Crystal engineering self-organication

As already mentioned, the fundamental precept of crystal engineering is that the driving force for formation of crystals is self-organization into networks. This is not necessarily or even often mutually exclusive with the idea that avoidance of vacuum drives crystal packing. As will become clear from the results described herein, this is especially so for coordination polymers, which can generate one-, two-, or three-dimensional architectures with a reasonable degree of control and predictability. Three basic strategies have thus far been successfully applied ... 

The exploitation of the reactivity of molecular crystals lies close to the origins of crystal engineering and is at the heart of the pioneering work of Schmidt [47a]. The idea is that of organizing molecules in the solid state using the principles of molecular recognition and self-assembly. Successful results have been obtained with bimolecular reactions, particularly [2+2] photoreactivity and cyclisation [47b,c]. Another important area is that of host-guest chemistry. 

Metal-containing NLO chromophores were involved in these different approaches but generally the metal does not play any role in the orienta-tion/organisation process. In this chapter the focus is on only two examples where the metallic centre is clearly responsible for the macroscopic orientation the supramolecular octupolar self-ordering within metallodendri-mers and crystal engineering using a metal/organic framework (MOF). 

Understanding the interactions that control molecular or ion recognition and self-assem.bly is one of the most relevant chemical problems of our time, with implications in all areas of chemistry, from biochemistry to organic, organonietallic, and physical chemistry, to encompass inaterials chemistry. The interest in the bonds between molecules is paradigmatic of supramolecular chemis-try Yhis perception is shared with molecular crystal engineering if the concept of bonds between molecules is convoluted with the translational symmetry of a molecular crystal (see Fig. I). 

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