Although the synthesis of polymers with highly controlled molecular architectures has gained increased importance due to the rising demand for specialty polymers that possess novel properties, their physical characteristics are direct consequences of the size and constitution of the covalent structures of the polymer. Our program aims to prepare and characterize polymers, whose structures and properties are determined by non-covalent interactions. These novel polymer architectures are comprised of macrocycles threaded by linear macromolecules and are called polyrotaxanes. Polyrotaxanes are considered to be physical analogs of block or graft copolymers or molecular interpenetrating systems. The design and synthesis of the macrocyclic component, "blocking groups" to constrain the macrocycles and the polyrotaxane will be described. / Ph. D.

Rotaxane chemistry provides a new direction of research in polymer architectures. Unlike conventional polymers, polyrotaxanes are molecular composites comprised of macrocycles threaded by linear polymer backbones with no covalent bonds between the two components. This novel class of materials displays unusual chemical and physical properties due to their unique architectures. The studies include crown ether and blocking group syntheses, synthetic methodologies leading to rotaxanes and polyrotaxanes and structure-property relationships of polyrotaxanes. Crown ethers (30-crown-10, 36-crown-12, 42-crown-14, 48-crown-16 and 60-crown-20) were systematically synthesized from low molecular weight glycols with 30 - 60% yields. Bis(p-phenylene)-32-crown-4 and bis(p-phenylene)-34-crown-10 (BPP34C10) were also synthesized in 8 - 13% yields; the latter was synthesized with four different synthetic routes. All crown ethers were prepared in large quantities. A series of monofunctionalized triaryl derivatives were also synthesized as rotaxane blocking groups. A series of polyrotaxanes comprised of a polyurethane backbone and crown ethers with ring size ranging from 36 - 60 membered were synthesized via the statistical threading method. The polyrotaxane formation was proven by multiple reprecipitations, ¹H-NMR and GPC analyses. The threading efficiency (rings per repeat unit) increases from 0.16 to 0.87 with an increase in ring size of crown ethers from 36 to 60 membered at 1.5 molar ratio of crown ether to linear glycol. Host-guest complexation of paraquat dication and BPP34C10 has been studied. A series of difunctionalized paraquat dication derivatives was synthesized and used to prepare host-guest complexes (pseudorotaxanes) with BPP34C10. X-Ray crystal structures of the complexes were determined. Furthermore, a class of viologen-containing polyurethane elastomeric polyrotaxanes was synthesized via this host guest complexation. The threading efficiencies from this method were quantitative. Through rotaxane formation, polymer solubilities increase and glass transition temperatures decrease. Evidenced by DSC and WAXS analyses, the crown ether forms crystalline domains without dethreading from the amorphous polyurethane backbone. This process is kinetically "retarded". It is time and temperature dependent and reversible. It can only be observed for polyrotaxanes with large rings and high ring contents, which provide high mobilities of rings along the backbone and also wide T_m - T_g windows. The study of recrystallization kinetics has also shown that 60-crown-20 recrystallizes much slower in a polyrotaxane than in its physical blend with the model polymer. / Ph. D.

Polyrotaxanes are novel polymer architectures consisting of theo components. One component is the macrocycel consisting of 24-60 atoms; it is threaded by he second component, i.e., the linear backbone polymer. / Ph. D.

The focus of the following research was to use the self-assembly process to create rotaxanes between several large bisphenylene crown ethers (> 22 atoms) with secondary ammonium salts. Also of great interest was to understand the complexation behavior of the crown ethers with the salts, with emphasis on determining the stoichiometries and association constants of the complexations in solution using NMR spectroscopy. The stoichiometry of the complexes was determined by the mole ratio method and the association constants were calculated graphically. Bis-(m-phenylene)-26-crown-8 did not form a complex in solution with several secondary ammonium salts even though the cavity size is large enough to allow the formation of pseudorotaxanes. However, the larger crown ether, bis-(m-phenylene)-32-crown-10 (BMP32C10), did form a complex. The complex stoichiometry varied between 1:1 (crown:salt) in solution and 1:2 in the solid state as evidenced by NMR and X-ray crystallography, respectively. The solid state complexes were pseudorotaxanes. Also, an interesting "exo" complex was formed in the solid state between BMP32C10 and a secondary diammonium salt. The major binding force for the complexes in the X-ray structures was hydrogen bonding. Weaker secondary stabilization was achieved via aryl-aryl aromatic interactions. The difference between the stoichiometries in the two phases and the observance of an "exo" complex demonstrates that one must be careful in describing the complexes in each phase. Also investigated was the complexation formed between dibenzo-24-crown-8 (DB24C8) and secondary diammonium salts. The association constants for the complexes were found to be relatively higher. Due to the weaker association constants and the different stoichiometries of complexation the meta-susbtituted bisphenylene crown ethers were not recommended for the formation of larger complexes, i.e. polyrotaxanes. However, it is suggested that the DB24C8 moiety be used in components of supramolecular assemblies. The functionalization of poly(propylene imine) dendrimers with two different crown ethers as peripheral moieties was attempted. The 1st, 3rd, and 5th generation poly(propylene imine) dendrimers were functionalized with 1,3-phenylene-16-crown-5 moieties by reacting the surface primary amines with the corresponding succinimide ester of the crown ether. The larger DB24C8 succinimide ester was not as reactive and full functionalization was not achieved. / Ph. D.

