By using 1-methyl-2-formyl-5-substituted pyrroles (1-Y), 1-methyl-2-formyl-5-substituted pyrrole phenylhydrazones (2-Y) and 1-methyl-2-formyl-5-substituted pyrrole (4-nitrophenyl)-hydrazones (3-Y) as model structures ...By using 1-methyl-2-formyl-5-substituted pyrroles (1-Y), 1-methyl-2-formyl-5-substituted pyrrole phenylhydrazones (2-Y) and 1-methyl-2-formyl-5-substituted pyrrole (4-nitrophenyl)-hydrazones (3-Y) as model structures for nitrogen-containing heterocyclic aromatic compounds, correlation analysis of their redox potential data show that the transition states (TS) of the polarographic process are mainly affected by the polar effects, but spin-delocalizatin effects also exist.展开更多
By using 1-methyl-2-formyl-5 -Y-substituted pyrrole (4-nitrophenyl)hydrazones as a model for nitrogen-containing heterocyclic aromatic compounds, the emission wavelength [lambda(max(em))] values df their fluorescence ...By using 1-methyl-2-formyl-5 -Y-substituted pyrrole (4-nitrophenyl)hydrazones as a model for nitrogen-containing heterocyclic aromatic compounds, the emission wavelength [lambda(max(em))] values df their fluorescence spectra have been measured. Correlation results show that the Delta E-em values are mainly affected by polar effects, but spin-delocalizatin effects also exist.展开更多
Three substituted α,β,β-trifluorostyrenes(TFS's),i.e.,p-thiomethyltrifluorostyrene(4), p-cyclopropyltrifluorostyrene(5)and p-t-butyltrifluorostyrene(6),have been synthesized.The rate constants(k_2)of the therma...Three substituted α,β,β-trifluorostyrenes(TFS's),i.e.,p-thiomethyltrifluorostyrene(4), p-cyclopropyltrifluorostyrene(5)and p-t-butyltrifluorostyrene(6),have been synthesized.The rate constants(k_2)of the thermal cyclodimerization of these compounds have been measured in the tem- perature range 120—160℃.The polar parameters σ_(mb) of these TFS's calculated from ^(19)F NMR chemi- cal shifts are:for p-thiomethyl,-0.18;p-cyclopropyl,-0.31 and p-t-butyl,-0.22.The spin delo- calization substituent parameters σ'_T(140°)of p-thiomethyl,cyclopropyl and t-butyl groups are 0.59, 0.27 and 0.30 respectively.Thus all of these groups act as electron-donating groups which can also effectively stabilize a spin.展开更多
基金the National Natural Science Foundation of China and the China Postdoctoral Science Foundation for financial support.
文摘By using 1-methyl-2-formyl-5-substituted pyrroles (1-Y), 1-methyl-2-formyl-5-substituted pyrrole phenylhydrazones (2-Y) and 1-methyl-2-formyl-5-substituted pyrrole (4-nitrophenyl)-hydrazones (3-Y) as model structures for nitrogen-containing heterocyclic aromatic compounds, correlation analysis of their redox potential data show that the transition states (TS) of the polarographic process are mainly affected by the polar effects, but spin-delocalizatin effects also exist.
文摘By using 1-methyl-2-formyl-5 -Y-substituted pyrrole (4-nitrophenyl)hydrazones as a model for nitrogen-containing heterocyclic aromatic compounds, the emission wavelength [lambda(max(em))] values df their fluorescence spectra have been measured. Correlation results show that the Delta E-em values are mainly affected by polar effects, but spin-delocalizatin effects also exist.
基金This work was financially supported by the National Natural Science Foundation of China.
文摘Three substituted α,β,β-trifluorostyrenes(TFS's),i.e.,p-thiomethyltrifluorostyrene(4), p-cyclopropyltrifluorostyrene(5)and p-t-butyltrifluorostyrene(6),have been synthesized.The rate constants(k_2)of the thermal cyclodimerization of these compounds have been measured in the tem- perature range 120—160℃.The polar parameters σ_(mb) of these TFS's calculated from ^(19)F NMR chemi- cal shifts are:for p-thiomethyl,-0.18;p-cyclopropyl,-0.31 and p-t-butyl,-0.22.The spin delo- calization substituent parameters σ'_T(140°)of p-thiomethyl,cyclopropyl and t-butyl groups are 0.59, 0.27 and 0.30 respectively.Thus all of these groups act as electron-donating groups which can also effectively stabilize a spin.
