Synthesis,antityrosinase activity of curcumin analogues,and crystal structure of (1<Emphasis Type="Italic">E</Emphasis>,4<Emphasis Type="Italic">E</Emphasis>)-1,5-bis(4-ethoxyphenyl)penta-1,4-dien-3-one

Five derivatives of curcumin analogue (R = OCH₂CH₃ (1), R = N(CH₃)₂ (2), R = 2,4,5-OCH₃ (3), R = 2,4,6-OCH₃ (4), and R = 3,4,5-OCH₃ (5)) were synthesized and characterized by ¹H NMR, FT-IR and UV–Vis spectroscopy. The synthesized derivatives were screened for antityrosinase activity, and found that 4 and 5 possess such activity. The crystal structure of 1 was determined by single crystal X-ray diffraction: monoclinic, sp. gr. P2₁/c, a = 17.5728(15) Å, b = 5.9121(5) Å, c = 19.8269(13) Å, β = 121.155(5)°, Z = 4. The molecule 1 is twisted with the dihedral angle between two phenyl rings being 15.68(10)°. In the crystal packing, the molecules 1 are linked into chains by C?H···π interactions and further stacked by π···π interactions with the centroid–centroid distance of 3.9311(13) Å.     

Synthesis and structure of oxovanadium(IV) complexes [VO(<Emphasis Type="Italic">Acac</Emphasis>)<Subscript>2</Subscript>] and [VO(<Emphasis Type="Italic">Sal</Emphasis>: <Emphasis Type="Italic">L</Emphasis>-alanine)(H<Subscript>2</Subscript>O)]

Bis(acetylacetonato)oxovanadium C₁₀H₁₄O₅V (I) and (S)-[2-(N-salicylidene)aminopropionate]oxovanadium monohydrate C₁₀H₉NO₅V (II) are synthesized. The crystal structures of compounds I and II are determined using single-crystal X-ray diffraction. Crystals of compound I are triclinic, a = 7.4997(19) Å, b = 8.2015(15) Å, c = 11.339(3) Å, α = 91.37(2)°, β = 110.36(2)°, γ = 113.33(2)°, Z = 2, and space group \(P\bar 1\). Crystals of compound II are monoclinic, a = 8.5106(16) Å, b = 7.373(2) Å, c = 9.1941(16) Å, β = 101.88(1)°, Z = 2, and space group P2₁. The structures of compounds I and II are solved by direct methods and refined to R₁ = 0.0382 and 0.0386, respectively. The oxovanadium complexes synthesized are investigated by vibrational spectroscopy.     

Crystal structures of complexes of the <Emphasis Type="Italic">cys-syn-cys</Emphasis> isomer of dicyclohexano-18-crown-6 with oxonium hexafluorotantalate and oxonium hexafluoroniobate

The crystal structures of [(cys-syn-cys-dicyclohexano-18-crown-6 · H₃O)][TaF₆] and [(cys-syn-cys-dicyclohexano-18-crown-6 · H₃O)][NbF₆] complex compounds are determined using X-ray diffraction analysis. The tantalum complex has two polymorphic modifications, namely, the monoclinic (I) and triclinic (II) modifications. The unit cell parameters of these compounds are as follows: a = 8.507(4) Å, b = 11.947(5) Å, c = 27.392(12) Å, β = 93.11(1)°, Z = 4, and space group P2₁/n for modification I; and a = 10.828(1) Å, b = 11.204(1) Å, c = 12.378(1) Å, α = 72.12(1)°, β = 79.40(1)°, γ = 73.70(1)°, Z = 2, and space group P-1 for modification II. The triclinic niobium complex [(cys-syn-cys-dicyclohexano-18-crown-6 · H₃O)][NbF₆] (III) with the unit cell parameters a = 10.796(3) Å, b = 11.183(3) Å, c = 12.352(3) Å, α = 72.364(5)°, β = 79.577(5)°, γ = 73.773(4)°, Z = 2, and space group P-1 is isostructural with tantalum complex II. The structures of all three complexes are ionic in character. The oxonium cation in complexes I–III is encapsulated by the crown ether and thus forms one ordinary and two bifurcated hydrogen bonds with the oxygen atoms of the crown ether. This macrocyclic cation is bound to the anions through the C-H...F contacts (H...F, 2.48–2.58 Å). The conformation of the macrocycle in complex I differs substantially from that in complex II (III).     

