- Mechanistic studies of electrode-assisted catalytic oxidation by flavinium and acridinium cations
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Electrochemical behavior of flavinium (Et-Fl+) and acridinium (Acr+) cations is presented, in order to investigate their activity toward catalytic water oxidation. Cyclic voltammograms of Acr+ and Et-Fl+ in acetonitrile are qualitatively similar, with oxidation peaks at highly positive potentials, and these oxidation peaks depend strongly on the type of the working electrode being used. However, the two model compounds exhibit different behaviors in the presence of water: while Et-Fl + facilitates electrocatalytic water oxidation through an electrode-assisted mechanism, water oxidation is not accelerated in the presence of Acr+. A comparative study of variable scan-rate cyclic voltammetry, concentration dependence, and spectroelectrochemical behavior of two model compounds suggest that Et-Fl+ and Acr+ exhibit different reaction pathways with the electrode surface. On the basis of the experimental results, a mechanism is proposed to account for the observed differences in electrocatalysis.
- Yang, Xin,Walpita, Janitha,Mirzakulova, Ekaterina,Oottikkal, Shameema,Hadad, Christopher M.,Glusac, Ksenija D.
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- Excited-state hydroxide ion release from a series of acridinol photobases
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The excited-state heterolysis of acridinol-based derivatives leads to the release of the OH-ion and the formation of the corresponding acridinium cations. To evaluate the parameters that control the reaction barriers, the kinetics of excited-state OH-release from a series of acridinol photobases were studied using transient absorption spectroscopy. The rate constants were obtained in three solvents (methanol, butanol, and isobutanol), and the data were modeled using Marcus theory. The intrinsic reorganization energies obtained from these fits were found to correlate well with the solvent reorganization energies calculated using dielectric continuum model, suggesting that the excited-state OH-release occurs along the solvent reaction coordinate. Furthermore, the ability of acridinol photobases to photoinitiate chemical reactions was demonstrated using the Michael reaction between dimethylmalonate and nitrostyrene.
- Xie, Yun,Ilic, Stefan,Skaro, Sanja,Maslak, Veselin,Glusac, Ksenija D.
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p. 448 - 457
(2017/12/08)
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- Mechanistic study of the photochemical hydroxide ion release from 9-hydroxy-10-methyl-9-phenyl-9,10-dihydroacridine
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The excited-state behavior of 9-hydroxy-10-methyl-9-phenyl-9,10- dihydroacridine and its derivative, 9-methoxy-10-methyl-9-phenyl-9,10- dihydroacridine (AcrOR, R = H, Me), was studied via femtosecond and nanosecond UV-vis transient absorption spectroscopy. The solvent effects on C-O bond cleavage were clearly identified: a fast heterolytic cleavage (τ = 108 ps) was observed in protic solvents, while intersystem crossing was observed in aprotic solvents. Fast heterolysis generates 10-methyl-9-phenylacridinium (Acr+) and -OH, which have a long recombination lifetime (no signal decay was observed within 100 μs). AcrOH exhibits the characteristic behavior needed for its utilization as a chromophore in the pOH jump experiment.
- Zhou, Dapeng,Khatmullin, Renat,Walpita, Janitha,Miller, Nicholas A.,Luk, Hoi Ling,Vyas, Shubham,Hadad, Christopher M.,Glusac, Ksenija D.
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p. 11301 - 11303
(2012/08/27)
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- Synthesis and antinociceptive activity of 9-phenyl-oxy or 9-acyl-oxy derivatives of xanthene, thioxanthene and acridine
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The synthesis of 9-alkyl-oxy or 9-acyl-oxy derivatives of xanthene, thioxanthene and acridine is reported.A potent antinociceptive activity was confirmed for the 9-phenyl-9-propionyl-oxy derivative bearing an oxygen or sulfur atom in the heteroaromatic structure. xanthene derivatives/ thioxanthene derivatives/ acridine derivatives/ trimepridine analogues/ antinociceptive activity
- Llama, Emilio F.,Campo, Carmen del,Capo, Miguel,Anadon, Maria
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p. 391 - 396
(2007/10/02)
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