(2E)-2-(4-Bromo­benzyl­idene)-2,3-di­hydro-1H-inden-1-one

The title indan-1-one derivative, C16H11BrO, is planar, the r.m.s. deviation for all 18 non-H atoms being 0.071 Å. The configuration about the C=C bond [1.337 (5) Å] is E. In the crystal, supra­molecular layers in the ab plane are formed by C—H⋯O inter­actions, involving the bifurcated carbonyl O atom, as well as C—H⋯π inter­actions. The studied crystal was an inversion twin

(2E)-2-[(2E)-3-Phenyl­prop-2-en-1-yl­idene]-2,3-dihydro-1H-inden-1-one

The title indan-1-one derivative, C18H14O, is planar with an r.m.s. deviation for all 19 non-H atoms of 0.098 Å. The conformation about each of the C=C bonds [1.343 (3) and 1.349 (3) Å] is E. Supra­molecular layers in the bc plane, mediated by C—H⋯O and π–π [ring centroid–centroid distance = 3.5282 (15) Å] inter­actions, feature in the crystal packing

(2E)-2-(Furan-2-yl­methyl­idene)-2,3-dihydro-1H-inden-1-one

In the title compound, C14H10O2, the five-membered ring of the inden-1-one residue is almost planar (r.m.s. deviation = 0.035 Å). A twist about the single bond linking the two residues is evident [C—C—C—C torsion angle = −13.2 (5)°]. The three-dimensional architecture is stabilized by C—H⋯O (involving the trifurcated carbonyl O atom), C—H⋯π and π–π inter­actions [between the five- and six-membered rings of inden-1-one residues; ring centroid–centroid distance = 3.7983 (17) Å]. The sample studied was a non-merohedral twin; the minor component refined to approximately 36%

(2E)-2-(4-Meth­oxy­benzyl­idene)-2,3-di­hydro-1H-inden-1-one

In the title compound, C17H14O2, the indan-1-one system is almost planar (r.m.s. deviation = 0.007 Å) and the benzene ring is twisted out of its plane by 8.15 (6)°. The conformation about the C=C double bond [1.348 (2) Å] is E. Helical supra­molecular chains along [010] feature in the crystal packing; these are sustained by C—H⋯O hydrogen bonds and π–π inter­actions between translationally related indan-1-one systems [centroid–centroid distance = 3.7970 (10) Å]

(2E)-2-[(2H-1,3-Benzodioxol-5-yl)methyl­idene]-2,3-dihydro-1H-inden-1-one

In the title compound, C17H12O3, each of the five-membered rings in the inden-1-one and 1,3-benzodioxole residues is almost planar (r.m.s. deviations = 0.041 and 0.033 Å, respectively). A small twist about the single bond linking the two residues is evident [the C—C—C—C torsion angle = 8.7 (4)°]. Supra­molecular zigzag layers propagating in the ac plane are formed in the crystal via C—H⋯O inter­actions. The layers are linked via π–π inter­actions between the five- and six-membered rings of 1,3-benzodioxole residues [centroid–centroid distance = 3.4977 (14) Å]