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Morawski OW, Gawryś P, Sobolewski AL. Harnessing Proton-Coupled Electron Transfer for Hydrogenation of Aza-Arenes: Photochemistry of Quinoxaline Derivatives in Methanol. J Phys Chem A 2023; 127:8871-8881. [PMID: 37842877 PMCID: PMC10614181 DOI: 10.1021/acs.jpca.3c05077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 10/02/2023] [Indexed: 10/17/2023]
Abstract
Three quinoxaline derivatives are investigated both experimentally and theoretically to assess their ability for the methanol oxidation and harvesting of hydrogen. In inert solvents, the nonplanar compounds exhibit very weak fluorescence from the lowest excited singlet state, whereas the planar and rigid chromophore emits non-Kasha fluorescence from the S2(ππ*) state despite the proximity of the S1(nπ*) state. In methanol, hydrogen-bonded complexes with solvent molecules are formed, and in all chromophores, the lowest singlet state is populated after excitation of the S2(ππ*) state. The switch from non-Kasha emission of the planar compound in inert solvents to regular emission in methanol is related to reduced symmetry of the hydrogen-bonded complex with methanol which results in effective mixing of ππ* and nπ* states and fast internal conversion to the lowest excited singlet state. The S1(nπ*) state of the hydrogen-bonded complex has charge-transfer character, and for all compounds in methanol, hydrogen transfer to the chromophore is observed. The chromophores retain the transferred hydrogen atoms, serving both as photocatalysts and as hydrogen storage materials. Undesired dark side reactions that occur are also discussed.
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Affiliation(s)
- Olaf W. Morawski
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Paweł Gawryś
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Andrzej L. Sobolewski
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
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Kao MH, Venkatraman RK, Sneha M, Wilton M, Orr-Ewing AJ. Influence of the Solvent Environment on the Ultrafast Relaxation Pathways of a Sunscreen Molecule Diethylamino Hydroxybenzoyl Hexyl Benzoate. J Phys Chem A 2021; 125:636-645. [PMID: 33416312 DOI: 10.1021/acs.jpca.0c10313] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The excited-state dynamics of photoexcited diethylamino hydroxybenzoyl hexyl benzoate (DHHB), a UVA absorber widely used in sunscreen formulations, are studied with transient electronic and vibrational absorption spectroscopy methods in four different solvents. In the polar solvents methanol, dimethyl sulfoxide (DMSO), and acetonitrile, strong stimulated emission (SE) is observed at early time delays after photoexcitation at a near-UV wavelength of λex = 360 nm, and decays with time constants of 420 fs in methanol and 770 fs in DMSO. The majority (∼95%) of photoexcited DHHB returns to the ground state with time constants of 15 ps in methanol and 25 ps in DMSO. In the nonpolar solvent cyclohexane, ∼ 98% of DHHB photoexcited at λex = 345 nm relaxes to the ground state with a ∼ 10 ps time constant, and the SE is weak. DHHB preferentially adopts an enol form in its ground S0 state, but excited state absorption (ESA) bands seen in TEAS are assigned to both the S1-keto and S1-enol forms, indicating a role for ultrafast intramolecular excited state hydrogen transfer (ESHT). This ESHT is inhibited by polar solvents. The two S1 tautomers decay with similar time scales to the observed recovery of ground state population. For molecules that avoid ESHT, torsion around a central C-C bond minimizes the S1-enol energy, quenches the SE, and is proposed to lead to a conical intersection with the S0 state that mediates the ground state recovery. A competing trans-enol isomeric photoproduct is observed as a minor competitor to parent recovery in polar solvents. Evidence is presented for triplet (T1) enol production in polar solvents, and for T1 quenching by octocrylene, a common UVB absorber sunscreen additive. The T1 keto form is observed in cyclohexane solution.
