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RESEARCH ARTICLE

Aqueous-phase photooxygenation of enes, amines, sulfides and polycyclic aromatics by singlet (a1Δg) oxygen: prediction of rate constants using orbital energies, substituent factors and quantitative structure–property relationships

Tom M. Nolte A D and Willie J. G. M. Peijnenburg B C
+ Author Affiliations
- Author Affiliations

A Department of Environmental Science, Institute for Water and Wetland Research, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands.

B National Institute of Public Health and the Environment, PO Box 1, 3720 BA Bilthoven, The Netherlands.

C Institute of Environmental Sciences (CML), Leiden University, PO Box 9518, 2300 RA, Leiden, The Netherlands.

D Corresponding author. Email: tom.m.nolte@gmail.com

Environmental Chemistry 14(7) 442-450 https://doi.org/10.1071/EN17155
Submitted: 19 July 2017  Accepted: 10 October 2017   Published: 31 January 2018

Environmental context. To aid the transition to sustainable chemistry there is a need to improve the degradability of chemicals and limit the use of organic solvents. Singlet oxygen, 1O2, is involved in organic synthesis and photochemical degradation; however, information on its aqueous-phase reactivity is limited. We developed cheminformatics models for photooxidation rate constants that will enable accurate assessment of aquatic photochemistry without experimentation.

Abstract. To aid the transition to sustainable and green chemistry there is a general need to improve the degradability of chemicals and limit the use of organic solvents. In this study we developed quantitative structure–property relationships (QSPRs) for aqueous-phase photochemical reactions by singlet (a1Δg) oxygen. The bimolecular singlet oxygen reaction rate constant can be reliably estimated (R2 = 0.73 for naphtalenes and anthracenes, R2 = 0.86 for enes and R2 = 0.88 for aromatic amines) using the energy of the highest occupied molecular orbital (EHOMO). Additional molecular descriptors were used to characterise electronic and steric factors influencing the rate constant for aromatic enes (R2 = 0.74), sulfides and thiols (R2 = 0.72) and aliphatic amines. Mechanistic principles (frontier molecular orbital, perturbation and transition state theories) were applied to interpret the QSPRs developed and to corroborate findings in the literature. Depending on resonance, the speciation state (through protonation and deprotonation) can heavily influence the oxidation rate constant, which was accurately predicted. The QSPRs can be applied in synthetic photochemistry and for estimating chemical fate from photolysis or advanced water treatment.

Additional keywords: degradation, organic photochemistry.


References

[1]  T. Montagnon, M. Tofi, G. Vassilikogiannakis, Using singlet oxygen to synthesize polyoxygenated natural products from Furans Acc. Chem. Res. 2008, 41, 1001.
Using singlet oxygen to synthesize polyoxygenated natural products from FuransCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXot1ahsbY%3D&md5=4390a6a8deefd775fba96d70b3ee9a6eCAS |

[2]  X. Gu, X. Li, Y. Chai, Q. Yang, P. Li, Y. Yao, A simple metal-free catalytic sulfoxidation under visible light and air Green Chem. 2013, 15, 357.
A simple metal-free catalytic sulfoxidation under visible light and airCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXhsVOntrY%3D&md5=07acec580b82e5553953210f0e1adfb8CAS |

[3]  H. Cheng, L. Gan, Y. Shi, X. Wei, A novel [2+3] cycloaddition reaction: Singlet oxygen mediated formation of 1,3-dipole from iminodiacetic acid dimethyl ester and its addition to maleimides J. Org. Chem. 2001, 66, 6369.
A novel [2+3] cycloaddition reaction: Singlet oxygen mediated formation of 1,3-dipole from iminodiacetic acid dimethyl ester and its addition to maleimidesCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3MXmtFSisLk%3D&md5=ad660f14bcda5da9e3da2a695e1c0d2aCAS |

[4]  S. M. Bonesi, M. Fagnoni, S. Monti, A. Albini, Reaction of singlet oxygen with some benzylic sulfides Tetrahedron 2006, 62, 10716.
Reaction of singlet oxygen with some benzylic sulfidesCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28XhtVCrsb3K&md5=2020001a386714839f54518f13c5c5f9CAS |

