Cocrystal of 1,1-Dicyano-2-(4-hydroxyphenyl)-ethene with l-Proline and Induced Conformational Polymorphism of 1,1-Dicyano-2-(4-hydroxy- 3-methoxyphenyl)-ethene

Abstract

Crystallization of 1,1-dicyano-2-(4-hydroxyphenyl)-ethene (I) and 1,1-dicyano-2-(4-hydroxy-3-methoxyphenyl)-ethene (II) with L-proline (III) and L-tartaric acid (IV) was carried out. Compound I formed cocrystals with L-proline I‚III. However, cocrystallization of II was unsuccessful; instead in the presence of III or IV formation of two conformational polymorphs IIa and IIb was observed. In cocrystals I‚III, hydrogen bonded chains of proline molecules with molecules of I attached to them were found. Similar synthons were found in the literature in other proline-containing crystals, and we believe that it is possible to use these acentric supramolecular associates in crystal engineering of nonlinear optical materials. Possible reasons for the formation of two conformational polymorphs of compound II are discussed based on the results of X-ray analysis, molecular and crystal structure energy calculations, and thermal behavior of compound II.

Thermally Stable Imines as New Potential Nonlinear Optical Materials

“…We noted earlier that for the series of compounds we have studied 26,27 the same effect of a rise of the melting points for analogous compounds with and without intermolecular hydrogen bonds might be even higher (more than 70°C). In particular, for two dicyanoethenyl derivatives, namely, 1,1-dicyano-2-(4-hydroxyphenyl)-ethene (DHE) and 1,1-dicyano-2-(4-methoxyphenyl)-ethene (DME) 26 (scheme below), the melting point of DHE which forms hydrogen bonds in a crystal is equal to 188-189°C, while for DME it is much lower, at 114-115°C.…”

“…In particular, for two dicyanoethenyl derivatives, namely, 1,1-dicyano-2-(4-hydroxyphenyl)-ethene (DHE) and 1,1-dicyano-2-(4-methoxyphenyl)-ethene (DME) 26 (scheme below), the melting point of DHE which forms hydrogen bonds in a crystal is equal to 188-189°C, while for DME it is much lower, at 114-115°C.…”

Polymorphism and solvolysis of 2-cyano-3-[4-(N,N-diethylamino)phenyl]prop-2-enethioamide

“…Moreover, related compounds have found applications as potential antitumor drugs (Hutchinson et al, 2001;Thacher et al, 2001;Wermuth, 2004). During thorough and systematic work, we have found many compounds that crystallize in different space groups and reveal polymorphism (Timofeeva et al, 2000;Timofeeva, Kuhn et al, 2003;Wang et al, 2001). Thus, cocrystallization of such compounds with chiral molecules can build non-centrosymmetric crystalline structures or polymorphs (Timofeeva et al, 2000), and polymorphism is a very important phenomenon in the pharmaceutical industry (Davey et al, 1997;Bernstein, 2002).…”

Crystal structure of (E)-1-(4-methoxyphenyl)ethanoneO-dehydroabietyloxime

“…However, no polymorphs of 8-hydroxyquinoline were found in Cambridge strustural database. The result presented here can be considered as a new example of so called "induced polymorphism" (Bernstein, 2002;Timofeeva et al, 2003).…”