TAUTOMERISM OF XANTHINE AND ITS PAIRING WITH 2,6- DIAMINOPYRIMIDINE:AN ABINITIO STUDY IN THE GAS PHASE AND AQUEOUS SOLUTION

The prototropic tautomerism of xanthine (XAN) has been studied both in the gas phase and in aqueous solution by means of theoretical methods. The most stable tautomeric form has been paired with 2,6-diaminopyrimidine (DAP). The structural and energetic changes that take place on pairing have also be...

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Autores principales:	Madariaga,S. T., Contreras,J. G.
Lenguaje:	English
Publicado:	Sociedad Chilena de Química 2003
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072003000400021
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spelling	oai:scielo:S0717-970720030004000212004-04-26TAUTOMERISM OF XANTHINE AND ITS PAIRING WITH 2,6- DIAMINOPYRIMIDINE:AN ABINITIO STUDY IN THE GAS PHASE AND AQUEOUS SOLUTIONMadariaga,S. T.Contreras,J. G.The prototropic tautomerism of xanthine (XAN) has been studied both in the gas phase and in aqueous solution by means of theoretical methods. The most stable tautomeric form has been paired with 2,6-diaminopyrimidine (DAP). The structural and energetic changes that take place on pairing have also been calculated. Applying an elimination procedure, two tautomeric forms of XAN survived, namely, N7-H and N9-H, whereas for DAP the amino form is by far the most important species and the amino-imino and diimino tautomers would not be present in appreciable concentration. In XAN, the N7-H species is more stable than N9-H by ca. 8 kcal/mol in the gas phase. The solute-solvent interactions were taken into account by applying Onsager 's simple SCRF model to the dipole term. The results indicate that the solvent does not alter the stability of these species, but reduces their energy difference to ca. 5 kcal/mol. The optimized geometries and the energetics obtained at the HF/6-31G and MP2/6-31G levels reveal large differences in the bonding patterns of these bases as well as lower interaction energies as compared with the natural adenine-thymine (AT) and guanine-cytosine (GC) and non-natural azaadenine-thymine (AA-T) and azaguanine-cytosine (AG-C) pairsinfo:eu-repo/semantics/openAccessSociedad Chilena de QuímicaJournal of the Chilean Chemical Society v.48 n.4 20032003-12-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072003000400021en10.4067/S0717-97072003000400021
institution	Scielo Chile
collection	Scielo Chile
language	English
description	The prototropic tautomerism of xanthine (XAN) has been studied both in the gas phase and in aqueous solution by means of theoretical methods. The most stable tautomeric form has been paired with 2,6-diaminopyrimidine (DAP). The structural and energetic changes that take place on pairing have also been calculated. Applying an elimination procedure, two tautomeric forms of XAN survived, namely, N7-H and N9-H, whereas for DAP the amino form is by far the most important species and the amino-imino and diimino tautomers would not be present in appreciable concentration. In XAN, the N7-H species is more stable than N9-H by ca. 8 kcal/mol in the gas phase. The solute-solvent interactions were taken into account by applying Onsager 's simple SCRF model to the dipole term. The results indicate that the solvent does not alter the stability of these species, but reduces their energy difference to ca. 5 kcal/mol. The optimized geometries and the energetics obtained at the HF/6-31G and MP2/6-31G levels reveal large differences in the bonding patterns of these bases as well as lower interaction energies as compared with the natural adenine-thymine (AT) and guanine-cytosine (GC) and non-natural azaadenine-thymine (AA-T) and azaguanine-cytosine (AG-C) pairs
author	Madariaga,S. T. Contreras,J. G.
spellingShingle	Madariaga,S. T. Contreras,J. G. TAUTOMERISM OF XANTHINE AND ITS PAIRING WITH 2,6- DIAMINOPYRIMIDINE:AN ABINITIO STUDY IN THE GAS PHASE AND AQUEOUS SOLUTION
author_facet	Madariaga,S. T. Contreras,J. G.
author_sort	Madariaga,S. T.
title	TAUTOMERISM OF XANTHINE AND ITS PAIRING WITH 2,6- DIAMINOPYRIMIDINE:AN ABINITIO STUDY IN THE GAS PHASE AND AQUEOUS SOLUTION
title_short	TAUTOMERISM OF XANTHINE AND ITS PAIRING WITH 2,6- DIAMINOPYRIMIDINE:AN ABINITIO STUDY IN THE GAS PHASE AND AQUEOUS SOLUTION
title_full	TAUTOMERISM OF XANTHINE AND ITS PAIRING WITH 2,6- DIAMINOPYRIMIDINE:AN ABINITIO STUDY IN THE GAS PHASE AND AQUEOUS SOLUTION
title_fullStr	TAUTOMERISM OF XANTHINE AND ITS PAIRING WITH 2,6- DIAMINOPYRIMIDINE:AN ABINITIO STUDY IN THE GAS PHASE AND AQUEOUS SOLUTION
title_full_unstemmed	TAUTOMERISM OF XANTHINE AND ITS PAIRING WITH 2,6- DIAMINOPYRIMIDINE:AN ABINITIO STUDY IN THE GAS PHASE AND AQUEOUS SOLUTION
title_sort	tautomerism of xanthine and its pairing with 2,6- diaminopyrimidine:an abinitio study in the gas phase and aqueous solution
publisher	Sociedad Chilena de Química
publishDate	2003
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072003000400021
work_keys_str_mv	AT madariagast tautomerismofxanthineanditspairingwith26diaminopyrimidineanabinitiostudyinthegasphaseandaqueoussolution AT contrerasjg tautomerismofxanthineanditspairingwith26diaminopyrimidineanabinitiostudyinthegasphaseandaqueoussolution
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TAUTOMERISM OF XANTHINE AND ITS PAIRING WITH 2,6- DIAMINOPYRIMIDINE:AN ABINITIO STUDY IN THE GAS PHASE AND AQUEOUS SOLUTION

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