Synthesis and structural characterization of a Cu(I) complex with 4-(1<Emphasis Type="Italic">H</Emphasis>-imidazol-1-yl)phenyl)methanone ligands

A copper complex with V-shaped ligands, [(L¹)Cu₂Cl₂] _n (1), (L1 = 4-(1H-imidazol-1-yl)phenyl) methanone) has been synthesized and characterized by IR spectroscopy, elemental analyses and singlecrystal X-ray diffraction. The crystal of 1 is monoclinic, sp. gr. C2/_c with the unit cell parameters a = 17.9496(13), b = 15.3440(13), c = 7.2983(7) Å, and β = 112.875(6)°, Z = 4, R₁ = 0.0681, and wR₂ = 0.1736 (I > 2 σ). The solid state structure of 1 consists of 2D metal aromatic chloride layers, which are propagating along the bc plane to form a 3D network through hydrogen bonds.     

Synthesis and Crystal Structures of Ethyl 2-(4-Methoxyphenyl)-1<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">d</Emphasis>]imidazole-5-carboxylate Dihydrate and Its Building Block 4-Fluoro-3-nitrobenzoic Acid

The title compound, ethyl 2-(4-methoxyphenyl)-1H-benzo[d]imidazole-5-carboxylate dihydrate (5), was synthesized and its crystal structure was studied by single-crystal X-ray diffraction technique. Compound 5 is crystallized in the centrosymmetric triclinic space group \(P\bar {1}\) with Z?=?4 and Z′?=?2, and unit-cell parameters of a?=?8.9190 (3) Å, b?=?12.6888 (4) Å, c?=?14.7111 (5) Å, α?=?98.4855 (10)°, β?=?101.6379 (9)°, γ?=?95.4346 (10)° and V?=?1599.43 (9) ų. Its starting material, 4-fluoro-3-nitrobenzoic acid (1), is crystallized in the non-centrosymmetric monoclinic space group P2₁ and Z?=?4 with unit-cell parameters of a?=?3.7170 (4) Å, b?=?12.6475 (13) Å, c?=?15.5237 (15) Å, α?=?90°, β?=?91.9786 (16)°, γ?=?90° and V?=?729.35 (13) ų. It was noted that strong hydrogen bonds play important roles in the crystal packing of both compounds, especially in 5, in which the co-crystallized water molecules act as both strong hydrogen bond donor and strong hydrogen bond acceptor.

Graphical Abstract

Two molecule of compound 5 crystallized in a non symmetrical manner with four co-crystallized water molecules which play an important role in the crystal packing as strong hydrogen-bond donors.

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Crystal structure of 2-(thiophen-2-yl)-1-(5-thioxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)ethenyl]benzamide : <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylformamide (1 : 1)

The title compound, 2-(thiophen-2-yl)-1-(5-thioxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)ethenyl] benzamide:N,N-dimethylformamide (1: 1), (C₁₅H₁₁N₃O₂S₂ · C₃H₇NO), was synthesized, and its structure was established by spectral analysis and X-ray diffraction studies. The compound crystallizes in the monoclinic space group P2₁/n with a = 10.8714(7), b = 9.0497(5), c = 19.8347(13) Å, β = 91.093(5)°, Z = 4. The crystal structure is stabilized by N–H···S, C–H···O and N–H···O hydrogen bonds. The π···π interactions are also observed between the rings.     