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Affiliation(s)
- Min-Hsien Kao
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
| | | | - Mahima Sneha
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
| | - Matthew Wilton
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
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Jiang S, Yang J, Fang DA. Transcriptome changes of Takifugu obscurus liver after acute exposure to the oxygenated-PAH 9,10-phenanthrenequione. Physiol Genomics 2020; 52:305-313. [PMID: 32538278 DOI: 10.1152/physiolgenomics.00022.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Contamination with polycyclic aromatic hydrocarbons (PAHs) causes noticeable ecological problems in aquatic ecosystems. 9,10-Phenanthrenequione (9,10-PQ) is an oxidized PAH and is highly toxic to aquatic animals. However, the effects of 9,10-PQ on the molecular metabolism of fish remain largely unknown. In this study, Takifugu obscurus juveniles were acutely exposed to 44.30 µg/L 9,10-PQ for 3 days. The transcriptome profile changes in their livers were compared between the 9,10-PQ treatment group and the control using T. rubripes as the reference genome. The results identified 22,414 genes in our transcriptome. Among them, 767 genes were differentially expressed after exposure to 9,10-PQ, which enriched 16 KEGG pathways. Among them, the glycolysis, phagosome, and FOXO signaling pathways were significantly activated in 9,10-PQ treatment compared with the control. These data indicate that 9,10-PQ increased the glycolysis capacity to produce more energy for resistance and harmed immune function. Moreover, several genes related to tumorigenesis were significantly upregulated in response to 9,10-PQ, displaying the carcinogenic toxicity of 9,10-PQ to T. obscurus. Genes in steroid biosynthesis pathways were downregulated in the 9,10-PQ treatment group, suggesting interference with the endocrine system. Overall, these findings provide information to help evaluate the environmental risks that oxygenated-PAHs present to T. obscurus.
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Affiliation(s)
- Shulun Jiang
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
| | - Jian Yang
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
| | - Di-An Fang
- Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
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Cytotoxicity of Air Pollutant 9,10-Phenanthrenequinone: Role of Reactive Oxygen Species and Redox Signaling. BIOMED RESEARCH INTERNATIONAL 2018; 2018:9523968. [PMID: 29984252 PMCID: PMC6015725 DOI: 10.1155/2018/9523968] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 04/30/2018] [Indexed: 01/22/2023]
Abstract
Atmospheric pollution has been a principal topic recently in the scientific and political community due to its role and impact on human and ecological health. 9,10-phenanthrenequinone (9,10-PQ) is a quinone molecule found in air pollution abundantly in the diesel exhaust particles (DEP). This compound has studied extensively and has been shown to develop cytotoxic effects both in vitro and in vivo. 9, 10-PQ has been proposed to play a critical role in the development of cytotoxicity via generation of reactive oxygen species (ROS) through redox cycling. This compound also reduces expression of glutathione (GSH), which is critical in Phase II detoxification reactions. Understanding the underlying cellular mechanisms involved in cytotoxicity can allow for the development of therapeutics designed to target specific molecules significantly involved in the 9,10-PQ-induced ROS toxicity. This review highlights the developments in the understanding of the cytotoxic effects of 9, 10-PQ with special emphasis on the possible mechanisms involved.
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Kayal S, Roy K, Umapathy S. Femtosecond coherent nuclear dynamics of excited tetraphenylethylene: Ultrafast transient absorption and ultrafast Raman loss spectroscopic studies. J Chem Phys 2018; 148:024301. [DOI: 10.1063/1.5008726] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Surajit Kayal
- Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore 560012, India
| | - Khokan Roy
- Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore 560012, India
| | - Siva Umapathy
- Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore 560012, India
- Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012, India
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Ecofriendly method to synthesize poly ( o -aminophenol) based on solid state polymerization and fabrication of nanostructured semiconductor thin film. POLYMER 2017. [DOI: 10.1016/j.polymer.2017.05.048] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Homocianu M, Airinei A. Intra-/inter-molecular interactions – Identification and evaluation by optical spectral data in solution. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2016.11.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Ravi Kumar V, Ariese F, Umapathy S. Triplet excited electronic state switching induced by hydrogen bonding: A transient absorption spectroscopy and time-dependent DFT study. J Chem Phys 2016; 144:114301. [PMID: 27004870 DOI: 10.1063/1.4943514] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The solvent plays a decisive role in the photochemistry and photophysics of aromatic ketones. Xanthone (XT) is one such aromatic ketone and its triplet-triplet (T-T) absorption spectra show intriguing solvatochromic behavior. Also, the reactivity of XT towards H-atom abstraction shows an unprecedented decrease in protic solvents relative to aprotic solvents. Therefore, a comprehensive solvatochromic analysis of the triplet-triplet absorption spectra of XT was carried out in conjunction with time dependent density functional theory using the ad hoc explicit solvent model approach. A detailed solvatochromic analysis of the T-T absorption bands of XT suggests that the hydrogen bonding interactions are different in the corresponding triplet excited states. Furthermore, the contributions of non-specific and hydrogen bonding interactions towards differential solvation of the triplet states in protic solvents were found to be of equal magnitude. The frontier molecular orbital and electron density difference analysis of the T1 and T2 states of XT indicates that the charge redistribution in these states leads to intermolecular hydrogen bond strengthening and weakening, respectively, relative to the S0 state. This is further supported by the vertical excitation energy calculations of the XT-methanol supra-molecular complex. The intermolecular hydrogen bonding potential energy curves obtained for this complex in the S0, T1, and T2 states support the model. In summary, we propose that the different hydrogen bonding mechanisms exhibited by the two lowest triplet excited states of XT result in a decreasing role of the nπ(∗) triplet state, and are thus responsible for its reduced reactivity towards H-atom abstraction in protic solvents.
