ISSN:
1572-8927
Keywords:
Enthalpy of solution
;
enthalpy of sublimation
;
enthalpy of hydration
;
enthalpy of cavity formation
;
enthalpy of interaction with water
;
N-methylated adenines
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Enthalpies of solution in water, ΔH sol o , and of sublimation, ΔH subl o , were determined experimentally for a number of crystalline N-methyl adenines: m6Ade, m 2 6,6 Ade, m9Ade, m 2 6,9 Ade, and m 3 6,6,9 Ade. Derived standard enthalpies of hydration ΔH hydr o , were corrected for the calculated cavity terms ΔH cav o to yield enthalpies of interaction ΔH int o of the solutes with their hydration shells. The increments of ΔH int o per unit area of the water-accessible molecular surface S B , δΔH int o (CH3)/δS B (CH3), for the particular methyl groups: is considered to be the net effect of the gain in the energy resulting from van der Waals' interactions and of the loss in the energy due to polar interactions upon methyl substitution. It proved to vary somewhat numerically in agreement with the theoretically predicted hydration schemes of adenine. Comparison of ΔH int o /S B value for adenine with those previously determined for uracil and thymine indicates that the aminopurine moiety is less hydrated than the diketopyrimidine ring.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00647691
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