[5]  V. Kotzabasaki, G. Vassilikogiannakis, M. Stratakis, Regiocontrolled synthesis of gamma-hydroxybutenolides via singlet oxygen-mediated oxidation of 2-thiophenyl furans J. Org. Chem. 2016, 81, 4406.
Regiocontrolled synthesis of gamma-hydroxybutenolides via singlet oxygen-mediated oxidation of 2-thiophenyl furansCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC28XmvFylsLw%3D&md5=eb0aa1ee2d7e90541bfcf57d9bed181cCAS |

[6]  A. Yavorskyy, O. Shvydkiv, C. Limburg, K. Nolan, Y. M. C. Delauréc, M. Oelgemöller, Photooxygenations in a bubble column reactor Green Chem. 2012, 14, 888.
Photooxygenations in a bubble column reactorCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38XksVKks70%3D&md5=6c01386b64b9170c1fb7089cdc016736CAS |

[7]  M. Hajimohammadi, N. Safari, H. Mofakham, A. Shaabani, A new and efficient aerobic oxidation of aldehydes to carboxylic acids with singlet oxygen in the presence of porphyrin sensitizers and visible light Tetrahedron Lett. 2010, 51, 4061.
A new and efficient aerobic oxidation of aldehydes to carboxylic acids with singlet oxygen in the presence of porphyrin sensitizers and visible lightCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXosVGksLs%3D&md5=1f482ec010400fcfbbde81f5c4c22304CAS |

[8]  M. Gmurek, M. Olak-Kucharczyk, S. Ledakowicz, Photochemical decomposition of endocrine disrupting compounds – A review Chem. Eng. J. 2017, 310, 437.
Photochemical decomposition of endocrine disrupting compounds – A reviewCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC28XosFWnt7k%3D&md5=acc0df5c9fe721365131b7251a0b214cCAS |

[9]  W. R. Haag, J. Hoigne, Singlet oxygen in surface waters. 3. Photochemical formation and steady-state concentrations in various types of waters Environ. Sci. Technol. 1986, 20, 341.
Singlet oxygen in surface waters. 3. Photochemical formation and steady-state concentrations in various types of watersCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL28XhtFGls7w%3D&md5=baf01dbbcf8c468c5c4deaee0828b56aCAS |

[10]  J. An, G. Li, T. An, X. Nie, Indirect photochemical transformations of acyclovir and penciclovir in aquatic environments increase ecological risk Environ. Toxicol. Chem. 2016, 35, 584.
Indirect photochemical transformations of acyclovir and penciclovir in aquatic environments increase ecological riskCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC28XitFGgsbo%3D&md5=1cc4871fcef54ca7f32b41e150c4d671CAS |

[11]  A. J. McCabe, W. A. Arnold, Seasonal and spatial variabilities in the water chemistry of prairie pothole wetlands influence the photoproduction of reactive intermediates Chemosphere 2016, 155, 640.
Seasonal and spatial variabilities in the water chemistry of prairie pothole wetlands influence the photoproduction of reactive intermediatesCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC28Xns1ekt7c%3D&md5=75e5e4cde9f89edee81e725c0adc2362CAS |

[12]  A. N. Onyango, Endogenous generation of singlet oxygen and ozone in human and animal tissues: mechanisms, biological significance, and influence of dietary components Oxid. Med. Cell. Longev. 2016, 2016, 2398573.
Endogenous generation of singlet oxygen and ozone in human and animal tissues: mechanisms, biological significance, and influence of dietary componentsCrossref | GoogleScholarGoogle Scholar |

[13]  J. L. Ravanat, J. Cadet, Reaction of singlet oxygen with 2′-deoxyguanosine and DNA – isolation and characterization of the main oxidation-products Chem. Res. Toxicol. 1995, 8, 379.
Reaction of singlet oxygen with 2′-deoxyguanosine and DNA – isolation and characterization of the main oxidation-productsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXkvVWksb4%3D&md5=c3d0e9bdf968389e5cecf623cd8b1a70CAS |

[14]  H. Yasui, S. Hayashi, H. Sakurai, Possible involvement of singlet oxygen species as multiple oxidants in P450 catalytic reactions Drug Metab. Pharmacokinet. 2005, 20, 1.
Possible involvement of singlet oxygen species as multiple oxidants in P450 catalytic reactionsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXhtFSrsLzF&md5=0a5a56b2e2aa2a476fc51e2327cac491CAS |

