Synthesis of a double helicene by a palladium-catalyzed cross-coupling reaction: structure and physical properties.

For this study, twisted π-extended helicene 1 and double helicene 2 with a helicene framework were synthesized through palladium-catalyzed C-H arylation or Suzuki-Miyaura coupling reaction. X-ray crystallography revealed grossly twisted structures that were soluble in various conventional organic solvents. Optical properties based on UV/Vis and fluorescence spectra were measured. Electrochemical properties were also studied by measurements of cyclic voltammetry in 1 and 2, which revealed their HOMO and the LUMO energies. Theoretical calculation supports their HOMO and LUMO energies and molecular orbitals. Furthermore, a racemization process of 2 predicted that the activation free energy at 300 K would be 31.8 kcal mol(-1) by DFT calculation, which indicated the static helicity at 300 K.

Electron microscopic analysis of heat-induced leakage of polyphosphate from a phoU mutant of Escherichia coli.

Heat treatment is a simple technique for releasing polyphosphate (polyP) from microbial cells. We investigated the ultrastructural alterations of polyP granules (PPGs) in response to heat treatment at 70 degrees C using a polyP-accumulating phoU mutant of Escherichia coli as a model organism. Electron microscopic and energy-dispersive X-ray analysis suggested concurrent occurrence of PPG degradation and polyP release in the cytoplasm. PolyP is probably released by cytoplasmic extrusion through breaks in the cell envelope.