et al. Organische Chemie 2004. Nachrichten aus der Chemie. 2005;53(3):251-272
Wavelength-Dependent Electron and Energy Transfer Pathways in a Side-to-Face Ruthenium Porphyrin / Perylene Bisimide Assembly
No full textA new side-to-face supramolecular array of chromophores, where a pyridyl-substituted perylene bisimide dye axially binds to two ruthenium porphyrin fragments, has been prepared by self-assembly. The array is formulated as DPyPBI[Ru(TPP)(CO)] 2 , where DPyPBI )N ,N ′-di(4-pyridyl)-1,6,7,12-tetra(4- tert -butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide and TPP ) 5,10,15,20-tetraphenylpor- phyrin. The photophysical behavior of DPyPBI[Ru(TPP)(CO)] 2 has been studied by fast (nanoseconds) and ultrafast (femtoseconds) time-resolved techniques. The observed behavior sharply changes with excitation wavelength, depending on whether the DPyPBI or Ru(TPP)(CO) units are excited. After DPyPBI excitation, the strong fluorescence typical of this unit is completely quenched, and time-resolved spectroscopy reveals the occurrence of photoinduced electron transfer from the ruthenium porphyrin to the perylene bisimide dye (ô ) 5.6 ps) followed by charge recombination (ô ) 270 ps)
Organische Chemie 2002
No full textWurthner F, Herges R, Brase S, et al. Organische Chemie 2002. Nachrichten aus der Chemie. 2003;51(3):286-315
Understanding the structural and charge transport property relationships for a variety of merocyanine single-crystals: A bottom up computational investigation
No full textMerocyanines consist of electronic donor (D) and acceptor (A) subunits connected via a methine bridge. They are highly polar organic π-conjugated molecules investigated for their self-assembly and optoelectronic properties. The accurate description of their structure-property relationships remains challenging. We report a comprehensive analysis modelling intra- and inter-molecular charge transport parameters for a library of merocyanines featuring different D/A combinations and lateral substituents. We found that constrained DFT correctly assesses the molecular and electronic structure in single crystals. The most effective charge transport pathways were identified and charge carrier mobilities were computed. We analyzed a large variety of single crystals highlighting the impact of alkyl substituents and casting conditions, drawing clear structure vs. charge transport relationships. Our modelling suggests that hole transport is maximized when dipolar molecules are packed in slipped not centrosymmetric pairs, arranged in 2D interconnected architectures. Computed and experimental charge mobilities for single crystals are in good agreement
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
John F. Kennedy telegram to Roosevelt
No full textJersey Homesteads (later the Borough of Roosevelt) was established in the 1930s as an agro-industrial cooperative community. It was established specifically for urban Jewish garment workers, many of whom had emigrated from Europe. President John F. Kennedy sent a telegram to the citizens of Roosevelt, New Jersey, apologizing for not being able to attend the memorial dedication in honor of former President Franklin Delano Roosevelt. (Jersey Homesteads became Roosevelt in 1945 in honor of the president.) President Kennedy expressed his gratitude to the people of Roosevelt for constructing the memorial, and commented that it will serve as a constant reminder of Roosevelt's good works
Chiral Exciton Coupling of Merocyanine Dyes within a Well-Defined Hydrogen-Bonded Assembly
No full textMultichromophoric hydrogen-bonded assemblies 13⋅(BAR)6 are studied that bear a remarkably close resemblance to commelinin, a naturally occurring assembly responsible for an intense blue color of flowers. The incorporated chromophores exhibit a hypsochromic shift in the UV/visible (Vis) absorption maximum (Δ λmax = 14 nm) compared with the free chromophores. In addition, the chiroptical properties of incorporated chromophores can be rationally controlled by changing the supramolecular chirality of the assembly. These properties have been used to study the stability of this type of assembly with UV and CD spectroscopy at concentrations far below the NMR sensitivity threshold (10−4 M). The determined C50% values of 2–3 μM in benzene show the extremely high stability of these hydrogen-bonded assemblies
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
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