NMR STUDY OF HOMO- AND HETERO-ASSOCIATION OF AROMATIC
MOLECULES IN AQUEOUS SOLUTION.
NUMERICAL SIMULATIONS
Diana Bogdan, C. Morari, M. Bogdan
National Institute for Research and Development of Isotopic and
Molecular Technologies, Cluj-Napoca, Romania
Investigation of the homo- and hetero-association of different molecules and their
competitive binding to receptors deal with some important aspects of molecular interactions.
These molecular interactions are of interest not only from the physico-chemical point of view,
enabling determination of the influence of the structures of the chromophores and their side
chains on association affinity, but also from the pharmacological point of view such
aggregates may influence drug activity, especially when drugs are used in combination.
Investigation of homo- and hetero-association are also necessary in order to elucidate
the molecular basis of the action of aromatic compounds as mediators of the pharmacological
activity of drugs and as protectors of DNA from binding with mutagenic aromatic molecules.
Although there have been a number of attempts, to develop models of homo- and
hetero-association of aromatic molecules [1,2], there are often limitations in their use because:
- rather approximate expressions for equilibrium concentrations are used [3];
- some models do not take into account the formation of "n-mer" aggregates for all the
components present in solution [4,5];
- consider only the formation of 1:1 heterocomplex without taking into account the selfassociation of molecules in solution [6].
In this report, we analyse different models in which indefinite aggregates exist for
both self- and hetero-association between molecules in solution.
Using these models based on numerical simulations a NMR analysis was developed
in order to determine the structural and thermodynamic parameters of molecular homo- and
hetero-association in solution using the chemical shifts variation of different protons as a
function of concentration.
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