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Affiliation(s)
- Venkatraman Ravi Kumar
- Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore 560012, India
| | - Freek Ariese
- Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore 560012, India
| | - Siva Umapathy
- Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore 560012, India
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Ravi Kumar V, Verma C, Umapathy S. Molecular dynamics and simulations study on the vibrational and electronic solvatochromism of benzophenone. J Chem Phys 2016; 144:064302. [DOI: 10.1063/1.4941058] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Kumar VR, Rajkumar N, Ariese F, Umapathy S. Direct Observation of Thermal Equilibrium of Excited Triplet States of 9,10-Phenanthrenequinone. A Time-Resolved Resonance Raman Study. J Phys Chem A 2015; 119:10147-57. [PMID: 26381591 DOI: 10.1021/acs.jpca.5b07972] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The photochemistry of aromatic ketones plays a key role in various physicochemical and biological processes, and solvent polarity can be used to tune their triplet state properties. Therefore, a comprehensive analysis of the conformational structure and the solvent polarity induced energy level reordering of the two lowest triplet states of 9,10-phenanthrenequinone (PQ) was carried out using nanosecond-time-resolved absorption (ns-TRA), time-resolved resonance Raman (TR(3)) spectroscopy, and time dependent-density functional theory (TD-DFT) studies. The ns-TRA of PQ in acetonitrile displays two bands in the visible range, and these two bands decay with similar lifetime at least at longer time scales (μs). Interestingly, TR(3) spectra of these two bands indicate that the kinetics are different at shorter time scales (ns), while at longer time scales they followed the kinetics of ns-TRA spectra. Therefore, we report a real-time observation of the thermal equilibrium between the two lowest triplet excited states of PQ, assigned to nπ* and ππ* of which the ππ* triplet state is formed first through intersystem crossing. Despite the fact that these two states are energetically close and have a similar conformational structure supported by TD-DFT studies, the slow internal conversion (∼2 ns) between the T(2)(1(3)nπ*) and T(1)(1(3)ππ*) triplet states indicates a barrier. Insights from the singlet excited states of PQ in protic solvents [ J. Chem. Phys. 2015 , 142 , 24305 ] suggest that the lowest nπ* and ππ* triplet states should undergo hydrogen bond weakening and strengthening, respectively, relative to the ground state, and these mechanisms are substantiated by TD-DFT calculations. We also hypothesize that the different hydrogen bonding mechanisms exhibited by the two lowest singlet and triplet excited states of PQ could influence its ISC mechanism.
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Affiliation(s)
- Venkatraman Ravi Kumar
- Inorganic and Physical Chemistry Department, Indian Institute of Science , Bangalore 560012, India
| | - Nagappan Rajkumar
- Inorganic and Physical Chemistry Department, Indian Institute of Science , Bangalore 560012, India
| | - Freek Ariese
- Inorganic and Physical Chemistry Department, Indian Institute of Science , Bangalore 560012, India
| | - Siva Umapathy
- Inorganic and Physical Chemistry Department, Indian Institute of Science , Bangalore 560012, India
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