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In the tricyclic title compound, C11H12N2OS, the 2,3,4,5-tetrahydropyridine ring adopts a half-chair conformation. This ring makes dihedral angles of 27.72 (7) and 45.17 (7)°, respectively, with the isoxazole and the cyclohexa-1,3-diene rings while the isoxazole ring is oriented at an acute angle of 63.46 (7)° with respect to the cyclohexa-1,3-diene ring. In the crystal, molecules associate via C—H...N hydrogen bonds and C—H...π interactions, forming a three-dimensional network.

In the title compound, C16H9FO4, (I), the benzene ring is oriented at an acute angle of 59.03 (15)° relative to the coumarin plane (r.m.s deviation = 0.009 Å). This conformation of (I) is stabilized by an intramolecular C—H...O hydrogen bond, which closes a five-membering ring. In the crystal, molecules of (I) form infinite zigzag chains along the b-axis direction, linked by C—H...O hydrogen bonds. Furthermore, the crystal structure is supported by π–π stacking interactions between neighbouring pyrone and benzene or coumarin rings [centroid–centroid distances in the range 3.5758 (18)–3.6115 (16) Å], as well as C=O...π interactions [O...centroid distances in the range 3.266 (3)–3.567 (3) Å]. The theoretical data for (I) obtained from quantum chemical calculations are in good agreement with the observed structure, although the calculated C—O—C—C torsion angle between the coumarin fragment and the benzene ring (73.7°) is somewhat larger than the experimental value [63.4 (4)°]. Hirshfeld surface analysis has been used to confirm and quantify the supramolecular interactions.

In the cation of the title hydrated molecular salt, C10H12N3O3S+·Cl−·H2O, the benzimidazolium ring system is almost planar (r.m.s. deviation = 0.006 Å) and the nitro group is inclined at an angle of 4.86 (9)° to this plane. In the crystal, C—H...O hydrogen bonds form centrosymmetricR22(20) dimers and these are further aggregated through N—H...O and O—H...Cl hydrogen bonds involving the water molecules and chloride anions. Aromatic π–π stacking interactions are also found between two parallel benzene rings or the benzene and imidazolium rings, with centroid–centroid distances of 3.5246 (9) and 3.7756 (9) Å, respectively. Analysis of the bond lengths and comparison with related compounds show that the nitro substituent is not involved in conjugation with the adjacent π-system and hence has no effect on the charge distribution of the heterocyclic ring.

This paper is focused on a combined experimental and theoretical study of 3-substituted coumarin derivative, the 2-oxo-2H-chromen-3-yl acetate (I). The compound was synthesized by reacting chroman-2,3-dione and acetic anhydride in dried diethyl ether in the presence of dried pyridine and crystallized in the orthorhombic crystal system with Pbca space group. The lattice parameters of the structure are a=14.6770 (1), b=7.1079 (1), c=17.6767 (2) A, α=β=γ=90° with 8 molecules per unit cell (Z=8). The compound has been characterized structurally by Spectroscopy utilizing 1H NMR, 13C NMR and IR techniques and by crystallography using the X-Ray diffraction (XRD) analysis. In the crystallographic study, the positions of the atoms were determined by direct methods and refined to a final R value of 0.038 for 1768 independent reflections. The stabilization of the structure is provided by intermolecular C-H•••O hydrogen bonds extending along [010] direction. Likewise, the presence and nature of intermolecular contacts are determined by the 3-D molecular Hirshfeld surface and 2-D fingerprint plot analysis which indicate the main contributions to the Hirshfeld surface, 38.7% for O ••• H and 28.7% for H •• H. Moreover, the molecular geometry of (I) was as well minimized utilizing density functional theory (DFT/RB3LYP), the frequency calculations with RB3LYP method, the basic ab initio model i.e the restricted Hartree-Fock (RHF) and the exchange component of Perdew and Wang’s 1991 functional B3PW91 methods with the 6-311++G(d, p) basis set in ground state. The derived structural parameters highlight very good correlation with the crystallographic results. Frontier molecular orbitals (HOMO-LUMO), their energy gap, the non-linear optical effects (NLO) and related reactive parameters were also computed to better apprehend the properties of the molecule.

The title co-crystalline compound, C10H10O3·C9H8O4, has been synthesized and characterized in a single-crystal X-ray diffraction study. In the 3-hydroxy-3-methylisochroman-1-one molecule, the six-membered heterocyclic ring lies between an envelope and a screw-boat conformation. In the 2-carboxymethylbenzoic acid, molecule, the 2-carboxymethyl substituent is almost planar (r.m.s deviation = 0.048 Å) and makes a dihedral angle of 79.59 (7)° with the planar benzene ring. In this molecule, intramolecular C—H...O contacts generate five- and six-membered rings, forming a tricyclic ring system. In the crystal, classical O—H...O and C—H...O hydrogen bonds combine with C—H...π(ring) and unusual C=O...π(ring) contacts to generate a three-dimensional network.

