Ethyl N‐[2‐(hydroxy­acetyl)­phenyl]­carbamate,ethyl N‐[2‐(hydroxy­acetyl)‐4‐iodo­phenyl]­carbamate and ethyl N‐[2‐(hydroxy­acetyl)‐4‐methyl­phenyl]­carbamate

In ethyl N‐[2‐(hydroxy­acetyl)phenyl]carbamate, C₁₁H₁₃NO₄, all of the non‐H atoms lie on a mirror plane in the space group Pnma; the mol­ecules are linked into simple chains by a single C—H⋯O hydrogen bond. The mol­ecules of ethyl N‐[2‐(hydroxy­acetyl)‐4‐iodo­phenyl]carbamate, C₁₁H₁₂INO₄, are linked into sheets by a combination of O—H⋯I and C—H⋯O hydrogen bonds and a dipolar I⋯O contact. Ethyl N‐­[2‐(hydroxy­acetyl)‐4‐methyl­phenyl]carbamate, C₁₂H₁₅NO₄, crystallizes with Z′ = 2 in the space group P; pairs of mol­ecules are weakly linked by an O—H⋯O hydrogen bond and these aggregates are linked into chains by two independent aromatic π–π stacking inter­actions.     

Hydrogen bonding in nitroaniline analogues: hydrogen‐bonded sheets in 2‐amino‐4,6‐dimethoxy‐5‐nitropyrimidine and π‐stacked hydrogen‐bonded sheets in 4‐amino‐2,6‐dimethoxy‐5‐nitropyrimidine

In 2‐amino‐4,6‐di­methoxy‐5‐nitro­pyrimidine, C₆H₈N₄O₄, the mol­ecules are linked by one N—H⋯N and one N—H⋯O hydrogen bond to form sheets built from alternating R(8) and R(32) rings. In isomeric 4‐amino‐2,6‐di­methoxy‐5‐nitro­pyrimidine, C₆H₈N₄O₄, which crystallizes with Z′ = 2 in P, the two independent mol­ecules are linked into a dimer by two independent N—H⋯N hydrogen bonds. These dimers are linked into sheets by a combination of two‐centre C—H⋯O and three‐centre C—H⋯(O)₂ hydrogen bonds, and the sheets are further linked by two independent aromatic π–π‐stacking interactions to form a three‐dimensional structure.     

rac‐(Z)‐Ethyl 2‐bromo‐2‐[(3R,5R)‐3‐bromo‐5‐methyl­tetra­hydro­furan‐2‐yl­idene]acetate

In the title compound, C₉H₁₂Br₂O₃, a (tetra­hydro­furan‐2‐yl­idene)acetate, the double bond has the Z form. In the tetra­hydro­furan group, the relative configuration of the Br atom in the 3‐position and the methyl group in the 5‐position is anti. The compound crystallizes with two independent mol­ecules per asymmetric unit and, in the crystal structure, the individual mol­ecules are linked to their symmetry‐equivalent mol­ecules by C—H⋯O hydrogen bonds, so forming centrosymmetric hydrogen‐bonded dimers.     

10‐(4‐Fluorophenyl)‐3,3,6,6,9‐pentamethyl‐3,4,6,7,9,10‐hexahydroacridine‐1,8(2H,5H)‐dione and 10‐(4‐fluorophenyl)‐3,3,6,6‐tetramethyl‐9‐­propyl‐3,4,6,7,9,10‐hexahydroacridine‐1,8(2H,5H)‐dione

10‐(4‐Fluoro­phenyl)‐3,3,6,6,9‐penta­methyl‐3,4,6,7,9,10‐hexa­hydro­acridine‐1,8(2H,5H)‐dione, C₂₄H₂₈FNO₂, (I), crystallizes with two crystallographically independent mol­ecules (which differ slightly in conformation), while 10‐(4‐fluoro­phenyl)‐9‐propyl‐3,3,6,6‐tetra­methyl‐3,4,6,7,9,10‐hexa­hydro­acridine‐1,8(2H,5H)‐dione, C₂₆H₃₂FNO₂, (II), crystallizes with one mol­ecule per asymmetric unit. In both structures, the central ring in the acridine moiety is in a sofa conformation, while the outer rings adopt intermediate half‐chair/sofa conformations. The central pyridine ring is orthogonal to the substituted phenyl ring. In both structures, the packing of the crystal is stabilized by C—H?O intermolecular hydrogen bonds.     

