Mean Plane Of Ring Research Articles

Synthesis and crystal structure of 1,3,5-tris[(1H-benzotriazol-1-yl)methyl]-2,4,6-triethylbenzene

In the crystal structure of the title compound, C33H33N9, the tripodal molecule exists in a conformation in which the substituents attached to the central arene ring are arranged in an alternating order above and below the ring plane. The three benzotriazolyl moieties are inclined at angles of 88.3 (1), 85.7 (1) and 82.1 (1)° with respect to the mean plane of the benzene ring. In the crystal, only weak molecular cross-linking involving C—H...N hydrogen bonds is observed.

Theoretical and experimental investigation on newly synthesized pyrazolopyridine derivatives: Insight into the compound activity, NLO response, and molecular dynamics

Pyrazolopyridine derivatives exhibiting biological activity are widely present in drug molecules. The title compound, ethyl 3-amino-6-methyl-4-(thiophen-2-yl)-1H-pyrazolo[3,4-b]pyridine-5-carboxylate (II), was designed and synthesized and the structure characterized by spectroscopic techniques and confirmed by single-crystal X-ray diffraction. The pyrazolopyridine moiety is not quite planar and the thiophene and ester groups are rotated well out of the mean plane of the pyridine ring. N—H···N and C—H···O hydrogen bonds plus π-stacking interactions form thick layers of molecules parallel to (001). Based on structural activity relationship studies, II exhibits potent activity against fibroblast collagenase-1 complexed to a diphenyl-ether sulphone-based hydroxamic acid or Matrix Metalloproteinase (MMP-1). Theoretical simulations were performed to probe the reactivity and electronic properties of II where the quantum theory of atoms in molecules and NBO analysis was used to describe the bonding nature and charge transfer excitation. The optical and nonlinear characteristics of II are also evidenced by its hyperpolarizability response. The kinetic and thermodynamic stability of II was monitored through a computed ab-initio molecular dynamics study. In addition, a Hirshfeld surface analysis was performed to assess the intermolecular interactions. Efficient binding of II in the MMP-1 complex system has been achieved through classical molecular dynamics and molecular docking calculations. An ADMET analysis was also carried out to explore the potential future drug candidacy of II.

Synthesis, crystal structure and Hirshfeld surface analysis of 1-[(1-octyl-1H-1,2,3-triazol-4-yl)methyl]-3-phenyl-1,2-di-hydro-quinoxalin-2(1H)-one.

In the title mol-ecule, C25H29N5O, the di-hydro-quinoxaline unit is not quite planar (r.m.s. deviation = 0.030 Å) as there is a dihedral angle of 2.69 (3)° between the mean planes of the constituent rings and the mol-ecule adopts a hairpin conformation. In the crystal, the polar portions of the mol-ecules are associated through C-H⋯O and C-H⋯N hydrogen bonds and C-H⋯π(ring) and C=O⋯π(ring) inter-actions, forming thick layers parallel to the bc plane and with the n-octyl groups on the outside surfaces.

Crystal Structure, Hirshfeld Surface Analysis, and Biological Activities of Schiff-Base Derivatives of 4-Aminoantipyrine.

Eight Schiff bases, synthesized by the reaction of 4-aminoantipyrine with different cinnamaldehydes, were studied in the solid state by using vibrational spectroscopy (IR) and X-ray diffraction techniques. The analysis was extended to the solution phase through ultraviolet-vis, fluorescence spectroscopy, and cyclic voltammetry. Finally, the crystal structures of four compounds (3b, 3d, 3g, and 3h) were determined and studied. In addition to the experimental study, theoretical calculations using the semiempirical method PM6/ZDO were performed to understand better the compound's molecular properties, UV-vis, and infrared spectra. The primary difference is the angular conformation of the terminal phenyl rings around the corresponding linking C-N and C-C σ-bonds. Furthermore, as a result of extended bonding, the > C=N- azomethine group-containing Cpyr-N=(CH)-(CR)=(CH)-Cbz chain (with R=H for 3b, 3d, and 3h, and R=CH3 for 3g) is planar, nearly coplanar, with the mean plane of the pyrazole ring. Hirshfeld surface (HS) analysis was used to investigate the crystal packing and intermolecular interactions, which revealed that intermolecular C-H···O and C-H···N hydrogen bonds, π···π stacking, and C-H···π and C=O···π interactions stabilize the compounds. The energy contributions to the lattice energies of potential hydrogen bonds were primarily dispersive and repulsive. All derivatives were tested in vitro on LPS-stimulated mouse macrophages to assess their ability to suppress the LPS-induced inflammatory responses. Only a slight reduction in the level of NO production was found in activated macrophages treated with 3h. Additionally, the derivatives were tested for antimicrobial activity against several clinical bacteria and fungi strains, including three biofilm-forming microorganisms. Nevertheless, only Schiff base 3f showed interesting antibacterial activities with minimum inhibitory concentration (MIC) values as low as 15.6 μM against Enterobacter gergoviae. On the other hand, Schiff base 3f and, to a lesser extent, 3b and 3h showed antifungal activity against clinical isolates of Candida. The lowest MIC value was for 3f against Candida albicans (15.6 μM). It is interesting to note that the same Schiff bases exhibit the highest activity in both biological evaluations.