[15]  F. Wilkinson, W. P. Helman, A. B. Ross, Rate constants for the decay and reactions of the lowest electronically excited singlet-state of molecular-oxygen in solution – an expanded and revised compilation J. Phys. Chem. Ref. Data 1995, 24, 663.
Rate constants for the decay and reactions of the lowest electronically excited singlet-state of molecular-oxygen in solution – an expanded and revised compilationCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXmtlamtLw%3D&md5=28587e52c7963afeb4437bd58b816cffCAS |

[16]  Q. Zhang, Predictive models on photolysis and photoinduced toxicity of persistent organic chemicals Front. Environ. Sci. Eng. 2013, 7, 803.
Predictive models on photolysis and photoinduced toxicity of persistent organic chemicalsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXhslCnsrbM&md5=6924de5d7e2503796f8c0778b5a0e153CAS |

[17]  C. M. Zhu, L. Y. Wang, L. R. Kong, X. Yang, L. S. Wang, S. J. Zheng, F. L. Chen, M. Z. Feng, Z. Huang, QSPR study of quenching of singlet oxygen by aliphatic amines Toxicol. Environ. Chem. 2001, 79, 47.
QSPR study of quenching of singlet oxygen by aliphatic aminesCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD38XmvFKqs7w%3D&md5=5c605cda281e1fca686e6e3755ed5dbfCAS |

[18]  W. A. Arnold, Y. Oueis, M. O’Connor, J. E. Rinaman, M. G. Taggart, R. E. McCarthy, K. A. Foster, D. E. Latch, QSARs for phenols and phenolates: oxidation potential as a predictor of reaction rate constants with photochemically produced oxidants Environ. Sci. Process. Impacts 2017, 19, 324.
QSARs for phenols and phenolates: oxidation potential as a predictor of reaction rate constants with photochemically produced oxidantsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC28XhvFymtbvP&md5=3d59a02f27ae16c26533aa524e2f12a8CAS |

[19]  T. M. Nolte, A. M. J. Ragas, A review of quantitative structure-property relationships for the fate of ionizable organic chemicals in water matrices and identification of knowledge gaps Environ. Sci. Process. Impacts 2017, 19, 221.
A review of quantitative structure-property relationships for the fate of ionizable organic chemicals in water matrices and identification of knowledge gapsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2sXktlyqtbY%3D&md5=7e1ca1e7c9c88d284a0f8013ab6669c3CAS |

[20]  A. Scott, Survey of Progress in Chemistry. 1973 (Academic Press: New York).

[21]  J. Ma, W. Lv, P. Chen, Y. Lu, F. Wang, F. Li, K. Yao, G. Liu, Photodegradation of gemfibrozil in aqueous solution under UV irradiation: kinetics, mechanism, toxicity, and degradation pathways Environ. Sci. Pollut. Res. Int. 2016, 23, 14294.
Photodegradation of gemfibrozil in aqueous solution under UV irradiation: kinetics, mechanism, toxicity, and degradation pathwaysCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC28XmtVGku7c%3D&md5=4fd96fab6a75ed951f3c7cb7786745d6CAS |

[22]  A. Salma, S. Thoröe-Boveleth, T. C. Schmidt, J. Tuerk, Dependence of transformation product formation on pH during photolytic and photocatalytic degradation of ciprofloxacin J. Hazard. Mater. 2016, 313, 49.
Dependence of transformation product formation on pH during photolytic and photocatalytic degradation of ciprofloxacinCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC28XlsVanu7Y%3D&md5=678940899bfb387c615a982a9a08787bCAS |

[23]  W. C. Lu, J. B. Liu, Deprotonated guanine.cytosine and 9-methylguanine.cytosine base pairs and their ‘non-statistical’ kinetics: a combined guided-ion beam and computational study Phys. Chem. Chem. Phys. 2016, 18, 32222.
Deprotonated guanine.cytosine and 9-methylguanine.cytosine base pairs and their ‘non-statistical’ kinetics: a combined guided-ion beam and computational studyCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC28XhslGqsb%2FE&md5=806fa1e43948675147d370005e1c542cCAS |

[24]  P. Calza, D. Vione, Surface Water Photochemistry 2015 (Royal Society of Chemistry: Cambridge, UK).

[25]  R. A. Larson, K. A. Marley, Singlet oxygen in the environment, in The Handbook of Environmental Chemistry (Ed. E. O. Hutzinger) 1999, p. 123 (Springer: Berlin Heidelberg).

