Crystal structures of (E)-1-{3-[(5-fluoro-2-hydroxybenzylidene)amino]phenyl}ethanone and of a fourth polymorph of (E)-1-{3-[(2-hydroxy-3-methoxybenzylidene)amino]phenyl}ethanone

Abstract

In the molecules of both (E)-1-{3-[(5-fluoro-2-hydroxybenzylidene)amino]-phenyl}ethanone, C 15 H 12 FNO 2 , (I), and (E)-1-{3-[(2-hydroxy-3-methoxybenzylidene)amino]phenyl}ethanone, C 16 H 15 NO 3 , (II), which crystallizes with Z 0 = 2 in space group Pca2 1 , there are intramolecular O-HÁ Á ÁN hydrogen bonds, and the non-H atoms in each molecule are essentially coplanar. In the crystal of (I), molecules are linked by a single C-HÁ Á ÁO hydrogen bond to form a C(8) chain, whereas in the crystal of (II), molecules are linked by three C-HÁ Á ÁO hydrogen bonds to form sheets within which orthogonal C 2 2 (16) and C 2 2 (17) chains can be identified. Comparisons are made with some related structures.

The crystal structure of (E)-2-ethyl-N-(4-nitrobenzylidene)aniline: three-dimensional supramolecular assembly mediated by C—H...O hydrogen bonds and nitro...π(arene) interactions

“…Schiff bases exhibit a very wide range of biological activities (da Silva et al, 2011) and are also of interest because of their photochromic and thermochromic properties (Hadjoudis & Mavridis, 2004;Minkin et al, 2011). In view of the general importance of Schiff bases, and in a continuation of our own structural study of compounds of this type (Girisha et al, 2017(Girisha et al, , 2018 we report here the molecular and supramoleuclar structure of (E)-2-ethyl-N-(4-nitrobenzylidene)aniline (I) ( Fig. 1), where the ethyl group turns out to be disordered over two sets of atomic sites and where the molecules are linked into a three-dimensional supramolecular array.…”

Eight Schiff bases derived from various salicylaldehydes: phenol–imine and keto–amine forms, conformational disorder, and supramolecular assembly in one and two dimensions

“…With these considerations in mind and as part of a wider structural study of Schiff bases (Girisha, Yathirajan et al, 2017Girisha, Sagar et al, 2018), we have now investigated five newly synthesized Schiff bases of this type, compounds (I)-(IV) and (VI) (Scheme 2), whose structures are reported here, and we have also re-investigated three further examples, i.e. compounds (V) (Chattopadhyay et al, 2009), (VII) (Kaur et al, 2014) and (VIII) (Maciejewska et al, 1999;Tunç et al, 2009); of these, the structures reported for compounds (V) and (VIII) leave room for uncertainty about their constitutions, while that for (VII) overlooked the possibility of conformational disorder.…”