X-ray crystal structures of two polymorphic forms,monoclinic and triclinic,of: 1-[(<Emphasis Type="Italic">E</Emphasis>)-2-(4-bromophenyl)1-diazenyl]-3-({3-[(<Emphasis Type="Italic">E</Emphasis>)-2-(4-bromophenyl)-1-diazenyl]-6-ethylhexahydro-1-pyrimidinyl}methyl)-4-ethylhexahydropyrimidine

1-[(E)-2-(4-bromophenyl)-1-diazenyl]-3-({3-[(E)-2-(4-bromophenyl)-1-diazenyl]-6-ethylhexahydro-1-pyrimidinyl}methyl)-4-ethylhexahydropyrimidine (1) has been synthesized by reaction of a mixture of formaldehyde and 1,3-pentanediamine{DYTEK^®EPdiamine} with p-bromobenzenediazonium chloride. This compound crystallizes in two polymorphic forms 1-α and 1-β whose crystal structures have been determined by single crystal X-ray diffraction analysis. Both polymorphs 1-α and 1-β display crystallographic disorder within the hexahydropyrimidine rings. The molecule of 1 is built up of two equivalent 3-(aryldiazenyl)-6-ethylhexahydro-1-pyrimidinyl groups in the s-trans orientation around the central methylene group (C13). In both structures the triazene moieties adopt the anti configuration around the N=N bonds, displaying significant π-conjugation. The crystal packings are determined only by van der Waals interactions. The crystal structures of 1-α and 1-β are compared with the previously reported structure of the 5,5-dimethylhexahydropyrimidine analogue 3. Compounds 1 and 3 are isomeric with respect to the hexahydropyrimidine moiety. The structures of 1 and 3 are very different in one respect; in 1 the aryldiazenyl-hexahydropyrimidinyl groups are in the s-trans orientation around the central methylene group, whereas in 3 the arrangement of the aryldiazenylhexahydropyrimidinyl groups is the s-cis orientation. Crystal data: 1-α C₂₅H₃₄N₈Br₂, monoclinic, space group P2(1)/c, a = 9.2150(3), b = 19.4059(6), c = 15.4324(5) Å, β = 98.738(1)^°, V = 2727.7(2) ų, for Z = 4; 1-β C₂₅H₃₄N₈Br₂, triclinic, space group P-1, a = 9.6009(3), b = 10.7509(4), c = 14.2169(5) Å, α = 99.830(2), β = 105.973(3), γ = 95.578(1)^°, V = 1373.9(1) ų, for Z = 2.     

Synthesis of 2-arylidenebenzocycloalkanones containing <Emphasis Type="Italic">N</Emphasis>-donor heterocyclic rings

A series of 2-arylidenebenzocycloalkanones containing heterocyclic rings 1–8 were prepared and characterized by IR, ¹H NMR and elemental analyses. X-ray diffraction study of 6 reveals that the cyclohexyl ring of the 3,4-dihydronaphthalen-1(2H)-one adopts a chair conformation with a maximum deviation of 0.547(3) Å and makes dihedral angles of 52.24(17)° and 11.23(16)°, respectively, with the benzene plane and the mean plane of the benzimidazole ring.     

Crystal structure of (2<Emphasis Type="Italic">Z</Emphasis>)-(3,3-dimethyl-3,4-dihydroisoquinolin- 1(2<Emphasis Type="Italic">H</Emphasis>)-ylidene)nitrosoacetonitrile

The crystal structure of (2Z)-(3,3-dimethyl-3,4-dihydroisoquinolin-1(2Н)-ylidene)nitrosoacetonitrile is determined (T = 150 K, R1 = 0.0435). The compound crystallizes as the E-cis and Z-cis isomers of the nitroso tautomer. Two independent molecules differ in the rotation of the nitroso group about the С–С bond between the dihydroisoquinoline group and the substituent. Analysis of bond lengths reveals their conjugation and prevailing contribution of the zwitter-ionic structures with the positive charge located on the isoquinoline fragment and the negative charge located on the substituent. Molecules having E and Z conformations are connected by the N–H···O hydrogen bond (N···O 2.922(3) Å) into dimers. The N–H group of the other molecule forms the intramolecular N–H···O hydrogen bond (N···O 2.544(3) Å) which closes a sixmembered cycle. Electronic absorption spectra are studied, and quantum-chemical modeling of the compound is performed.     

