Molecular conformation structure-property relations

Molecular conformation is highly related to functional properties. Since the conformation of the crystalline solids can be precisely determined by diffraction methods, molecular modeling is most important for interpreting molecular structures in solution. This is, however, even more difficult for theoreticians. While carbohydrates dissolve in a variety of solvents, the important solvent for biological systems is water and this solvent deserves special emphasis. 

II Conjugation alone cannot be relied upon to significantly enhance the optical nonlinearities. The conformational effects and the role of the substituents so that understanding of the molecular structure-property relation can be improved have been studied (89JPC7916). In the case of the thiophene oligomers, a rapid increase in the y value (large microscopic nonlinearity) as a function of N is found. 

An extensive chapter on crystalline polymers set the paradigm for structure-property relations in this class of materials. A thorough understanding of the structure at all levels was stressed. The local molecular conformation, the unit cell, the microcrystalline structure, and the overall morphology, including both crystalline and amorphous domains, were included. 

Given atomic coordinates for a particular conformation of a molecule and some property value assigned to each atom, one can easily calculate a chirality function that distinguishes enantiomers, is zero for an achiral molecule, and is a continuous function of the coordinates and properties. This is useful as a quantitative measure of chirality for molecular modeling and structure-activity relations. 

Study described in this chapter is to explore such substituent effects and to relate structural aspects of the solid state, such as molecular conformation and packing, with the physical properties of the solid, in particular its luminescence behavior. 

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