Semiempirical quantum-chemical calculations on the protonation of some N-bridgehead heterocycles

P. Nagy, K. Hankó-Novák, G. Szász

Research output: Contribution to journalArticle

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Abstract

CNDO/2 calculations have been carried out on the protonation of some 4H-pyrido-(1,2-a)pyrimidine-4-one derivatives of biological interest. The calculated gas-phase protonation energy and the molecular electrostatic potential at the site of the protonation correlate satisfactorily with the experimentally determined basicity (pKa) measured in aqueous solution. Making use of our linear regression equation obtained between the protonation energy and pKa we estimated the pKa value of a new derivative prior to experiment. The solvent effect on the basicity of compounds has been studied using the supermolecule approach. Calculated energy changes even for a simple monohydrated form make possible reasonable interpretation of a somewhat anomalous pKa value of the 9-CH3 derivative found experimentally.

Original languageEnglish
Pages (from-to)59-66
Number of pages8
JournalJournal of Molecular Structure: THEOCHEM
Volume153
Issue number1-2
DOIs
Publication statusPublished - 1987

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Protonation
Static Electricity
Linear Models
Gases
Alkalinity
Derivatives
pyrimidines
energy
regression analysis
Linear regression
electrostatics
vapor phases
aqueous solutions
Electrostatics
pyrimidine
Experiments

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Computational Theory and Mathematics
  • Atomic and Molecular Physics, and Optics

Cite this

Semiempirical quantum-chemical calculations on the protonation of some N-bridgehead heterocycles. / Nagy, P.; Hankó-Novák, K.; Szász, G.

In: Journal of Molecular Structure: THEOCHEM, Vol. 153, No. 1-2, 1987, p. 59-66.

Research output: Contribution to journalArticle

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