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Photodehydration mechanisms of quinone methide formation from 2-naphthol derivatives. J Photochem Photobiol A Chem 2022. [DOI: 10.1016/j.jphotochem.2022.114171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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2
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Cink RB, Zhou Y, Du L, Rahman MS, Phillips DL, Simpson MC, Seed AJ, Sampson P, Brasch NE. Mechanistic Insights into Rapid Generation of Nitroxyl from a Photocaged N-Hydroxysulfonamide Incorporating the (6-Hydroxynaphthalen-2-yl)methyl Chromophore. J Org Chem 2021; 86:8056-8068. [PMID: 34107217 DOI: 10.1021/acs.joc.1c00457] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
HNO is a highly reactive molecule that shows promise in treating heart failure. Molecules that rapidly release HNO with precise spatial and temporal control are needed to investigate the biology of this signaling molecule. (Hydroxynaphthalen-2-yl)methyl-photocaged N-hydroxysulfonamides are a new class of photoactive HNO generators. Recently, it was shown that a (6-hydroxynaphthalen-2-yl)methyl (6,2-HNM)-photocaged derivative of N-hydroxysulfonamide incorporating the trifluoromethanesulfonamidoxy group (1) quantitatively generates HNO. Mechanistic studies have now been carried out on this system and reveal that the ground state protonation state plays a key role in whether concerted heterolytic C-O/N-S bond cleavage to release HNO occurs versus undesired O-N bond cleavage. N-Deprotonation of 1 can be achieved by adding an aqueous buffer or a carboxylate salt to an aprotic solvent. Evidence is presented for C-O/N-S bond heterolysis occurring directly from the singlet excited state of the N-deprotonated parent molecule on the picosecond time scale, using femtosecond time-resolved transient absorption spectroscopy, to give a carbocation and 1NO-. This is consistent with the observation of significant fluorescence quenching when HNO is generated. The carbocation intermediate reacts rapidly with nucleophiles including water, MeOH, or even (H)NO in the absence of a molecule that reacts rapidly with (H)NO to give an oxime.
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Affiliation(s)
- Ruth B Cink
- School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.,The Photon Factory, School of Chemical Sciences and Department of Physics, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.,The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6012, New Zealand.,The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand
| | - Yang Zhou
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Lili Du
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR 99077, P. R. China
| | - Mohammad S Rahman
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR 99077, P. R. China
| | - M Cather Simpson
- The Photon Factory, School of Chemical Sciences and Department of Physics, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.,The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6012, New Zealand.,The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand
| | - Alexander J Seed
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Paul Sampson
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Nicola E Brasch
- School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.,The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand.,The Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
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Photochemical Reactivity of Naphthol-Naphthalimide Conjugates and Their Biological Activity. Molecules 2021; 26:molecules26113355. [PMID: 34199541 PMCID: PMC8199699 DOI: 10.3390/molecules26113355] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 05/21/2021] [Accepted: 05/28/2021] [Indexed: 11/17/2022] Open
Abstract
Quinone methide precursors 1a–e, with different alkyl linkers between the naphthol and the naphthalimide chromophore, were synthesized. Their photophysical properties and photochemical reactivity were investigated and connected with biological activity. Upon excitation of the naphthol, Förster resonance energy transfer (FRET) to the naphthalimide takes place and the quantum yields of fluorescence are low (ΦF ≈ 10−2). Due to FRET, photodehydration of naphthols to QMs takes place inefficiently (ΦR ≈ 10−5). However, the formation of QMs can also be initiated upon excitation of naphthalimide, the lower energy chromophore, in a process that involves photoinduced electron transfer (PET) from the naphthol to the naphthalimide. Fluorescence titrations revealed that 1a and 1e form complexes with ct-DNA with moderate association constants Ka ≈ 105–106 M−1, as well as with bovine serum albumin (BSA) Ka ≈ 105 M−1 (1:1 complex). The irradiation of the complex 1e@BSA resulted in the alkylation of the protein, probably via QM. The antiproliferative activity of 1a–e against two human cancer cell lines (H460 and MCF 7) was investigated with the cells kept in the dark or irradiated at 350 nm, whereupon cytotoxicity increased, particularly for 1e (>100 times). Although the enhancement of this activity upon UV irradiation has no imminent therapeutic application, the results presented have importance in the rational design of new generations of anticancer phototherapeutics that absorb visible light.
