甲醇-水二元混合物中Co(bpb)与叠氮离子反应的动力学研究

Co(bpb) bpbH2 is N,N'-o-phenylenebis(pyridine-2-carboxamide), C18H12N4O2] complex has active axial sites like a porphyrin complex. We studied the coordination of azide ion (N-3) to Co(bpb) in binary methanol-water mixtures by spectrophotometric method at the temperature range of 283-303 K. From the temperature dependence of the rate constant, activation parameters (Ea, △H#, △S#, and △G#) were obtained. An isokinetic temperature at about 302 K was observed at which the formation rate of Co(bpb)-N-3 was more or less independent of the solvent composition. The resulting △H against T△S plot showed a good linear correlation, indicating the existence of enthalpy-entropy compensation in azide complexation process. Under optimum conditions and based on the absorbance of Co(bpb)-N-3 produced through complex formation, a spectrophotometric method for the determination of N-3 in solution was developed.Alinear relationship between the absorbance and N-3 concentration was obtained in the range of (0.85-5.00)×10-4 mol·L-1 (3.6-21.0 μg·mL-1). The detection limit was 2.5×10-5 mol·L-1 (1.0 μg·mL-1). The proposed method was applied to the determination of N-3 anion in real water samples.

Kinetics Studies of the Reaction of Co(bpb) with the Azide Ion in Binary Methanol-Water Mixtures

Co(bpb)bpbH2 is N,N'-o-phenylenebis(pyridine-2-carboxamide),C18H12N4O2] complex has active axial sites like a porphyrin complex.We studied the coordination of azide ion (N3-) to Co(bpb) in binary methanol-water mixtures by spectropbotometric method at the temperature range of 283-303 K.From the temperature dependence of the rate constant,activation parameters (Ea,△H#,△S#,and △G# were obtained.An isokinetic temperature at about 302 K was observed at which the formation rate of Co(bpb)-N3- was more or less independent of the solvent composition.The resulting △H against TAS plot showed a good linear correlation,indicating the existence of enthalpy-entropy compensation in azide complexation process.Under optimum conditions and based on the absorbance of Co(bpb)-N3- produced through complex formation,a spectrophotometric method for the determination of N3- in solution was developed.A linear relationship between the absorbance and N3- concentration was obtained in the range of (0.85-5.00)× was applied to the determination of N3- anion in real water samples.Key Words: Spectrophotometric;Kinetics;Binary mixture;Azide determination;Water sample