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Title: The structural and spectroscopic characterisation of 2-aryl and 2-heteroaryl isatogens.
Author: Stoddart, Barry.
ISNI:       0000 0001 3486 4745
Awarding Body: Sunderland Polytechnic
Current Institution: University of Sunderland
Date of Award: 1990
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This work reviews the current knowledge of the synthesis , properties , structures and biological activities of isatogens. The unequivocal 2 C NMR assignment of 2-phenylisatogen 1S reported and used to assign the spectra for a range of 2-(4-substituted-phenyl)isatogens. Molecular dynamics of 2-phenylisatogen in chloroform are reported and indicate that there is little if any inter-ring mesomeric resonance in this compound. 1~C , ~N NMR and UV-Visible spectroscopic data are reported for a range of 2-(4-substituted-phenyl)isatogens. Analysis of this data indicates a small but significant degree of inter-ring mesomeric resonance is present in these compounds especially those with strongly electron donating or withdrawing substituents. An interesting correlation is found between ~sN substituent chemical shifts and molar absorbtivity of the visible transitions. The X-ray crystal structure of 2-(4-chlorophenyl)isatogen is reported and shows a small but significant shortening of the inter-ring bond length compared to 2-phenylisatogen , further supporting the hypothesis of inter-ring mesomeric resonance in these compounds. 1 H and ~C NMR data are reported for the 2-(pyrid-2-inium)isatogen cation and indifate the presence of intramolecular interaction between the ~---H and N~O groups in the molecule. The X-ray crystal structure of the perchlorate salt of the cation and the ~H solid state NMR spectrum both support this conclusion. The molecular structure indicates that the intramolecular interaction is comprised of coulombic and hydrogen bonding interactions leading to a near coplanar structure for the cation compared to the noncoplanar structure for the parent base, 2-(pyrid-2-yl)isatogen. A hypothesis is put forward to explain molecular packing and configuration differences in 2-heteroarylisatogens. The molecular packing and configuration is controlled by a balance of intermolecular dipole attraction and repulsion. Predictions of molecular packing and configuration are made for a number of 2-heteroarylisatogens. The X-ray crystal structure of 2-(pyrid-3-yl)isatogen is reported and found to be in complete agreement with the predictions of the hypothesis. Further studies are proposed involving the synthesis of ~N and ~~O labelled isatogens , the study of inclusion complexes with cyclodextrins and the study of isatogens with the potential for increased mesomeric interactions. ,
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Isatogens crystal structures