The intramolecular process of Mg ( Ⅱ ) - , Sc ( Ⅲ ) - , Y ( Ⅲ ) - , In(Ⅲ)-and Pb ( Ⅱ )-trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA) complexes was studied by the method of proton dynamic NMR(DNMR). The top...The intramolecular process of Mg ( Ⅱ ) - , Sc ( Ⅲ ) - , Y ( Ⅲ ) - , In(Ⅲ)-and Pb ( Ⅱ )-trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA) complexes was studied by the method of proton dynamic NMR(DNMR). The top limit of. the experimental temperature range of deuterium oxide solutions was extended from 100℃ to 167 ℃ instead of the previous 100 ℃ by using sealed, thick-walled tubes to observe experimental phenomena further. It was found that another intramolecular process, i. e. B, R (Bonded State, Rotational State) conversion, exists in these complexes formed by polyaminepolycarboxylic ligands in addition to △,A conversion and nitrogen inversion. A quantitative treatment was proposed to estimate the relative populations of acetate groups in B and R states.展开更多
The influences of methanol-d_4(MeOD), dimethylsulfoxide-d_6 (Me_2SO(D)) and dioxane(C_4H_8O_2) solvents on the intramolecular processes are studied by NMR. It has been shown that the addition of these solvents in CdEG...The influences of methanol-d_4(MeOD), dimethylsulfoxide-d_6 (Me_2SO(D)) and dioxane(C_4H_8O_2) solvents on the intramolecular processes are studied by NMR. It has been shown that the addition of these solvents in CdEGTA complex aqueous solution can increase the rate constant (k) of the nitrogen inversion and decrease the activation energy of this process. The linear relations between In(k) and the reciprocal of the solvent dielectric constants (1/ε) are obtained for all the three solvents.展开更多
The luminescence behaviors of 4’-dimethyldrinoflavone derivarive with different structures have been studied in different conditions. Results show that the luminescence behavior depends dramatically on the solvent po...The luminescence behaviors of 4’-dimethyldrinoflavone derivarive with different structures have been studied in different conditions. Results show that the luminescence behavior depends dramatically on the solvent polarity. The reason is attributed to the different conformations in different solvents. The planar conformation is proved to be favorable to the fluorescence emission. In addition, results of viscosity-dependent luminescence property show that for compound 3 with the rigidized planar structure the luminescence behavior do not depend on the medium viscosity. But, for compound 1 and 2 the fluorescence quantum yields increase with increasing medium viscosity evidently,indicating that the rotation relaxation process of benzene ring in the molecule is yery important for the nonradiative decay process of excited molecules of compounds.展开更多
EGTA is a kind of highly selective calcium-binding chelate, whose preference for the binding of Ca<sup>2+</sup> over Mg<sup>2+</sup> is about 10<sup>6</sup>, therefore it is conside...EGTA is a kind of highly selective calcium-binding chelate, whose preference for the binding of Ca<sup>2+</sup> over Mg<sup>2+</sup> is about 10<sup>6</sup>, therefore it is considered as a model for the binding sites in calcium-binding proteins. Although the crystal structure of Ca （EGTA） has been reported, its structure in aqueous solution is still unclear. Considering that Ca<sup>2+</sup> ionic radius （0.99（?）） falls in the range for those of lanthanide series （1.06—0.85（?））, Ln （EGTA） （Ln=La, Y, Lu and Sc） is studied in this note so as to展开更多
基金Supported by the National Natural Science Foundation of China
文摘The intramolecular process of Mg ( Ⅱ ) - , Sc ( Ⅲ ) - , Y ( Ⅲ ) - , In(Ⅲ)-and Pb ( Ⅱ )-trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA) complexes was studied by the method of proton dynamic NMR(DNMR). The top limit of. the experimental temperature range of deuterium oxide solutions was extended from 100℃ to 167 ℃ instead of the previous 100 ℃ by using sealed, thick-walled tubes to observe experimental phenomena further. It was found that another intramolecular process, i. e. B, R (Bonded State, Rotational State) conversion, exists in these complexes formed by polyaminepolycarboxylic ligands in addition to △,A conversion and nitrogen inversion. A quantitative treatment was proposed to estimate the relative populations of acetate groups in B and R states.
文摘The influences of methanol-d_4(MeOD), dimethylsulfoxide-d_6 (Me_2SO(D)) and dioxane(C_4H_8O_2) solvents on the intramolecular processes are studied by NMR. It has been shown that the addition of these solvents in CdEGTA complex aqueous solution can increase the rate constant (k) of the nitrogen inversion and decrease the activation energy of this process. The linear relations between In(k) and the reciprocal of the solvent dielectric constants (1/ε) are obtained for all the three solvents.
文摘The luminescence behaviors of 4’-dimethyldrinoflavone derivarive with different structures have been studied in different conditions. Results show that the luminescence behavior depends dramatically on the solvent polarity. The reason is attributed to the different conformations in different solvents. The planar conformation is proved to be favorable to the fluorescence emission. In addition, results of viscosity-dependent luminescence property show that for compound 3 with the rigidized planar structure the luminescence behavior do not depend on the medium viscosity. But, for compound 1 and 2 the fluorescence quantum yields increase with increasing medium viscosity evidently,indicating that the rotation relaxation process of benzene ring in the molecule is yery important for the nonradiative decay process of excited molecules of compounds.
基金Project supported by the National Natural Science Foundation of China and the Science Foundation of Laboratory of Rare Earth Chemistry and Physics.
文摘EGTA is a kind of highly selective calcium-binding chelate, whose preference for the binding of Ca<sup>2+</sup> over Mg<sup>2+</sup> is about 10<sup>6</sup>, therefore it is considered as a model for the binding sites in calcium-binding proteins. Although the crystal structure of Ca （EGTA） has been reported, its structure in aqueous solution is still unclear. Considering that Ca<sup>2+</sup> ionic radius （0.99（?）） falls in the range for those of lanthanide series （1.06—0.85（?））, Ln （EGTA） （Ln=La, Y, Lu and Sc） is studied in this note so as to