Methyl 4‐(2‐chloro‐5‐nitro­phenyl)‐2,7,7‐tri­methyl‐5‐oxo‐1,4,5,6,7,8‐hexa­hydro­quinoline‐3‐carboxyl­ate

The title compound, C₂₀H₂₁ClN₂O₅, has potential calcium modulatory properties. The 1,4‐di­hydro­pyridine ring has the usual shallow boat conformation. The 2‐chloro‐5‐nitro­phenyl ring is oriented such that the chloro substituent is in a synperiplanar orientation with respect to the 1,4‐di­hydro­pyridine ring plane, while the nitro substituent sits over the 1,4‐di­hydro­pyridine ring. The cyclo­hexenone ring has a conformation that is approximately half‐way between that of an envelope and that of a half‐chair. The mol­ecules are linked into chains by intermolecular N—H⋯O hydrogen bonds.     

16‐(4‐Cyanobenzylidene)‐3β‐pyrrolidinoandrost‐5‐en‐17β‐ol monohydrate

In the title compound, C₃₁H₄₀N₂O·H₂O, the outer two six‐membered rings are in chair conformations, while the central ring is in an 8β,9α‐half‐chair conformation. The five‐membered ring adopts a 13β‐envelope conformation and the cyano­benzyl­idene moiety has an E configuration with respect to the hydroxyl group at position 17. The steroid nuclei are linked by intermolecular O—H?O and O—H?N hydrogen bonds to form a molecular network. The molecular packing has an interesting feature, with the steroids aligned parallel to the b axis, forming a closed loop through hydrogen bonds linked via water mol­ecules.     

Adducts of 1,1,1‐tris(4‐hydroxy­phenyl)­ethane with 1,2‐bis(4‐pyridyl)­ethane and 1,2‐bis(4‐pyridyl)­ethene: continuously interwoven structures in three dimensions

In the adduct 1,2‐bis(4‐pyridyl)­ethane–1,1,1‐tris(4‐hydroxy­phenyl)­ethane (1/2), C₁₂H₁₂N₂·2C₂₀H₁₈O₃, the bipyridyl component lies across an inversion centre in P. The tris‐phenol mol­ecules [systematic name: 4,4′,4′′‐(ethane‐1,1,1‐triyl)­triphenol] are linked by O—H?O hydrogen bonds to form sheets built from R(38) rings, and symmetry‐related pairs of sheets are linked by the bipyridyl mol­ecules via O—H?N hydrogen bonds to form open bilayers. Each bilayer is interwoven with two adjacent bilayers, forming a continuous three‐dimensional structure. In the adduct 1,2‐bis(4‐pyridyl)­ethene–1,1,1‐tris(4‐hydroxy­phenyl)­ethane–methanol (1/1/1), C₁₂H₁₀N₂·C₂₀H₁₈O₃·CH₄O, the mol­ecules are linked by O—H?O and O—H?N hydrogen bonds into three interwoven three‐dimensional frameworks, generated by single spiral chains along [010] and [001] and a triple‐helical spiral along [100].     

1‐(2‐Hydro­xy‐4‐methoxy­phenyl)‐3‐(2,3,4‐tri­methoxy­phenyl)­prop‐2‐en‐1‐one

The title compound, C₁₉H₂₀O₆, crystallizes in the centrosymmetric space group P2₁/c with one mol­ecule in the asymmetric unit. The mol­ecule is approximately planar and the dihedral angle between the phenyl rings is 11.0 (1)°. The H atoms of the central propenone group are trans. There is an intramolecular O—H⃛O hydrogen bond and the mol­ecules are crosslinked by four intermolecular C—H⃛O hydrogen bonds, producing a three‐dimensional network.     

