Browsing by Subject "Calixarenes"
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Item Effects of structural variation within polyether and calix[4]arene ligands and matrix variation on metal ion complexation(Texas Tech University, 2002-05) Chun, SangkiNot availableItem Metal ion complexation by acyclic and cyclic multidentate ligands(Texas Tech University, 1999-08) Elkarim, Nazar Saied AwadThe objective of this work is to evaluate the different factors that dictate the binding ability of multidentate polyether ligands towards alkali metal and some heavy metal cations with special emphasis on crown ether compounds. The evaluation will involve the use of different analytical techniques, such as solvent extraction, ion-selective electrodes and fluorometry. A primary objective is to investigate the influence of structural variations within a crown ether compound upon the selectivity and efficiency of alkali metal cation extraction. The research will involve a series of new crown ethers with different ring sizes containing multiple benzo or cyclohexano groups in the polyether ring. The conventional picrate extraction method will be used and the results will be compared with those from other more sophisticated extraction methods. Other factors (solvent and anion effects) that influence the complexing ability of crown ethers in solvent extraction will be probed. Assessment of anion and solvent effects on the extraction efficiency and selectivity by a series of crown ether compounds with varying ring sizes will be conducted. The complexing ability of crown ethers will also be evaluated in solvent polymeric membrane electrodes. Crown ethers will be incorporated as active components in PVC-matrix type membrane electrodes and their selective binding towards alkali metal cations will be tested. Special attention will be paid to Na selective ligands due to the importance of this cation in the field of medicine. Solvent extraction will be performed with lipophilic pseudocyclic polyether dicarboxylic acids. In solvent extraction, these ligands do not require concomitant transfer of the aqueous phase anion into the organic phase. The ligands are known to have good binding ability towards Pb(n) which is an environmentally hazardous metal cation. A supplementary study will be performed to evaluate the stoichiometrics of Pb(II) and Cu(II) complexes formed with these ligands. The final part of this work will be contribution to the growing field of chemosensors. A new calixarene-based fluorogenic reagent for selective Hg(II) recognition will be tested as a prospective chemosensor.Item Metal Ion Extraction With New Di-ionizable Ligands(2010-12) Crawford, Jennifer D.; Bartsch, Richard A.; Korzeniewski, Carol; Pappas, DimitriThis study seeks to evaluate several series of novel di-ionizable multidentate ligands for the separation of metal ions by solvent extraction. The ligands studied included calix[4]arenes, calix[4]arene-crown ethers, and acyclic polyether ligands, each containing either carboxylic acid functionalities or “acidity-tunable” N-(X)sulfonyl carboxamide moieties in which the X-group was varied. Both single species and competitive extractions of metal cations were performed using solutions of the ligands in chloroform. The study of novel di-ionizable calix[4]arene ligands sought to determine the effect of several structural variations on the ligands’ efficiency to extract lead(II), mercury(II), alkali metal cations, and alkaline earth metal cations from an aqueous phase into chloroform. These structural variations included ligand conformation, upper and lower rim functionalization, addition of a crown-ether ring to the lower rim, and identity of the ionizable groups. The ionizable groups were located either on the upper or lower rim of the calix[4]arene structure. The pH dependence of the ligand extraction efficiency was also determined in order to compare ligand acidities. The results of the study indicate that all of these structural variations have an effect on the efficiency and selectivity with which the ligands extract metal ions. Novel di-ionizable acyclic polyether ligands were utilized in solvent extraction studies of divalent metal cations. Three series of ligands containing various ionizable groups were used, in which systematic structural variations were made to determine the effect of the end-group identity and placement on ligand performance. The pH dependence of the ligand extraction behavior was investigated to elucidate information about ligand acidity. It was determined from the results of these studies that the these ligands do have a propensity to complex Pb2+ and Hg2+ in single ion extractions, and exhibit selectivity for Ba2+ in competitive extractions of alkaline earth metal cations. The identity and attachment site of the end group, as well as the identity of the ionizable groups, did have an effect on extraction efficiency, selectivity, and acidity of the ligands studied.Item New Calixarene and Cyclophane Macrocycles(2011-05) Son, Pillhun; Bartsch, Richard A.; Mayer, Michael F.; Fuertes, Michael J.; Niwayama, SatomiThe design, synthesis and analysis of new supramolecular hosts are rapidly developing areas of chemistry. This dissertation research presents the synthesis of new calix[4]arene ligands, new cyclophane derivatives and a new type of crown ether corrals accompanied by fluorescence binding analysis. A variety of calix[4]arene ligands have been developed in the past for various applications. Novel di-ionizable tetrabutoxycalix[4]arenes in four different conformations have been synthesized in this dissertation research. In contrast with the tetrabutoxycalix[4]arene ligands which are conformationally fixed, a conformationally mobile methoxy-tributoxy-calix[4]arene was synthesized. The synthetic exploration of calix[4]arene ligands was expanded into multicalix[4]arenes and cyclophane-bridged calix[4]arenes. Cyclophanes have been applied to diverse areas of supramolecular chemistry. A cyclophane with rigid α,α’-bis[(4-hydroxyphenyl]-1,4-diisopropyl-benzene components has been previously termed “corrals”. New synthetic routes, methods, techniques