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Nalawade P, Naumov S, Kapoor S. Hidden chemistry of substituted aniline radical cations in water: a mechanistic study. J PHYS ORG CHEM 2014. [DOI: 10.1002/poc.3386] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Pradnya Nalawade
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Trombay Mumbai 400 085 India
| | - Sergej Naumov
- Leibniz-Institut für Oberflächenmodifizierung; Permoserstrasse 15 D-04318 Leipzig Germany
| | - Sudhir Kapoor
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Trombay Mumbai 400 085 India
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Nalawade P, Naumov S, Kapoor S. Comparative study of p-amino benzhydrazide and m-amino benzhydrazide by free radicals and free electron transfer. J PHYS ORG CHEM 2013. [DOI: 10.1002/poc.3182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Pradnya Nalawade
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Trombay Mumbai 400 085 India
| | - Sergej Naumov
- Leibniz-Institut für Oberflächenmodifizierung; Permoserstrasse 15 D-04318 Leipzig Germany
| | - Sudhir Kapoor
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Trombay Mumbai 400 085 India
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Sreekanth R, Prasanthkumar KP, Sunil Paul MM, Aravind UK, Aravindakumar CT. Oxidation reactions of 1- and 2-naphthols: an experimental and theoretical study. J Phys Chem A 2013; 117:11261-70. [PMID: 24093754 DOI: 10.1021/jp4081355] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The transients formed during the reactions of oxidizing radicals with 1-naphthol (1) and 2-naphthol (2) in aqueous medium have been investigated by pulse radiolysis with detection by absorption spectroscopy and density functional theory (DFT) calculations. The transient spectra formed on hydroxyl radical ((•)OH) reactions of 1 and 2 exhibited λ(max) at 340 and 350 nm at neutral pH. The rate constants of the (•)OH reactions of 1 (2) were determined from build-up kinetics at λ(max) of the transients as (9.63 ± 0.04) × 10(9) M(-1) s(-1) ((7.31 ± 0.11) × 10(9) M(-1) s(-1)). DFT calculations using the B3LYP/6-31+G(d,p) method have been performed to locate favorable reaction sites in both 1 and 2 and identification of the pertinent transients responsible for experimental results. Calculations demonstrated that (•)OH additions can occur mostly at C1 and C4 positions of 1, and at C1 and C8 positions of 2. Among several isomeric (•)OH adducts possible, the C1 adduct was found to be energetically most stable both in 1 and 2. Time-dependent density functional theory (TDDFT) calculations in the solution phase has shown that the experimental spectrum of 1 was mainly attributed by 1a4 (kinetically driven (•)OH-adduct) formed via the addition of (•)OH at the C4 position which was 0.73 kcal/mol endergonic compared to 1a1 (thermodynamic (•)OH adduct), whereas 2a1 (thermodynamic/kinetic (•)OH-adduct) was mainly responsible for the experimental spectrum of 2. Naphthoxyl radicals of 1 and 2 have been predicted as the transient formed in the reaction of (•)OH at basic pH. In addition, the same transient species resulted from the reactions of oxide radical ion (O(•-)) at pH ≈ 13 and azide radical (N3(•)) at pH 7 with 1 and 2. Further, UV photolysis of aqueous solutions of 1 and 2 containing H2O2 (UV/H2O2) were used for the (•)OH induced oxidation product formations up on 60% degradations of 1 and 2; profiling of the oxidation products were performed by using an ultraperformance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) method. According to the UPLC-Q-TOF-MS analyses, the preliminary oxidation products are limited to dihydroxy naphthalenes and naphthoquinones with N2-saturation, while some additional products (mainly isomeric monohydroxy-naphthoquinones) have been observed in the degradations of 1 and 2 in the presence of O2. We postulate that dihydroxy naphthalenes are derived explicitly from the most favorable (•)OH-adducts speculated (preference is in terms of the kinetic/thermodynamic dominancy of transients) by using theoretical calculations which in turn substantiate the proposed reaction mechanisms. The observations of (•)OH-adducts for an aromatic phenol (herein for both 1 and 2 at pH 7) rather than phenoxyl type radical in the pulse radiolysis experiments is a distinct and unique illustration. The present study provides a meaningful basis for the early stages associated with the (•)OH initiated advanced oxidation processes of 1- and 2-naphthols.
