Synthesis of Palladium Clusters with the P--N--P Assembling Ligands (Ph2P)2CH2 (dppm) and (Ph2P)2NH (dppa). Crystal Structure of [Pd4(μ-Cl)2(μ-dppm)2(μ-dppa)2](PF6)2

Tetrapalladium clusters containing dppa or dppa and dppm bridging ligands were prepared by condensation of dinuclear units. Reaction of [Pd₂Cl₂(-dppa)₂] with [Cu(PPh₃)]PF₆ (generated in situ in THF) yielded [Pd₄(-Cl)₂(-dppa)₄] (PF₆)₂ (4) in a virtually quantitative yield but [Pd₄(-Cl)₂(-dppm)₂(-dppa)₂] (PF₆)₂ (6) was best prepared in CH₂Cl₂ from [Pd₂Cl₂(-dppm)₂] and [Pd₂(MeCN)₂(-dppa)₂](PF₆)₂ (2). The structure of 6·2(CH₃)₂CO·2H₂O was determined by X-ray diffraction. It consists of a planar, centrosymmetric 10-membered ring structure. The four bridging diphosphine ligands are of two types: two dppa ligands support the Pd Pd bonds [2.6055(4) Å], whereas the two dppm ligands bridge between two palladium atoms separated by 3.722(4) Å, which are also bridged by a chloride ligand.     

Approche méthodologique directe et continue du processus d'oxydation des bitumes par spectroscopie infrarouge à transformée de Fourier

(Direct continuous method for studying oxidation of bitumens by Fourier-transform infrared spectrometry). The method is based on the standard rolling thin-film oven test with oxidation in air at 163°C. A specially designed infrared cell is used. FTIR spectrometry provides spectral fingerprints which are characteristic for each bitumen.     

Polycyclotrimerization of aromatic diynes: Synthesis,thermal stability,and light‐emitting properties of hyperbranched polyarylenes

New aromatic diyne monomers of 1,4‐diethynyl‐2,5‐(dihexyloxy)benzene ( 1 ), 1,6‐diethynyl‐2‐(hexyloxy)naphthalene ( 2 ), and 9,9‐bis(4‐ethynylphenyl)fluorene ( 3 ) are synthesized. Their homopolymerizations and copolymerizations with 1‐octyne ( 4 ) or phenylacetylene ( 5 ) are effected by TaBr₅–Ph₄Sn and CpCo(CO)₂–hν, giving soluble hyperbranched polyarylenes with high molecular weights (M_w up to ～ 2.9 × 10⁵) in high yields (up to 99%). The structures and properties of the polymers are characterized and evaluated by IR, NMR, UV, PL, and TGA analysis. The polymers show excellent thermal stability (T_d > 400 °C) and carbonize when pyrolyzed at 900 °C. Upon photoexcitation, the polymers emit deep blue light in the vicinity of ～400 nm with fluorescence quantum yields up to 92%. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4249–4263, 2007     

Hyperbolicity versus partial-hyperbolicity and the transversality-torsion phenomenon

In this paper, we describe a process to create hyperbolicity in the neighbourhood of a homoclinic orbit to a partially hyperbolic torus for three degrees of freedom Hamiltonian systems: the transversality-torsion phenomenon.     

signal of NMSSM at the LHC

For the Benjamin Ono equation, the Hirota bilinear method and long wave limit method are applied to obtain the breathers and the rogue wave solutions. Bright and dark rogue waves exist in the Benjamin Ono equation, and their typical dynamics are analysed and illustrated. The semirational solutions possessing rogue waves and solitons are also obtained, and demonstrated by the three-dimensional figures. Furthermore, the hybrid of rogue wave and breather solutions are also found in the Benjamin Ono equation.     

