Synthesis, properties and applications of single-component anion-exchange materials
Date
2009
Authors
Caamaño, Samira, author
Strauss, Steven H., advisor
Meersmann, Thomas, committee member
Rickey Dawn, committee member
Elliott, Cecil Michael, committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Several tetraalkylated ferrocenium salts and neutral modified ferrocenes, both new and previously synthesized, were studied in detail. Some of these salts have been used in the past as anion-exchange extractants for attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Different crystallographic, electrochemical and spectroscopic parameters were analyzed to study properties like cation size and its effect in selectivity, morphology of thin films made from these salts, both in the surface and in the bulk of the film, and film changes with time. It was found that when relative cation sizes are compared for different cations in these salts, the size increases in one dimension, which affects ion-exchange selectivity depending on what the non-aqueous phase containing the extractant is (either a water-immiscible solvent, a three-dimensional thin film or a monolayer self-assembled on an electrode surface). The effect of C–H...O hydrogen bonding in the cation–anion interactions was investigated. A model was proposed for the structure of thin films of a particular type of the ferrocenium salts, which was based on atom distances from the crystallographic data. Atomic force microscopy was used to study the morphology of surfaces of thin films, which had never been done before; the results were consistent with the hypothesis that there is a clear difference in the way that organic solutions of ferrocenium+NO3- and ferrocenium+ClO4− arrange molecularly as solvent evaporates, forming very different thin films. The use of an ATR-FTIR technique previously developed for the detection and quantification of anionic pollutants was investigated and optimized for new sample volumes, film thicknesses and analytes. Multiple-anion detection in aqueous media was examined. Among the new analytes studied was dodecylsulfate, (DDS−), the anion in the detergent sodium dodecylsulfate (SDS). These studies constituted a novel application of the ATR-FTIR spectroscopy technique in heart-valve research, which uses the detergent to decellularize tissue samples with the objective of preparing biological scaffolds free of cytotoxicity. A new ferrocene salt containing a nitrogen atom, which bears the positive charge of the cation, was successfully synthesized. This compound displayed better stability in biological solutions than other ferrocenium salts used previously. The use of this compound aided in answering the question of whether SDS leaches out of SDS-treated tissues after a soaking regime has been implemented: SDS does leach from treated tissues in potentially cytotoxic concentrations which are dependent on the initial treatment. It was also discovered that SDS leaches both as a free anion and, in initial stages of the soaking regime, complexed to other species. A new method was developed to detect and quantify anions in aqueous samples. This method also mitigated instability issues present in the use of certain ferrocenium salts and opened doors for conventional FTIR quantification of species using this kind of extractant. The synthesis of [35S]SDS was evaluated by successfully synthesizing SDS in the Strauss Research Group laboratories, using standard starting materials, one of which (H2SO4) can be obtained in its radioactively labeled form. A long term objective of this synthesis was to eventually quantify [35S]SDS directly in [35S]SDS-treated tissue samples, after a soaking regime, using beta scintillation counting.
Description
Department Head: Anthony K. Rapp�.