Kristopher McNeill


Last Name

McNeill

First Name

Kristopher

ORCID

0000-0002-2981-2227

Organisational unit

03850 - McNeill, Kristopher / McNeill, Kristopher

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Publications1 - 10 of 211
  • Fluorescent Molecular Probes for Detection of One-Electron Oxidants Photochemically Generated by Dissolved Organic Matter
    Item type: Journal Article
    Lin, Vivian S.; Grandbois, Matthew; McNeill, Kristopher (2017)
    Environmental Science & Technology
    We report a dual probe system based on 4′-substituted biphenyl-2-carboxylic acids (BPAs) for analysis of photooxidants generated by dissolved organic matter. The BPA probes are converted to the corresponding benzocoumarins (BZCs) at different rates depending on the mechanism of oxidation; thus, two probes used simultaneously can differentiate strong triplet excited state sensitizers from hydroxylating species such as hydroxyl radical (•OH) present in dissolved organic matter (DOM). Comparison of the ratios of BZC–CH3 and BZC–CF3 product formation using model photooxidants such as NaNO2, a •OH precursor, and model triplet sensitizer lumichrome gave a range of 2 to 250. Application of these probes to DOM isolates and whole natural waters afforded intermediate ratios. Although the oxidation potential of BPAs (>ca. 1.80 V SHE) is significantly higher than the estimated average reduction potential of typical 3CDOM* samples, these results have demonstrated the presence of a small pool of oxidants in the selected DOM isolates and whole water samples that is capable of oxidizing aromatic carboxylates. As an analytical tool, this probe pair can be used between pH 4–6 without affecting the product formation ratio and may find applications in various systems involving complex mixtures of photochemically produced oxidants of differing natures.
  • Dark Formation of Hydroxyl Radical in Arctic Soil and Surface Waters
    Item type: Journal Article
    Page, Sarah E.; Kling, George W.; Sander, Michael; et al. (2013)
    Environmental Science & Technology
  • Furan Carboxamides as Model Compounds to Study the Competition between Two Modes of Indirect Photochemistry
    Item type: Journal Article
    Ossola, Rachele; Schmitt, Markus; Erickson, Paul R.; et al. (2019)
    Environmental Science & Technology
    Singlet oxygen (1O2) and triplet chromophoric dissolved organic matter (3CDOM*) are photochemically produced reactive intermediates responsible for the photodegradation of several micropollutants in the sunlit surface waters. However, elucidating the mechanism of reactions involving both 1O2 and 3CDOM* can be complicated by the deeply interconnected nature of these two reactive species. In this work, we synthesized a series of model compounds inspired by the chemical structure of fenfuram, a fungicide used in the 1980s, and used them to investigate structure−reactivity relationships in photodegradation reactions involving 1O2 and 3CDOM*. A combination of steady-state and time-resolved approaches was employed to successfully predict the extent of 1O2-induced degradation. Conversely, the prediction of triplet-induced reactivity was complicated by the presence of repair mechanisms whose extent and relative importance were difficult to predict. The results of our work indicate that bimolecular rate constants measured via time-resolved techniques alone are not sufficient to accurately predict environmental half-lives, as intrinsic differences in the reaction mechanism can amplify the importance of secondary degradation pathways.
  • Photochemical Chain Scissions Enhance Polyethylene Glycol Biodegradability: from Probabilistic Modeling to Experimental Demonstration
    Item type: Journal Article
    Kleemann, Kevin; Jaggi, Madalina; Bernasconi, Stefano M.; et al. (2025)
    Environmental Science & Technology
    Polyethylene glycols (PEGs), a major class of water-soluble polymers (WSPs), are widely used in diverse applications, from which PEGs may be released into the environment. This work investigates the effect of PEG reaction with photochemically produced hydroxyl radicals (•OH), an important environmental oxidant, on the molecular weight (MW) distribution of PEGs and their subsequent biodegradation in soil and sediment. Monte Carlo simulations demonstrated a pronounced decrease in the PEG MW after only a few •OH-reaction-induced chain scissions on initial PEG molecules. The simulation results were validated by experimentally reacting 13C-labeled PEGs ( 𝑀¯n = 6380 ± 400 Da) with photochemically produced •OH to three extents and by analyzing the formed low MW PEG reaction products. Incubation of unreacted and •OH-reacted PEGs in both a sediment and a soil over 150 days demonstrated increasing rates and extents of PEG biodegradation into 13CO2 with increasing •OH-reaction extent and thus increasing amounts of low MW PEG products. This work underscores the importance of considering WSP MW distributions and dynamics caused by biotic or abiotic chain scission reactions when advancing a detailed understanding of WSP fate and biodegradability in natural and engineered receiving environments.
  • Photochemistry of Dissolved Combined Amino Acids
    Item type: Conference Paper
    Lundeen, Rachel A.; Schaelchli, Jeremy; McNeill, Kristopher (2013)
    Mineralogical Magazine
  • UV/Vis+ photochemistry database: Structure, content and applications
    Item type: Journal Article
    Noelle, Andreas; Vandaele, Ann C.; Martin-Torres, Javier; et al. (2020)
    Journal of Quantitative Spectroscopy and Radiative Transfer
    The “science-softCon UV/Vis+ Photochemistry Database” (www.photochemistry.org) is a large and comprehensive collection of EUV-VUV-UV–Vis-NIR spectral data and other photochemical information assembled from published peer-reviewed papers. The database contains photochemical data including absorption, fluorescence, photoelectron, and circular and linear dichroism spectra, as well as quantum yields and photolysis related data that are critically needed in many scientific disciplines. This manuscript gives an outline regarding the structure and content of the “science-softCon UV/Vis+ Photochemistry Database”. The accurate and reliable molecular level information provided in this database is fundamental in nature and helps in proceeding further to understand photon, electron and ion induced chemistry of molecules of interest not only in spectroscopy, astrochemistry, astrophysics, Earth and planetary sciences, environmental chemistry, plasma physics, combustion chemistry but also in applied fields such as medical diagnostics, pharmaceutical sciences, biochemistry, agriculture, and catalysis. In order to illustrate this, we illustrate the use of the UV/Vis+ Photochemistry Database in four different fields of scientific endeavor.
  • Best Papers from 2021 published in the Environmental Science journals of the Royal Society of Chemistry
    Item type: Other Journal Item
    Novak, Paige J.; Donahue, Neil M.; McNeill, Kristopher; et al. (2022)
    Environmental Science: Atmospheres
  • The impact of photochemistry on the cloud condensation nuclei (CCN) activity of organic aerosols
    Item type: Other Conference Item
    Borduas-Dedekind, Nadine; Ossola, Rachele; Kanji, Zamin; et al. (2017)
  • Isotope Fractionation Associated with the Photochemical Dechlorination of Chloroanilines
    Item type: Journal Article
    Ratti, M.; Canonica, S.; McNeill, Kristopher; et al. (2015)
    Environmental Science & Technology
  • Hydrodefluorination and Hydrogenation of Polyfluorinated Benzenes under Mild Aqueous Conditions
    Item type: Other Conference Item
    Baumgartner, Rebekka; McNeill, Kristopher (2012)
Publications1 - 10 of 211