The synthesis and crystal structure of (4<Emphasis Type="Italic">E</Emphasis>)-5(3-chlorophenyl)-<Emphasis Type="Italic">N</Emphasis>-(4-chlorophenyl)-2-diazo3-oxopent-4-enoic acid amide

(4E)-5-(3-Chlorophenyl)-N-(4-chlorophenyl)-2-diazo-3-oxopent-4-enoic acid amide (5) was synthesized from p-chloroaniline to N-(4-chlorophenyl)-2-diazo-3-oxo-butyramide (4) with 3-chlorobenzaldehyde. The yielded product 5 was investigated with X-ray crystallographic, NMR, MS, and IR techniques. Compound 5 (C₁₇H₁₁Cl₂N₃O₂, Formula wt = 360.19), crystallizes in the monoclinic space group P21/c with unit cell parameters a = 10.516(2), b = 17.996(4), c = 8.902(2) Å, α = 90.00, β = 105.36(3), γ = 90.00^°. V = 1624.5(6) ų, Z = 4, D _x = 1.473 Mg m^?3. The final R was 0.0511.     

Crystal structure of <Emphasis Type="Italic">L</Emphasis>-alanine phosphate

The crystal structure of L-alanine phosphate (C₃O₂NH₇ · H₃PO₄) is determined by the single-crystal diffraction technique; a = 11.918(1) Å, b = 9.117(1) Å, c = 7.285(1) Å, γ = 104.7(1)°, space group P2₁, and Z = 4. The amino group of the alanine is protonated by the hydrogen atom of the phosphoric acid. Pairs of H₂PO ₄ ^? hydrogen-bonded ions are packed into layers alternating with layers of alanine molecules in the crystal. No hydrogen bonds are formed immediately between the alanine molecules.     

X-ray crystallography of methyl (6-amino-5-cyano-2-methyl-4-(2-nitrophenyl)-4<Emphasis Type="Italic">H</Emphasis>-pyran)-3-carboxylate

The organic carbonitrile namely methyl (6-amino-5-cyano-2-methyl-4-(2-nitrophenyl)-4H-pyran)- 3-carboxylate is synthesized via one-pot multi-component reaction at room temperature using commercially available urea as inexpensive and environmentally benign organo-catalyst and its crystal structure is determined by X-ray technique. The crystals are monoclinic, sp. gr. C2/c, a = 12.3069(8) Å, b = 9.7023(7) Å, c = 24.812(2) Å, β = 94.862(6)°, Z = 8. The dihedral angle between pyran and phenyl rings is 87.8(1)°; the pyran ring is almost planar The dihedral angle between the mean planes of phenyl ring and nitro group is 44.4(2)°. The crystal structure is stabilized by N?H···N and N?H···O hydrogen bonds. In addition, C?H···π interactions are also observed in the crystal structure.     

Synthesis,Characterization, Crystal Structure,and Hirshfeld Surface Analysis of Ethyl 2-(4-bromophenyl)-1-cyclohexyl-1<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">d</Emphasis>]imidazole-5-carboxylate

The title compound, C₂₂H₂₃N₂BrO₂ was synthesized via one-pot reductive cyclization method and characterized by CNH analysis, FT-IR, UV-visible, mass, ¹H and ¹³C NMR spectra, thermogravimetric analysis (TGA) and single crystal X-ray diffraction method. The compound crystallizes in monoclinic crystal system: sp. gr. P2₁/c, Z = 4. The crystal data reveals that the intermolecular interactions of the C–H···π and π···π type connect the molecules which was also visualized with the help of Hirshfeld surface analysis.     

