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Removing centrosymmetric packing using host -guest inclusion
Nonlinear optics is the study of the interaction of materials with electromagnetic fields to produce new fields that are different from the input field in phase frequency or modulation. The most familiar example is second harmonic generation (SHG) in which the frequency of the output field is twice that of the incident field. ^ Organic molecular crystals are of great interest due to their large nonlinear optical properties and their large damage threshold. Effective SHG is attained in organic materials that have both a high molecular polarizability and a high bulk polarizability. It has been shown that organic molecules having conjugated pi electron systems and a donor-acceptor pair, possess large second order polarizabilities. However most aromatic crystals such as p-nitroaniline pack in a centrosymmetric fashion that forbids SHG. ^ This dissertation describes research aimed at using host-guest inclusion as a way for removing centrosymmetric packing in organic nonlinear optical molecules. In this method inclusion complex formation of organic molecules, which pack in a centrosymmetric fashion, with β-cyclodextrin and deoxycholic acid as host molecules is carried out. The inclusion complexes thus formed are seen to pack in non-centrosymmetric space groups. ^
Rashid, Ali N, "Removing centrosymmetric packing using host -guest inclusion" (2001). ETD collection for University of Nebraska - Lincoln. AAI3009733.