Non-Linear Optical Properties of Supramolecular Species

Organic and inorganic substances presenting a large electronic polarizability are likely to display marked optical non-linearities that depend first on molecular features [8.79-8.84], but novel effects should arise on going to the supramolecular level [8.85, 8.86]. 

The design of molecules, supermolecules and materials presenting NLO activity involves molecular and supramolecular engineering. At the molecular level, a high polarizability, leading to large quadratic ft and cubic y hyperpolarizability coeffi- 

They display intramolecular charge transfer [8.87] and marked second-harmonic generation. The determination of the hyperpolarizabilities of such compounds 

The incorporation of such compounds into mixed Langmuir-Blodgett films built from a fatty acid (see 97) [8.92] or from an amphiphilic cyclodextrin [8.93] produces oriented arrangfements presenting marked NLO features. 

Other polyunsaturated substances such as oligothiophenes [8.95a] or dyes [8.95b] as well as organometallic or coordination compounds [8.85, 8.95c] may also present pronounced NLO properties. 

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