Synthesis and crystal structures of two 1H-benzo[d]imidazole derivatives: DFT and anticorrosion studies, and Hirshfeld surface analysis.

The title benzimidazole compounds, namely, 2-(4-methoxynaphthalen-1-yl)-1H-benzo[d]imidazole, C18H14N2O (I) and 2-(4-methoxynaphthalen-1-yl)-1-[(4-methoxynaphthalen-1-yl)methyl]-1H-benzo[d]imidazole ethanol monosolvate, C30H24N2O2·C2H6O (II), were synthesized by the condensation reaction of benzene-1,2-diamine with 4-methoxynaphthalene-1-carbaldehyde in the ratios 1:1 and 1:2, respectively. In I, the mean plane of the naphthalene ring system is inclined to that of the benzimidazole ring by 39.22 (8)°, while in II, the corresponding dihedral angle is 64.76 (6)°. This difference is probably influenced by the position of the second naphthalene ring system in II; it is inclined to the benzimidazole ring mean plane by 77.68 (6)°. The two naphthalene ring systems in II are inclined to one another by 75.58 (6)°. In the crystal of I, molecules are linked by N-H...N hydrogen bonds to form chains propagating along the a-axis direction. Inversion-related molecules are also linked by a C-H...π interaction linking the chains to form layers lying parallel to the ac plane. In the crystal of II, the disordered ethanol molecule is linked to the molecule of II by an O-H...N hydrogen bond. There are a number of C-H...π interactions present, both intra- and intermolecular. Molecules related by an inversion centre are linked by C-H...π interactions, forming a dimer. The dimers are linked by further C-H...π interactions, forming ribbons propagating along the b-axis direction. The interatomic contacts in the crystal structures of both compounds were explored using Hirshfeld surface analysis. The molecular structures of I and II were determined by density functional theory (DFT) calculations at the M062X/6-311+g(d) level of theory and compared with the experimentally determined molecular structures in the solid state. Local and global reactivity descriptors were computed to predict the reactivity of the title compounds. Both compounds were shown to exhibit significant anticorrosion properties with respect to iron and copper.

Syntheses, crystal structures, Hirshfeld surface analyses and energy frameworks of two 4-amino-anti-pyrine Schiff base compounds: (E)-4-{[4-(di-ethyl-amino)-benzyl-idene]amino}-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one and (E)-4-[(4-fluoro-benzyl-idene)amino]-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one.

The title Schiff base compounds, C22H26N4O (I) and C18H16FN3O (II), were each synthesized by a single-step condensation reaction. The substituted benzyl-idene ring is inclined to the pyrazole ring mean planes by 22.92 (7)° in I and 12.70 (9)° in II. The phenyl ring of the 4-amino-anti-pyrine unit is inclined to the pyrazole ring mean plane by 54.87 (7)° in I and by 60.44 (8)° in II. In the crystal of I, the mol-ecules are linked by C-H⋯O hydrogen bonds and C-H⋯π inter-actions to form layers lying parallel to (001). In the crystal of II, the mol-ecules are linked by C-H⋯O and C-H⋯F hydrogen bonds and C-H⋯π inter-actions, thereby forming layers lying parallel to (010). Hirshfeld surface analysis was employed to further qu-antify the inter-atomic inter-actions in the crystals of both compounds.