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Affiliation(s)
- R Sreekanth
- School of Chemical Sciences, ‡School of Environmental Sciences, #Advanced Centre of Environmental Studies and Sustainable Development, §Inter University Instrumentation Centre, Mahatma Gandhi University , Kottayam 686560, India
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Škalamera Đ, Mlinarić-Majerski K, Uzelac L, Kralj M, Wan P, Basarić N. Photosolvolysis of bulky (4-hydroxyphenyl)naphthalene derivatives. Photochem Photobiol Sci 2013; 12:2043-56. [DOI: 10.1039/c3pp50190f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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8
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Sekine M, Sekiya H, Nakata M. Infrared and Electronic Spectra of Radicals Produced from 2-Naphthol and Carbazole by UV-Induced Hydrogen-Atom Eliminations. J Phys Chem A 2012; 116:8980-8. [DOI: 10.1021/jp307259f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Masahiko Sekine
- Graduate School
of BASE (Bio-Applications and Systems Engineering), Tokyo University of Agriculture and Technology, Naka-cho,
Koganei, Tokyo 184-8588, Japan
| | - Hiroshi Sekiya
- Department of Chemistry, Faculty of Sciences,
Graduate School of Molecular Chemistry, Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812-8581,
Japan
| | - Munetaka Nakata
- Graduate School
of BASE (Bio-Applications and Systems Engineering), Tokyo University of Agriculture and Technology, Naka-cho,
Koganei, Tokyo 184-8588, Japan
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Basarić N, Došlić N, Ivković J, Wang YH, Mališ M, Wan P. Very Efficient Generation of Quinone Methides through Excited State Intramolecular Proton Transfer to a Carbon Atom. Chemistry 2012; 18:10617-23. [DOI: 10.1002/chem.201201144] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Indexed: 11/09/2022]
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10
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Veljković J, Uzelac L, Molčanov K, Mlinarić-Majerski K, Kralj M, Wan P, Basarić N. Sterically congested adamantylnaphthalene quinone methides. J Org Chem 2012; 77:4596-610. [PMID: 22533612 DOI: 10.1021/jo3002479] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Five new (2-adamantyl)naphthol derivatives (5-9, quinone methide precursors, QMP) were synthesized and their photochemical reactivity was investigated by preparative photolyses, fluorescence spectroscopy, and laser flash photolysis (LFP). Excitation of QMP 5 to S(1) leads to efficient excited state intramolecular proton transfer (ESIPT) coupled with dehydration, giving quinone methide QM5 which was characterized by LFP (in CH(3)CN-H(2)O, λ(max) = 370 nm, τ = 0.19 ms). On irradiation of QMP 5 in CH(3)OH-H(2)O (4:1), the quantum yield of methanolysis is Φ = 0.70. Excitation of naphthols QMP 6-8 to S(1) in CH(3)CN leads to photoionization and formation of naphthoxyl radicals. In a protic solvent, QMP 6-8 undergo solvent-assisted PT giving QM6 or zwitterion QM8 that react with nucleophiles delivering adducts, but with a significantly lower quantum efficiency. QMP 9 in a protic solvent undergoes two competitive processes, photosolvolysis via QM9 and solvent-assisted PT to carbon atom of the naphthalene giving zwitterion. QM9 has been characterized by LFP (in CH(3)CN-H(2)O, λ(max) > 600 nm, τ = 0.9 ms). In addition to photogenerated QMs, two stable naphthalene QMs, QM10 and QM11 were synthesized thermally and characterized by X-ray crystallography. QM10 and QM11 do not react with H(2)O but undergo acid-catalyzed fragmentation or rearrangement. Antiproliferative activity of 5-9 was investigated on three human cancer cell lines. Exposure of MCF-7 cells treated with 5 to 300 nm irradiation leads to an enhanced antiproliferative effect, in accordance with the activity being due to the formation of QM5.
