Browsing by Subject "Macrocyclic compounds"
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Item New crown ether compounds and their alkali metal ion complexation(Texas Tech University, 1994-05) Torun, LokmanNOT AVAILABLEItem New syntheses of crown and proton-ionizable lariat ethers(Texas Tech University, 1999-05) Hanes, Robert E.Macrocyclic polyethers (crown ethers) are known for their ability to bind metal ions within their central cavities. This allows crown ether compounds to be utilized in the separation and determination of metal ion species. Traditional routes for crown ether synthesis often give only low yields due to competitive cyclization and oligomentation reactions. The efficacy of cesium-assisted cyclizations for the preparation of lipophilic benzocrown ether compounds and of di-, tri-, and tetrabenzocrown ethers has been explored. In the synthesis of lipophilic benzocrown ethers by cesium-assisted cyclizations, the desired [1+1] cyclization products were found to be contaminated with corresponding [2-1-2] adducts. The influences of reactant concentrations, stirring method and rate, reactant addition method and rate, and leaving group identity were investigated to determine optimized conditions for formation of the highest possible proportion of the [l + l] adduct in the product mixture. For formation of 18-membered rings or larger, the synthesis of di-, tri-, and tetrabenzocrown ether compounds by cesium-assisted cyclizations produced only the desired [1+1] adducts in good-to-excellent yields. These results provide insight into the nature of the "cesium effect" in cylization reactions. Solid-state structures for several of the benzo group-substituted crown ether compounds and for one crown ether-metal salt complex have been determined. Alkali metal cation binding selectivity for the lipophilic benzocrown ether compounds was assessed by solvent extraction and with solvent polymeric membrane electrodes. For use in the study of ring size effects upon the efficiency and selcctivity of alkali metal cation complexation by proton-ionizablc lanat ethers (crown ethers with an attached arm bearing a teminal acidic group), a series of N-(X) sulfonyl sym-(dccyl)diben/o-13-crown-4-oxyacctamides was prepared. In this series, variation of X is used to "tunc" the acidity of the pendant acidic function.Item Novel calixpyrrole-like anion receptors(2004) An, Deqiang; Sessler, Jonathan L.Calix[n]pyrroles (n ≥ 4) are venerable anion receptors that are based on single pyrroles and ketones as building blocks. However, the existence of only one variable, n, that defines the nature of the systems, limits this class of macrocycles to only a few core structures. To overcome this limitation, a series of building blocks other than single pyrroles, have been applied to the construction of novel calixpyrrole-like systems. These building blocks include bipyrrole, furan, thiophene, and 1,3-bispyrrolylbenzenes. Based on bipyrrole as the sole building block, a series of calix[n]bipyrroles (n = 3, 4) was synthesized. Based on bipyrrole, furan or thiophene as co-building blocks, calix[2]bipyrrole[m]furan[n]thiophene (m + n = 2) were obtained. Based on 1,3- bispyrrolylbenzenes, calix[n]bispyrrolylbenzenes (n = 2 - 4) were synthesized. These novel calixpyrrole-like macrocycles contain different core structures than calix[n]pyrroles, and thus display different anion binding properties than their parent systems. This, in turn, means that these new systems are not only helping to the chemistry of calixpyrroles, but also giving rise to selective receptors that find applications in anion coordination chemistry.Item Sessler, Jonathan L. Pyrrole-based anion receptors : binding studies and progress towards attachment to solid support(2007-12) Barkey, Natalie Marie, 1980-; Sessler, Jonathan L.Anions have a wide range of importance both in chemical, as well as biological, systems; thus, the design and synthesis of novel receptors with the ability to selectively recognize or bind a specific class of anions is a rapidly developing field of supramolecular chemistry. A series of novel, acyclic pyrrole-based anion receptors will be presented. These systems, which are based on pyridine 2,6-dicarboxamides, bind nitrite and carboxylate anions with good selectivity in dichloroethane solution and are also capable of binding cyanide anions weakly. Control systems, incorporating a benzene-1,3-dicarboxamide spacer, or those wherein the connectivity of the amide linkage is "reversed," either failed to act as effective anion receptors or displayed very different selectivities. Such observations provide support for the notion that small perturbations in the structure of these receptors can lead to drastic changes in their anionbinding properties. Furthermore, efforts have been made to attach macrocyclic phosphate-binding receptors developed in the Sessler Group to cellulose solid supports. The idea is that these macrocycles, once bound to cellulose, will be capable of extracting phosphate from solutions. Studies on the macrocyclic loading level and extraction abilities of the receptors are underway, and will be presented herein.Item Synthesis of crown and lariat ether compounds(Texas Tech University, 1996-05) Ivy, Sheryl N.The following thesis describes the design and synthesis of crown and lariat ether compounds for two purposes. The first objective is to compare a synthetic route to dibenzocrown ethers with a method developed earlier by J. C. Lee. The second goal is to synthesize a new type of proton-ionizable lariat ether. To access the degree that starting materials affect crown ether yields in cesium ion-assisted cydizations, a synthetic route developed by Lee will be followed with different combinations of reactants. The effect on yield will be examined.