Natural structures, chemical sensing

While it is true that materials of identical chemical structure have the same odor qualities and are indistinguishable in their effect upon the skin irrespective of their origin, it is also true that very often synthetic and natural perfume materials that have the same name are not really identical in the chemical sense. Rhodinol from geranium oil consists of a different mixture of optical isomers than synthetic rhodinol. Eugenol from clove leaf oil is accompanied by different impurities than synthetic eugenol. Hence the natural and synthetic materials do differ in their odor quality, and they may differ in their effects upon the skin. 

One of the main driving forces behind the development of supramolecular chemistry has been the urge to understand how natural systems operate to form supramolecular arrays and then to extend this understanding to wholly synthetic molecular and supramolecular structures with perhaps novel functions, such as chemical sensing or information- processing. ... 

Whenever it is possible to extract the chromophore, or better, to isolate the integral photoreceptor unit, all chemical, biochemical, and physicochemical assa) can be used to carefiiUy characterize the structural and functional properties of the chromophore. The chromophore, for instance, can be purified by HPLC, and its molecular weight and structure can be determined by mass, IR, and NMR spectroscopy."- Information on the apoprotein-chromophore complex, as another example, can be obtained by means of column chromatographies, mono- and bidimensional gel electrophoresis, and enzymatic assays. When reliable hypotheses are available on the chemical nature of the sensing chromophore, specific inhibitors of its biosynthesis can advantageously be employed. ... 

Typical results for a semiconducting liquid are illustrated in figure Al.3.29 where the experunental pair correlation and structure factors for silicon are presented. The radial distribution function shows a sharp first peak followed by oscillations. The structure in the radial distribution fiinction reflects some local ordering. The nature and degree of this order depends on the chemical nature of the liquid state. For example, semiconductor liquids are especially interesting in this sense as they are believed to retain covalent bonding characteristics even in the melt. 

In particular, in the field of fine chemicals, natural products - in the broadest sense - will serve as functional molecules and are often appropriate starting structures for other target systems. 

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