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Affiliation(s)
- Jelena Veljković
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia
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11
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Ruiz G, Juliarena M, Ferraudi G, Lappin A, Boggess W, Feliz M. On the homogeneous catalysis of the photochemical and thermal O2-degrading of lignin in aqueous solution. Mechanistic observations on the processes catalyzed by AlIII(phthalocyaninetetrasulfonate)3− and CoIII dimethylglyoximate complexes. Polyhedron 2012. [DOI: 10.1016/j.poly.2012.02.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Brede O, Naumov S. Free electron transfer--relations between molecule dynamics and reaction kinetics. Chem Soc Rev 2010; 39:3057-71. [PMID: 20523928 DOI: 10.1039/b917327g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron transfer in non-polar media (alkanes, alkyl chlorides) exhibits some essential peculiarities. For instance the reaction of hetero-substituted aromatics with parent solvent radical cations results in the parallel formation of metastable donor radical cations and fragmentation products, in comparable amounts. The fragmentation products originate from a dissociative donor radical cation which decays extremely rapidly, i.e., in a few femtoseconds. This phenomenon is explained in terms of intramolecular dynamic motions which cause changes of the electron density (pi- and n-orbitals) in dependence on the deformation angle between the substituents and the aromatic ring. Hence femtosecond dynamics is reflected in the nanosecond time range and can be observed with real-time spectroscopy. Therefore, the process is named free electron transfer (FET) which corresponds to an unhindered electron jump occurring in the first approach of the reactants. This dynamic controlled process is compared with the classical electron transfer theories which are based on equilibrium kinetics. From the FET mechanism some new aspects for chemical reaction kinetics can be derived (critical review, 69 references).
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Affiliation(s)
- Ortwin Brede
- University of Leipzig, Wilhelm Ostwald Institute of Physical and Theoretical Chemistry, Linnestr. 2, 04103 Leipzig, Germany.
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Baidak A, Naumov S, Hermann R, Brede O. Ionization of Amino-, Thio- and Hydroxy-naphtalenes via Free (Unhindered) Electron Transfer. J Phys Chem A 2008; 112:11036-43. [DOI: 10.1021/jp806711m] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aliaksandr Baidak
- Interdisciplinary Group Time-resolved Spectroscopy, University of Leipzig, Permoserstrasse 15, 04303 Leipzig, Germany, and Leibniz Institute of Surface Modification, Permoserstrasse 15, 04303 Leipzig, Germany
| | - Sergej Naumov
- Interdisciplinary Group Time-resolved Spectroscopy, University of Leipzig, Permoserstrasse 15, 04303 Leipzig, Germany, and Leibniz Institute of Surface Modification, Permoserstrasse 15, 04303 Leipzig, Germany
| | - Ralf Hermann
- Interdisciplinary Group Time-resolved Spectroscopy, University of Leipzig, Permoserstrasse 15, 04303 Leipzig, Germany, and Leibniz Institute of Surface Modification, Permoserstrasse 15, 04303 Leipzig, Germany
| | - Ortwin Brede
- Interdisciplinary Group Time-resolved Spectroscopy, University of Leipzig, Permoserstrasse 15, 04303 Leipzig, Germany, and Leibniz Institute of Surface Modification, Permoserstrasse 15, 04303 Leipzig, Germany
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Baidak A, Naumov S, Brede O. Kinetic and Energetic Analysis of the Free Electron Transfer. J Phys Chem A 2008; 112:10200-9. [DOI: 10.1021/jp8053982] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aliaksandr Baidak
- Interdisciplinary Group Time-Resolved Spectroscopy, University of Leipzig, Permoserstrasse 15, 04303 Leipzig, Germany, and Leibniz Institute of Surface Modification, Permoserstrasse 15, 04303 Leipzig, Germany
| | - Sergej Naumov
- Interdisciplinary Group Time-Resolved Spectroscopy, University of Leipzig, Permoserstrasse 15, 04303 Leipzig, Germany, and Leibniz Institute of Surface Modification, Permoserstrasse 15, 04303 Leipzig, Germany
| | - Ortwin Brede
- Interdisciplinary Group Time-Resolved Spectroscopy, University of Leipzig, Permoserstrasse 15, 04303 Leipzig, Germany, and Leibniz Institute of Surface Modification, Permoserstrasse 15, 04303 Leipzig, Germany
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Okamoto K, Kozawa T, Natsuda K, Seki S, Tagawa S. Formation of intramolecular poly(4-hydroxystyrene) dimer radical cation. J Phys Chem B 2008; 112:9275-80. [PMID: 18630855 DOI: 10.1021/jp801949s] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Poly(4-hydroxystyrene) (PHS) has been used in lithography as a backbone polymer and is also a promising material for extreme-ultraviolet or electron beam lithography. The dynamics of PHS radical cations generated upon exposure to electron beam were investigated. The transient absorption of PHS was observed in the near-infrared region in p-dioxane solutions by pulse radiolysis. Charge resonance (CR) bands that represent pi-pi interaction between the two chromophores of the intramolecular PHS dimer radical cation were observed, whereas p-cresol shows no distinct CR band. Although the radical cations of phenol derivatives are known to be easily deprotonated, it was found that the dimer radical cation formation leads to less deprotonation by its charge resonance stabilization.
