New chiral cyclooctatriene-based polycyclic architectures

The synthesis and properties of new chiral polycyclic architectures that display both helicity and a saddle-type shape are described. The enantiomers have been separated, and their absolute configuration was determined by VCD and ECD. The unprecedented molecular architecture is based on a cyclooctatriene core surrounded by an association of benzo[c]fluorene and ortho-phenylene units.     

Binaphthyl platform as starting materials for the preparation of electron rich benzo[g,h,i]perylenes. Application to molecular architectures based on amino benzo[g,h,i]perylenes and carborane combinations

Valuable amino benzo[g,h,i]perylenes have been obtained through a one pot electrophilic aromatic substitution--Scholl reaction sequence. Novel molecular architectures combining 3D-o-carborane and planar amino benzo[g,h,i]perylene units are described. Photophysical properties of amino benzo[g,h,i]perylene and the carborane-appended derivatives are discussed.     

Notes on analytical procedures : Determination of the hardness of boiler water

A survey of the commoner methods for the determination of the hardness of boiler water is given. The stearate method is recommended.     

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Structural and solvent effects on the 13C and 15N NMR chemical shifts of indoloquinoline alkaloids: experimental and DFT study

Indoloquinoline alkaloids represent an important class of antimalarial, antibacterial and antiviral compounds. They have been shown to bind to DNA via intercalation preferentially at GC-rich sequences containing nonalternating CC sites. The stability of complexes formed with biological macromolecules depends on noncovalent binding. In the present study, the ability of indoloquinolines to form intermolecular interactions with solvents was investigated by using NMR spectroscopy and density functional theory (DFT) (B3LYP/6-31G**) calculations. NMR data measured for indoloquinoline bases and the corresponding hydrochlorides are discussed in relation to the structure. DFT calculations of shielding constants in vacuo and in solution allowed the investigation of the influence of the environment on the NMR parameters. Calculations incorporating solvent effects indicated significant changes in the anisotropy of the electron distribution, reflected in the span of the chemical shielding tensor (Omega = sigma11 - sigma33). Solvent effects on the span of the 13C and 15N shielding tensor depended on the type of atom and the data indicated a significant influence of solute-solvent interactions.     

Strong inhibition of cholera toxin binding by galactose dendrimers

Galactose-containing dendrimers with long spacer arms inhibit cholera toxin binding as strongly as the natural ganglioside GM1 oligosaccharide does.     

Modelling overall particle motion in fluidised beds for top-spray coating processes

A mathematical model predicting the overall particle motion in liquid-sprayed gas–solid fluidised beds has been developed. The proposed model is a superposition of bubble-induced particle motion and particle random walk. The model was validated using experimental particle residence times from literature. Good agreement between experimental and model-predicted residence times was obtained for those cases where atomisation air was absent and on the condition of the inclusion of a so-called “dead zone”. The “dead zone”, being a region of stagnant particles in the annular bottom part of the bed, has also been previously reported in literature. In case atomisation air was present, a less favourable agreement was seen between the model and the experiment. As the atomisation air has been shown to significantly alter the ejection distance of particles in the freeboard, recalibration of the ejection height parameter has been demonstrated to obtain an acceptable agreement between model-predicted and experimental data.     

Enantiopure nanohoops through racemic resolution of diketo[n]CPPs by chiral derivatization as precursors to DBP[n]CPPs

Strained conjugated nanohoops are attractive synthetic targets due to the bending of their π-system, which leads to intriguing optoelectronic properties, among others. By incorporating non-mirror-symmetric aromatic panels, chiral nanohoops can be obtained. We herein present a strategy to enantiopure nanohoops by racemic resolution through chiral derivatization of diketone-embedded hoops. The resulting diketo[n]CPPs (n = 6, 7) contain two stereogenic carbon atoms each and possess high fluorescence quantum yields paired with circularly polarized luminescence. These are versatile precursors to chiral dibenzo[a,e]pentalene-based nanohoops DBP[n]CPPs with antiaromatic character and ambipolar electrochemical behavior. Due to their strained structures the DBP[n]CPPs do not racemize at room temperature, which is supported by high calculated isomerization barriers. X-ray crystallographic investigations on the DBP[n]CPPs and their precursors as well as DFT calculations provide insight into the build-up of strain energy during the synthetic transformations.

Racemic resolution of diketone-embedded cycloparaphenylenes by derivatization with a chiral auxiliary provides scalable access to enantiopure hoops with chiroptical properties.     

Kinetics of Temperature-induced and Reaction-induced Phase Separation Studied by Modulated Temperature DSC

Temperature-induced phase separation of P(EO75-ran-PO25)/PES and reaction-induced phase separation of DGEBA/MDA modified with PVME are studied using MTDSC as an in-situ tool. Phase separation can be probed by the onset of an ‘excess’ contribution in the MTDSC heat capacity signal, in good correspondence with the cloud point temperature. This feature enables the complete construction of the state diagram of P(EO75-ran-PO25)/PES. The detection of phase separation-induced partial vitrification of the high-T_g phase (PES-rich phase) enables to sub-divide the LCST-type heterogeneous region in a zone 1 (no interference of partial vitrification) and a zone 2 (interference of partial vitrification of the PES-rich phase). This sub-division of the heterogeneous region has drastic implications on the remixing behavior of demixed blends. In DGEBA/MDA modified with PVME, reaction-induced phase separation accompanied by an increase in reaction rate, followed by a vitrification step of the epoxy-amine phase can be detected in-situ. In non-isothermal conditions, a diffusion-controlled reaction after vitrification and a final devitrification of the system is also observed.