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Compounds of palladium with many different chelated bisphosphine ligands were investigated for their catalysis of alternating copolymerization of propylene (P) with carbon monoxide (CO). The bisphosphine structure and chelate ring size influence strongly the activity, regio- and stereo-selectivity of the catalysts. Molecular mechanics calculations on $\pi$-olefin complex showed that the non-bonded interaction between propylene and the ligands on Pd is both regio- and stereo-selective. Electronic factor and presence of chiral center were crucial for the regio- and stereo-regularity control of the catalyst, respectively. Primary insertion is more probable than secondary insertion, and the enantioselective catalysts favor the meso enchainment of propylene. The crystalline copolymer has the hexagonal unit cell structure with a = b = 15.5 A, and c = 8.97 A. The single crystalline copolymer chain is a 3$\sb1$ fold helix. GC-MS of oligomers showed that most chains are initiated by Pd-H species; and $\beta$-hydrogen elimination is the dominant chain termination process. The anaerobic photodegradation behaviors of bulk alternating copolymers of P-CO and E-CO have been studied by irradiation with 2537 A light. Photolysis of the former resulted in weight loss, molecular weight depression, cross-linking, and the formation of hydroxyl and terminal vinyl groups. The room temperature quantum yields of chain scission and Norrish type II reactions were found to be 0.015 $\pm$ 0.002 and 0.011 $\pm$ 0.002. P-CO alternating copolymer was blended with poly(methyl methacrylate) (PMMA) by solution precipitation. Various aspects of blends behavior were studied by DSC, DMTA, DETA, FTIR, and CP-MAS solid state NMR. The blends exhibited single $T\rm\sb{g}$'s at all compositions, which is an indication of the miscible blends. $\beta$-relaxation of P-CO copolymer was detected by DETA at $-65\sp\circ$C for the first time. The measurement of rotating frame NMR relaxation time, $\rm T\sb{1\rho}\sp{H}$, showed that the average distance between P-CO and PMMA is less than 30 A.

The ability of two different pseudomonads, Pseudomonas oleovorans and Pseudomonas putida to metabolize and produce polymers from functional carbon substrates, in particular phenyl-containing substrates was investigated. A comparison of the two bacteria revealed P. putida to be the superior microorganism in that it produced higher cell yields and polymer yields regardless of the substrate on which it was grown. The bacterial polyester produced when P. oleovorans was grown on a mixture of 5-phenylvaleric acid and nonanoic acid, included both a homopolymer, poly-3-hydroxyphenylvalerate (PHPV) and a copolymer, poly-3-hydroxynonanoate (PHN). The intracellular location of each of these polymers was determined by selective staining of the inclusion body granules with ruthenium tetraoxide. Examination of the stained granules by transmission electron microscopy showed that both types of polyesters occurred sequentially in the same granule. Poly-3-hydroxynonanoate was synthesized first, and was present in the center of the granule, while poly-3-hydroxyphenylvalerate accumulated afterwards around the PHN inclusion body. The enzymes associated with the inclusion bodies were separated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). In all cases, two polymerase enzymes of molecular weights of 59 and 55 KD were present, which suggests that the same polymerase enzymes may have been responsible for the production of both PHN and PHPV. In addition, attempts were made to produce a random copolymer containing both alkyl and phenylalkyl repeat unit by varying the growth conditions, but a mixture of two polymers was produced instead. PHPV is a homopolymer and 100% isotactic. However, it does not exhibit crystallinity. Various different annealing experiments carried out on PHPV did not result in the induction of crystallinity. However, a crystalline phenyl-containing polymer, poly-3-hydroxy-5-(4$\sp\prime$-tolyl)valerate was produced when either P. oleovorans or P. putida was grown on 5-(4$\sp\prime$-tolyl)valeric acid. To the best of our knowledge, this is the first report of a crystalline phenyl-containing microbially produced polyester. Intracellular degradation studies were carried out on P. oleovorans cells which contained either PHN, PHPV or a blend of PHN/PHPV. Fairly rapid intracellular degradation occurred when PHN was the sole storage polymer. The intracellular degradation rate of PHPV was much slower. However, when both polymers were present as intracellular storage polymer the rate of degradation of PHPV was greater than when PHPV was the sole intracellular storage polymer. It is possible that both polymers are degraded by the same intracellular depolymerase, which is more efficient in the presence of PHN.