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Affiliation(s)
- Kazumasa Okamoto
- The Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan.
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Brede O, Naumov S. Femtodynamics Reflected in Nanoseconds: Bimolecular Free Electron Transfer in Nonpolar Media. J Phys Chem A 2006; 110:11906-18. [PMID: 17064178 DOI: 10.1021/jp063489c] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The (free) electron transfer (FET) from electron donor molecules to parent solvent radical cations of alkanes and alkyl chlorides exhibits mechanistic peculiarities that are conditioned by the low polarity of these solvents. Because of the negligible solvation of ions in such systems and the almost complete lack of an activation barrier, the electron jump takes place at the very first encounter of the reactants and, as such, in extremely short times of <or=10(-15) s. Molecular oscillations (deformation, bending) occurring within the femtosecond time domain result directly in significant changes of the pi- or n-electron distribution in the HOMO ground state of the donor molecule, thereby generating a distribution of conformers. This is considered to be a rationale for a possible generation of different product radical cations in the free electron transfer, which exhibit different spin and charge distribution and, consequently different stability. Experimentally, the latter has been verified for aromatic donors, substituted with mobile, i.e., not rigidly fixed heteroatom-centered groups (various phenol type compounds, thiophenols, aromatic amines, benzyltrimethylsilanes etc.). The individually characteristic product distribution could be visualized and quantified by time-resolved spectroscopy in the nanosecond time domain. On the basis of a manifold of experimental data and supported by quantum-chemical calculations, the free electron transfer phenomenon is analyzed and discussed in detail in this summarizing report. The results presented here stand also for a, seemingly paradox, situation in which the products of a diffusion-controlled bimolecular reaction are governed by femtosecond events.
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Affiliation(s)
- Ortwin Brede
- Interdisciplinary Group Time-Resolved Spectroscopy, University of Leipzig, Permoserstrasse 15, 04303 Leipzig, Germany.
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Tachikawa T, Tojo S, Fujitsuka M, Majima T. Photocatalytic one-electron oxidation of biphenyl derivatives strongly coupled with the TiO2 surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:2753-2759. [PMID: 15835148 DOI: 10.1021/la0361262] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
One-electron oxidation of various biphenyl derivatives such as biphenyl (BP), 4-hydroxybiphenyl (HBP), 4,4'-biphenol (DHBP), 4-methoxy-4'-hydroxybiphenyl (MHBP), 4-cyano-4'-hydroxybiphenyl (CNHBP), 4-biphenylmethanol (BPM), and 4-biphenylethanol (BPE) adsorbed on the surface of TiO2 powder slurried in acetonitrile has been investigated by time-resolved diffuse reflectance spectroscopy. From the Langmuir adsorption isotherms for BP and HBP, it is suggested that the OH group plays an important role in adsorbing on the surface ofTiO2. The spectroscopic characteristics of charge transfer complexes of substrates and the TiO2 surface have been studied by steady-state diffuse reflectance spectroscopy. The high efficiency of a one-electron oxidation reaction was observed for hydroxyl-substituted BPs (HBP, DHBP, MHBP, CNHBP), compared with BPM and BPE, indicating that the strength of the electronic coupling element (H(DA)) between the electron acceptor and donor is a key factor in the one-electron oxidation of a substrate adsorbed on the TiO2 powder. The effects of the distance between the electron donor and the acceptor on the electronic coupling element are also discussed.