Synthesis of <I>N</I>'-(2,3-dihydroxybenzylidene)-4-methylbenzohydrazide: Spectroscopic Characterization and X-ray Structure Determination

p-Toluic hydrazide was used for synthetizing a new Schiff base <I>N</I>'-(2,3-dihydroxybenzylidene)-4-methylbenzohydrazide (I). The prepared compound was characterized by elemental analysis, infrared and ¹H and ¹³C NMR spectroscopy techniques, and the structure of compound (I) was determined by single-crystal X-ray diffraction study. The compound (C₁₅H₁₄N₂O₃) crystallises in the monoclinic space group <I>P</I>2₁/<i>n</i> with the following unit cell parameters: <i>a</i> = 11.7820 (6) Å, <i>b</i> = 8.5278 (4) Å, <i>c</i> = 13.6054 (7) Å, <i>β</i> = 109.346 (5)°, <I>V </I>= 1289.81 (12) ų, <I>Z</I> = 4, <I>R</I>₁ = 0.071 and <i>wR</i>₂ = 0.197. The X-ray structure shows that the compound (I) adopts an <I>E</I> configuration with respect to the double bond C7=N1. The carbonyl oxygen atom O3 and the nitrogen atom N1 of the hydrazide moiety are in a <i>syn</i> conformation with respect to C8—N2 bond. The crystal packing of compound (I) is stabilized by intramolecular O(phenol)–H•••N(carbohydrazide) which results in an <I>S</I>(6) ring motif and intermolecular O(phenol)–H•••O(carbohydrazide) hydrogen bonds which form chains. The carbonohydrazide moiety C=N–N–C(O)–N–N=C fragment is almost coplanar with the two benzene rings with dihedral angles of their mean planes of 10.35° [C1—C6] and 7.99° [C9—C14], respectively. The dihedral angle between the mean planes of the phenyl rings is 2.46°.

Molecular structure analysis of 4-fluoro phenyl(4-methyl piperidin-1-yl) methanone and a comparative study of its optical, antimicrobial and antioxidant activities with 4-chloro phenyl (4-methyl piperidin-1-yl) methanone

A new fluoro derivative of 4-methyl piperidine (FPMPM) was synthesized by Scholten-Baumann condensation reaction, and the crystal structure was elucidated using single-crystal X-ray diffraction intensities. The molecules are arranged in monoclinic P21/n symmetry allowing for a dihedral angle of 36.76 (8)° observed between the mean plane of the benzene ring and the mean plane of the piperidine chair. Essentially projected non-bonded interactions were corroborated through Hirshfeld surface analysis. Predominant H…H and long-ranged halogen interactions packed with weak dispersion forces suggest the sizeable hydrophobic surface area. The chloro analogue (CPMPM) of FPMPM was compared for its FT-IR and FT-Raman spectra displaying their characteristic vibration modes of the functional groups. The bandgaps of 2.82 and 3.97 eV in FPMPM and CPMPM divulged by the Tauc's plots of UV–vis spectral data are concomitant with the optical band gaps disclosed by photoluminescence spectra. A longer delayed fluorescence lifetime of 31.5(8) and 33.1(1) ns with relatively high contribution confirmed the intermediate triplet state in the materials. The fast, prompt fluorescence decay of 3.72 (2) and 2.85 (1) ns in FPMPM and CPMPM with 54 (1) and 69 (1) % percent fractional contribution are promising shreds of evidence for the materials to act as an optical imaging fluorophore and an imminent scintillating material at moderate temperatures. Relatively moderate values of nonlinear susceptibility (3.44 and 3.85) × 10−6 (e. s. u.) and positive nonlinear absorption coefficient with z-scan measurements supported thermal concave lensing behavior and reverse saturable absorption in both the materials. Thermogravimetry coupled with Differential Scanning Calorimetry (DSC) declares the moderately low melting point (70.4 and 107 °C) for the material, FPMPM, and CPMPM, respectively. The F substituent in FPMPM possesses high hydrophobicity and lipophilicity, mitigating antibacterial activity, while moderate H…F and C-H…π interactions allow for susceptible antimicrobial activities. CPMPM exhibits robust antifungal activity against Trichoderma with reference to amphotericin-B. The antioxidant scavenging property is reflected by relatively high proton reactivity sites in FPMPM and hence relatively low % DPPH activity in CPMPM.

