ABSTRACT
Quinone-based, aqueous redox flow batteries are a promising technology for large-scale, low-cost energy storage. To understand the influence of substituent and substituent pattern effects of quinone-based derivatives on the redox potential, a screening study was performed that included benzoquinone, naphtaquinone, and anthraquinone derivatives. The order of substituent influence is -OH>-Me/-OMe for decreasing the redox potential and -F<-SO3 - <-CN, -NO2 for increasing the redox potential, which is in agreement with general expectations. We found that the consideration of resonance and inductive effects design strategies of redox-active materials can be extended by the ability of intramolecular hydrogen bond formation, steric hindrance, and energetic differences of conformers for oxidized and reduced species. Due to the complexity and overlap of these effects, theoretical screening studies can provide guidance for the design of new molecular materials. In addition to the redox potential, other parameters such as stability, solubility, and kinetic rate constant or synthetic accessibility are crucial to consider.
Subject(s)
Eukaryota , Periodicals as Topic/history , Animals , Germany , History, 20th Century , Malaria/history , Research/historyABSTRACT
Geosiphon pyriforme, an endosymbiotic association between a fungus and the cyanobacterium Nostoc, was shown by tracer studies to acquire carbon photosynthetically from CO2 or bicarbonate. The organism also fixes inorganic carbon in darkness, at lower rates than in the light. The patterns of label distribution are indicative of the operation of the reductive pentose-phosphate pathway in the light and of the phosphoenolpyruvate-carboxylase reaction in the dark. The results are discussed in relation to the evolution of photoautotrophic endosymbiotic associations.