Dibenzo-30-crown-10 (DB30C10) is one of the first-generation macrocyclic hosts discovered by Pedersen. Crown ethers originally attracted attention due to their ability to encapsulate metal cations and render them soluble in organic solvents. These studies helped to launch host-guest chemistry as a discipline within supramolecular chemistry. Crown ethers form complex molecules containing organic cations and neutral organic molecules. Additionally, they form components in supramolecular architectures such as catenanes, rotaxanes, and supramolecular polymers. They have been used as selective hosts in diverse applications such as wastewater treatment, switchable catalysis, therapeutic agents, sensors, molecular machines, and stimuli responsive materials "smart polymers". Despite the vigorous research activity in the field, DB30C10 has received surprisingly little attention. DB30C10 was reported in 1967 and has been commercially available since 1992; however, it has been mostly overlooked as a host in favour of smaller crown ethers such as DB24C8, B15C5, 18C6 and 15C5. Herein we present an improved synthetic route that improves the yield of the cyclization step in the synthesis of DB30C10 from 25% to 88% enabling us to prepare multiple grams of the material without the use of pseudo high-dilution techniques. The same methodology was applied to three other crown ethers with similar improvement in yield. Four new rotaxanes based on the DB30C10-paraquat binding motif were used to investigate the binding conformation of DB30C10 and paraquat. The new rotaxanes were characterized by 1H, 13C and 2D-NOESY NMR, mp, and HRMS. A single crystal X-ray structure of one of the [2]rotaxanes was obtained. To our knowledge, this is the first crystal structure of a rotaxane based on this particular binding motif. This result illustrated that DB30C10 was a suitable host for the construction of supramolecular systems and polymers. Our eventual goal is to use DB30C10 in the construction of supramolecular polymers with novel topologies. Therefore, the relative threading efficiency of DB30C10 in solution had to be determined. A series of segmented polyurethane poly(pseudorotaxanes) with paraquats in the backbone were synthesized with different crown ether or cyptand hosts. The threading efficiency was determined by 1H NMR. / Ph. D.

The theoretical model of Beratan and Onuchic predicts a large attenuation of ET rates through hydrogen bonds; however, the effect of individual hydrogen bond on electron transfer reaction has not been systematically studied. The organic complexes in this study are a series of crown ether/ammonium salt, which incorporate a redox partner on each component of the complex. The dimethoxynaphthalene redox donor was attached to the crown ether and a series of ammonium salts was synthesized which bear substituted quinone and naphthoquinone acceptor. The complexes characterization and preliminary electron transfer rate measurement were completed with UV/Vis and steady-state emission spectroscopy.

A novel cryptand was synthesized which contained a 3,5-disubstituted-4- oxahexacyclo[5.4.1.02,6.03,10.05,9.08,11] dodecane "cage" moiety. In alkali metal picrate extraction experiments the cryptand exhibited high avidity towards Rb+ and Cs+, when compared with the corresponding model compound. A computational study of a series of cage-functionalized cryptands and their alkali metal-complexes was performed. The X-ray crystal structure of a K+-complexed bis-cage-annulated 20-crown-6 was obtained. The associated picrate anion was found to be intimately involved in stabilization of the host-guest complex. The interaction energy between the host-guest complex and picrate anion has been calculated, and the energy thereby obtained has been corrected for basis set superposition error.

