2,2′-[2,4-Bis(naphthalen-1-yl)cyclo­butane-1,3-di­yl]bis­(1-methyl­pyridinium) diiodide: thermal-induced [2 + 2] cyclo­addition reaction of a heterostilbene

The asymmetric unit of the title compound, C₃₆H₃₂N₂²⁺·2I⁻, consists of one half-mol­ecule of the cation and one I⁻ anion. The cation is located on an inversion centre. The dihedral angle between the pyridinium ring and the naphthalene ring system in the asymmetric unit is 19.01 (14)°. In the crystal, the cations and the anions are linked by C—H...I inter­actions into a layer parallel to the bc plane. Intra- and inter­molecular π–π inter­actions with centroid–centroid distances of 3.533 (2)–3.807 (2) Å are also observed.

2-(2,4,5-Trimeth­oxy­phen­yl)-2,3-dihydro­quinolin-4(1H)-one

In the title aza-flavanone, C₁₈H₁₉NO₄, an intra­molecular cyclization product of chalcone, the central heterocyclic ring is in an envelope conformation and the dihedral angle between the benzene rings is 51.03 (10)°. The meth­oxy groups at the ortho and para positions are slightly twisted from the benzene ring to which they are bound [C—O—C—C = 21.9 (3) and −171.93 (18)°, respectively], whereas the meth­oxy group at the meta position is almost coplanar [C—O—C—C = 3.5 (3)°]. In the crystal, mol­ecules are linked by N—H...O hydrogen bonds and weak C—H...O inter­actions into chains along the [001] direction. Weak C—H...π inter­actions also occur.

1-Methyl-2-[(E)-2,4,5-trimeth­oxy­styr­yl]­pyridinium benzene­sulfonate mono­hydrate

The asymmetric unit of the title compound, C₁₇H₂₀NO₃⁺·C₆H₅O₃S⁻·H₂O, comprises two 1-methyl-2-[(E)-2,4,5-trimeth­oxy­styr­yl]pyridinium cations, two benzene­sulfonate anions and two water mol­ecules. The cations exist in the E conformation with respect to the C=C bond; one cation is essentially planar while the other is slightly twisted, the dihedral angles between the pyridinium and phenyl rings being 1.23 (14) and 6.64 (13)°, respectively. In the crystal, cations, anions and water mol­ecules are linked by O—H...O hydrogen bonds and weak C—H...O inter­actions into chains along the b axis. π–π inter­actions with centroid–centroid distances in the range 3.5557 (16)–3.6876 (16) Å are observed. C—H...π inter­actions and a C...O short contact [2.94 (4) Å] are also observed.

8-O-Acetyl-8-epi-9-de­oxygoniopypyrone

The title compound (systematic name: 7-oxo-3-phenyl-2,6-dioxabicyclo­[3.3.1]nonan-4-yl acetate), C₁₅H₁₆O₅, is a styryllactone derivative which was isolated from Goniothalamus macrophyllus. The mol­ecule has two fused rings consisting of a tetra­hydro-2H-pyran and a lactone ring, with the benzene ring and the acetyl group attached to the tetra­hydro-2H-pyran ring. The tetra­hydro-2H-pyran ring is in a standard chair conformation, whereas the lactone ring is in an envelope conformation. In the crystal, mol­ecules are linked by weak C—H...O inter­actions into sheets parallel to the ac plane. Weak C—H...π inter­actions are also observed.

4-Bromo-N-phenyl­benzamide

The mol­ecule of the title benzamide derivative, C₁₃H₁₀BrNO, is twisted with the dihedral angle between the phenyl and 4-bromo­phenyl rings being 58.63 (9)°. The central N—C=O plane makes dihedral angles of 30.2 (2) and 29.2 (2)° with the phenyl and 4-bromo­phenyl rings, respectively. In the crystal, mol­ecules are linked by N—H...O hydrogen bonds into chains along [100]. C—H...π contacts combine with the N—H...O hydrogen bonds, to form a three-dimensional network.

