Donor-substituted distyrylpyrazines: Influence of steric congestion on UV-Vis absorption and fluorescence
Di(p-aminostyryl)pyrazines with voluminous substituents on the nitrogen and in the adjacent positions were prepared via twofold aldol condensation. Absorption and emission spectra are influenced by increasing steric hindrance because the orbital overlap between nitrogen and π-system is modulated by voluminous groups. Strong solvatochromism of the fluorescence and huge Stokes shifts result from amplified donor-acceptor interaction in the excited state. Protonation occurs at the terminal amino groups first, followed by protonation of the central pyrazine. With increasing strength of acid, absorption and emission spectra are first shifted to the blue followed by a redshift. Copyright
Wink, Christoph,Detert, Heiner
p. 144 - 150
(2013/03/13)
4-PHENYLPYRANE-3,5-DIONES, 4-PHENYLTHIOPYRANE-3,5-DIONES AND 2-PHENYLCYCLOHEXANE-1,3,5-TRIONES AS HERBICIDES
Pyrandione, thiopyrandione and cyclohexanetrione compounds, which are suitable for use as herbicides.
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Page/Page column 156-157
(2009/07/17)
Tandem optimization of target activity and elimination of mutagenic potential in a potent series of N-aryl bicyclic hydantoin-based selective androgen receptor modulators
Pharmacokinetic studies in cynomolgus monkeys with a novel prototype selective androgen receptor modulator revealed trace amounts of an aniline fragment released through hydrolytic metabolism. This aniline fragment was determined to be mutagenic in an Ames assay. Subsequent concurrent optimization for target activity and avoidance of mutagenicity led to the identification of a pharmacologically superior clinical candidate without mutagenic potential.
Hamann, Lawrence G.,Manfredi, Mark C.,Sun, Chongqing,Krystek Jr., Stanley R.,Huang, Yanting,Bi, Yingzhi,Augeri, David J.,Wang, Tammy,Zou, Yan,Betebenner, David. A.,Fura, Aberra,Seethala, Ramakrishna,Golla, Rajasree,Kuhns, Joyce E.,Lupisella, John A.,Darienzo, Celia J.,Custer, Laura L.,Price, Jennifer L.,Johnson, James M.,Biller, Scott A.,Zahler, Robert,Ostrowski, Jacek
p. 1860 - 1864
(2008/02/04)
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