[26]  G. Jiang, J. Chen, J.-S. Huang, C.-M. Che, Highly efficient oxidation of amines to imines by singlet oxygen and its application in Ugi-type reactions Org. Lett. 2009, 11, 4568.
Highly efficient oxidation of amines to imines by singlet oxygen and its application in Ugi-type reactionsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXhtFKns7vL&md5=bc8fe0bd96ca14dc5183bd2268bc6b1fCAS |

[27]  K. Briviba, T. P. A. Devasagayam, H. Sies, S. Steenken, Selective parahydroxylation of phenol and aniline by singlet molecular-oxygen Chem. Res. Toxicol. 1993, 6, 548.
Selective parahydroxylation of phenol and aniline by singlet molecular-oxygenCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK3sXks1Ggu70%3D&md5=7301afa56b9615ecccc3e5a976e52840CAS |

[28]  J. Al-Nu’airat, M. Altarawneh, X. Gao, P. R. Westmoreland, B. Z. Dlugogorski, Reaction of aniline with singlet oxygen (O2 1Δg) J. Phys. Chem. A 2017, 121, 3199.
Reaction of aniline with singlet oxygen (O2 1Δg)Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2sXlvF2ksb4%3D&md5=15bd4351cb0a2363843016ba1eff821bCAS |

[29]  R. H. Young, R. L. Martin, N. Chinh, C. Mallon, R. H. Kayser, Substituent effects in dye-sensitized photooxidation reactions of furans Can. J. Chem. 1972, 50, 932.
Substituent effects in dye-sensitized photooxidation reactions of furansCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE38XhsFaqs70%3D&md5=0e07fe8ce0b3f69195cad58e6fa911deCAS |

[30]  M. J. Kamlet, J. L. M. Abboud, M. H. Abraham, R. W. Taft, Linear solvation energy relationships. 23. A comprehensive collection of the solvatochromic parameters, .pi.*, .alpha. and .beta., and some methods for simplifying the generalized solvatochromic equation J. Org. Chem. 1983, 48, 2877.
Linear solvation energy relationships. 23. A comprehensive collection of the solvatochromic parameters, .pi.*, .alpha. and .beta., and some methods for simplifying the generalized solvatochromic equationCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL3sXkvVOgsbc%3D&md5=ab9c51dcd780f8b355d3c03d602ed5b2CAS |

[31]  E. Lemp, C. Valencia, A. L. Zanocco, Solvent effects on reactions of singlet molecular oxygen, O2(1Δg), with antimalarial drugs J. Photochem. Photobiol. A – Chem. 2004, 168, 91.
Solvent effects on reactions of singlet molecular oxygen, O2(1Δg), with antimalarial drugsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXnvVCjtL0%3D&md5=5d2a2fdaca5954d161065c6958ea13b1CAS |

[32]  P. T. Chou, A. U. Khan, L-ascorbic-acid quenching of singlet delta molecular oxygen in aqueous-media: generalized antioxidant property of vitamin C Biochem. Biophys. Res. Commun. 1983, 115, 932.
L-ascorbic-acid quenching of singlet delta molecular oxygen in aqueous-media: generalized antioxidant property of vitamin CCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL2cXltVymtw%3D%3D&md5=da343548df7a27261ce5b3993e2330e6CAS |

[33]  N. A. Kuznetsova, E. V. Pykhtina, L. A. Ulanova, O. L. Kaliya, Type-I and type-II photoprocesses in the system photosense-ascorbic acid J. Photochem. Photobiol. A – Chem. 2004, 167, 37.
Type-I and type-II photoprocesses in the system photosense-ascorbic acidCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXmtFCmur4%3D&md5=8c7828d97e8a4b23ab6316e48d711d3aCAS |

[34]  N. N. Breslavskaya, S. P. Dolin, A. A. Markov, T. Yu. Mikhailova, N. I. Moiseeva, A. E. Gekhman, Quantum-chemical simulation of the elementary step of the oxidation reactions of styrene and its derivatives involving 1O2 (1Δg) Russ. J. Inorg. Chem. 2016, 61, 1554.
Quantum-chemical simulation of the elementary step of the oxidation reactions of styrene and its derivatives involving 1O2 (1Δg)Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC28XitVWlsrbO&md5=d30e415b2d52bb39560581f54068415eCAS |

[35]  M. Garavelli, F. Bernardi, M. Olivucci, M. A. Robb, DFT study of the reactions between singlet-oxygen and a carotenoid model J. Am. Chem. Soc. 1998, 120, 10210.
DFT study of the reactions between singlet-oxygen and a carotenoid modelCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK1cXmtVenuro%3D&md5=a7bea04faf03caba365b7c273baaed23CAS |

[36]  D. Dolphin, The Porphyrins (Biochemistry, Part 4). Vol. 6. 1979 (Academic Press: London).