and ring-closure components have been applied to achieve 77 new corral derivatives, which selectively possess attractive properties, such as chirality, selective functionalization, asymmetry, and fluorescence. For some of the new cyclophane hosts synthesized fluorescence binding analysis was conducted. A total of 75 metal salt species was tested with two crown ether corrals resulting in interesting cation recognition, anion effects and selective fluorescence effects on shaking.Item Synthesis of Calix[4]arene ligands with multiple proton-ionizable groups for complexation of multivalent metal ions(Texas Tech University, 2004-05) Fernandez, Fernando AdolfoA series of new conformationally mobile tri-ionizable calix[4]arenes has been prepared for the complexation of trivalent lanthanide ions by matching the metal ion charge (3+) with the same number of proton-ionizable groups. The A-(X)sulfonyI carboxamide group, -C(0)NHS02X, was chosen as the proton-ionizable function because its acidity may be tuned by variation of X. Three series of new di-ionizable calix[4]arene-l,3-crown-5 ethers have been prepared in the cone, 1,3-aItemate and partial cone conformations to probe the influence of conformation, acidity variations and the crown ether ring size in solvent extraction of metal ions. A dansyl fluorescent group was coupled to di-ionizable calix[4]arene-l,3- crown-5 to produce potential fluorogenic ligands.Item Synthesis of new calixarene ligands(Texas Tech University, 2002-12) Liu, DazhanIonic recognition is major field of application for supramolecular chemistry. This has led to the development of extractants that selectively exfract desired cations from an aqueous phase, chemosensors (e.g., chromoionphores and fluoroionophores), ionselective elecfrodes for detecting certain cations selectively and directiy in aqueous phases, stationary phases of chromatographic columns for ion separations and membranes for fransporting a desired cation selectively. Recent studies of the Bartsch Research Group on calix[4]arenes have focused on preparation of conformationally mobile or restricted calix[4]renes and calixbiscrown ethers for metal ion separations.'^^'''^ N-(X)sulfonyl groups were attached to the calix[4] arene to give proton-ionizable calix[4]arenes with tunable acidity. The object of the thesis research is the synthesis of di-ionizable calix[4]arenecrown compounds. By infroducing two proton-ionizable groups into calix[4]arene-crown-6 compounds, the ligands will be conformational fixed. The possibility of synthesizing different conformational isomers will be probed. By attaching the two proton-ionizable groups to different positions, 1,2- and 1,3- disubstituted calixcrowns can be prepared. While the basic platform is retained, dansyl (5-dimethylamino-l-aaphthalene-sulfonyl) fluorescent groups (Figure 1.8) will be attached to provide potential fluoroionophores.Item Synthesis of new ligands for metal ion complexation(Texas Tech University, 2001-05) Zhao, QingxiangThe ability of crown ethers to selectively bind alkali and alkaline earth metal cations was discovered in 1967 and tremendous developments in this field have been achieved to date. Many dibenzocrown ethers with a substituent on each benzo unit have been obtained and investigated in various studies as mixtures of regioisomers. Since the regioisomers may have different complexing properties, a synthetic route has been developed in this thesis to prepare disubstituted dibenzocrown ethers in which the two substituents are in specific positions. Allyl groups were incorporated into these disubstituted dibenzocrown ethers which can be utilized for further transformation. Nuclear waste treatment is an important and worldwide problem. Recently, interest in applying tridentate organophosphoryl ligands to separate actinides from nuclear waste arose. A synthetic intermediate to these tridentate ligands was synthesized in this thesis with a much improved yield from previous work. In solvent extraction of actinides, long chain carboxylic acids have been used as co-extractants with crown ethers and were found to enhance the extraction efficiency and selectivity. A highly lipophilic carboxylic acid was prepared on large scale to be utilized in actinide extraction. Calixarenes were developed in the late 1970's and have been investigated as complexing ligands for molecular, cationic and anionic species. However, p-t-butylcalix- [4]arene, the most widely studied calixarene, and its derivatives have limited solubility in organic solvents. A series of calix[4]arenes with r-octyl groups as the para substituents were synthesized and increased solubility in organic solvents was observed.Item Synthesis of proton-ionizable lariat ethers and calix[4]arenes(Texas Tech University, 2001-05) Park, ChunkyungProton-ionizable N-(X)sulfonylcarboxamide groups were incorporated into the sidearm of lariat ethers and on the lower rim of calixL4]arenes to make extraction efficiency independent of the aqueous phase anion during solvent extraction of metal cations. Acidities of N-(X)sulfonylcarboxamide groups are dependent upon the electron-withdrawing ability of X. A series of N-(X)sulfonyl 5ym-(decyl)dibenzo-19-crown-6-oxyacetamides was prepared to investigate die effect of cavity size on selectivity toward alkali metal cations together with 5>'m-(decyl)dibenzo-19-crown-6-oxymethylphosphonic acid. A dansyl (5- dimethylamino-1-naphthalenesulfonyl) fluorescent group was coupled with three sym- (R)dibenzo-16-crown-Soxyacetamides to produce potential fluoroionophores. New methodologies were developed to prepare calix[4]arenes with two carboxylic acid groups in the cone, partial cone-1 (carbonyl-up), partial cone-2 (butylup), and 1,3-altemate conformations. The conformational outcome (i.e., relative percentage of isomers in the cmde product) indicates an influence of the para substituent in the calix[4]arene during the conformation-determining step. Their conformations are fixed due to the butyl and acetate groups on the lower rim and the conformations are retained during the transformation of the di(carboxylic acid)s into the bis[(N-Xsulfonylaminocarbonyl) methoxy]s.