Conjugation and hydrogen bonding in a curcumin analogue

Abstract

Electronic paper This paper is published electronically. It meets the data-validation criteria for publication in Acta Crystallographica Section C. The submission has been checked by a Section C Co-editor though the text in the`Comments' section is the responsibility of the authors.

Weak hydrogen bonds in 5-(4-methoxyphenyl)-1-phenylpent-4-ene-1,3-dione

“…In curcuminoid molecules, the enol H atoms always seem to be involved in a strong intramolecular hydrogen bond, and never engaged in intermolecular interactions. Therefore, when such molecules are without other classical hydrogen-bond donors, the packing of the molecules in the crystal structure is dominated by weak hydrogen bonding, as reported in earlier papers (Arrieta & Mostad 2000, 2003, 2004a. The molecule in the present study, (I), is depicted in Fig.…”

Orthorhombic form of 6-phenylhex-5-ene-2,4-dione

“…The molecular packing is dominated by a number of CÐHÁ Á ÁO contacts where at least one, C8ÐH8Á Á ÁO1( 1 2 + x, 1 2 À y, 2 À z) is a clear-cut intermolecular hydrogen bond. The CÐHÁ Á ÁO short contacts observed between molecules related by a center of symmetry [HÁ Á ÁO distances of 3.00 (2) and 3.19 (2) A Ê ] are similar to a mode seen in the crystal structures of related molecules (Mostad, 1994;Arrieta et al, 1995Arrieta et al, , 2000. In the solid state, the phenyl rings pack along the cell direction b forming an angle of 72.5 .…”

Ethyl 2-trans-cinnamoylacetoacetate

“…The closest contacts between molecules occur through C-H•••O interactions. The geometry of these interactions (Table 2) and the fact that such interactions are repeatedly found in the crystal structures of this group of molecules (Mostad, 1994;Arrieta et al, 1995Arrieta et al, , 2000, indicate that they may be considered as examples of weak hydrogen bonds (Desiraju & Steiner, 1999). A drawing of the molecule with the numbering of the atoms and their vibrational elipsoids is given in Fig.…”