[37]  L. S. Slater, P. R. Callis, Molecular orbital theory of the 1La and 1Lb states of indole. 2. An ab-initio study J. Phys. Chem. 1995, 99, 8572.
Molecular orbital theory of the 1La and 1Lb states of indole. 2. An ab-initio studyCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXls1yrtb4%3D&md5=e410912dfd662bfdf08896b2d5080e30CAS |

[38]  A. S. Eisenberg, L. J. Juszczak, The broken ring: reduced aromaticity in lys-trp cations and high pH tautomer correlates with lower quantum yield and shorter lifetimes J. Phys. Chem. B 2014, 118, 7059.
The broken ring: reduced aromaticity in lys-trp cations and high pH tautomer correlates with lower quantum yield and shorter lifetimesCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXptVWqtLg%3D&md5=1ab45adffcb2405071f30eec7932d752CAS |

[39]  N. M. O’Boyle, M. Banck, C. A. James, C. Morley, T. Vandermeersch, G. R. Hutchison, Open Babel: An open chemical toolbox J. Cheminform. 2011, 3, 33.
| 1:CAS:528:DC%2BC3MXhsVWjurbF&md5=d65ed2657824236d39c84a798d2c8205CAS |

[40]  J. J. P. Stewart, MOPAC. 2016 (Stewart Computational Chemistry: Colorado Springs, CO).

[41]  D.-S. Cao, Q.-S. Xu, Q.-N. Hu, Y.-Z. Liang, ChemoPy: freely available python package for computational biology and chemoinformatics Bioinformatics 2013, 29, 1092.
ChemoPy: freely available python package for computational biology and chemoinformaticsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXlvVKitr0%3D&md5=963c4aeb648a34cf4471d7411fa1ec07CAS |

[42]  R. Sustmann, H. Trill, Substituent effects in 1,3-dipolar cycloadditions of phenyl azide Angew. Chem. Int. Ed. 1972, 11, 838.
Substituent effects in 1,3-dipolar cycloadditions of phenyl azideCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE3sXivFSksg%3D%3D&md5=20aa709fb9ca6aef7d1bc5c9ce6635cdCAS |

[43]  C. Sousa, A. M. B. do Rego, T. S. E. Melo, Singlet oxygen reactivity in water-rich solvent mixtures Quim. Nova 2008, 31, 1392.
Singlet oxygen reactivity in water-rich solvent mixturesCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXht1WhtrbI&md5=6331db53c1e87fd1e3173f8893d7289aCAS |

[44]  D. J. Adams, L. R. Morgan, Tumor physiology and charge dynamics of anticancer drugs: implications for camptothecin-based drug development Curr. Med. Chem. 2011, 18, 1367.
Tumor physiology and charge dynamics of anticancer drugs: implications for camptothecin-based drug developmentCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXktVOrsr4%3D&md5=36630bc9ca9015fdc5f066c3b4df1c2cCAS |

[45]  E. L. Clennan, Persulfoxide: key intermediate in reactions of singlet oxygen with sulfides Acc. Chem. Res. 2001, 34, 875.
Persulfoxide: key intermediate in reactions of singlet oxygen with sulfidesCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3MXmvVKisbo%3D&md5=faaa228acd12d09709f8365188fc456aCAS |

[46]  O. Devinyak, D. Havrylyuk, R. Lesyk, 3D-MoRSE descriptors explained J. Mol. Graph. Model. 2014, 54, 194.
3D-MoRSE descriptors explainedCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXhvV2ms7fM&md5=ca956cdb887eaf7841b3880b2ec492c0CAS |

[47]  E. Dumont, R. Grüber, E. Bignon, C. Morell, Y. Moreau, A. Monari, J.-L. Ravanat, Probing the reactivity of singlet oxygen with purines Nucleic Acids Res. 2016, 44, 56.
Probing the reactivity of singlet oxygen with purinesCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC28XnsFGntbc%3D&md5=953f50ed4e58752eb92deb72585c65eeCAS |

