Copper Inhibition of Triplet-Induced Reactions Involving Natural Organic Matter

Pan, Yanheng; Garg, Shikha; Waite, T. David; Yang, Xin

doi:10.1021/acs.est.7b05655

Cited by 40 publications

(54 citation statements)

References 66 publications

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“…Further studies using complimentary techniques are needed to validate these findings, given the limitations of this study. It has been shown previously that NOM reactivity, via the formation of singlet oxygen, decreases in the presence of metals, 56,68,92 so the results of this study show that this decrease is not due to conformational changes affecting the ability of ground state oxygen to quench the excited triplet. We also showed that the analysis performed in this study, although very simplified, is applicable to both fluorescence quenching and enhancement interactions.…”

Section: Discussionsupporting

confidence: 60%

Relating natural organic matter conformation, metal complexation, and photophysics

Stirchak

Donaldson

2021

Can. J. Chem.

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We investigated the relationship between changes in fluorescence intensity and in fluorescence anisotropy for Suwannee River Natural Organic Matter (SRNOM) due to the formation of NOM-metal complexes with divalent and trivalent metals commonly present in both fresh water and sea water environments. We chose metal ions whose complexes give rise to both fluorescence quenching (Fe3+, Cu2+) and fluorescence enhancement (Al3+ and Mg2+). Stern-Volmer type analyses quantified the changes in the SRNOM fluorescence as a function of metal concentration. All metals display strong complexation with SRNOM, associated with their effect on fluorescence. Experiments with Fe3+ further show strong effects due to NOM aggregation at all but the lowest metal concentrations studied here. There was little to no change in the conformation of SRNOM as inferred from fluorescence anisotropy caused by increasing metal concentration. These results suggest that there is no correlation between photophysical changes and conformational changes in NOM associated with complexation by the metal ions.

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Section: Discussionsupporting

confidence: 60%

Relating natural organic matter conformation, metal complexation, and photophysics

Stirchak

Donaldson

2021

Can. J. Chem.

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“…Phosphorescence quenching was mainly attributed to the following two reasons: (i) metal ion coordination disturbed the hydrogen bonds between the interdots, leading to destabilization of the triplet state and (ii) quenching of the excited triplet state due to the paramagnetic perturbations. 37 In addition, the developed CDs also showed strong binding ability to lanthanide ions. Tb 3+ and Eu 3+ ions were selected owing to their ladder-like energy levels and prominent luminescent performance.…”

Section: Resultsmentioning

confidence: 97%

“…Meanwhile, the phosphorescence of CDs-4 was effectively quenched by Cu 2+ ions (Figure f). Phosphorescence quenching was mainly attributed to the following two reasons: (i) metal ion coordination disturbed the hydrogen bonds between the interdots, leading to destabilization of the triplet state and (ii) quenching of the excited triplet state due to the paramagnetic perturbations …”

Section: Resultsmentioning

confidence: 99%

Modulating Triplet Excited-State Energy in Phosphorescent Carbon Dots for Information Encryption and Anti-Counterfeiting

Zhang

Zheng

et al. 2021

ACS Appl. Mater. Interfaces

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Room-temperature phosphorescent carbon dots (RTP-CDs) may be used in anti-counterfeiting, information encryption, and optoelectronic devices, but modulating their triplet-state energy is still challenging. Here, a type of RTP-CDs was developed via hydrothermal polymerization–carbonization of azamacrocycle and poly(acrylic acid). The introduction of nitrogen heterocycle promotes the intersystem crossing from the singlet state to the triplet state, and the functional groups of CDs can form interdot hydrogen bonds to protect the triplet state. In addition, the uncarbonized heterocycle groups in the CDs provide coordination sites for metal ions. In this case, the excited triplet-state energy of CDs is quenched by paramagnetic ions (Co2+ and Cu2+) or transfers to luminescent ions (Tb3+ and Eu3+). Furthermore, the modulation of the triplet state by metal ion binding was demonstrated in information encryption and anti-counterfeiting applications.

