AI Article Synopsis

  • The article examines the dynamics of excited-state intramolecular double proton transfer in the compound [2,2'-bipyridyl]-3,3'-diol (BP(OH)) in various alcohol-water mixtures using femtosecond fluorescence upconversion techniques.
  • It reveals that the proton transfer pathway is sequential and experiences anomalous slowdowns in specific mole fraction ranges across different mixtures, indicating the complex role of the water network in these dynamics.
  • The study indicates that water accessibility is reduced due to cluster formation, particularly slowing down proton transfer in the TBA-water mixture; beyond a mole fraction of 0.40, a shift to a different proton transfer mechanism occurs, suggesting a transition from water-mediated to concerted

Article Abstract

In this article, we have investigated the excited-state intramolecular double proton transfer dynamics of [2,2'-bipyridyl]-3,3'-diol, BP(OH), in three alcohol-water binary mixtures, namely, ethanol (EtOH)-water, -propanol (PrOH)-water, -butyl alcohol (TBA)-water, and dimethyl sulfoxide (DMSO)-water utilizing the femtosecond fluorescence upconversion technique. We have found that in alcohol-water binary mixtures the proton transfer (PT) pathway of BP(OH) is sequential and the anomalous slowdown in PT dynamics is observed in mole fraction (χ) ranges χ = 0.04-0.07, χ = 0.23-0.28, χ = 0.17-0.30, χ = 0.12-0.21, and χ = 0.40-0.46. Our study sheds light on the involvement of water network in the PT dynamics. Reduction in water accessibility due to the involvement of water molecules in cluster formation results in hindered PT dynamics, and this retardation is more for the TBA-water binary mixture compared to that for the other two mixtures. Additionally, we have found two anomalous regions for the DMSO-water binary mixture in ranges χ = 0.12-0.16 and χ = 0.26-0.34. However, most interestingly, beyond χ = 0.40, we do not find any growth component in the femtosecond fluorescence upconversion trace, which may be due to the change in the PT mechanism from a sequential water-mediated pathway to a concerted intramolecular pathway.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6641458PMC
http://dx.doi.org/10.1021/acsomega.7b01833DOI Listing

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