[48]  C. Sheu, C. S. Foote, Reactivity toward singlet oxygen of a 7,8-dihydro-8-oxoguanosine (‘8-hydroxyguanosine’) formed by photooxidation of a guanosine derivative J. Am. Chem. Soc. 1995, 117, 6439.
Reactivity toward singlet oxygen of a 7,8-dihydro-8-oxoguanosine (‘8-hydroxyguanosine’) formed by photooxidation of a guanosine derivativeCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXlvFahtrg%3D&md5=cec3971bcb7279735914cee9543d2c24CAS |

[49]  D. A. Singleton, C. Hang, M. J. Szymanski, M. P. Meyer, A. G. Leach, K. T. Kuwata, J. S. Chen, A. Greer, C. S. Foote, K. N. Houk, Mechanism of ene reactions of singlet oxygen. A two-step no-intermediate mechanism J. Am. Chem. Soc. 2003, 125, 1319.
Mechanism of ene reactions of singlet oxygen. A two-step no-intermediate mechanismCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3sXivFWrtA%3D%3D&md5=b49026667cd6466bf2f6b14b913fdc0aCAS |

[50]  S. P. Dolin, N. N. Breslavskaya, A. A. Markov, T. Yu. Mikhailova, N. I. Moiseeva, A. E. Gekhman, Mechanism and energetics of 1,2-addition of dioxygen 1O2(1Δg) to ethylene Russ. J. Inorg. Chem. 2015, 60, 1495.
Mechanism and energetics of 1,2-addition of dioxygen 1O2(1Δg) to ethyleneCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2MXhvFagt7jL&md5=4500187c23b48379e42d699ffd447c86CAS |

[51]  D. B. Allen, K. N. Taylor, N. H. Martin, Semi-empirical molecular orbital calculations on the reaction of singlet oxygen with vinylamine; examination of a charge-transfer mechanism J. Elisha Mitchell Sci. Soc. 1991, 107, 89.
| 1:CAS:528:DyaK38XhsFSqt74%3D&md5=fbd1b529c754032541a7904c7c3d52e3CAS |

[52]  E. L. Clennan, A. Pace, Advances in singlet oxygen chemistry Tetrahedron 2005, 61, 6665.
Advances in singlet oxygen chemistryCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXltlent7Y%3D&md5=5817cc3c14599246c066997d01a5b1e1CAS |

[53]  S. Nonell, C. Flors, Singlet Oxygen: Applications in Biosciences and Nanosciences. Vol. 1. 2016 (Royal Society of Chemistry: Cambridge, UK).

[54]  S. H. Chien, M.-F. Cheng, K.-C. Lau, W.-K. Li, Theoretical study of the Diels-Alder reactions between singlet (1Δg) oxygen and acenes J. Phys. Chem. A 2005, 109, 7509.
Theoretical study of the Diels-Alder reactions between singlet (1Δg) oxygen and acenesCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXmvFSrsLs%3D&md5=781518dc8dcbbd0ef85784fc340485e2CAS |

[55]  M. Lee, S. G. Zimmermann-Steffens, J. S. Arey, K. Fenner, U. von Gunten, Development of prediction models for the reactivity of organic compounds with ozone in aqueous solution by quantum chemical calculations: the role of delocalized and localized molecular orbitals Environ. Sci. Technol. 2015, 49, 9925.
Development of prediction models for the reactivity of organic compounds with ozone in aqueous solution by quantum chemical calculations: the role of delocalized and localized molecular orbitalsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2MXhtVygsb7F&md5=bb624c16ee2b7d5921c3be2a878c3b12CAS |

[56]  L. J. Kong, R. G. Zepp, Production and consumption of reactive oxygen species by fullerenes Environ. Toxicol. Chem. 2012, 31, 136.
Production and consumption of reactive oxygen species by fullerenesCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXhs1yktr%2FN&md5=1b563db3529c1f31dee048f6c63155d7CAS |

[57]  E. Baciocchi, T. Del Giacco, A. Lapi, Quenching of singlet oxygen by tertiary aliphatic amines. Structural effects on rates and products Helv. Chim. Acta 2006, 89, 2273.
Quenching of singlet oxygen by tertiary aliphatic amines. Structural effects on rates and productsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28Xht1Whu7%2FO&md5=439d362d490ace3914bbc8ba0db525ffCAS |

[58]  R. S. Davidson, K. R. Trethewey, Photosensitized oxidation of amines: mechanism of oxidation of trimethylamine J. Chem. Soc., Perkin Trans. 2 1977, 173.
| 1:CAS:528:DyaE2sXhslSmtbw%3D&md5=9e064b3d55bc1b0e2bc80c080f0aa1fdCAS |