X-Ray Crystal Structure of <Emphasis Type="Italic">trans</Emphasis>-PdCl<Subscript>2</Subscript>(PPh<Subscript>2</Subscript>C<Subscript>12</Subscript>H<Subscript>7</Subscript>S<Subscript>3</Subscript>)<Subscript>2</Subscript>, a New Morphology

Herein we report the crystal structure of trans-PdCl₂(PPh₂C₁₂H₇S₃)₂, 1, in a different morphology than has previously been reported [Stott et al. (Dalton Trans (4):652–653, 2005]. This structure crystallizes in a P-1 space group with a = 9.4249(19) Å, b = 11.540(2) Å, c = 12.559(3) Å, α = 79.07(3)°, β = 78.04(3)°, γ = 69.44(3)°, Z = 1. The earlier structure possessed a P2₁/n space group. Additionally the terthienyl moieties of 1 demonstrate the anti orientation exclusively while the P2₁/n space group structure has some syn and even syn/anti mixed geometries included.     

Crystal structure of <Emphasis Type="Italic">L</Emphasis>-serine phosphate

The crystal structure of L-serine phosphate (C₃O₃NH₇ · H₃PO₄) is determined by single-crystal X-ray diffraction. The unit cell parameters are as follows: a = 9.134(5) Å, b = 9.489(5) Å, c = 4.615(5) Å, γ = 99.54(5)°, space group P2₁, and Z = 2. The amino group of serine is protonated by a hydrogen atom of the phosphoric acid. The H₂PO ₄ ^1? ions are linked by hydrogen bonds into infinite ribbons aligned along the twofold screw axes. The ribbons form layers alternating with layers of serine molecules, which are directly linked by hydrogen bonds.     

Crystal structure of <Emphasis Type="Italic">p</Emphasis>-carboxyphenylhydrazone benzoylacetone

The crystal structure of p-carboxyphenylhydrazone benzoylacetone is determined. The crystals are monoclinic, a = 13.614(4) Å, b = 11.388(2) Å, c = 20.029(6) Å, β = 104.82(2)°, V = 2339(9) ų, Z = 8, space group C2/c, and R = 0.038 for 1622 reflections with I > 2σ(I). The crystal is built of C₁₇H₁₄N₂O₄ neutral molecules that are linked by O-H?O hydrogen bonds between the carboxyl groups into centrosymmetric pseudodimers. The effect of carboxylation of the phenylhydrazone fragment and the position of the carboxyl group on the molecular packing in the crystal is determined. The N(1)-H(1N)?O(1) intramolecular hydrogen bond (N-H, 0.94 Å; H?O, 1.87 Å; N?O, 2.59 Å; and the N-H?O angle, 133°) is formed in the molecule.     

Crystal structure of (<Emphasis Type="Italic">E</Emphasis>)-3-fluoro-N-((5-nitrothiophen-2-yl)methylene)aniline

The structure of the title compound C₁₁H₇FN₂O₂S was characterized by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P2₁/n with Z = 12, i.e. with three molecules in asymmetric unit. The molecules are not planar: the dihedral angles between the planes of thiophene and the benzene rings are 42.3(3)°, 42.0(3)°, and 48.9(2)°. In the crystal, intermolecular C–H···F interactions link the molecules through R₂² (14) ring motif. The crystal packing is also stabilized by π···π interactions.     

X-ray mapping in heterocyclic design: XV. Tricyclic heterocycles based on 2-oxo-2,5,6,7-tetrahydro-1<Emphasis Type="Italic">H</Emphasis>-cyclopenta[<Emphasis Type="Italic">b</Emphasis>]pyridine-3-carbonitrile

