5337-49-5Relevant academic research and scientific papers
Synthesis, characterization, photophysics and photochemistry of pyrylogen electron transfer sensitizers
Clennan, Edward L.,Liao, Chen
, p. 344 - 357 (2014/04/03)
A series of new dicationic sensitizers that are hybrids of pyrylium salts and viologens has been synthesized. The electrochemical and photophysical properties of these "pyrylogen" sensitizers are reported in sufficient detail to allow rationale design of new photoinduced electron transfer reactions. The range of their reduction potentials (+0.37-+0.05 V vs SCE) coupled with their range of singlet (48-63 kcal mol-1) and triplet (48-57 kcal mol-1) energies demonstrate that they are potent oxidizing agents in both their singlet and triplet excited states, thermodynamically capable of oxidizing substrates with oxidation potentials as high as 3.1 eV. The pyrylogens are synthesized in three steps from readily available starting materials in modest overall 11.4-22.3% yields. These sensitizers have the added advantages that: (1) their radical cations do not react on the CV timescale with oxygen bypassing the need to run reactions under nitrogen or argon and (2) have long wavelength absorptions between 413 and 523 nm well out of the range where competitive absorbance by most substrates would cause a problem. These new sensitizers do react with water requiring special precautions to operate in a dry reaction environment. Hybrids of pyrylium salts and viologens photochemically generate radical-cation/radical-cation pairs with substantial intra-ion repulsion that increases the rate constant of separation, kSEP, and competitively inhibits energy wasting return electron transfer. These first representatives of dicationic charge-shift sensitizers generate radical cations that do not react with oxygen on the CV timescale and absorb between 413 and 523 nm well outside the range where competitive absorbance by most substrates would cause a problem.
A new free and immobilized pyrylogen electron transfer sensitizer
El-Idreesy, Tamer T.,Clennan, Edward L.
experimental part, p. 1249 - 1251 (2010/04/29)
The synthesis, photophysical, and electrochemical characterization of N-allyl-2,6-diphenyl-4,4′-pyrylogen bis tetrafluoroborate is reported. The pyrylogen is reduced under dissolving metal reduction conditions with formation of the radical cation. In addi
Pyrylogens: Synthesis, structural, electrochemical, and photophysical characterization of a new class of electron transfer sensitizers
Clennan, Edward L.,Liao, Chen,Ayokosok, Erambo
, p. 7552 - 7553 (2008/12/22)
The synthesis and photophysical properties of a new series of dicationic electron transfer sensitizers have been reported. These new materials, pyrylogens, are hybrids of pyrylium cations and Viologen dications. Electron transfer reactions of neutral orga
One-pot synthesis of 1,5-diketones catalyzed by barium isopropoxide
Yanagisawa, Akira,Takahashi, Hiroshi,Arai, Takayoshi
, p. 8581 - 8585 (2008/02/10)
A tandem cross-coupling reaction of aryl methyl ketones with aromatic aldehydes has been accomplished employing barium isopropoxide as a catalyst, in which barium enolates are generated and then three consecutive reactions (aldol reaction/β-elimination/co
1,5-Diketone synthesis promoted by barium hydride or barium alkoxides
Takahashi, Hiroshi,Arai, Takayoshi,Yanagisawa, Akira
, p. 2833 - 2835 (2008/02/13)
A tandem cross-coupling reaction of ketones with aldehydes has been achieved using barium hydride or isopropoxide as a promoter, in which barium enolates are generated in situ and then three successive reactions (aldol reaction-β-elimination-Michael addit
Syntheses and UV/Vis-spectroscopic properties of hydrophilic 2-, 3-, and 4-pyridyl-substituted solvatochromic and halochromic pyridinium N-phenolate betaine dyes as new empirical solvent polarity indicators
Reichardt, Christian,Che, Daqing,Heckenkemper, Guido,Schaefer, Gerhard
, p. 2343 - 2361 (2007/10/03)
Syntheses and negative solvatochromism of nine new hydrophilic 2-, 3-, and 4-pyridyl-substituted pyridinium N-phenolate betaine dyes 3-11 are described. These were produced in order to obtain zwitterionic dyes better soluble in water and other aqueous media (such as binary water/solvent mixtures, aqueous ionophore solutions) than the rather hydrophobic standard betaine dyes 1 and 2, which have been used to establish an empirical scale of solvent polarity, called the ET(30) scale. Betaine dye 8, in which three of the peripheral phenyl groups of 1 are replaced by two 3-pyridyl rings and one 4-pyridyl ring, proved to be particularly suitable for the determination of ET(30) values in aqueous media. Wiley-VCH Verlag GmbH, 2001.
Kinetics and Mechanisms of Nucleophilic Displacements with Heterocycles as Leaving Groups. Part 4. 2,4,6-Triaryl-N-benzylpyridinium Cations: Rate Variation with Electronic Effects in the Leaving Group
Katritzky, Alan R.,Adamson, Jeffrey,Elisseou, E. Michael,Musumarra, Giuseppe,Patel, Ranjan C.,et al.
, p. 1041 - 1048 (2007/10/02)
Electron-withdrawing groups in the 4-phenyl ring of 2,4,6-triphenylpyridine modestly increase its activity as a leaving group.Replacement of 2-phenyl by heteroaryl has a small effect for monoheteroaryl groups, but significantly larger for 2-benzimidazol-2-yl and especially for 2-benzothiazol-1-yl.
