ISSN:
0020-7608
Keywords:
Computational Chemistry and Molecular Modeling
;
Atomic, Molecular and Optical Physics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
First- and second-order perturbation theory in a polarization approximation was employed to calculate interaction energies of planar xanthine-xanthine pairs in stable configurations. Electrostatic energy was obtained in the atomic-dipole approximation. The results provided a basis for formulation of a four-stranded model of poly(xanthylic acid) that allows two hydrogen bonds per base. The model accounts satisfactorily for the unusual thermal stability and the observed pH transition of the polymer. The latter is due to the gradual dissociation of the N3 protons accompanying by disrupture of the weak N3—H ··· O6 hydrogen bonds. However, the structure is only moderately weakened since the configuration of the coplanar bases remains stabilized by four N1—H ··· O2 hydrogen bonds.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/qua.560170212