Access to Paullone Analogues by Intramolecular Heck Reaction

The syntheses of paullone ( 1a ) and three paullone derivatives, including a sulfur analogue ( 2a ), a tricyclic derivative ( 2b ), and a ring‐enlarged variant ( 2c ), are described, Pd‐catalyzed intramolecular Heck reaction being the key step. The kinase‐inhibitory properties of the novel paullone analogues were investigated.     

Femtosecond electronic relaxation of excited metalloporphyrins in the gas phase

A systematic study of the ultrafast decay of metalloporphyrins containing various transition metals with partially filled 3d shells and zinc (3d filled) is reported here after excitation in the second excited state of the system (Soret band). Both time-of-flight mass spectrometry and velocity map imaging have been used for detection. A general biexponential decay with a short time constant tau1 approximately 100 fs is observed for the transition metal porphyrins, followed by a tau2 approximately 1 ps time decay. This evolution is interpreted as a porphyrin-to-metal charge transfer, tau1, followed by a back transfer, tau2, which leads to an excited state (d,d*) localized on the metal. These conclusions stem from the different behaviors of zinc and the transition metal porphyrins. A porphyrin-to-metal charge transfer model is chosen to describe the relaxation mechanism, based upon the fact that transition metalloporphyrins can accept electrons on the metal site, in contrast to zinc porphyrins.     

Bis{bis­[5‐tert‐butyl‐2‐oxido‐3‐(1‐pyridinio­methyl)­phenyl]­methane}­dioxouranium bis­(tri­fluoro­methane­sulfonate) pyridine disolvate: a uranyl bis­(diphenoxide) complex resulting from homooxacalixarene cleavage

The title compound, [UO₂(C₃₃H₃₈N₂O₂)₂](CF₃SO₃)₂·2C₅H₅N, has been obtained by reaction of U^IV tri­fluoro­methane­sulfonate with p‐tert‐butyl­tetrahomodioxacalix­[4]­arene in pyridine. The uranyl ion lies on an inversion centre and is bound to two O atoms from each diphenoxide ligand, which gives the usual square‐planar equatorial environment. The zwitterionic diphenoxide species results from nucleophilic attack by pyridine on the benzylic ether C atoms of the homooxacalixarene, assisted by initial U coordination to the ether groups, with subsequent metal oxidation giving the uranyl moiety.     

Multiscale laminar flows with turbulentlike properties

By applying fractal electromagnetic force fields on a thin layer of brine, we generate steady quasi-two-dimensional laminar flows with multiscale stagnation point topology. This topology is shown to control the evolution of pair separation (Delta) statistics by imposing a turbulentlike locality based on the sizes and strain rates of hyperbolic stagnation points when the flows are fast enough, in which case Delta(2) approximately t(gamma) is a good approximation with gamma close to 3. Spatially multiscale laminar flows with turbulentlike spectral and stirring properties are a new concept with potential applications in efficient and microfluidic mixing.     

Skew codes of prescribed distance or rank

In this paper we generalize the notion of cyclic code and construct codes as ideals in finite quotients of non-commutative polynomial rings, so called skew polynomial rings of automorphism type. We propose a method to construct block codes of prescribed rank and a method to construct block codes of prescribed distance. Since there is no unique factorization in skew polynomial rings, there are much more ideals and therefore much more codes than in the commutative case. In particular we obtain a [40, 23, 10]₄ code by imposing a distance and a [42,14,21]₈ code by imposing a rank, which both improve by one the minimum distance of the previously best known linear codes of equal length and dimension over those fields. There is a strong connection with linear difference operators and with linearized polynomials (or q-polynomials) reviewed in the first section.      

Sweeping process with regular and nonregular sets

Differential inclusions involving the normal cone to a moving set are investigated. A special attention is paid to the sweeping process associated with sets for which no regularity assumption is required.     

A simple theoretical model for dual phosphorescence

A simple theoretical model is presented to explain the observed anomalous dual phosphorescences of certain aromatic carbonyl compounds in some rigid media. The phenomenon of dual phosphorescence for large molecules violates the well-known Kasha rule stating that the emission can occur only from the lowest excited electronic state of a given multiplicity. For a small energy gap between the second triplet state (T₂) and the first triplet state (T₁), the sparse density of T₁ vibronic levels, isoenergetic with the T₂ vibrationless level, leads to a rather slow T₂ → T₁ radiationless process which is unable to quench the T₂ emission completely. Two cases of T₁ = ³nπ^*, T₂ = ³ππ^* and T₁ = ³ππ^*, T₂ = ³nπ^* are discussed at both the low-temperature and the high-temperature limits.