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Affiliation(s)
- Takashi Tachikawa
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
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SVIRIDENKO FB, STASS DV, MOLIN YUN. Study of interaction of aliphatic alcohols with primary radical cations ofn-alkanes using MARY spectroscopy. Mol Phys 2003. [DOI: 10.1080/0026897031000099943] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Čík G, Hubinová M, Šeršeň F, Brezová V. Study of the Influence of Water on Oxidative Properties of Fe3+ in ZSM-5 Zeolite Channels. ACTA ACUST UNITED AC 2002. [DOI: 10.1135/cccc20021743] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The interactions of phenol and thiophene with Fe3+ ions have been studied in ZSM-5 zeolite channels in the presence of water. The Fe-ZSM-5 was prepared by the ion exchange of Fe3+ for Na+. The Fe3+ ions in zeolite channels have unsaturated co-ordination spheres and oxidize organic substrates (phenol, thiophene) at room temperature. The interaction of Fe3+ with phenol gives rise to the stabilized cation-radical PhOH•+ and thiophene forms low oligomers (2-6 monomeric units). The oligomers are present in the neutral as well as oxidized form as cation-radicals (polarons). The formation of dications (bipolarons) has not been observed.
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Le HT, Flammang R, Gerbaux P, Bouchoux G, Nguyen MT. Ionized Phenol and Its Isomers in the Gas Phase. J Phys Chem A 2001. [DOI: 10.1021/jp012679e] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Hung Thanh Le
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium, Laboratoire de Chimie Organique, Université de Mons-Hainaut, Avenue Maistriau 19, B-7000 Mons, Belgium, Laboratoire des Mécanismes Réactionnels, UMR CNRS 7651, Ecole Polytechnique, F-91128 Palaiseau cedex, France, and Group of Computational Chemistry, Faculty of Chemical Engineering, HoChiMinh City University of Technology, Vietnam
| | - Robert Flammang
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium, Laboratoire de Chimie Organique, Université de Mons-Hainaut, Avenue Maistriau 19, B-7000 Mons, Belgium, Laboratoire des Mécanismes Réactionnels, UMR CNRS 7651, Ecole Polytechnique, F-91128 Palaiseau cedex, France, and Group of Computational Chemistry, Faculty of Chemical Engineering, HoChiMinh City University of Technology, Vietnam
| | - Pascal Gerbaux
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium, Laboratoire de Chimie Organique, Université de Mons-Hainaut, Avenue Maistriau 19, B-7000 Mons, Belgium, Laboratoire des Mécanismes Réactionnels, UMR CNRS 7651, Ecole Polytechnique, F-91128 Palaiseau cedex, France, and Group of Computational Chemistry, Faculty of Chemical Engineering, HoChiMinh City University of Technology, Vietnam
| | - Guy Bouchoux
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium, Laboratoire de Chimie Organique, Université de Mons-Hainaut, Avenue Maistriau 19, B-7000 Mons, Belgium, Laboratoire des Mécanismes Réactionnels, UMR CNRS 7651, Ecole Polytechnique, F-91128 Palaiseau cedex, France, and Group of Computational Chemistry, Faculty of Chemical Engineering, HoChiMinh City University of Technology, Vietnam
| | - Minh Tho Nguyen
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium, Laboratoire de Chimie Organique, Université de Mons-Hainaut, Avenue Maistriau 19, B-7000 Mons, Belgium, Laboratoire des Mécanismes Réactionnels, UMR CNRS 7651, Ecole Polytechnique, F-91128 Palaiseau cedex, France, and Group of Computational Chemistry, Faculty of Chemical Engineering, HoChiMinh City University of Technology, Vietnam
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Brede O, Hermann R, Naumov S, Mahal H. Discrete ionization of two different short-living conformers of selenophenol by rapid free electron transfer to solvent parent radical cations. Chem Phys Lett 2001. [DOI: 10.1016/s0009-2614(01)01281-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Mohanty J, Pal H, Saini RD, Sapre AV, Mittal JP. Triplet-State Characteristics and Photoionization Behavior of 2,2‘- and 4,4‘-Biphenyldiol Studied by 248 nm Laser Flash Photolysis in Aqueous Solutions. J Phys Chem A 2001. [DOI: 10.1021/jp012445v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. Mohanty
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - H. Pal
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - R. D. Saini
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - A. V. Sapre
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - J. P. Mittal
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
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Mohanty J, Pal H, Saini R, Sapre A. Triplet state characteristics of 2,2′- and 4,4′-biphenyldiols studied by 248 nm nanosecond laser flash photolysis. Chem Phys Lett 2001. [DOI: 10.1016/s0009-2614(01)00538-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Radiolytically generated benzene triplets as sensitizers for energy and combined electron/proton transfer processes. J Photochem Photobiol A Chem 2001. [DOI: 10.1016/s1010-6030(01)00396-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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26