The structures of five compounds are studied using single-crystal X-ray diffraction: 2-oxo-2,5,6,7-tetrahydro-1H-cyclopenta[b]pyridine-3-carbonitrile [a = 15.641(8) Å, b = 9.373(5) Å, c = 7.387(4) Å, β = 92.91(5)°, Z = 4, space group P2₁/c]; 1-[2-(4-chlorophenyl)-2-oxoethyl]-2-oxo-2,5,6,7-tetrahydro-1H-cyclopenta[b]pyridine-3-carbonitrile [a = 4.728(4) Å, b = 28.035(11) Å, c = 11.184(3) Å, Z = 4, space group P2₁2₁2₁]; 2-[2-(4-chlorophenyl)-2-oxoethoxy]-6,7-dihydro-5H-cyclopenta[b]pyridine-3-carbonitrile [a = 10.1202(13) Å, b = 11.2484(18) Å, c = 13.4323(19) Å, β = 102.05(1)°, Z = 4, space group P2₁/c]; 2-(4-chlorophenyl)-3a, 6,7,8-tetrahydrocyclopenta[e][1.3]oxazolo[3.2-a]pyridine-4-carboxamide perchlorate [a = 7.702(2) Å, b = 9.599(3) Å, c = 23.798(5) Å, β = 93.44(2)°, Z = 4, space group P2₁/c]; and (3-amino-6,7-dihydro-5H-cyclopenta[b]furo[3.2-e]pyridin-2-yl)(4-chlorophenyl)methanone [a = 7.3273(2) Å, b = 13.390(3) Å, c = 28.792(8) Å, Z = 8, space group Pbca]. The structures are solved using direct methods and refined by the full-matrix least-squares procedure in the anisotropic approximation to R = 0.0580, 0.0724, 0.0469, 0.0477, and 0.0418, respectively.     

Cluster self-organization of crystal-forming systems: Suprapolyhedral cluster precursors and self-assembly of the icosahedral structure of ZrZn<Subscript>22</Subscript>(<Emphasis Type="Italic">c</Emphasis>F184)

The mechanism of self-assembly of symmetrically and topologically different chains and microlayers (in the form of planar nets) from cyclic three-node clusters A ₃ is considered in the model system. The obtained nets correspond to the uninodal Shubnikov nets N 3 12 12 and N 3 6 3 6 and the new binodal net N1 3 6 3 6 + N2 3 3 6 6 (1: 2). A complete three-dimensional reconstruction of the self-assembly of the icosahedral structure of the ZrZn₂₂ compound (cF184) is performed using computer methods (with the TOPOS program package) according to the following scheme: cluster precursor → primary chain → microlayer → microframework (supraprecursor) → ... → framework. It is revealed that the suprapolyhedral cluster precursor (nanocluster ～12 Å in size) of the AB ₂ composition is formed by three polyhedra shared by vertices in a cyclic manner: the A-ZrZn₁₆ polyhedron (sixteen-vertex polyhedron with the point symmetry \(\bar 4\)3m) and two B-ZrZn₁₂ polyhedra (icosahedra with the point symmetry \(\bar 3\) m). The AB ₂ cluster precursor in the structure retains the symmetry m. It is established that the structural mechanism of self-assembly of the two-dimensional layer in the ZrZn₂₂ structure is described by the binodal net N1 3 6 3 6 + N2 3 3 6 6 (1: 2) constructed in the modeling.     

Specific stereochemical features of metallochelate complexes with tridentate <Emphasis Type="Italic">N,N,N</Emphasis>(<Emphasis Type="Italic">N,N</Emphasis>,O)-donating ligands

Earlier X-ray diffraction studies of a series of 12 adducts (I–XII) between metallochelate complexes [M = Co(II), Ni(II), and Cu(II)] with tridentate N,N,N(N,N,O)-donating Schiff bases (L) and monodentate or bidentate ligands (L′) revealed a similarity in the stereochemistry of these compounds. The coordination polyhedron of metal atoms in compounds I–XII is a tetragonal pyramid (bipyramid) with two vertices occupied competitively. The L ligand occupies three coordination sites in the base of the pyramid. The L′ ligand approaches the metal atom, as a rule, in a direction perpendicular to the basal plane. The fourth site in the base of the pyramid and the apical vertex are occupied competitively. Different patterns of occupation of these positions are observed: they include the donor atoms of both the L and L′ ligands.