The asymmetric unit of the title compound, C17H12O4, consists of two independent mol­ecules. The chromen-2-one ring and the 4-methyl­benzoate side chain are inclined to one another at a dihedral angle of 64.79 (10)° in one mol­ecule and 88.3 (1)° in the other. In the crystal, mol­ecules form R 2 2(8) centrosymmetric dimers via C—H⋯O hydrogen bonds. These dimers are stacked by C—H⋯O hydrogen bonds, resulting in R 2 2(18) and R 3 2(16) ring motifs. π–π stacking inter­actions between two parallel chromen-2-one rings, with centroid–centroid distances of 3.743 (1) and 3.771 (1) Å, are also present.

The title compound (C12H10O4) crystallizes in the triclinic space group P1̄ with a = 7.367(3), b = 8.1188(3), c = 9.549(5) Å, α = 74.034(1)°, β = 84.374(2)°, γ = 64.581(3)°, Z = 2, and dcalc = 1.462 g cm−3. It exhibits a strong intramolecular O-H···O hydrogen bond and exists as the exocyclic enolic tautomer as it has been observed in solution. The structure is stabilized by C-H···π, C-O···π and π-π stacking interactions between benzene and pyran rings.

In the title mol­ecule, C17H12O5, the chromen-2-one ring and the 4-meth­oxy­benzoate side chain are inclined to one another at a dihedral angle of 69.82 (9)°. The crystal structure features parallel sheets of centrosymmetric R 2 2(6) dimers joined by a C(7) chain, resulting in centrosymetric tetra­mers of hydrogen-bonded mol­ecules with graph-set motif R 4 4(40). These centrosymetric tetra­mers are connected by a pair of hydrogen bonds described by an R 2 2(8) ring motif and a C(7) chain via C—H⋯O inter­actions. In the structure, there are also π–π stacking inter­actions between chromene benzene and the six-membered heterocyclic rings [centroid–centroid distance = 3.691 (2) Å] and weak C=O⋯π inter­actions [O⋯(ring centroid) distance = 3.357 (3) Å].

In the molecule of the title compound, C14H12N2S, the benzimidazole ring system and the phenyl ring form a dihedral angle of 81.36 (7)°. The crystal structure exhibits intermolecular C—H...N and N—H...N hydrogen bonds.

The structure of a coumarin ester is reported and compared with the results of a quantum chemical calculation. In the crystal, inter­molecular C—H⋯O contacts generate an infinite C(6) chain along the b axis. C=O⋯π and π–π stacking inter­actions also occur. Hirshfeld surface analysis was used to confirm and qu­antify the supra­molecular inter­actions.

In the title compound, C12H10O4, the atoms of the 2-oxo-2H-chromene ring system and the non-H atoms of the 4-substituent all lie on a crystallographic mirror plane. The mol­ecular structure exhibits an intra­molecular C—H⋯O hydrogen bond, which generates an S(6) ring. In the crystal, mol­ecules form R 3 2(12) trimeric units via C—H⋯O inter­actions which propagate into layers parallel to the ac plane. These layers are linked by weak C—H⋯O inter­actions along the [010] direction, generating a three-dimensional network.

In the title mol­ecule, C18H15NO4, the benzoate ring is oriented at a dihedral angle of 43.43 (6)° with respect to the planar [maximum deviation = 0.038 (2) Å] chromene ring. The crystal structure features R 2 2(12) centrosymetric dimers formed via C—H⋯O inter­actions and these dimeric aggregates are connected by C—H⋯π inter­actions.

The structure of a coumarin ester stabilized by C—H⋯O hydrogen bonds and C=O⋯π and π–π stacking inter­actions has been studied by X-ray diffraction, Hirshfeld surface analysis and quantum chemical calculations.