Theoretical fluorescence yields and widths of the K shell and the L subshells,for the Ne,Ar, and Kr isoelectronic sequences

In this work, we present fluorescence yield and width values of Ne-, Ar-, and Kr-like ion levels for selected values of Z, using a state-of-the-art multiconfiguration Dirac–Fock approach. The results may be useful for the interpretation of spectra from plasmas, in both laboratory and astrophysics, as well as from ion collision experiments.     

BODIPY Dye,the Most Versatile Fluorophore Ever?

BODIPY laser dyes constitute a fascinating topic of research in modern photochemistry due to the large variety of options its chromophore offers, which is ready available for a multitude of synthetic routes. Indeed, in the literature one can find a huge battery of compounds based on the indacene core. The possibility of modulating the spectroscopic properties or inducing new photophysical processes by the substitution pattern of the BODIPY dyes has boosted the number of scientific and technological applications for these fluorophores. Along the following lines, I will overview the main results achieved in our laboratory with BODIPYs oriented to optoelectronic as well to biophotonic applications, stressing the more relevant photophysical issues to be considered in the design of a tailor‐made BODIPY for a certain application and pointing out some of the remaining challenges.

     

Synthesis and Characterization of m‐Terphenyl (1,3‐Diphenylbenzene) Compounds Containing Trifluoromethyl Groups

The bis(silyl)triazene compound 2,6‐(Me₃Si)₂‐4‐Me‐1‐(N?N? NC₄H₈)C₆H₂ ( 4 ) was synthesized by double lithiation/silylation of 2,6‐Br₂‐4‐Me‐1‐(N?N? NC₄H₈)C₆H₂ ( 1 ). Furthermore, 2,6‐bis[3,5‐(CF₃)₂‐C₆H₃]‐4‐Me‐C₆H₂‐1‐(N?N? NC₄H₈)C₆H₂ derivative 6 can be easily synthesized by a C,C‐bond formation reaction of 1 with the corresponding aryl‐Grignard reagent, i.e., 3,5‐bis[(trifluoromethyl)phenyl]magnesium bromide. Reactions of compound 4 with KI and 6 with I₂ afforded in good yields novel phenyl derivatives, 2,6‐(Me₃Si)₂‐4‐MeC₆H₂? I and 2,6‐bis[3,5‐(CF₃)₂? C₆H₃]‐4‐MeC₆H₂? I ( 5 and 7 , resp.). On the other hand, the analogous m‐terphenyl 1,3‐diphenylbenzene compound 2,6‐bis[3,5‐(CF₃)₂? C₆H₃]C₆H₃? I ( 8 ) could be obtained in moderate yield from the reaction of (2,6‐dichlorophenyl)lithium and 2 equiv. of aryl‐Grignard reagent, followed by the reaction with I₂. Different attempts to introduce the ^tBu (Me₃C) or neophyl (PhC(Me)₂CH₂) substituents in the central ring were unsuccessful. All the compounds were fully characterized by elemental analysis, melting point, IR and NMR spectroscopy. The structure of compound 6 was corroborated by single‐crystal X‐ray diffraction measurements.     

Tetrameric aggregate of 1,c‐3‐diphenyltetran‐r‐1‐ol via an R44(8) homodromic ring

The compound 1,c‐3‐diphenyltetran‐r‐1‐ol (systematic name: 1,c‐3‐diphenyl‐1,2,3,4‐tetrahydro‐r‐1‐naphthol), C₂₂H₂₀O, which possesses the tetrahydronaphthalene core that is found in a large number of natural products, crystallizes with Z′ = 4 and with the four molecules forming a hydrogen‐bonded cyclic aggregate. The aliphatic six‐membered rings are present with two different conformations in the molecules of the asymmetric unit. A comparison with similar fragments reveals their conformational flexibility. In addition, the structure demonstrates the relative stereochemistries of the chiral centers, which are important since the title compound is used in the stereoselective synthesis of compounds with therapeutic activity.     

Claisen rearrangements-xiv : Synthesis of the coumarin, benahorin and revision of the structure of marmelide

The natural coumarin, benahorin 1 has been synthesised in five steps from xanthotoxol 4. Marmelide has been shown to be the 3,3-dimethylallyl ether of xanthotoxol (imperatorin 9) and not as believed the 1,1-dimethylallyl ether 7.     

Identification of polymeric procyanidins from pine bark by mass spectrometry

Pine bark is an important source of polyphenolic compounds, mainly procyanidins, with reported protective effects against disease. In previous works, barks of two varieties of pine (P. pinaster and P. radiata) were extracted with ethanol, and partially purified to obtain the aqueous fractions (FA), that contained mainly polymeric procyanidins. The mean degree of polymerization was 7.9 for radiata (rFA) and 10.6 for pinaster (pFA). FAs were chromatographed on Sephadex LH‐20 by using a gradient of methanol, water and acetone, to render a series of sub‐fractions. In this work, the procyanidin compositions of these sub‐fractions were analyzed using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS). The mass spectra of sub‐fractions from FA of P. pinaster showed signals of procyanidin polymers up to tridecamers, whereas for those from P. radiata the maximum degree of polymerization was 15. For this latter case, the MALDI‐TOF mass spectra detected the presence of prodelphinidins in a small amount. Copyright © 2009 John Wiley & Sons, Ltd.     

Thermodynamic properties of liquid mixtures of carbon monoxide and methane

The equations of state of liquid methane at 125.00 K and of six liquid mixtures of carbon monoxide and methane at 116.30, 120.00 and 125.00 K have been measured from just above the saturation vapour pressure to the freezing pressure of methane. The results show that the excess volume V^E is large and negative at low pressures but becomes less negative as the pressure is increased, being almost zero at the highest pressures. The curve of V^E against the mole fraction x is very asymmetrical at low pressures, but becomes more symmetrical with rising pressure.The effect of pressure on the excess functions G^E, H^E and T·S^E has been calculated. H^E and T·S^E prove to be much more sensitive to pressure than G^E.Conformal solution theory, in the van der Waals one-fluid form, reproduces the experimental results very successfully.     

Black hole formation in c=1 string field theory

A suggestion on how black holes may appear in Das-Jevicki collective field theory is given. We study the behaviour of a “test” particle when energy is sent into the system. A perturbation moving near the potential barrier can create a large-distance black hole geometry where the seeming curvature singularity is at the position of the barrier. In the simplest “static” case the exact D=2 black hole metric emerges.