[59]  C. J. M. van den Heuvel, J. W. Verhoeven, Th. J. de Boer, A frontier orbital description of the reaction of singlet oxygen with simple aromatic systems Recl. Trav. Chim. Pays-Bas 1980, 99, 280.
A frontier orbital description of the reaction of singlet oxygen with simple aromatic systemsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL3cXmtlymtLs%3D&md5=711ff466b97b5a05658ce0aafc20f6a0CAS |

[60]  A. P. Darmanyan, W. S. Jenks, P. Jardon, Charge-transfer quenching of singlet oxygen O2(1Δg) by amines and aromatic hydrocarbons J. Phys. Chem. A 1998, 102, 7420.
Charge-transfer quenching of singlet oxygen O2(1Δg) by amines and aromatic hydrocarbonsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK1cXltlyhsb4%3D&md5=132b411aee7868157c182a1a524b2718CAS |

[61]  Z. Chen, X. Yu, X. Huang, S. Zhang, Prediction of reaction rate constants of hydroxyl radical with organic compounds J. Chil. Chem. Soc. 2014, 59, 2252.
Prediction of reaction rate constants of hydroxyl radical with organic compoundsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXhsVyqsr7E&md5=c35c123fd41949cee9f93072edc01255CAS |

[62]  D. Minakata, K. Li, P. Westerhoff, J. Crittenden, Development of a group contribution method to predict aqueous phase hydroxyl radical (HO) reaction rate constants Environ. Sci. Technol. 2009, 43, 6220.
Development of a group contribution method to predict aqueous phase hydroxyl radical (HO) reaction rate constantsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXos1ehsLk%3D&md5=a6db51176ccea46f11896fcf93a27774CAS |

[63]  B. Cazin, J. M. Aubry, J. Rigaudy, Is water the best or the worst solvent for [2 + 4] cycloadditions of singlet oxygen to aromatic-compounds? J. Chem. Soc. Chem. Commun. 1986, 952.
Is water the best or the worst solvent for [2 + 4] cycloadditions of singlet oxygen to aromatic-compounds?Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL2sXktl2i&md5=3b5e7989f34506dc304ab1e4b04197e7CAS |

[64]  A. L. Zanocco, E. Lemp, G. Gunther, A kinetic study of the reaction between boldine and singlet oxygen [O2(1Δg)] J. Chem. Soc., Perkin Trans. 2 1997, 1299.
A kinetic study of the reaction between boldine and singlet oxygen [O2(1Δg)]Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2sXksl2msbs%3D&md5=5f39b2f50b5fe14cdca847c3ce8891a9CAS |

[65]  M. Egli, On stacking, in Structure and Function (Ed. P. Compa) 2010, pp. 177–196 (Springer: London).

[66]  A. Jain, V. Ramanathan, R. Sankararamakrishnan, Lone pair … pi interactions between water oxygens and aromatic residues: quantum chemical studies based on high-resolution protein structures and model compounds Protein Sci. 2009, 18, 595.
| 1:CAS:528:DC%2BD1MXms1Wnu74%3D&md5=be63106c22e1b6f38e4c1329987d496eCAS |

[67]  X. Song, M. G. Fanelli, J. M. Cook, F. Bai, C. A. Parish, Mechanisms for the reaction of thiophene and methylthiophene with singlet and triplet molecular oxygen J. Phys. Chem. A 2012, 116, 4934.
Mechanisms for the reaction of thiophene and methylthiophene with singlet and triplet molecular oxygenCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38XlvVSiu70%3D&md5=16a3d2ce531dd276314616db21680923CAS |

[68]  J. L. Packer, J. J. Werner, D. E. Latch, K. McNeill, W. A. Arnold, Photochemical fate of pharmaceuticals in the environment: naproxen, ibuprofen, diclofenac and clofibric acid Abstr. Papers Am. Chem. Soc. 2003, 225, U832.

