page_title: Crystal engineering
section_title: Property design
hierarchical_section_title: Crystal engineering / Property design
caption_attribution_description: English: A resorcinol based templating strategy described by Macgillivray and co workers to illustrate the control of photodimerization outcome, J. Am. Chem. Soc., 2000, 122, 7817-7818.
context_page_description: Crystal engineering is the design and synthesis of molecular solid state structures with desired properties, based on an understanding and use of intermolecular interactions. The two main strategies currently in use for crystal engineering are based on hydrogen bonding and coordination bonding. These may be understood with key concepts such as the supramolecular synthon and the secondary building unit.
context_section_description: The design of crystal structures with desired properties is the ultimate goal of crystal engineering. While major advances towards this have been made in coordination polymers, the application of successful strategies to design properties in purely organic solids is still limited. Most of the initial studies related to the crystal engineering of organic molecular solids were concentrated upon understanding the intermolecular interaction and identification of supramolecular synthons. In recent years, considerable attention has been given to the design the organic solids with specific properties. The early attempts to apply of crystal engineering principles to design the functional solids were focused upon the synthesis of non-linear optical materials, especially those with second harmonic generation (SHG) properties.
  Another major development in this area is related to the control of photodimerization reactions through templates by application of crystal engineering strategies. The importance of topochemical control in solid-state reactions was first realized by Schmidt. However, with the advent of cocrystals, multiple strategies have been discovered over the years to get photodimerization products from the molecules which are otherwise photo inactive with precise stereochemistry. A more recent development in property design is linked with the mechanical properties in relation with the crystal structures. Various mechanical properties such as bending, shearing or brittleness have been explained on the basisy of crystal packing. It has also been shown that solids of desired mechanical properties can be designed through the precise control of packing features. More recently, nanoindentation techniques are used in quantification of some of these properties in terms of hardness and elasticity.
  Apart from these properties, significant efforts have been made to control the photophysical properties as well. Despite all the developments made so far, this area of property design, especially in the purely organic solids, is still at an evolving stage and needs more directed approaches to understand the connectivity between the crystal structures and their respective properties.
caption: A resorcinol based templating strategy described by Macgillivray and co workers to illustrate the control of photodimerization outcome, J. Am. Chem. Soc., 2000, 122, 7817-7818.