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Ganapathi MR, Naumov S, Hermann R, Brede O. Nucleophilic effects on the deprotonation of phenol radical cations. Chem Phys Lett 2001. [DOI: 10.1016/s0009-2614(01)00216-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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27
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Brede O, Ganapathi MR, Naumov S, Naumann W, Hermann R. Localized Electron Transfer in Nonpolar Solution: Reaction of Phenols and Thiophenols with Free Solvent Radical Cations. J Phys Chem A 2001. [DOI: 10.1021/jp002701o] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ortwin Brede
- Interdisciplinary Group Time-Resolved Spectroscopy, University of Leipzig, Permoserstr. 15, D-04303 Leipzig, Germany, and Institute of Surface Modification, Permoserstr 15, D-04303 Leipzig, Germany
| | - Mahalaxmi R. Ganapathi
- Interdisciplinary Group Time-Resolved Spectroscopy, University of Leipzig, Permoserstr. 15, D-04303 Leipzig, Germany, and Institute of Surface Modification, Permoserstr 15, D-04303 Leipzig, Germany
| | - Sergej Naumov
- Interdisciplinary Group Time-Resolved Spectroscopy, University of Leipzig, Permoserstr. 15, D-04303 Leipzig, Germany, and Institute of Surface Modification, Permoserstr 15, D-04303 Leipzig, Germany
| | - Wolfgang Naumann
- Interdisciplinary Group Time-Resolved Spectroscopy, University of Leipzig, Permoserstr. 15, D-04303 Leipzig, Germany, and Institute of Surface Modification, Permoserstr 15, D-04303 Leipzig, Germany
| | - Ralf Hermann
- Interdisciplinary Group Time-Resolved Spectroscopy, University of Leipzig, Permoserstr. 15, D-04303 Leipzig, Germany, and Institute of Surface Modification, Permoserstr 15, D-04303 Leipzig, Germany
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28
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Electron transfer from phenolic compounds to parent n -butyl chloride radical cations—a quantum chemical study of product transient formation and stability. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s0166-1280(00)00513-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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29
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Tyrakowska B, Soffers AE, Szymusiak H, Boeren S, Boersma MG, Lemańska K, Vervoort J, Rietjens IM. TEAC antioxidant activity of 4-hydroxybenzoates. Free Radic Biol Med 1999; 27:1427-36. [PMID: 10641737 DOI: 10.1016/s0891-5849(99)00192-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The influence of pH, intrinsic electron donating capacity, and intrinsic hydrogen atom donating capacity on the antioxidant potential of series of hydroxy and fluorine substituted 4-hydroxybenzoates was investigated experimentally and also on the basis of computer calculations. The pH-dependent behavior of the compounds in the TEAC assay revealed different antioxidant behavior of the nondissociated monoanionic form and the deprotonated dianionic form of the 4-hydroxybenzoates. Upon deprotonation the radical scavenging ability of the 4-hydroxybenzoates increases significantly. For mechanistic comparison a series of fluorobenzoates was synthesized and included in the studies. The fluorine substituents were shown to affect the proton and electron donating abilities of 4-hydroxybenzoate in the same way as hydroxyl substituents. In contrast, the fluorine substituents influenced the TEAC value and the hydrogen atom donating capacity of 4-hydroxybenzoate in a way different from the hydroxyl moieties. Comparison of these experimental data to computer-calculated characteristics indicates that the antioxidant behavior of the monoanionic forms of the 4-hydroxybenzoates is not determined by the tendency of the molecule to donate an electron, but by its ability to donate a hydrogen atom. Altogether, the results explain qualitatively and quantitatively how the number and position of OH moieties affect the antioxidant behavior of 4-hydroxybenzoates.
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Affiliation(s)
- B Tyrakowska
- Faculty of Commodity Science, Poznań University of Economics, Poland.
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Dey G, Hermann R, Naumov S, Brede O. Encounter geometry determines product characteristics of electron transfer from 4-hydroxythiophenol to n-butyl chloride radical cations. Chem Phys Lett 1999. [DOI: 10.1016/s0009-2614(99)00738-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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31
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Mohan H, Mittal J. Formation, excited state and electron transfer properties of the phenoxyl radical of 4,4′-thiodiphenol. J Photochem Photobiol A Chem 1999. [DOI: 10.1016/s1010-6030(99)00077-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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