6-Chloro-4-oxo-4H-chromene-3-carb­aldehyde

In the title compound, C₁₀H₅ClO₃, a chlorinated 3-formyl­chromone derivative, the non-H atoms are essentially coplanar (r.m.s. deviation = 0.0456 Å) with the largest deviation from the least-squares plane [0.1136 (16) Å] being found for the ring-bound carbonyl O atom. In the crystal, mol­ecules are linked through stacking inter­actions along the b axis [shortest centroid-centroid distance between the pyran and benzene rings = 3.4959 (15) Å].

Diethyl 4-oxo-4H-[1,4′-bi­quinoline]-3,3′-di­carboxyl­ate

In the title mol­ecule, C₂₄H₂₀N₂O₅, the quinoline and quinolinone moieties are practically perpendicular to each other, forming a dihedral angle of 89.06 (3)°. In the crystal, each moiety forms coplanar π-stacked couples with the respective inversion equivalents. The quinolinone moieties overlap with their benzene rings with a centroid–centroid separation of 3.641 (2) Å, whereas the quinoline moieties overlap with their pyridine rings with a separation of 3.592 (2) Å. The resulting supra­molecular chains propargate along [101].

6,8-Di­iodo-4-oxo-4H-chromene-3-carbalde­hyde

The title compound, C₁₀H₄I₂O₃, is an iodinated 3-formyl­chromone derivative, and the atoms are essentially coplanar [r.m.s. deviation = 0.049 Å, largest deviation from the least-squares plane = 0.111 (9) Å for the CH(=O) C atom]. In the crystal, mol­ecules are linked into a three-dimensional network through halogen bonds [I...O = 3.352 (5) and 3.405 (7) Å, C—I...O = 144.2 (3) and 154.5 (3)°, and C=O...I = 134.9 (6) and 146.0 (6)°], and π–π stacking inter­actions [centroid–centroid distance = 3.527 (6) Å].

6-Chloro-8-nitro-4-oxo-4H-chromene-3-carbaldehyde

In the title compound, C₁₀H₄ClNO₅, the non-H atoms of the 6-chloro­chromone unit are coplanar (r.m.s. deviation = 0.017 Å) with the largest deviation from the mean plane [0.031 (2) Å] being found for the C=O C atom. The nitro group (NO₂) is inclined to the chromone unit mean plane by 13.3 (2) °. The formyl group is also twisted with respect to the attached ring [C—C—C—O torsion angles = 10.8 (4) and −171.8 (2)°]. In the crystal, mol­ecules are linked via C-H...O hydrogen bonds forming slab-like networks lying parallel to (-301). The slabs are linked by π–π inter­actions involving the benzene rings of the chromone units [centroid–centroid distance = 3.770 (3) Å].

6-Bromo-4-oxo-4H-chromene-3-carb­alde­hyde

In the title compound, C₁₀H₅BrO₃, a brominated 3-formyl­chromone derivative, the non-H atoms are essentially coplanar (r.m.s. deviation = 0.0420 Å), with the largest deviation from its mean plane [0.109 (2) Å] being found for the ring-bound carbonyl O atom. In the crystal, mol­ecules are linked through halogen bonds [Br...O = 3.191 (2) Å, C—Br...O = 167.32 (10)° and C=O...Br = 168.4 (2)°] along [101]. Mol­ecules are assembled into layers parallel to (101) via π–π stacking inter­actions along the b axis [shortest centroid–centroid distance between the pyran and benzene rings = 3.495 (2) Å].

(E)-4-Methyl-N′-[(4-oxo-4H-chromen-3-yl)methyl­idene]benzohydrazide

In the title chromone-tethered benzohydrazide derivative, C₁₈H₁₄N₂O₃, the 4H-chromen-4-one and the –CH=N–NH–CO– units are each essentially planar, with the largest deviations from thei planes being 0.052 (2) and 0.003 (2) Å, respectively. The dihedral angles between the 4H-chromen-4-one and the –CH=N–NH–CO– units, the 4H-chromen-4-one unit and the benzene ring of the 4-tolyl group, and the benzene ring of the 4-tolyl group and the –CH=N–NH–CO– unit are 8.09 (7), 9.94 (5) and 17.97 (8)°, respectively. In the crystal, the mol­ecules form two types of centrosymmetric dimers: one by N—H...O hydrogen bonds and the other by π–π stacking inter­actions between the 4H-chromen-4-one unit and the 4-tolyl group [centroid–centroid distance = 3.641 (5) Å]. These dimers form one-dimensional assemblies extending along the a-axis direction. Additional π–π stacking inter­actions between two 4H-chromen-4-one units [centroid–centroid distance = 3.591 (5) Å] and two 4-tolyl groups [centroid–centroid distance = 3.792 (5) Å] organize the mol­ecules into a three-dimensional network.

6-Fluoro-4-oxo-4H-chromene-3-carbalde­hyde

In the title compound, C₁₀H₅FO₃, the non-H atoms are essentially coplanar (r.m.s. deviation = 0.0071 Å), with the largest deviation from the mean plane [0.0203 (15) Å] being found for the ring C atom in the 2-position. In the crystal, mol­ecules are linked into a three-dimensional architecture via C—H...O hydrogen bonds and π–π stacking inter­actions between the chromone units along the a-axis direction [centroid–centroid distance between the benzene and pyran rings = 3.707 (2) Å].