Cyclo(l‐leucyl‐α,β‐dehydro­phenyl­alanine): the first diketopiperazine containing an α,β‐dehydro­phenyl­alanine residue

The title compound (systematic name: 3‐benzyl­idene‐6‐iso­butyl­piperazine‐2,5‐dione), C₁₅H₁₈N₂O₂, an α,β‐dehydro­phenyl­alanine containing diketopiperazine, crystallizes in the space group P1 with two mol­ecules in the asymmetric unit arranged antiparallel to one another. The α,β‐dehydro­phenyl­alanine (ΔPhe) residue in this cyclic peptide retains its planarity but deviates from the standard conformations observed in its linear analogues. Each type of mol­ecule forms a linear chain with mol­ecules of the same type via pairwise N—H⋯O hydrogen bonds, while weaker C—H⋯O inter­actions link the chains together to form a three‐dimensional network.     

Bis­[4‐(2‐pyridyl­methyl­ene­amino)­phenyl] ether

The title compound, C₂₄H₁₈N₄O, is a bis‐bidentate Schiff base ligand exhibiting pseudo‐C₂ symmetry. The mol­ecule is twisted about the central ether linkage and exhibits an imine E configuration. In the crystal, the mol­ecules are linked by weak intermolecular C—H?N hydrogen bonds.     

3′,4′‐Bis(4‐chloro­phenyl)­spiro­[chroman‐3,5′(4′H)‐isoxazol]‐4‐one

The title compound, C₂₃H₁₅Cl₂NO₃, crystallizes with two independent mol­ecules in the asymmetric unit. The chroman­one moiety consists of a benzene ring fused with a six‐membered heterocyclic ring which adopts a sofa conformation. The five‐membered spiro­isoxazoline ring is in an envelope conformation. The p‐chloro­phenyl rings bridged by the five‐membered ring are nearly perpendicular to each other. The chromanone moiety of one mol­ecule packs into the cavity formed by the p‐chloro­phenyl rings of a second mol­ecule through the formation of C—H?π interactions. The structure is stabilized by weak C—H?O, C—H?Cl and C—H?π interactions.     

5‐Chloro‐N‐(2‐hydroxy‐5‐methyl­phenyl)­salicyl­ald­imine

The title compound, N‐(5‐chloro‐2‐oxido­benzyl­idene)‐2‐hydroxy‐5‐methyl­anilinium, C₁₄H₁₂ClNO₂, is a tridentate Schiff base with almost planar molecules. Each mol­ecule contains a strong intramolecular N—H?O hydrogen bond [2.576 (2) Å]. There is also an intermolecular O—H?O hydrogen bond [2.695 (2) Å] linking neighbouring mol­ecules into infinite chains along the [101] direction.     

N‐(2‐Amino‐1,6‐di­hydro‐5‐nitro­so‐6‐oxopyrimidin‐4‐yl)‐l‐isoleucine–water (4/1): interplay of molecular and supramolecular structures

In the title compound, 2C₁₀H₁₅N₅O₄·0.5H₂O, there are two independent mol­ecules of the pyrimidinyl­isoleucine in general positions and a water mol­ecule lying on a twofold rotation axis. The bond lengths within the organic moieties demonstrate significant polarization of the electronic structure. Each of the organic mol­ecules participates in 12 intermolecular hydrogen bonds, of O—H?O and N—H?O types, while the water mol­ecule acts as a double donor and as a double acceptor of O—H?O hydrogen bonds. The organic components are linked by the hydrogen bonds into a single three‐dimensional framework, reinforced by the water mol­ecules.     

2′‐(4‐Fluoro­phenyl)‐[1,2,3]­triazolo[4′,5′:16,17]­androst‐5‐en‐3β‐ol methanol hemisolvate

The asymmetric unit of the title compound, C₂₅H₃₀FN₃O·0.5CH₃OH, contains four symmetry‐independent steroid and two methanol mol­ecules. The conformations of the independent steroid mol­ecules are very similar. Intermolecular O—H⋯O hydrogen bonds create two independent chains, each of which links two of the independent steroid mol­ecules plus one methanol mol­ecule via a co‐operative O—H⋯O—H⋯O—H pattern. Intermolecular C—H⋯O and C—H⋯F interactions are also observed.     

4,4′‐Bis(4‐iodo­phenyl­amino­methyl)­azoxy­benzene: hydrogen‐bonded sheets built from C—H⃛O and C—H⃛π(arene) hydrogen bonds

Borohydride reduction of N‐(4‐nitro­benzyl­idene)‐4‐iodo­aniline has yielded the title compound, 1,2‐bis­[4‐(4‐iodo­phenyl­amino­methyl)­phenyl]­diazene 1‐oxide, C₂₆H₂₂I₂N₄O. The mol­ecules lie across centres of inversion in P2₁/c, with the azoxy O atom disordered over two sites, each having an occupancy of 0.5. The mol­ecules are linked into sheets by a combination of C—H⃛O and C—H⃛π(arene) hydrogen bonds.     

