In the title compound, C19H25NO2, the pyrrolidine ring adopts an envelope form, with the spiro C atom as the flap, while the cyclo-hexane ring shows a chair form. A weak intra-molecular C-H⋯O inter-action supports the mol-ecular conformation, generating an S(6) ring motif. In the crystal, pairs of C-H⋯O inter-actions connect the mol-ecules into inversion dimers with an R 2 (2)(16) ring motif. T...

In the title compound, C(38)H(32)N(2)O(2), the pyrrolidine ring adopts an envelope conformation, whereas the cyclo-hexa-none ring in the tetra-hydro-naphthalene fused-ring system adopts a half-chair conformation. The benzyl ring is oriented at an angle of 67.1 (1)° with respect to the naphthyl ring system. Four intra-molecular C-H⋯O close contacts and C-H⋯π inter-action are observed. In the cry...

The benzene ring of the title compound, C(13)H(12)N(2)O(6), is twisted away from the planes of the amino-methyl-ene unit and the dioxane ring by 30.13 (4) and 35.89 (4)°, respectively. The dioxane ring exhibits a half-boat conformation, in which the C atom between the dioxane O atoms is 0.553 (8) Å out-of-plane. An intra-molecular N-H⋯O hydrogen bond stabilizes the conformation of the dioxane r...

In the title compound, C(23)H(23)NO(5)S·0.125H(2)O, the pyrrolidine ring has a twist conformation and the dihydro-pyran ring adopts a half-chair conformation; the two rings are cis-fused. The mol-ecule adopts a folded conformation. The sulfonyl-bound phenyl ring and the pyran ring of the coumarin ring system are stacked over one another, with a centroid-centroid distance of 3.7470 (7) Å; the di...

In the title compound, C(24)H(17)N(2)O(4) (+)·NO(3) (-)·0.25H(2)O, the central pyridine ring of the 2',6'-bis-(4-carb-oxy-phen-yl)-4,4'-bipyridin-1-ium cation is almost coplanar with one benzene ring [dihedral angle = 1.03 (5)°], while it makes dihedral angles of 9.59 (5)° with the other benzene ring and 13.66 (6)° with the pyridinium ring. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds link th...

In the title compound, C(23)H(24)N(4)O(3)·H(2)O, the 1,3-oxazoline ring is nearly planar [maximum deviation = 0.059 (2) Å] and its mean plane is twisted by 30.12 (8)° with respect to the quinoxaline fused-ring system; the benzene ring is nearly coplanar with the quinoxaline fused-ring system [dihedral angle = 2.52 (2)°]. The water mol-ecule of crystallization is hydrogen-bond donor to an N atom...

In the structure of the title compound, C(20)H(15)BrN(4)O·C(2)H(6)O, the hydrogenated pyridinone ring adopts an envelope conformation. The dihedral angle between the bromo-substituted phenyl ring and the pyrazole ring is 79.6 (1)°, and that between the non-substituted phenyl ring and the pyrazole ring is 51.2 (1)°. In the crystal structure, mol-ecules are linked via inter-molecular N-H⋯O and O-...

In the title compound, C(20)H(22)O(5), an S(6) ring motif is formed by an intra-molecular C-H⋯O hydrogen bond, which contributes to the stabilization of the mol-ecule. In the xanthene system, the cyclo-hexane ring adopts a chair conformation, the cyclo-hexene ring adopts a half-boat conformation and the tetra-hydro-pyran ring adopts a half-chair conformation. The mean plane of the four essentia...

The title compound, C(10)H(9)NO(4), forms R(2) (2)(8) dimers due to inter-molecular O-H⋯O hydrogen bonding in the crystal structure. Two dimers are further linked to each other through two inter-molecular C-H⋯O hydrogen bonds, forming an R(3) (3)(7) ring motif. The nitro groups form an intra-molecular C-H⋯O hydrogen bond mimicking a five-membered ring. As a result of these hydrogen bonds, polym...

In the title compound, C(4)H(8)N(3)O(+)·C(4)H(3)O(4) (-), the cations and anions are linked through N-H⋯O hydrogen bonds making a ionic pair with an R(2) (2)(8) ring motif. These ionic pairs are further connected through another N-H⋯O hydrogen bond, leading to an R(6) (6)(16) ring motif around the inversion centres of the unit cell. These approximately planar aggregates are further connected th...