Propylene was isospecifically polymerized by binary zirconocenium catalysts derived from rac-$\rm C\sb2H\sb4(\eta\sp5$-$\rm C\sb9H\sb6)\sb2Zr(CH\sb3)\sb2$ (11) and the cation forming agents Ph$\sb3\rm CB(C\sb6F\sb5)\sb4$ (10) and B(C$\sb6\rm F\sb5)\sb3$ (14). Polymerizations were also performed with the ternary systems of $rac$-$\rm C\sb2H\sb4(\eta\sp5$-$\rm C\sb9H\sb6)\sb2ZrCl\sb2$ (9), AlEt$\sb3$ and the cation forming agents. The systems with the counter-ion B(C$\sb6\rm F\sb5)\sb4$- have much higher activity and stereoselectivity than the ones with the CH$\sb3\rm B(C\sb6F\sb5)\sb3$- counter-ion. Much less active are the cocatalysts Ph$\sb3\rm CB(C\sb6H\sb5)\sb4$ (15) and Ph$\sb3\rm CBF\sb4$ (16). Similar but smaller effects of counter-ion structure on ethylene polymerization were observed. ($\eta\sp5$-$\rm C\sb5H\sb5)\sb2TiCl\sb2$ (1) together with its derivatives ($\eta\sp5$-$\rm C\sb5H\sb4CF\sb3)\sb2TiCl\sb2$ (18) and $\lbrack \eta\sp5$-$\rm C\sb5H\sb4N(CH\sb3)\sb2\rbrack\sb2TiCl\sb2$ (19) have been compared as catalysts for ethylene and propylene polymerizations using both MAO and 10/TIBA as cocatalysts. The differences of polymerization activities of these three "free" titanocenium ions and the M$\sb{w}$ of the polyolefins produced by them may be attributable to the relative stabilities of the intermediate olefin-titanocenium $\pi$-complexes. Isotactic propylene polymerizations were catalyzed by C$\sb2\rm H\sb4(1{\bf S}$-$\rm \eta\sp5$-$\rm C\sb9H\sb{10})\sb2Zr\lbrack {\it O}$-${\bf R}$-$\rm CH\sb3CO\sb2CH(C\sb6H\sb5)CO\sb2\rbrack\sb2$ (20) and a mixture (21) of 20 and C$\sb2\rm H\sb4(1{\bf R}$-$\eta\sp5$-$\rm C\sb9H\sb{10})\sb2Zr\lbrack {\it O}$-${\bf R}$-$\rm CH\sb3CO\sb2CH(C\sb6H\sb5)CO\sb2\rbrack\sb2$. Under the same conditions the polymers obtained with 20 are much more stereo- and regioregular than with 21. The stereoselectivity of 21 was appreciably raised by using a low catalyst concentration, low polymerization temperature or immobilizing 21 on silica. A possible pathway for exchange of propagating chains between opposite enantiomers in 21 was proposed. Effects of reaction conditions including catalyst concentration, reaction temperature and immobilization of catalyst on support has also been investigated for syndiospecific propylene polymerization by "bare" zirconocenium ion generated from Ph$\sb2\rm C(\eta\sp5$-$\rm C\sb5H\sb4)(\eta\sp5$-$\rm C\sb{13}H\sb8)ZrCl\sb2$ (26) precursor. Syndiotacticity of the produced s-PP as judged from T$\sb{m}$ and homosteric r-pentad population by $\sp{13}$C NMR were both proportional to polymer molecular weight but independent of the reaction conditions which is in marked contrast to isospecific propylene polymerization catalyzed by $C\sb2$ symmetric racemic metallocenes.

<p>Dendrimers provide an ideal scaffold for molecular imaging and therapeutics due to their mono-disperse structure and easily modifiable core, interior, and periphery. The controlled-stepwise synthesis leads to perfect, defined architectures that can easily be modified to incorporate targeting and imaging moieties. Specifically poly (2,2-bis(hydroxymethyl)-propanoic acid) (PMPA) dendrimer structures exhibit excellent aqueous solubility, low toxicity, biocompatibility and biodegradability, which are necessary requirements for an ideal <em>in vivo</em> imaging scaffold.</p> <p>Fever of unknown origin (FUO) is a common condition involving elevated temperatures above 101°F, which goes undiagnosed after a week of investigation. The primary causes of FUO are infection and cancer, however methods of diagnosis are non-specific and quite slow. Developing a method to detect bacterial infections, and therefore rule out more severe conditions such as cancer, would be very useful in diagnosis of this condition. Approximately two thirds of infection cases in hospitals are determined to be caused by one of six pathogens known as the ESKAPE pathogens and developing a molecular imaging probe that would detect these specific pathogens would be a very useful FUO diagnostic tool.</p> <p>Siderophores are naturally occurring molecules that exhibit a high affinity for Fe³⁺, and are effective at entering bacterial cells after complexing iron. In particular, Desferal, a commercially available siderophore used for iron chelation therapy, has been successfully modified, radiolabeled, and studied as an imaging agent. Dendrimers were modified with Desferal and used to investigate the effect of multivalent display of siderophores on a single macromolecular structure.^1-3</p> <p>We herein discuss the preparation of a series of siderophore-terminated PMPA dendrimers that were radiolabeled and studied to compare bacterial uptake between a monomeric siderophore and a macromolecule displaying multiple siderophores on its periphery. To introduce Desferal to the periphery of a dendrimer, activated p-nitrophenyl carbonates were used. A series of Desferal-terminated dendrimers of generations 1-3 was synthesized in yields of 59-89 % and evaluated for suitability as an infection-imaging probe.</p> <p>The Desferal-terminated dendrimer series was evaluated for its affinity to iron(III) and gallium(III), as well as tested for steric hindrance effects at the periphery. The series was successfully radiolabeled with ⁶⁷Ga using mild conditions and <em>in vitro</em> bacterial uptake studies were performed with <em>Staphylococcus aureus</em>, one of the ESKAPE pathogens, to determine if multivalency increases bacterial uptake.</p> <p>Preliminary results indicate that the poor water solubility of the Desferal-terminated dendrimer series needs to be improved in order to increase bacterial uptake of the compounds, however viable candidates for metal chelation were successfully produced.</p> / Master of Science (MSc)