Inclusion compounds of 2,5‐di­phenyl­hydro­quinone

The crystal structures of three 1:2 inclusion compounds that consist of host mol­ecule 2,5‐di­phenyl­hydro­quinone (C₁₈H₁₄O₂) and the guest mol­ecules 2‐pyridone (C₅H₅NO), 1,3‐di­phenyl‐2‐propen‐1‐one (chalcone, C₁₅H₁₂O) and 1‐(4‐meth­oxy­phenyl)‐3‐phenyl‐2‐propen‐1‐one (4′‐methoxy­chal­cone, C₁₆H₁₄O₂) were determined in order to study the ability of guest mol­ecules in inclusion compounds to undergo photoreaction. All of the crystals were found to be photoresistant. The three inclusion compounds crystallize in triclinic space group . In each case, the host/guest ratio is 1:2, with the host mol­ecules occupying crystallographic centers of symmetry and the guest mol­ecules occupying general positions. The guest mol­ecules in each of the inclusion compounds are linked to the host mol­ecules by hydrogen bonds. In the inclusion compound where the guest mol­ecule is pyridone, the host mol­ecule is disordered so that the hydroxy groups are distributed between two different sites, with occupancies of 0.738 (3) and 0.262 (3). The pyridone mol­ecules form dimers via N—H⋯O hydrogen bonds.     

2‐Hydroxy‐3‐(3‐oxobut­yl)naphthalene‐1,4‐dione

The title compound, C₁₄H₁₂O₄, forms crystals which appear monoclinic but are actually twinned triclinic. The asymmetric unit consists of two similar mol­ecules, which differ only in the conformation of the 3‐oxobutyl side chain. The mol­ecular conformation is characterized by an intra­molecular O—H⋯O hydrogen bond between the hydroxy group and the adjacent carbonyl O atom. The crystal structure is stabilized by O—H⋯O hydrogen bonds connecting the mol­ecules into zigzag chains running along the b axis.     

Self‐assembly of 2‐pivaloyl‐6‐chloro­pterin

In the title compound, N‐(6‐chloro‐4‐oxo‐3,4‐di­hydro­pteridin‐2‐yl)­‐2,2‐di­methyl­propan­amide, C₁₁H₁₂ClN₅O₂, the rings in the pterin moiety are planar. The amide carbonyl O atom is in syn‐periplanar conformation while the C—N—C—C propanamide linkage is antiperiplanar. The N—H?N and N—H?O intermolecular hydrogen bonds transform the mol­ecules into infinite chains.     

The new chiral ligand 3‐ethoxy‐4‐[(1R,2S)‐(2‐hydroxy‐1,2‐di­phenyl­ethyl)­amino]‐3‐cyclo­butene‐1,2‐dione

The asymmetric unit of C₂₀H₁₉NO₄ contains two mol­ecules with slightly different conformations. In the crystal, the mol­ecules are linked by O—H?O and N—H?O hydrogen bonds [O?O 2.764 (3) and 2.811 (3) Å; N?O 2.907 (3) and 2.968 (3) Å] to form a two‐dimensional network.     

Triclinic and orthorhombic polymorphs of 2‐iodo‐4‐nitro­aniline: interplay of hydrogen bonds,nitro⃛I interactions and aromatic π–π‐stacking interactions

In the triclinic polymorph of 2‐iodo‐4‐nitro­aniline, C₆H₅IN₂O₂, space group P, the mol­ecules are linked by paired N—­H?O hydrogen bonds into C(8)[R(6)] chains of rings. These chains are linked into sheets by nitro?I interactions, and the sheets are pairwise linked by aromatic π–π‐stacking interactions. In the orthorhombic polymorph, space group Pbca, the mol­ecules are linked by single N—H?O hydrogen bonds into spiral C(8) chains; the chains are linked by nitro?O interactions into sheets, each of which is linked to its two immediate neighbours by aromatic π–π‐stacking inter­actions, so producing a continuous three‐dimensional ­structure.