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Weak Emission (weak + emission)
Selected Abstracts85-GHz BIMA observations of the double-hotspot radio galaxy 3C 20MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2001M. J. Hardcastle We present 85-GHz observations of the archetypal double-hotspot radio source 3C 20 made with the BIMA millimetre array. The resolution of BIMA allows us to separate the two components of the eastern hotspot. By comparing the BIMA observations with existing VLA data, we show that the spectra of the two hotspot components are very similar, despite the clear differences in their radio structure and their wide separation. We discuss the implications for models of double hotspot formation. Weak emission from the lobes of 3C 20 is detected at 85 GHz, at a level consistent with the predictions of standard spectral ageing models. [source] Construction of 1D and 2D Copper(I) Coordination Polymers Assembled by PhS(CH2)nSPh (n = 1, 2) Dithioether Ligands: Surprising Effect of the Spacer Length on the Dimensionality, Cluster Nuclearity and the Fluorescence Properties of the Metal,Organic Framework,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2007Harmel N. Peindy Abstract Treatment of CuI with PhSCH2SPh in MeCN solution affords, by a self-assembly reaction, the monodimensional metal,organic coordination polymer [Cu4I4{,-PhS2CH2SPh}2]n (1), in which Cu4(,3 -I)4 cluster units are linked by the dithioether ligand in a 1D necklace structure. In contrast, the reaction of PhSCH2CH2SPh with CuI results in the formation of the metallopolymer [(CuI)2{,-PhS(CH2)2SPh}2]n (2). The 2D network of 2 is built from dimeric Cu2I2 units which are connected by 1,2-bis(phenylthio)ethane bridging ligands. The solid-state luminescence spectrum of 1 exhibits a strong emission around 532 nm, whereas a weak emission centred at 413 nm is observed in the case of 2. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Synthesis, Crystal Structure, and Photoluminescent Properties of a Tetracarbonyl(naphthyridylcarbamoyl)rhenium(I) Complex and a Highly Emissive Tetracarbonyl(naphthyridylamido)rhenium(I) ComplexEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2003Jing-Lin Zuo Abstract The reactions of Re(CO)5X (X = Cl, Br) with 7-amino-2,4-dimethyl-1,8-naphthyridine (H2L1) and 7-[2-(6-chloropyridyl)amino]-2,4-dimethyl-1,8-naphthyridine (HL2) in the presence of tBuOK afforded the ,1 -naphthyridylcarbamoyl complex [Re(CO)4(HL1CO)] (1) and the naphthyridylamido complex [Re(CO)4(L2)] (2), respectively. The structures of HL2, 1·CHCl3, 1·HL3·2CH2Cl2 [HL3 = (7-chloronaphthyridyl)(5,7-dimethylnaphthyridyl)amine], and 2 have been determined by X-ray crystallography. Complex 1 displays a weak emission at 453 nm in an EtOH/MeOH (1:4, v/v) glassy solution at 77 K; complex 2 exhibits an intense (quantum yield: 0.22 in CH2Cl2) and long-lived emission (46 ,s in CH2Cl2), with a solvent-sensitive ,max, in degassed solutions at room temperature. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2003) [source] BODIPY-Tetrazine Multichromophoric DerivativesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2010Cécile Dumas-Verdes Abstract New dyes based on BODIPY and tetrazine fluorophores connected through a phenyl spacer have been synthesized and their absorption, emission and electrochemical properties characterized. BODIPY can be reversibly oxidized into a stable cation radical whereas tetrazine can be reduced to a stable anion radical. The electrochemical and absorption studies demonstrate that both fluorophores behave independently. The bichromophoric compounds show an expected very weak emission by the BODIPY core that is quenched by the phenoxytetrazine mainly through energy transfer. DFT calculations and spectroelectrochemistry experiments demonstrate that photoinduced electron transfer and energy transfer remain possible when the tetrazine moiety is reduced electrochemically, which prevents switching on of the fluorescence of the BODIPY unit. [source] Dinuclear Iridium(III) Complexes Linked by a Bis(,-diketonato) Bridging Ligand: Energy Convergence versus Aggregation-Induced EmissionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2010Chang Hwan Shin Abstract Novel iridium(III)/iridium(III) and iridium(III)/platinum(II) dinuclear complexes, [{Ir(ppyFF)2}2(,2 - L)] (4) and [{Ir(ppyFF)2}(,2 - L){Pt(ppy)}] (5) [ppyFF = 2-(2,4-difluorophenyl)pyridine, ppy = 2-phenylpyridine, L = 1,3-bis(3-phenyl-3-oxopropanoyl)benzene], linked by an L bridging ligand were prepared, and their photophysical properties were investigated in solution and in the solid state. The photophysical properties of mononuclear iridium(III) and platinum(II) complexes, [Ir(ppyFF)2(dbm)] (1) and [Pt(ppy)(dbm)] (2) bearing a dibenzoylmethane (dbm) ligand were also compared. Whereas the UV/Vis absorption spectra of 4 and 5 show independent light absorption at each metal-centered moiety, the photoluminescence spectra of 4 and 5 display almost identical features, but very weak emissions in solution at both room temperature and 77 K. The weak emission in solution is found to mainly originate from a 3LX state of the L bridging ligand, which reflects the occurrence of efficient energy convergence from the triplet states of the Pt(ppy) and Ir(ppyFF) moieties to the 3LX state of L. By contrast, intense orange-red emission, that is, aggregation-induced emission, is produced in the solid state of 4 and 5. Inspection of the crystal-packing structures of 5 reveals that strong intermolecular ,,, interactions between the adjacent pyridine rings of ppyFF ligands in the Ir-centered moieties are responsible for the emissive metal-to-ligand,ligand charge-transfer [3M(LL)CT] state of the solid-state dinuclear systems. The electrochemical properties of 4 and 5 further indicate that the first two reductions occur at the dbm moieties of the L bridging ligand linked to each metal center, which is consistent with the fact that the lowest-energy excited state of the L bridging ligand dominates the excited-state properties of 4 and 5 in solution. [source] | ||||||||||