Thesis (Ph.D.) - University of St Andrews, October 2008. / Restricted until 29th October 2009.

Currently, very little information is available for an in-depth understanding of the molecular binding interactions with molecularly imprinted polymers (MIPs). To address this issue MIPs that have high binding affinities for their template compounds were made so that the nature of these interactions could be elucidated using spectroscopic techniques. 12 functional MIPs were prepared using a series of azobenzene and anthracenyl derivatives as the templates. Affinities of these MIPs for the corresponding templates and analogues were determined by performing batch and competitive binding tests. It was found that extensively conjugated compounds that contain at least two OH groups, an electron-withdrawing substituent and have limited conformational freedom were effective templates. The most efficient MIP, M34, was prepared with 4-[(4-nitrophenyl)azo]-1,2-benzenediol (12). M34 exhibited high affinities for azobenzene derivatives of catechol, and bound those that did not contain non electron-withdrawing substituents more specifically. M34 did not lose affinity for 12 in the presence of analogues, and vice versa, in competitive binding tests. These observations suggested a distribution of different binding sites on M34. M34 bound substrates rapidly, which was attributed to its highly porous polymer matrix giving ready access to binding sites. Formation of the porous matrix was facilitated by the use of DMF as the porogen in the preparation of M34. DMF is not a conventional choice of porogen because use of such highly polar H-bonding solvents is thought to disrupt complexation between template and polymer precursors, which is required for the formation of binding sites. Significant changes in the wavenumbers and the intensities of absorption bands assigned to the catechol substructure of 12 were observed in the FT-Raman spectra of 12 bound to M34. These findings suggested that the catechol substructure was responsible for interactions of 12 with M34 that are critical to rebinding and imprinting. In-situ analyses of dithranol (8) being removed from and bound to its MIP, M23, were performed using ATR-IR spectroscopy. Only one band, assigned to the aromatic substructure of 8, was not obstructed by solvent bands in the spectra of unwashed M23 and washed M23 that was treated with the rebinding solution. The wavenumbers of the corresponding bands in the two spectra were significantly different. This observation suggested that there were differences in the vibrational characteristics of 8 bound to M23 under the two conditions. Evidence was found for H-bonding between OH groups of 8 and C=O group of methacrylic acid using transmission FT-IR spectroscopy. However, no evidence was found that showed significant interactions between 12 and 2-vinylpyridine. Methacrylic acid and 2-vinylpyridine were used as the functional monomers in the preparations of M23 and M34. The FT-IR spectra of mixtures of 12 and 4-vinylpyridine showed three new bands assigned to H-bonded OH stretches. These observations indicated that 4-vinylpyridine H-bonds with 12, and would be a more effective functional monomer than 2-vinylpyridine in the preparation of the MIPs for 12. Titration of 12 with 2-vinylpyridine was analysed by �H NMR spectroscopy. Only small changes to the signals of the corresponding compounds were observed. This lack of change was attributed to the use of d₇DMF, which would compete against 2-vinylpyridine for H-bonding interactions. The findings made using ATR-IR spectroscopy and FT-Raman were novel because previously reported data on bound templates obtained using the corresponding techniques did not show changes in the vibrational characteristics of templates as they bind to MIPs. This investigation has shown that rebinding and spectroscopic studies can provide information about the nature of the binding interactions in MIPs.

