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Oldest Peach Pits Found in China.

Big Gene Bank to Anchor Precision Medicine.

Koning Receives China Food and Drug Administration Clearance.

UC Berkeley, Berkeley Lab Partner with China's Tsinghua on Clean Energy.

China's Temperature, Sea Level Rise Faster than Global Average.

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Pollen Chains Associated with Secondary Pollen Presentation in a Wild Ginger Species.

Researchers Find Structural Isomerism in Gold Nanoparticles.

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Mt. Qomolangma Glaciers Shrink 28 pct in 40 Years: Report.

DNA Dates Dog Domestication Back 33,000 Years.

Crystal Structures of Human TIM Members: Ebolavirus Entry-enhancing Receptors.

This work presents the synthesis and characterization of a series of substituted pyridylpentafluroporphyrins, including the separation of the cis- and trans-isomers, the latter being characterized by X-ray crystallography. The spectroscopic and electrochemical properties of the series are dependent on the number of electron withdrawing pentafluorophenyl substituent, but they do not depend on the symmetry of the molecule. Ongoing from the monosubstituted to the more substituted pentafluorophenyl porphyrin H₂(MPyTFPP) derivative, the Soret bands are slightly red-shifted and their quantum fluorescence yields range from 0.035 to 0.046, consistent with the value of 0.045 for the fully substituted 5,10,15,20-tetrapentafluorophenylporphyrin (dichloromethane solutions). The redox potentials of the reductive processes of monoanion and dianion formation are also sensitive to the number of pentafluoro substituents, shifting 180 mV to more positive values for the P⁰/P^-1 process ongoing from the monopentafluoro to the tris-pentafluorophenyl substituted derivative.

The stability of an organic compound depends on its nature and the environment in which it is placed. It depends on the presence or absence of reagents (acid, base, oxidizing agent, reducing agent, light, etc.) and catalysts. The stability may not be the same in the solid, liquid or gaseous state. In a homogenous solution, the stability might be affected by the polarity of the solvent and its concentration. For instance a polar solvent favors ionization. In a non-polar solvent ionization is difficult. In the gas phase ionization never occurs. In the gas phase and in solution stability depends on pressure and the presence of impurities. We are interested here in the thermal stability of pure compounds in the gas phase or in non-polar solvents under one atmosphere…