Bowling Green State University

About: Bowling Green State University is a education organization based out in Bowling Green, Ohio, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 8315 authors who have published 16042 publications receiving 482564 citations. The organization is also known as: BGSU.

Synthesis, stability, and photochemistry of pentacene, hexacene, and heptacene: a matrix isolation study.

Abstract: The photochemical bisdecarbonylation of bridged α-diketones (Strating−Zwanenburg reaction) to give the oligoacenes pentacene (2), hexacene (3), and heptacene (4) is investigated in solid inert gas matrices at cryogenic temperatures. The photodecomposition using visible light irradiation cleanly produces the corresponding oligoacene without formation of observable intermediates. This synthetic approach to the higher acenes allows a comprehensive comparative study of their electronic absorption and infrared spectral properties under identical conditions for the first time. In addition, the route makes it possible to investigate the thermal and photochemical stability of these higher acenes and addresses the problem of heptacene stability which dates back almost 70 years. This largest known member of the acene series is found to be unstable at room temperature. Furthermore, all oligoacenes 2−4 undergo a photoredox reaction upon 185 nm excitation, resulting in the concurrent formation of radical cations and a...

Comparison of killing of gram-negative and gram-positive bacteria by pure singlet oxygen.

Abstract: Gram-negative and gram-positive bacteria were found to display different sensitivities to pure singlet oxygen generated outside of cells. Killing curves for Salmonella typhimurium and Escherichia coli strains were indicative of multihit killing, whereas curves for Sarcina lutea, Staphylococcus aureus, Streptococcus lactis, and Streptococcus faecalis exhibited single-hit kinetics. The S. typhimurium deep rough strain TA1975, which lacks nearly all of the cell wall lipopolysaccharide coat and manifests concomitant enhancement of penetration by some exogenous substances, responded to singlet oxygen with initially faster inactivation than did the S. typhimurium wild-type strain, although the maximum rates of killing appeared to be quite similar. The structure of the cell wall thus plays an important role in susceptibility to singlet oxygen. The outer membrane-lipopolysaccharide portion of the gram-negative cell wall initially protects the bacteria from extracellular singlet oxygen, although it may also serve as a source for secondary reaction products which accentuate the rates of cell killing. S. typhimurium and E. coli strains lacking the cellular antioxidant, glutathione, showed no difference from strains containing glutathione in response to the toxic effects of singlet oxygen. Strains of Sarcina lutea and Staphylococcus aureus that contained carotenoids, however, were far more resistant to singlet oxygen lethality than were both carotenoidless mutants of the same species and other gram-positive species lacking high levels of protective carotenoids.