Symmetrical cage-annulated podands were synthesized via highly efficient synthetic strategies. Mechanisms to account for the key reaction steps in the syntheses are proposed; the proposed mechanisms receive support from the intermediates that have been isolated and characterized. An unusual complexation-promoted elimination reaction was studied, and a mechanism is proposed to account for the course of this reaction. This unusual elimination may generalized to other rigid systems and thus may extend our understanding of the role played by the host molecules in "cation-capture, anion-activation" via complexation with guest molecules. Thus, host-guest interaction serves not only to activate the anion but also may activate the leaving groups that participate in the complexation. Complexation-promoted elimination provides a convenient method to desymmetrize the cage while avoiding protection/deprotection steps. In addition, it offers a convenient method to prepare a chiral cage spacer by introducing 10 chiral centers into the host system in a single synthetic step. Cage-annulated monocyclic hosts that contain a cage-butylenoxy spacer were synthesized. Comparison of their metal ion complexation behavior as revealed by the results of electrospray ionization mass spectrometry (ESI-MS), alkali metal picrate extraction, and pseudohydroxide extraction with those displayed by the corresponding hosts that contain cage-ethylenoxy or cage-propylenoxy spacers reveals the effect of the length of the cage spacer upon the host-guest behavior. A series of cage-annulated cryptands, cavitands and the corresponding non-cage-annulated model compounds have been synthesized. These host molecules display unusual behavior when examined by using ESI-MS techniques, i.e., they bind selectively to smaller alkali metal ions (i.e., Li+ and Na+), a result that deviates significantly from expectations based solely upon consideration of the size-fit principle. It seems likely that this behavior results from the effect of the host topology on host-guest behavior. A series of non-cage-annulated cryptands also have been synthesized. These compounds can serve as starting materials for cavitand construction.

In this dissertation, we discuss the development of new phase transfer agents, which are capable of rapid fluorination of silicon. These are 18-C-6 derivatives containing a hydroxyl group in the side arm (podand), also known as C-pivot lariats. The syntheses of these lariats including several that have not been previously reported and their efficient purification are described. The synthesis route leads to a robust and generalized approach to obtain these lariats on the gram scale. These agents were initially designed for applications in positron emission tomography (PET). In this medical imaging modality, tracer agents containing silicon have found promising utility as fluoride receptors for more rapid radiolabeling. Phase transfer agents are generally required for 18F-labeling due to the low solubility in organic reaction media and reactivity of cyclotron-generated [18F]potassium fluoride. We envisioned that 18-C-6 derivatives may serve as both phase transfer agents as well as nucleophilic catalysts (CENCs). In this conception, CENCs were rapidly pre-complexed with KF followed by silicon fluorination, which takes advantage of a previously established silicon dianion mechanism. In collaboration with researchers at the NIH, we studied the effect of various linkers connecting the metal chelating unit to the nucleophilic hydroxyl group on the radiofluorination of silicon under mild condition. A hydrolysis resistant aryl silicon fragment has also been developed that contains various functional groups for convenient attachment to the potential PET radiotracer agents. In a second project, we demonstrate the unique reactivity of γ-silyl allenyl esters. Taking advantage of the silyl group as a fluoride acceptor, these allenoates readily underwent addition to a variety of carbon electrophiles, including aryl fluorides, to afford all-carbon quaternary centers bearing an ethynyl group. Surprisingly, in the presence of aldehydes, exclusive bis-substitution occurs at the γ-position to afford the dicarbinol. Details relating to reaction optimization and substrate scope for both the reactions are presented. Dicarbinol allenes were subsequently converted to highly substituted δ-lactones, a novel 6-hydro-2-pyrone as single diastereomers. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

The phosphine crown ether, 16-(4'diphenylphosphinophenyl)-1,4,7,10,13-pentaoxa-16azacyclooctadecane (III), was synthesized using a reaction scheme beginning with n-phenyldiethanolamine and the dichloride of tetraethylene glycol, with an overall yield of 4%. Platinum and Palladium complexes of the ligand, of the form MC12L2, were synthesized as well. 13C NMR and picrate extraction data indicate III and IV (the crown-5 analog) both moderately bind sodium (14%, 15%) and potassium ions (17%, 28%). Compound V (a crown-5, triphenylphosphine-based ligand) will bind both sodium and potassium ions as well (18%, 6%). When IV is complexed to nickel carbonyl (Ni(CO)3), the addition of sodium and potassium ions cause the Al carbonyl stretching frequency to increase slightly (0.3 cm-1, 0.2 cm 1). For comparison, the addition of a proton causes the A1 carbonyl stretching frequency to increase 5.2 cm-1. However, the shift in the A1 carbonyl stretching frequency upon the addition of sodium or potassium ions indicates that ion binding by the crown ether is communicated to the phosphorus and finally to the carbonyl groups.Ball State UniversityMuncie, IN 47306 / Department of Chemistry