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Abstract:
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In this thesis different strategies for modelling cyclic organic molecules are studied. One significant part of the thesis is dedicated to conformational analysis. The interest is focused on conformers of cyclic molecules. Two strategies for conformational analysis are approached, grid search and inverse kinematics. The strategies considered use molecular mechanics, semiempirical and ab initio methods. The molecular mechanics are fast and will be used for a first evaluation of the structures and their corresponding energies. This is especially useful because during the conformational analysis a large number of structures need to be evaluated. The computational demands (computation time and memory requirements) increase fast with the level of theory. Therefore the semiempirical and ab initio methods were used only for some structures of interest. The modeling methods were applied to calix[4]arene and its derivatives. One of the main results is the development of an efficient strategy for building the2,8,14,20-Tetraundecylpentacyclo[19.3.1.1.1.1]octacosa1(25),3,5,7(28), 9,11,13(27),15,17,19(26),21,23-dodecaene- 5,11,17,23-tetraethoxymethyl-4,6,10,12,16,18,22,24-octol (CRA) molecule. The adopted strategy proved to be efficient in the case of big molecule like CRA which contains 232 atoms. An other important result is the introduction of the computational geometry and inverse kinematics, a new and efficient method which makes possible the analysis of the whole conformational space of complex cyclic molecules in an efficient manner. /Kir10 |