Some chalcones derived from thio-phene-3-carbaldehyde: synthesis and crystal structures.

The synthesis, spectroscopic data and crystal and mol-ecular structures of four 3-(3-phenyl-prop-1-ene-3-one-1-yl)thio-phene derivatives, namely 1-(4-hydroxy-phen-yl)-3-(thio-phen-3-yl)prop-1-en-3-one, CHOS, (), 1-(4-meth-oxy-phen-yl)-3-(thio-phen-3-yl)prop-1-en-3-one, CHOS, (), 1-(4-eth-oxy-phen-yl)-3-(thio-phen-3-yl)prop-1-en-3-one, CHOS, (), and 1-(4--bromophen-yl)-3-(thio-phen-3-yl)prop-1-en-3-one, CHBrOS, (), are described. The four chalcones have been synthesized by reaction of thio-phene-3-carbaldehyde with an aceto-phenone derivative in an absolute ethanol solution containing potassium hydroxide, and differ in the substituent at the position of the phenyl ring: -OH for , -OCH for , -OCHCH for and -Br for . The thio-phene ring in was found to be disordered over two orientations with occupancies 0.702 (4) and 0.298 (4). The configuration about the C=C bond is . The thio-phene and phenyl rings are inclined by 4.73 (12) for , 12.36 (11) for , 17.44 (11) for and 46.1 (6) and 48.6 (6)° for , indicating that the -OH derivative is almost planar and the -Br derivative deviates the most from planarity. However, the substituent has no real influence on the bond distances in the α,β-unsaturated carbonyl moiety. The mol-ecular packing of features chain formation in the -axis direction by O-H⋯O contacts. In the case of and , the packing is characterized by dimer formation through C-H⋯O inter-actions. In addition, C-H⋯π(thio-phene) inter-actions in and C-H⋯S(thio-phene) inter-actions in contribute to the three-dimensional architecture. The presence of C-H⋯π(thio-phene) contacts in the crystal of results in chain formation in the -axis direction. The Hirshfeld surface analysis shows that for all four derivatives, the highest contribution to surface contacts arises from contacts in which H atoms are involved.