Crystal tailor-made auxiliaries

Control of Crystal Polymorphism with the Assistance of "Tailor-Made" Auxiliaries... 

According to McCrone [46], a polymorph is a solid crystalline phase of a given compound resulting from the possibility of at least two or more different arrangements of the molecules of that compound in the solid state. Polymophs play an important role in a large variety of fields. Lahav and co-workers [47] have carried out very incisive studies on the control of nucleation and crystal polymophism using tailor-made auxiliaries. The importance of polymorphs to an organic solid-state photochemist is obvious. 

Weissbuch, I. Popovitz-Biro, R. Lahav, M. Leiserowitz, L. Understanding and control of nucleation, growth, habit, dissolution, and structure of two- and three-dimensional crystals using Tailor-Made auxiliaries. Acta Crystallogr. Sect. B. Struct. Sci. 1995, B51, 115-148. 

Growth of Crystals in the Presence of Tailor-made Auxiliaries... 

Weissbuch, I, Lahav, M., and Leiserowitz, L. (1999). Towards an Understanding and Control of Nueleatlon, Growth, Habit and Structure of Crystals Using Tailor-Made Auxiliaries." In Molecular Modeling Approaches in Crystallization (Myerson, A.S., ed.), Chapter 4, Cambridge University Press, Cambridge, UK. 

Recent application of these principles to polymorphic control is shown schematically in Fig. 15 for a hypothetical dimorphic system in which one polymorph is centrosymmetric and the other crystallizes in a polar space group [36]. In the former crystal, the molecules are arranged in antiparallel orientation whereas in the latter they are aligned along a common direction. A tailor-made auxiliary which binds to both crystals would do so at the two (indistinguishable) ends of the centrosymmetric crystal but only at one end of the polar crystal. The latter would therefore grow at the expense of the former and polymorphic control will have been achieved. 

I. Weissbuch, R. Popovitz-Biro, M. Lahav, and L. Leiserowitz, Acta Crystallogr., Sect. B, 51, 115 (1995). Understanding and Control of Nucleation, Habit, Dissolution and Structure of Two- and Three-Dimensional Crystals Using Tailor-Made Auxiliaries. 

Weissbuch, I., Leiserowitz, L. and Lahav, M. (1994). Tailor-made charge-transfer auxiliaries for the control of the crystal polymorphism of glycine. Adv. Mater, 6, 952-6. [93]... 

Asymmetric alkylation of carboxylic acid derivatives has been studied intensively for about 20 years. [1] Numerous auxiliaries, tailor-made structures with high steric demands for effective RelSi face differentiation, have been synthesized and their efficiency tested. [1, 2] In recent years besides the preparative aspects of enolates, physico-chemical investigations into their structure-reactivity relationships have gained interest. [3] Crystal structure analyses, osmometric measurements, and NMR studies in solution are helpful in the investigation of the factors that may control enolate reactions. [3-5]... 

Weissbuch I Leisorowitz L, Lahav M (1994) Tailor-made and chtiige-transfer auxiliaries for the control of the crystal polymorphism of glycine. Adv Mater 6 952—956 Weissbuch I, Zbaida D, Addadi L, Leiserowitz L, Lahav M (1987) Design of polymeric inhibitors for the control of crystal polymorphism— induced enantiomeric resolution of racemic histidine by crystallization at 25-Degrees-C. 1 Am Chem Soc 109 1869—1871 Yamashita K, Nakate T, Okimoto K, Ohike A, Tokunaga Y, Ibuki R, Higaki K, Kimura T (2003) Estabhshment of new preparation method for soUd dispersion formulation of tacrolimus. Int J Pharm 267 79-91... 

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