Currently, very little information is available for an in-depth understanding of the molecular binding interactions with molecularly imprinted polymers (MIPs). To address this issue MIPs that have high binding affinities for their template compounds were made so that the nature of these interactions could be elucidated using spectroscopic techniques. 12 functional MIPs were prepared using a series of azobenzene and anthracenyl derivatives as the templates. Affinities of these MIPs for the corresponding templates and analogues were determined by performing batch and competitive binding tests. It was found that extensively conjugated compounds that contain at least two OH groups, an electron-withdrawing substituent and have limited conformational freedom were effective templates. The most efficient MIP, M34, was prepared with 4-[(4-nitrophenyl)azo]-1,2-benzenediol (12). M34 exhibited high affinities for azobenzene derivatives of catechol, and bound those that did not contain non electron-withdrawing substituents more specifically. M34 did not lose affinity for 12 in the presence of analogues, and vice versa, in competitive binding tests. These observations suggested a distribution of different binding sites on M34. M34 bound substrates rapidly, which was attributed to its highly porous polymer matrix giving ready access to binding sites. Formation of the porous matrix was facilitated by the use of DMF as the porogen in the preparation of M34. DMF is not a conventional choice of porogen because use of such highly polar H-bonding solvents is thought to disrupt complexation between template and polymer precursors, which is required for the formation of binding sites. Significant changes in the wavenumbers and the intensities of absorption bands assigned to the catechol substructure of 12 were observed in the FT-Raman spectra of 12 bound to M34. These findings suggested that the catechol substructure was responsible for interactions of 12 with M34 that are critical to rebinding and imprinting. In-situ analyses of dithranol (8) being removed from and bound to its MIP, M23, were performed using ATR-IR spectroscopy. Only one band, assigned to the aromatic substructure of 8, was not obstructed by solvent bands in the spectra of unwashed M23 and washed M23 that was treated with the rebinding solution. The wavenumbers of the corresponding bands in the two spectra were significantly different. This observation suggested that there were differences in the vibrational characteristics of 8 bound to M23 under the two conditions. Evidence was found for H-bonding between OH groups of 8 and C=O group of methacrylic acid using transmission FT-IR spectroscopy. However, no evidence was found that showed significant interactions between 12 and 2-vinylpyridine. Methacrylic acid and 2-vinylpyridine were used as the functional monomers in the preparations of M23 and M34. The FT-IR spectra of mixtures of 12 and 4-vinylpyridine showed three new bands assigned to H-bonded OH stretches. These observations indicated that 4-vinylpyridine H-bonds with 12, and would be a more effective functional monomer than 2-vinylpyridine in the preparation of the MIPs for 12. Titration of 12 with 2-vinylpyridine was analysed by �H NMR spectroscopy. Only small changes to the signals of the corresponding compounds were observed. This lack of change was attributed to the use of d₇DMF, which would compete against 2-vinylpyridine for H-bonding interactions. The findings made using ATR-IR spectroscopy and FT-Raman were novel because previously reported data on bound templates obtained using the corresponding techniques did not show changes in the vibrational characteristics of templates as they bind to MIPs. This investigation has shown that rebinding and spectroscopic studies can provide information about the nature of the binding interactions in MIPs.

Thesis (Ph.D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2008. / Committee Chair: Boris Mizaikoff; Committee Member: Andrew Lyon; Committee Member: Ching-Hua Huang; Committee Member: David Collard; Committee Member: Facundo M. Fernandez.

Thesis (Ph. D.)--University of Massachusetts Amherst, 2009. / Includes bibliographical references (p. 98-113). Print copy also available.

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Chemistry, 2006. / Includes bibliographical references.

No description available.

