UNDERSTANDING AND CONTROL OF NUCLEATION, GROWTH, HABIT, DISSOLUTION AND STRUCTURE OF 2-DIMENSIONAL AND 3-DIMENSIONAL CRYSTALS USING TAILOR-MADE AUXILIARIES

Tailor-made auxiliaries for the control of nucleation and growth of mo lecular crystals may be classified into two broad categories: inhibito rs and promoters. Tailor-made inhibitors of crystal growth can be used for a variety of purposes, which include morphological engineering an d etching, reduction of crystal symmetry, assignment of absolute struc ture of chiral molecules and polar crystals, elucidation of the effect of solvent on crystal growth, and crystallization of a desired polymo rph. As for crystal growth promoters, monolayers of amphiphilic molecu les on water have been used to induce the growth of a variety of three -dimensional crystals at the monolayer-solution interface by means of structural match, molecular complementarity or electrostatic interacti on. A particular focus is made on the induced nucleation of ice by mon olayers of water-insoluble aliphatic alcohols. The two-dimensional cry stalline structures of such monolayers have been studied by grazing in cidence X-ray diffraction. It has become possible to monitor, by this method, the growth, dissolution and structure of self-aggregated cryst alline nonolayers, and indeed multilayers, affected by the interaction of solvent molecules in the aqueous. suphase with the amphiphilic hea dgroups, and by the use of tailor-made amphiphilic additives.