Multidentate chelating ligands derived from aminoethanethiols and/or heterocycles as models for nitrile hydratase and carbonic anhydrase /
Novel multidentate chelating ligands, 2,6-bis(substituted-z-mercaptoethylamino-methyl)pyridines, N,N'-bis(substituted-2-mercaptoethyl)-2,5-thiophenedicarboxamides and 1,3,5-tri(2,6)pyrinacyclohexaphanes are designed. Their syntheses are investigated for the possibility that they may form Fe(III...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1999.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=731686071&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Novel multidentate chelating ligands, 2,6-bis(substituted-z-mercaptoethylamino-methyl)pyridines, N,N'-bis(substituted-2-mercaptoethyl)-2,5-thiophenedicarboxamides and 1,3,5-tri(2,6)pyrinacyclohexaphanes are designed. Their syntheses are investigated for the possibility that they may form Fe(III) or Zn(II) complexes similar to the metal centers found in the metalloenzymes nitrile hydratase or carbonic anhydride. The former enzyme is the only example of a non-heme, low-spin, mononuclear and redox inactive Fe(III) protein having a N₂S₃O ligand coordination and has stimulated considerable research on mononuclear iron thiolate compounds. 2,6-Bis(substituted-2-mercaptoethylaminomethyl)pyridines are synthesized by condensation between 2,6-pyridinedicarboxaldehyde and 2-aminoethanethiolls, with and without thiol protection, followed by reduction. N,N'-Bis(substituted-2-mercaptoethyl)-2,5-thiophenedicarboxamides are synthesized agitation of 2,5-thiophenedicarbonyl dichloride with 2-aminoethanethiols. Studies are made on the prevention of the facile oxidative polymerization resulting from disulfide bonding, and on the optimization of the strategies of synthesis and isolation of these dithiolate compounds. Studies are also made on the iron complication of these pentadentate mixed N/S dithiolate lizards. In addition to the formation of a variety of iron complexes, they all can form soluble green complexes. The green complex from PE320 has been successfully crystallized. Studies on the green crystals have shown that it is a low-spin, octahedral Fe(III) complex involving a labile Cl⁻. Studies have also revealed that the labile Cl⁻ can be replaced by H₂O and the water can be deprotonated. These iron complexes are shown to be even more air-sensitive than the corresponding ligands. 1,3,5-Tri(2,6)pyridinacyclohexaphanes are synthesized by a nucleophilic substitution of dimethyl-2,6-pyridinedicarboxylate with 6-bromo-2-lithiopyridine, followed by cyclization with LiCH₂CN. 1,3,5-Tri(2,6)pyridinacyclohexaphane-2,4-dione is isolated and its oxidative digitization is studied. Studies also reveal that the diketone may be reduced to 1,3,5-tri(2,6)pyridinacyclohexaphane. Spectroscopic studies on both 6-cyano-2,4-bis(1,3-dioxolan-2-yl)-l,3,5-tri(2,6)pyridinacyclohexaphane and 1,3,5-tri(2,6)pyridina-cyclo-hexaphane-2,4-dione show that these compounds may involve proton migration, H-bonding, tautomerism, and partial electron demoralization. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xv, 136 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 108-114). |