S-Shaped Fused Azacorannulene Dimer: Structural and Redox Properties

S-Shaped Fused Azacorannulene Dimer: Structural and Redox Properties

Crystal structure and Hirshfeld surface analysis of 4-bromo-2-[3-methyl-5-(2,4,6-tri-methyl-benz-yl)oxazolidin-2-yl]phenol.

The title compound, C20H24BrNO2, is chiral at the carbon atoms on either side of the oxygen atom of the oxazolidine ring and crystallizes as a racemate. The 1,3-oxazolidine ring adopts an envelope conformation with the N atom in an endo position. The mean plane of the oxazolidine ring makes dihedral angles of 77.74 (10) and 45.50 (11)°, respectively, with the 4-bromo-phenol and 1,3,5-tri-methyl-benzene rings. In the crystal, adjacent mol-ecules are connected via C-H⋯O hydrogen bonds and C-H⋯π inter-actions into layers parallel to the (200) plane. The packing is strengthened by van der Waals inter-actions between parallel mol-ecular layers. A Hirshfeld surface analysis shows that H⋯H (58.2%), C⋯H/H⋯C (18.9%), and Br⋯H/H⋯Br (11.5%) inter-actions are the most abundant in the crystal packing.

Syntheses and crystal structures of a nitro-anthracene-isoxazole and its oxidation product.

The syntheses and structures of an unexpected by-product from an iodination reaction, namely, ethyl 5-methyl-3-(10-nitro-anthracen-9-yl)isoxazole-4-carb-oxy-l-ate, C21H16N2O5, (I), and its oxidation product, ethyl 3-(9-hy-droxy-10-oxo-9,10-di-hydro-anthracen-9-yl)-5-methyl-isoxazole-4-carboxyl-ate, C21H17NO5 (V) are described. Compound (I) crystallizes with two mol-ecules in the asymmetric unit in which the dihedral angles between the anthracene fused-ring systems and isoxazole ring mean planes are 88.67 (16) and 85.64 (16)°; both mol-ecules feature a disordered nitro group. In (V), which crystallizes with one mol-ecule in the asymmetric unit, the equivalent dihedral angle between the almost planar anthrone ring system (r.m.s. deviation = 0.029 Å) and the pendant isoxazole ring is 89.65 (5)°. In the crystal of (I), the mol-ecules are linked by weak C-H⋯O inter-actions into a three-dimensional network and in the extended structure of (V), inversion dimers linked by pairwise O-H⋯O hydrogen bonds generate R 2 2(14) loops.

Crystal structure, Hirshfeld surface analysis and DFT study of 2,2''-({[(1E,1'E)-(diselanedi-yl)bis-(2,1-phenyl-ene)]bis-(methane-ylyl-idene)}bis-(aza-neylyl-idene))bis-[3',6'-bis-(di-ethyl-amino)-4a',9a'-di-hydro-spiro-[isoindoline-1,9'-xanthen]-3-one

The title compound, C70H70N8O4Se2, is a spiro bicyclic diselenide, made up of two [SeC6H4CH=N-N(CO)C6H4(C)C6H3NEt2(O)C6H3NEt2] units related by a twofold crystallographic symmetry element bis-ecting the diselenide bond. The compound crystallizes in a non-centrosymmetric polar space group (tetra-gonal, P b2) and the structure was refined as an inversion twin. The two diethyl amine groups and their attached phenyl groups of the xanthene ring are disordered over two orientations, with occupancies of 0.664 (19)/0.336 (19) and 0.665 (11)/0.335 (11), respectively. The dihedral angles between the mean planes of the central isoindoline and the phenyl rings are 26.8 (2) and 2.5 (4)°, respectively. The mean plane of the central xanthene ring forms dihedral angles of 2.0 (5), 8.8 (5), 1.7 (5) and 7.9 (6)° with the peripheral phenyl rings. The isoindoline and xanthene rings subtend a dihedral angle of 89.8 (2)°. The mol-ecular conformation is stabilized by an intra-molecular C-H⋯O hydrogen bond generating an S(6) ring motif. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds together with C-H⋯π (ring) inter-actions, forming a three-dimensional network. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (68.1%), C⋯H/H⋯C (21.2%) and O⋯H/H⋯O (8.7%) contacts. The optimized structure calculated using density functional theory (DFT) at the B3LYP/6 - 31 G(d) level is compared with the experimentally determined mol-ecular structure in the solid state. The HOMO-LUMO behaviour was used to determine the energy gap and the mol-ecular electrostatic potential (MEP) of the compound was investigated.