A facile design for multifunctional AIEgen based on tetraaniline derivatives

Aniline oligomers have been widely used in many fields due to their excellent physicochemical properties. Owing to strong intermolecular interactions, their emission is always weakened or quenched when they are in high concentration or aggregated state, which greatly limits their fluorescent applications. Inspired by the concept of aggregation-induced emission(AIE), herein we introduced large steric groups onto the aniline oligomer to prevent the formation of packing structure. In particular, diphenyl vinyl group was bonded with oligomeric tetraaniline by a facile synthetic procedure with high yield. The obtained aniline oligomer derivative exhibited typical AIE features, which was also confirmed by density functional theoretical calculation. More importantly, this AIE oligomer was able to detect Fe~(3+) ions selectively and quantitatively. The fluorescence intensity decreased linearly along with the increment of Fe~(3+) concentration. Moreover, we demonstrated that this AIE oligomer could stain live bacteria, such as E. coli and S. aureus efficiently. All these results suggest that such a readily accessible and multifunctional tetraaniline derivative provides a new platform for the construction of fluorescent materials.     

Phase transition behavior and structure of the thermotropic liquid crystal 6‐{[(4′‐{[(undecyl)carbonyl]oxy}biphenyl‐4yl)carbonyl]oxy}‐1‐hexyne

The phase transition behaviors and corresponding structures of 6‐{[(4′‐{[(undecyl)carbonyl]oxy}biphenyl‐4yl)carbonyl]oxy}‐1‐hexyne (A4EE11) were investigated using differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and wide angle X‐ray diffraction (WAXD). In comparison with the published homologues, 5‐{[(4′‐heptoxy‐biphenyl‐4‐yl)carbonyl]oxy}‐1‐pentyne (A3EO7) which shows a monotropic smectic A (SmA) phase and a metastable monotropic smectic C (SmC) phase; 5‐{[(4′‐heptoxy‐biphenyl‐4‐yl)oxy]carbonyl}‐ 1‐pentyne (A3E'O7) that exhibits three enantiotropic stable liquid crystalline (LC) phases, SmA phase, SmC phase and smectic X (SmX) phase; 5‐{[(4′‐heptoxy‐biphenyl‐4‐yl)carbonyl]oxy}‐1‐undecyne (A9EO7) which has a monotropic SmA phase and a metastable crystal phase, A4EE11 integrates the enantiotropy, monotropy and metastability of the LC phases of those three compounds. Upon cooling from isotropic state to room temperature, in the temperature range of 62.0 to 58.5°C, A4EE11 shows an enantiotropic smectic A (SmA) phase with a layer spacing d=32.69Å. Further lowering the temperature, it enters into a metastable monotropic smectic B (SmB) phase with a longer layer spacing d=34.22Å which has a tendency towards crystallization. The metastability of the liquid crystalline phase may associate to the linkage order of the ester bridge between the mesogenic core and the flexible spacer. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Making silole photovoltaically active by attaching carbazolyl donor groups to the silolyl acceptor core

Appending carbazolyl groups to a hexaphenylsilole core yielded thermally and morphologically stable carbazolylsiloles; the silole carrying two carbazolyl peripheral groups showed photovoltaic activity.     

Determination of ¹J(⁵⁹Co-⁵⁹Co) scalar coupling constants in the tetrahedral mixed-metal cluster HFeCo₃(CO)₁₀(PCyH₂)(PPh₂[CH₂C(O)Ph]) using COSY-type NMR experiments

Two-dimensional ??Co correlation spectroscopy (COSY) and double-quantum-filtered (DQF) COSY NMR experiments are reported for the tetrahedral mixed-metal cluster HFeCo?(CO)??(PCyH?)(PPh?[CH?C(O)Ph]), which consists from the point of view of ??Co NMR spectroscopy, of an AMX system of three-spin S=7/2. Both 2D NMR spectra prove the existence of a J scalar coupling constant between non-equivalent ??Co nuclei. By contrast to what happens with the conventional 2D ??Co COSY NMR spectrum, it was possible to simulate the 2D ??Co DQF-COSY NMR spectrum by density matrix calculations in order to extract the values of the 1J(??Co-??Co) coupling constants. The comparison between experimental and theoretical 2D NMR spectra gives spin-couplings constants of several hundreds Hertz for this cluster.