Absolute configuration of xerophenone A

The title compound, C₃₃H₄₂O₅, known as xerophenone A {systematic name: (1R,3R,4R,6S,8E,10R)-10-hy­droxy-8-[hy­droxy(phen­yl)methyl­ene]-4-methyl-1,6-bis­(3-methyl­but-2-en-1-yl)-3-(3-methyl­but-3-en-1-yl)-11-oxatricyclo­[4.3.1.1^4,10]undecane-7,9-dione} is a naturally occurring rearranged benzophenone compound which was isolated from the twigs of Garcinia propinqua. The absolute configuration was determined by refining the Flack parameter to 0.18 (16). The absolute configurations at positions 1, 3, 4, 6 and 10 of the xerophenone A are R, R, R, S and R. In the mol­ecule, the cyclo­hexane-1,3-dione, tetra­hydro-2H-pyran and tetra­hydro­furan rings adopt twisted boat, standard chair and envelope conformations, respectively. The 3-methyl­but-3-en-1-yl substituent is disordered over two sets of sites in a 0.771 (11):0.229 (11) ratio. An intra­molecular O—H...O hydrogen bond generates an S(6) ring motif. In the crystal, mol­ecules are linked by O—H...O and weak C—H...O inter­actions into a chain along the a axis. A very weak C—H...π inter­action and C...O short contact [2.989 (2) Å] are also present.

3-O-Methyl-1-isomangostin

In the title xanthone derivative [systematic name: 9-hy­droxy-5,10-dimeth­oxy-2,2-dimethyl-11-(3-methyl­but-2-en-1-yl)-2,3,4,12-tetra­hydro-1,7-dioxatetra­phen-12-one], C₂₅H₂₈O₆, the xanthone ring system is roughly planar, with an r.m.s. deviation of 0.1038 (1) Å. The chromane ring is in a half-chair conformation and the 3-methyl­but-2-enyl substituent is axially attached with an (+)-anti­clinal conformation. Two weak intra­molecular C—H...O inter­actions generate two S(6) ring motifs. In the crystal, mol­ecules are linked into ribbons along the c axis by O—H...O and weak C—H...O hydrogen bonds. A π–π inter­action, with a centroid–centroid distance of 3.5413 (8) Å, is also observed.

5-Amino-3-eth­oxy-1,8,8-trimethyl-2-aza­bicyclo­[2.2.2]octa-2,5-diene-4,6-dicarbo­nitrile

The title 2-aza­bicyclo­[2.2.2]octa-2,5-diene derivative, C₁₄H₁₈N₄O, crystallized out with two independent mol­ecules with similar conformations in the asymmetric unit. In each mol­ecule, the three six-membered rings adopt boat conformations. The mol­ecules exist in the enamine form. In the crystal, mol­ecules are linked by N—H...O and N—H...N hydrogen bonds into a two-dimensional network parallel to the ab plane.

(E)-1-(2,4-Dinitro­phen­yl)-2-[1-(3-nitro­phen­yl)ethyl­idene]hydrazine

In the asymmetric unit of the title compound, C₁₄H₁₁N₅O₆, there are three crystallographically independent mol­ecules with similar conformations but some differences in bond angles. The mol­ecules are slightly twisted with the dihedral angles between the benzene rings being 10.02 (14), 8.41 (15) and 1.40 (14)°. In each mol­ecule, an intra­molecular N—H...O hydrogen bond generates an S(6) ring motif. In the crystal, mol­ecules are linked by weak C—H...O inter­actions into a three-dimensional network. π–π inter­actions with centroid–centroid distances of 3.5635 (17)–3.8273 (18) Å are observed.

(E)-2-[4-(Diethyl­amino)­styr­yl]-1-methyl­pyridinium 4-meth­oxy­benzene­sulfonate monohydrate

In the cation of the title compound, C₁₈H₂₃N₂⁺·C₇H₇O₄S⁻·H₂O, one ethyl group of the diethyl­amino unit is disordered over two sets of sites in a 0.665 (6):0.335 (6) ratio. The styrylpyridinium unit is nearly planar, with a dihedral angle between the pyridinium and benzene rings of 4.27 (8)°. In the crystal, the anion ring is almost perpendicular to the aromatic rings of the cation; the sulfonate-substituted benzene ring forms dihedral angles of 89.60 (8) and 89.37 (8)°, respectively, with the pyridinium and benzene rings of the cation. In the crystal, the three components are linked into a three-dimensional network by O—H...O and C—H...O hydrogen bonds. π–π inter­actions with centroid–centroid distances of 3.6999 (9) and 3.7106 (9) Å are also present.