Crystal structure, Hirshfeld surface and frontier mol-ecular orbital analysis of 9-(3-bromo-4-hy-droxy-5-meth-oxy-phen-yl)-3,3,6,6-tetra-methyl-3,4,5,6,7,9-hexa-hydro-1H-xanthene-1,8(2H)-dione.

In the fused ring system of the title compound, C24H27BrO5, the mean plane and maximum deviations of the central pyran ring are 0.0384 (2) and 0.0733 (2) Å, respectively. The cyclo-hexenone rings both adopt envelope conformations with the tetra-substituted C atoms as flap atoms, whereas the central pyran ring adopts a flattened boat conformation. The central pyran and phenyl substituent rings are almost perpendicular to each other, making a dihedral angle of 89.71 (2)°. In the crystal, pairs of mol-ecules are linked via O-H⋯O hydrogen bonds, forming inversion dimers with an R 2 2(20) ring motif. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (50.6%), O⋯H/H⋯O (22.9%) and C⋯H/H⋯C (11.1%) contacts. Quantum chemical calculations for the frontier mol-ecular orbitals were undertaken to determine the chemical reactivity of the title compound.

Synthesis, crystal structure and Hirshfeld surface analysis of 5-cyclo-propyl-N-(2-hy-droxy-eth-yl)-1-(4-methyl-phen-yl)-1H-1,2,3-triazole-4-carboxamide.

The title compound, C15H18N4O2, was obtained via a two-step synthesis (Dimroth reaction and amidation) for anti-cancer activity screening and was selected from a 1H-1,2,3-triazole-4-carboxamide library. The cyclo-propyl ring is oriented almost perpendicular to the benzene ring [dihedral angle = 87.9 (1)°], while the dihedral angle between the mean plane of the cyclo-propyl ring and that of the triazole ring is 55.6 (1)°. In the crystal, the mol-ecules are linked by O-H⋯O and C-H⋯N inter-actions into infinite ribbons propagating in the [001] direction, which are inter-connected by weak C-H⋯O inter-actions into layers. The inter-molecular inter-actions were characterized via Hirshfeld surface analysis, which indicated that the largest fingerprint contact percentages are H⋯H (55.5%), N⋯H/H⋯N (15.4%), C⋯H/H⋯C (13.2%) and O⋯H/H⋯O (12.9%).

13-Benzyl-4,11-dihy-droxy-1,8-diphen-yl-2,9-di-thia-13-aza-dispiro-[4.1.4.3]tetra-decan-6-one.

In the title compound, C30H31NO3S2, the piperidine ring adopts a distorted chair conformation. The thio-phene rings have twisted conformations about the C-C bonds. The mean plane of the piperidine ring makes a near orthogonal conformation with the toluene ring. Two of the phenyl rings in the structure are positionally disordered over two sets of sites with occupancies of 0.56 (2)/0.44 (2) and 0.672 (16)/0.328 (16). A region of disordered electron density was corrected for using the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] routine in PLATON. The given chemical formula and other crystal data do not take into account the unknown solvent mol-ecule. In the crystal, O-H⋯O hydrogen bonds are observed along with intra-molecular S⋯H, O⋯H, C⋯H and H⋯H contacts.

SYNTHESIS OF (Z)-N'-(PHENYL(PYRIDIN-2-YL)METHYLENE)-NICOTINOHYDRAZIDE: STRUCTURAL CHARACTERIZATION AND ANTIOXIDANT ACTIVITY SCREENING

Asymmetrical ligand ( Z )- N '-(phenyl(pyridin-2-yl)methylene)nicotinohydrazide ( I ) was synthesized from the condensation of nicotinic acid hydrazide with 2-benzoylpyridine. The compound was characterized by physicochemical analyses, elemental analysis, FTIR, 1 H and 13 C NMR spectroscopy techniques. The structure of the compound was determined by a single-crystal X-ray diffraction study. The ligand crystallizes in the triclinic space group P-1 with the following unit cell parameters: a = 8.2699 (11) A, b = 8.6514 (8) A, c = 11.583 (11) A, a = 91.308 (3)°, b = 94.155 (5)°, g = 109.008 (4)°, V = 755.17 (14) A 3 , Z = 2, R 1 = 0.050, wR 2 = 0.145. The carbonohydrazone moiety of the molecule is slightly twisted as reflected by the torsion angles values of -1.2 (2)° [O1—C13—N3—N2]. The dihedral angle between the mean planes of the pyridine rings is 11.799 (9)°. The crystal packing of compound ( I ) is stabilized by intramolecular N(carbohydrazide)–H···N(pyridine) and intermolecular C(phenyl)–H···O(amide) and C(phenyl)–H···N(hydrazino) hydrogen bonds, leading to the formation of sheets parallel to ac plane. The compound screened for antioxidant activity showed variable DPPH inhibition value for different concentrations of DPPH solution.

