Electrode Kinetics and Complex Formation of [Zn-Antibiotics-Cephalothin] System vis a vis Kinetics of Electrode Reactions

摘要

Charge transfer reactions between a dropping mercury electrode and a [Mn-antibiotics-cephalothin] system were studied at pH = 7.30 ± 0.01, μ = 1.0 M NaClO_4 at 298 K. The antibiotics were doxycycline, chlortetracycline, oxytetracycline, tetracycline, minocycline, amoxicillin and chloramphenicol used as primary ligands and cephalothin as secondary ligand formed 1:1:1, 1:1:2 and 1:2:1 complexes with Zn~2. Electrode kinetics was discussed on the basis of kinetic parameters viz. transfer coefficient (α), degree of irreversibility (λ), diffusion coefficient (D) and rate constant (k). The values of a varied from 0.40 to 0.57 (0.50) confirm that 'transition state' behaves between reactant and product response to applied potential and it lies always between d.m.e. and solution interface. A small variation in potential affects the rate and rate constant greatly.