Structure direction in the synthesis of phosphate-based materials (aluminophosphates, AlPOs; magnesiumaluminophosphates, MgAPOs; silicoaluminophosphates, SAPOs; magnesiumsilicoaluminophosphates, MgAPSOs), has been investigated through co-templating synthesis studies supported by molecular modelling. These solids have been characterised by diffraction and solid-state NMR, and their properties in gas adsorption and catalysis have been measured. The parameters in the hydrothermal synthesis of SAPO STA-7, St Andrews porous solid number 7, (SAV), in which the macrocycle 1,4,7,11- tetraazacyclotetradecane (cyclam) and tetraethylammonium (TEA) cations are used as co-templates, were investigated in detail. A new route involving a reversal of the mixing order of reagents leads to the formation of single crystals up to 50 μm with perfect tetragonal prismatic morphology that was not achieved via previous synthetic routes. For the first time in SAPO STA-7, X-ray diffraction locates the tetraethylammonium cation (TEA) in tg.tg. conformation. The synthesis and full characterisation of a novel aluminophosphate structure designated STA-14 (KFI) represents the first example of a designed synthesis of a zeotype. The synthesis route is based on a co-templating approach supported by molecular modelling to design the specific template for one of the two types of cages within the structure. The first, a larger type of cage, also present in AlPO-42 (LTA), is templated by the azaoxacryptand 4,7,13,16,21,41-diaza-1,10-bicyclo[8,8,8]- hexocosane (‘Kryptofix 222’, hereafter K222). The modelled co-template configuration, in this case TEA in the tt.tt configuration, was experimentally observed by X-ray diffraction. Modifying the gel chemistry leads to SAPO and MgAPSO STA-14, which display high pore volumes for N₂ adsorption, similar to those of STA-7 and SAPO-34 (CHA). Furthermore, during these synthetic studies, a novel fully tetrahedrally- coordinated magnesiumaluminophosphate layer phase has been prepared, with a structure of relevance to hypothetical VPI-5 (VFI) type extended structures. Molecular modelling was also applied in another aluminophosphate-based material, that of STA-2 (SAT), to predict a template that could be prepared from inexpensive reagents. Existing routes required the use of expensive quinuclidine as a precursor to the template 1,4-bisquinuclidinium butane. The template suggested by modelling, 1,4-diazabicyclo (2,2,2)octane butane (NC₆H₁₂N⁺-C₄H₈-⁺NC₆H₁₂N), labelled DABCO_C4, templated AlPO STA-2 successfully. Structure characterisation of the as- prepared form of AlPO STA-2 using X-ray synchrotron data suggest the formation of Al- OH-Al units to accommodate the positively-charged template within the neutral framework and a combination of ¹³C, ¹⁴N and ¹⁵N NMR studies have been used to give further details of the template environment in the cages. The gas adsorption behaviour of the stable materials STA-7, STA-14 and STA-2 was evaluated for CO₂. High pressure adsorption (0 to 40 bars) on STA-7 and STA-14 shows similar behaviour due to their structural and chemical similarities. The total uptake of CO₂ for SAPO STA-7 is less than for the zeolite NaX (FAU) (3.4 and 5.2 mmolg -1 respectively at 373 K and 12 bars) but the usable capacity for pressure swing adsorption technology (PSA) between 1 to 20 bar for STA-7 is twice the value for NaX. The affinity of adsorption towards CO₂ and its low uptake at 1 bar made SAPO STA-7 a desirable sorbent for PSA. The zeotype affinity of adsorption for different probe gases is different, CO₂ >> CH₄ > CO, to that for zeolite NaX CO₂ >> CO > CH₄. Low pressure CO₂ adsorption (0 to 1 bar) in STA-7, STA-14 and STA-2 at temperatures between 273 and 303 K demonstrates that the topology and therefore the total free pore volume accessible to the gas molecules is the most important factor in determining the uptake in these solids, but that the composition and distribution of the silicon cations within the framework also has an important effect. For example at 273 K and 1 bar, the uptake of the STA-2 framework in the SAPO form is ca. 2wt% higher than in the AlPO form, but compared with SAPO STA-7, the uptake due to pore volume limitations is 10wt% lower under same conditions. In addition, the high quality of the SAPO STA-7 crystals obtained by the new route made them suitable in collaborations for the direct observation of diffusion of methanol by interference microscopy (IFM) and the study of their crystal growth by combined atomic force microscopy (AFM) and high resolution scanning electron microscopy (HRSEM). The catalytic applications of the STA-7 and STA-14 for the methanol-to-olefins reaction (MTO) and the argon adsorption at 87 K were also performed collaboratively. The results are reported and discussed here in the light of their structure and composition.

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Chemistry, 2006. / Includes bibliographical references.

Thesis (M.Sc.) - Carleton University, 2004. / Includes bibliographical references. Also available in electronic format on the Internet.