159394-73-7Relevant articles and documents
Zn(II)-Induced Ground-State π-Deconjugation and Excited-State Electron Transfer in N,N-Bis(2-pyridyl)amino-Substituted Arenes
Yang, Jye-Shane,Lin, Yan-Duo,Lin, Yu-Hsi,Liao, Fen-Ling
, p. 3517 - 3525 (2007/10/03)
The synthesis and X-ray crystal structures of two N,N-bis(2-pyridyl)amino (dpa)-substituted aromatic systems (Ar-dpa) 1 (Ar = 4,4′-disubstituted trans-stilbene) and 2 (Ar = 1,4-disubstituted benzene) and their ZnCl 2 complexes (1/ZnCl2 and 2/ZnCl2) are reported. The fluoroionophoric behavior of 1-2 in response to Zn(II) in acetonitrile also has been investigated. In addition, compound 3DPA has been prepared and served as a π-deconjugated model for 1DPA. The observed crystal structures for 1/ZnCl2 and 2/ZnCl2 could be divided into two distinct types, the planar and the twisted forms, depending on the aryl-dpa (Cph-NC3) dihedral angle. The twisted form is more favorable for these complexes unless the arene has a strong " push-pull" character. Nonetheless, the degree of π-conjugation between the N-pyridyl and the N-aryl group is reduced in both complex forms when compared with the free ligands. Such a Zn(II)-induced π-deconjugation not only directly affects the internal charge transfer (ICT) fluorescence of the dpa-substituted stilbenes but also facilitates the occurrence of photoinduced electron transfer (PET) from the stilbene donor to the dpa/Zn(II) acceptor. The PET process is particularly important in accounting for the observed Zn-(II)-induced fluorescence quenching for 1DPA as well as 3DPA.
Substituent effects on the genotoxicity of 4-nitrostilbene derivatives
Hooberman,Brezzell,Das,You,Sinsheimer
, p. 57 - 69 (2007/10/03)
4-Nitrostilbene and twelve of its derivatives (eleven E-stilbenes and two Z-stilbenes) were examined for possible quantitative structure-activity relationships of their in vitro and in vivo genotoxicity. Relative mutagenicity was studied with and without S9 activation in Salmonella strains TA98 and TA100, as well as in the nitroreductase deficient strains TA98/NR and TA100/NR. Chromosomal aberrations in the bone-marrow cells of mice following intraperitoneal administration of the nitrostilbenes were observed as an indicator of in vivo genotoxicity. All of the compounds were active in TA98 and TA100 without S9 activation, with the exception of 4-amino-4'-nitrostilbene in TA100. Mutagenic activity was greatly reduced or eliminated in the NR strains, which is consistent with metabolic activation of the compounds by bacterial reductase. The presence of S9 lowered the activity of most of the nitrostilbenes presumedly by enzymatic detoxication. Hammet values of substituents, partition coefficients and frontier orbital energies (E(LUMO) and E(HOMO)) were studied for correlations with mutagenicity of the eleven E-stilbenes. Correlations could be established between mutagenicity in TA98 without S9 activation and the Hammet values. The same mutagenicity could also be correlated to E(LUMO). Rationales for these correlations include the concept that electron-withdrawing groups which lower E(LUMO) should facilitate the reduction of the nitro group, leading to the proximate mutagen hydroxylamine. The correlations are also explained by the concept that electron-withdrawing groups should help stabilize the hydroxylamine intermediate and make the ultimate mutagenic species, the nitrenium ions, more reactive toward DNA. The relationship between mutagenicity and electronic effects of substituent groups found in vitro could not be extended to the in vivo results. However, except for the dinitrostilbenes, where insolubility prevented their testing, all the nitrostilbenes produced a statistically significant increase in chromosomal aberrations compared to the negative solvent control.
