The design and preparation of materials with desired properties are among the principal goals of scientists in a variety of disciplines. Achieving that goal depends critically on understanding and controlling the relationship between the structure of a material and the properties in question. Variability in structure is manifested in variability in properties. Polymorphism is the existence of more than one solid phase of a given compound resulting from at least two ordered arrangements of the atoms/ions/molecules in the solid state, while solvates are ordered structures that include solvent molecules along with the principal component. Both structural phenomena are well known but their industrial and economic importance has been increasingly recognized only recently as they often lead to a radical, sometimes undesired diversity of properties. Experimental problems include, for example, variable or diffuse melting points, crystalline batches with inconsistent physical properties (filtering, drying, electrical or thermal conductivity, hardness, color) composition/identification uncertainties (photo- or thermal stability, solubility) or problematic behaviour (bioavailability, tabletting, dissolution rate) for a finalized pharmaceutical product.

This event is designed to provide a sound background on the phenomena of crystalline purification used by chemists for generations : the existence of the diversity of polymorphs and solvates can wreak havoc in the practice of that technique. It will provide

a. the theoretical basis for the existence of these diverse structural forms,

b. the methodology to control the form, from the nucleation to macroscopic growth

c. the techniques used the characterize the variety of products obtained,

d. the advantages resulting by this way of surveying structure/property relations for the design and preparation of new materials.

By its very nature this event requires the involvement of a broad spectrum of practitioners from a variety of fields. Polymorphs and solvates have had an increasing impact on product development and on the protection of intellectual property rights particularly in the pharmaceutical field over the past two decades : developments in other areas such as pigments, high energy materials, organic magnets and high temperature superconductors have also been influenced by the discovery, investigation, understanding and utilization of the multiplicity of structures for a single chemical entity. There has been a number of symposia covering research and development issues on these topics ; however (see next points 9. an 10.), there has not yet been a comprehensive course to introduce the variety of issues involved to new practitioners in the field – from graduate students to experienced scientists from other fields.