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“…Laboratory and field studies have also noted that a photosensitizer, such as natural organic matter (NOM), is typically required to initiate the formation of VOCs at the interface and may influence the concentration and identity of the VOCs produced. ,,, NOM is an important component of surface waters, present at concentrations between 0.1 and 20 mg L –1 , − and is strongly enriched at the air–water interface, particularly when a microlayer is present. ,, In the aquatic environment, NOM is photochemically active due to the presence of chromophoric species, as it can act as a photosensitizer via its excited triplet state, − and the excited triplet state also leads to the formation of different reactive intermediates such as singlet oxygen ( 1 O 2 ) − and the hydroxyl radical (OH • ). − Additionally, it has been reported that riverine and oceanic natural organic matter exhibit different photosensitizing properties, which are highly variable due to the intrinsic link with local geology and biology. In particular, the activity of marine natural organic matter shows even day to day variability, related to its origin and the sampling procedures used. , It has also been shown previously that the water composition, such as the presence of halides and different metals, alters the formation of the different reactive intermediates, − thereby affecting the role that NOM plays in the photochemistry of surface waters. NOM can also participate in heterogeneous, light-induced reactions at the interface with trace gases, such as NO 2 , and ozone with chlorophyll .…”

Section: Introductionmentioning

confidence: 90%

“…In particular, the activity of marine natural organic matter shows even day to day variability, related to its origin and the sampling procedures used. 68,69 It has also been shown previously that the water composition, such as the presence of halides and different metals, alters the formation of the different reactive intermediates, [70][71][72][73][74][75][76] thereby affecting the role that NOM plays in the photochemistry of surface waters. NOM can also participate in heterogenous, light-induced reactions at the interface with trace gases, such as NO 2 , 51 and ozone with chlorophyll.…”

Section: Introductionmentioning

confidence: 90%

Differences in Photosensitized Release of VOCs from Illuminated Seawater versus Freshwater Surfaces

Stirchak

Abis

Kalalian

et al. 2021

ACS Earth Space Chem.

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Recent studies have shown that photochemical reactions occurring at the air-water interface are a source of volatile organic compounds (VOCs) to the atmosphere. We report here the photosensitized formation of VOCs from illuminated freshwater and seawater mimics containing nonanoic acid (NA) and/or Suwannee River natural organic matter (SRNOM). Under an atmosphere of air, the total blank-corrected steady-state concentration of VOCs formed from illuminated seawater coated with nonanoic acid is somewhat smaller than that formed from freshwater, suggesting some differences in photochemical pathways for the two substrates. The total blank-corrected steady-state concentration of VOCs more than doubles from both freshwater and seawater NA-coated surfaces under nitrogen compared to air. The addition of SRNOM as a photosensitizer induces some photochemistry from the seawater sample under air, but no chemistry is seen with freshwater, or under nitrogen for either substrate. Adding SRNOM to the nonanoic acid-containing solutions roughly doubles the total steady-state concentration of VOCs emitted from both freshwater and seawater surfaces under air. The small differences in product formation for the two substrates implies some difference in the photochemical mechanisms operating in freshwater versus seawater, which may be due to the presence of halides and metals as well as pH differences between the two aqueous systems. importance and interest. 1,2 The presence of an organic coating, even as little as a sub-monolayer, at a water surface may alter the kinetics of heterogeneous reactions there, with the exact effect depending upon the composition of the monolayer. [3][4][5][6] The air-water interface is also exposed to sunlight for large portions of time, suggesting the importance of heterogeneous photochemistry processes that may occur there. 7 Recent studies have focused on understanding how the air-water interface influences the formation of volatile organic compounds (VOCs) in the aqueous phase and their release into the atmosphere. Field studies found evidence to suggest that the air-water interface is a source of VOCs, such as isoprene and formic acid, [8][9][10][11] which suggests that a marine source of VOCs is more important than previously thought for the global VOC budget. [12][13][14] In addition, it has been suggested that the type of aquatic environment (fresh versus saline) may influence the production of VOCs. 15 Recent laboratory studies, 16-24 using simplified aquatic environments, have shown that photochemistry at the air-water interface serves as a major abiotic source of functionalized VOCs, [25][26][27] which has further implications towards the oxidative capacity of the atmosphere and the formation of secondary aerosols.These laboratory studies have also highlighted the importance of a microlayer in the formation of the gas-phase products. The sea surface microlayer (SML) has been shown to play a crucial role as a boundary in the physical and chemical exchange between the ocean and the atmosphere. 28,2...

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Copper Inhibition of Triplet-Induced Reactions Involving Natural Organic Matter

Cited by 40 publications

References 66 publications

Relating natural organic matter conformation, metal complexation, and photophysics

Relating natural organic matter conformation, metal complexation, and photophysics

Modulating Triplet Excited-State Energy in Phosphorescent Carbon Dots for Information Encryption and Anti-Counterfeiting

Differences in Photosensitized Release of VOCs from Illuminated Seawater versus Freshwater Surfaces

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