Crystal structures of (1E,4E)-1,5-bis­(5-bromo­thio­phen-2-yl)-2,4-di­methyl­penta-1,4-dien-3-one and (E)-4-(5-bromo­thio­phen-2-yl)-1,3-di­phenyl­but-3-en-2-one

The title compounds, C(15)H(12)Br(2)OS(2), (I), and C(20)H(15)BrOS, (II), were synthesized by employing Claisen–Schmidt condensation of pentan-3-one and di­benzyl­acetone with 5-bromo­thio­phene-2-carbaldehyde in the presence of methano­lic KOH. Even though 1:2 products were expected in both of the reactions, 1:2 and 1:1 products were obtained as (I) and (II), respectively. In (I), the two methyl groups are trans to each other, 29.5 (7) and 28.7 (7)° away from the central carbonyl bond between them, whereas the two phenyl rings of di­benzyl­acetone subtend a dihedral angle of 53.09 (18)°. In the crystal of (I), C—H⋯O hydrogen bonds define mol­ecular chains along c. A second type of mol­ecular chain is formed along b by means of C—Br⋯π inter­actions. These two families of mol­ecular chains are stacked by π–π inter­actions, forming a three-dimensional supra­molecular architecture. In (II), similar C—H⋯O hydrogen bonds as in (I) define inversion dimers, whilst C—H⋯.π inter­actions build a staircase structure along the a axis.