ESI-MS/MS Study On Oxygenation And Aging Process Of Polyamine Cobalt Complexes

The polyamine cobalt complexes were the ideal model compounds for the studyof oxygen carriers because of their features of small molecular weight, simplestructure, multiple chelate ring and worse reversibility. Then, the ESI-MS/MS methodwas used to investigate the oxygenation reaction and the aging process of polyaminecobalt complexes. For the sake of the important contribution the ESI-MS/MS methodmade in both structure characterization and mechanism study, we chose it as mainanalysis tool in the following study.1. A brief discussion on the development of coordination chemistry, oxygencarrier study and polyamine cobalt complex were made, as well as the applicationprocess of ESI-MS and ESI-MS/MS method.2. Ethylenedianmine cobalt complex was synthesized by solid-phase method andcharacterized by ESI-MS/MS method. According to the tandem mass spectrum andthe daughter ion spectrum, the reasonable structures were given. The results manifestthat the ESI-MS/MS technique could be used as a method to study the oxygenationreaction and characterize the oxygenation complex.3. On the basis of the first part, different oxygenation stage of diethylenetriaminecobalt complexes were analyzed by ESI-MS method. The results showed that theoxygenation process was a changing process of oxygenation structures. The structureand mechanism of the complexes were also deduced.4. The oxygenation reaction and aging process of triethylenetetramine cobaltcomplexes were analyzed by ESI-MS and UV-vis，as well as the factors thatinfluenced oxygenation reversibility. Results showed that the structure of CAT-0.1hmainly exist as mononuclear form; the structure of CAT-5h was double oxygen dualbridge format; the CAT-350h was probably as double hydroxyl dual bridge Co (Ⅲ)complex form. The ESI-MS result of different trien-Co complexes and the acid dissociation experiment verified the accuracy of these results. The factors affectingthe oxygenation-deoxygenation reversibility were explored by UV-vis method.Results showed that strong polar organic solvents and low temperature wouldpromote the oxygenation-deoxygenation reversibility.5. A comparison study was conducted on the oxygenated en-Co, dien-Co andtrien-Co complexes by ESI-MS and UV-vis methods. Results indicated that the threegroup oxygenation complexes have same structure and coordination mode, and havestrong regularity in fragmentation process. The UV-vis results manifest that theoxygenation ability of the three group complexes was wear off with the increase ofthe aliphatic chain. The ESI-MS/MS results display that the complex of en-Co hadgreater plasticity which made it a very promising oxygenation material for practicalapplications. With the increase of the aliphatic chain the coordination numbersdecreased, via as: en-Co>dien-Co>trien-Co. Which also verified that the higherdenticity the small coordination numbers.