[69]  S. Criado, D. Mártire, P. Allegretti, J. Furlong, S. Bertolotti, E. La Falce, N. García, Mass spectrometric study of the photooxidation of the ophthalmic drugs timolol and pindolol Pharmazie 2003, 58, 551.
| 1:CAS:528:DC%2BD3sXms1Wmt7k%3D&md5=c5e35cd50cc1d46e0a19af37486d3235CAS |

[70]  M. Selke, L. Rosenberg, J. M. Salvo, C. S. Foote, Reactions of singlet oxygen with organometallic compounds. 4. Photooxidation of cationic iridium(I) and rhodium(I) complexes with weakly bonded ligands Inorg. Chem. 1996, 35, 4519.
Reactions of singlet oxygen with organometallic compounds. 4. Photooxidation of cationic iridium(I) and rhodium(I) complexes with weakly bonded ligandsCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK28Xjsl2rtL0%3D&md5=177be876010a80482bc6162862e6ddbcCAS |

[71]  J. Mendez-Hurtado, M. I. Menéndez, R. López, M. F. Ruiz-López, Unraveling the intramolecular cyclization mechanism of oxidized tryptophan in aqueous solution as a function of pH Org. Biomol. Chem. 2015, 13, 8695.
Unraveling the intramolecular cyclization mechanism of oxidized tryptophan in aqueous solution as a function of pHCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2MXhtFOktL7P&md5=89634a1d8bf8ee763abdd140804a2ea4CAS |

[72]  B. Thapa, B. H. Munk, C. J. Burrows, H. B. Schlegel, Computational study of oxidation of guanine by singlet oxygen (1Δg) and formation of guanine:lysine cross-links Chem. – Eur. J. 2017, 23, 5804.
Computational study of oxidation of guanine by singlet oxygen (1Δg) and formation of guanine:lysine cross-linksCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2sXlsFSgsbo%3D&md5=a5458b8325c77e6b041c8e9704eea311CAS |

[73]  H. Santoke, W. Song, W. J. Cooper, B. M. Peake, Advanced oxidation treatment and photochemical fate of selected antidepressant pharmaceuticals in solutions of Suwannee River humic acid J. Hazard. Mater. 2012, 217–218, 382.
Advanced oxidation treatment and photochemical fate of selected antidepressant pharmaceuticals in solutions of Suwannee River humic acidCrossref | GoogleScholarGoogle Scholar |

[74]  P. Gramatica, P. Pilutti, E. Papa, Ranking of phenols for abiotic oxidation in aqueous environment: a QSPR approach Ann. Chim. 2005, 95, 199.
Ranking of phenols for abiotic oxidation in aqueous environment: a QSPR approachCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXkvF2ltr0%3D&md5=20eb3331a1966c5c5998bad0804e8772CAS |

[75]  E. Rorije, W. J. G. M. Peijnenburg, QSARs for oxidation of phenols in the aqueous environment, suitable for risk assessment J. Chemometr. 1996, 10, 79.
QSARs for oxidation of phenols in the aqueous environment, suitable for risk assessmentCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK28XhslWntr4%3D&md5=ee3bf5f4b3815a0a0d14620085aa5d58CAS |

[76]  P. Mignon, S. Loverix, J. Steyaert, P. Geerlings, Influence of the π–π interaction on the hydrogen bonding capacity of stacked DNA/RNA bases Nucleic Acids Res. 2005, 33, 1779.
Influence of the π–π interaction on the hydrogen bonding capacity of stacked DNA/RNA basesCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXjtlens7s%3D&md5=766847cac10d2e9802b9e56bacf842bcCAS |

[77]  J. Sanchez-Marquez, Introducing new reactivity descriptors: ‘Bond reactivity indices.’ Comparison of the new definitions and atomic reactivity indices J. Chem. Phys. 2016, 145, 194105.
Introducing new reactivity descriptors: ‘Bond reactivity indices.’ Comparison of the new definitions and atomic reactivity indicesCrossref | GoogleScholarGoogle Scholar |

[78]  J. I. Martinez-Araya, Why is the dual descriptor a more accurate local reactivity descriptor than Fukui functions? J. Math. Chem. 2015, 53, 451.
Why is the dual descriptor a more accurate local reactivity descriptor than Fukui functions?Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2cXhvVKlsbvL&md5=fb4326a3bef45cf5e1fb6d08fde470b4CAS |

[79]  S. Canonica, P. G. Tratnyek, Quantitative structure-activity relationships for oxidation reactions of organic chemicals in water Environ. Toxicol. Chem. 2003, 22, 1743.
Quantitative structure-activity relationships for oxidation reactions of organic chemicals in waterCrossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3sXotF2gsrs%3D&md5=64b55e46b947a780853ded141fad239fCAS |