In the title compound, C17H12O4, the benzoate ring is oriented at an acute angle of 60.14 (13)° relative to the coumarin plane (r.m.s. deviation = 0.006 Å). This conformation is stabilized by an intramolecular C—H...O weak hydrogen bond, which forms a five-membered ring. Also present are π–π stacking interactions between neighbouring pyrone and benzene rings [centroid-to-centroid distances in the range 3.6286 (1)–3.6459 (1) Å] and C=O...π interactions [O...centroid distances in the range 3.2938 (1)–3.6132 (1) Å]. Hirshfeld surface analysis has been used to confirm and quantify the supramolecular interactions.

WOS:000428789400024; In the title compound, C20H18O4, the benzoate ring is oriented at an acute angle of 33.10 (12)degrees with respect to the planar (r.m.s deviation = 0.016 angstrom) coumarin ring system. An intramolecular C-H center dot center dot center dot O hydrogen bond closes an S(6) ring motif. In the crystal, C-H center dot center dot center dot O contacts generate infinite C(6) chains along the b-axis direction. Also present are pi-pi stacking interactions between neighbouring pyrone and benzene rings [centroid-centroid distance = 3.7034 (18) A degrees] and C=O center dot center dot center dot pi interactions [O center dot center dot center dot centroid = 3.760 (3) angstrom]. The data obtained from quantum chemical calculations performed on the title compound are in good agreement with the observed structure, although the calculated C-O-C-C torsion angle between the coumarin ring system and the benzoate ring (129.1 degrees) is somewhat lower than the observed value [141 .3 (3)degrees]. Hirshfeld surface analysis has been used to confirm and quantify the supramolecular interactions.

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.

MEDLINE:24046679; International audience; 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 mol-ecular structure exhibits an intra-molecular C-H⋯O hydrogen bond, which generates an S(6) ring. In the crystal, mol-ecules form R 3 (2)(12) trimeric units via C-H⋯O inter-actions which propagate into layers parallel to the ac plane. These layers are linked by weak C-H⋯O inter-actions along the [010] direction, generating a three-dimensional network.

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 R22(8) centrosymmetric dimers via C—H...O hydrogen bonds. These dimers are stacked by C—H...O hydrogen bonds, resulting in R22(18) and R32(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.

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 R22(6) dimers joined by a C(7) chain, resulting in centrosymetric tetramers of hydrogen-bonded molecules with graph-set motif R44(40). These centrosymetric tetramers are connected by a pair of hydrogen bonds described by an R22(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 title molecule, C20H18O4, the three methyl groups of the tert-butyl substituent show rotational disorder. Each methyl group is split over three positions, with refined site-occupation factors of 0.711 (4), 0.146 (3) and 0.144 (4). The benzene ring of the benzoate group is oriented at a dihedral angle of 60.70 (7)° with respect to the planar chromene ring [maximum deviation = 0.046 (2) Å]. The crystal structure features centrosymmetric R22(8) dimers formed via C—H...O interactions, and these dimeric aggregates are connected by C—H...π interactions.

WOS:000298966100077; International audience; In the title compound, C17H12O4, the six-membered heterocyclic ring adopts a distorted screw-boat conformation. The molecular structure exhibits an S(6) ring motif, owing to an intramolecular O-H center dot center dot center dot O hydrogen bond. In the crystal, weak C-H center dot center dot center dot O contacts generate an infinite chain along the c axis. There are also pi-pi stacking interactions between neighbouring isochromanedione benzene rings, with a centroid-centroid distance of 3.755 (1) angstrom, and C-O center dot center dot center dot pi interactions with an O center dot center dot center dot centroid distance of 3.964 (2) angstrom.

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 R22(12) centrosymetric dimers formed via C—H...O interactions and these dimeric aggregates are connected by C—H...π interactions.

In the title compound, C16H9ClO4, the six-membered heterocyclic ring adopts a screw-boat conformation. The benzene rings are oriented to each other at a dihedral angle of 59.26 (9)°. The molecular structure exhibits a ring motif, viz. S(6), owing to an intramolecular O—H...O hydrogen bond. The presence of C—H...O contacts generates an infinite chain along [001]. Also present are π–π stacking interactions between neighbouring isochromanedione benzene rings [centroid–centroid distance = 3.746 (1) Å], and C—O...π interactions [O...centroid = 3.934 (2) Å].

In the title compound, C10H12N2OS, the asymmetric unit consists of two independent molecules. In the crystal structure, molecules form R44(28) centrosymmetric tetramers via O—H...N hydrogen bonds. These tetramers are stacked along the c axis via C—H...O hydrogen bonds. C—H...π and π–π interactions are also present; in the latter, the centroid–centroid distances are 4.075 (1) and 3.719 (1) 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.

Molecules of the title compound, C10H12N2OS, are interconnected by N—H...O hydrogen bonds of moderate strength into infinite chains. There are also intramolecular O—H...N bonds of moderate length. Weaker interactions are represented by C—H...N bonds as well as by π–π interactions between the imidazole and benzene rings [distance between centroids = 3.6865 (8) Å].

In the title compound, C13H17N3OS, the morpholine ring has a chair conformation. The crystal structure exhibits intermolecular C—H...O and C—H...N interactions to form a consolidated array.