Crystal structures of 2-amino-2-oxoethyl 4-bromo-benzoate, 2-amino-2-oxoethyl 4-nitro-benzoate and 2-amino-2-oxoethyl 4-amino-benzoate monohydrate.

The title mol-ecules were synthesized by the reaction of 4-substituted sodium benzoates with chloro-acetic acid amide in the presence of di-methyl-formamide. The yields of 2-amino-2-oxoethyl 4-bromo-benzoate, C9H8BrNO3, I, 2-amino-2-oxoethyl 4-nitro-benzoate, C9H8N2O5, II, and 2-amino-2-oxoethyl 4-amino-benzoate monohydrate, C9H10N2O3·H2O, III, are 86, 78 and 88%, respectively. The low yield of II is explained by the reduced reactivity of the mol-ecule in a nucleophilic exchange reaction because of the negative induction and negative mesomeric effects of the nitro group on the benzene ring. Single crystals were obtained from the products under the same (temperature and solvent) conditions. In the case of III, the crystals formed as a monohydrate. In all three crystal structures, the same type of inter-molecular N-H⋯O hydrogen bonds are observed, but the mol-ecules differ in some torsion angles as well as in the dihedral angles between the mean planes of the benzene rings and the amide groups.

Synthesis, crystal structure, Hirshfeld surface analysis, MEP study and mol-ecular docking of N-{3-[(4-meth-oxy-phen-yl)carbamo-yl]phen-yl}-3-nitro-benzamide as a promising inhibitor of hfXa.

The title compound, C21H17N3O5, consists of three rings, A, B and C, linked by amide bonds with the benzene rings A and C being inclined to the mean plane of the central benzene ring B by 2.99 (18) and 4.57 (18)°, respectively. In the crystal, mol-ecules are linked via N-H⋯O and C-H⋯O hydrogen bonds, forming fused R 2 2(18), R 3 4(30), R 4 4(38) rings running along [0] and R 3 3(37) and R 3 3(15) rings along [001]. Hirshfeld analysis was undertaken to study the inter-molecular contacts in the crystal, showing that the most significant contacts are H⋯O/O⋯H (30.5%), H⋯C/C⋯H (28.2%) and H⋯H (29.0%). Two zones with positive (50.98 and 42.92 kcal mol-1) potentials and two zones with negative (-42.22 and -34.63 kcal mol-1) potentials promote the N-H⋯O inter-actions in the crystal. An evaluation of the mol-ecular coupling of the title compound and the protein with enzymatic properties known as human coagulation factor Xa (hfXa) showed the potential for coupling in three arrangements with a similar minimum binding energy, which differs by approximately 3 kcal mol-1 from the value for the mol-ecule Apixaban, which was used as a positive control inhibitor. This suggests the title compound exhibits inhibitory activity.

11,11-Diphenyl-11H-indeno-[1,2-b]quinoxaline.

In the title compound, C27H18N2, the mean planes of the pendant benzene rings are approximately perpendicular to one another, making a dihedral angle of 79.3 (5)°; the indeno-[1,2-b]quinoxaline ring system (r.m.s. deviation = 0.1197 Å) is twisted with respect to the pendant benzene rings by 70.0 (4) and 67.6 (3)°. Weak aromatic π-π stacking [centroid-centroid separation = 3.628 (2) Å] and C-H⋯π inter-actions occur in the crystal.

Structural (at 100 K) and DFT studies of 2'-nitro-flavone.

The geometry of the title mol-ecule [systematic name: 2-(2-nitro-phen-yl)-4H-chromen-4-one], C15H9NO4, is determined by two dihedral angles formed by the mean plane of phenyl ring with the mean planes of chromone moiety and nitro group, being 50.73 (5) and 30.89 (7)°, respectively. The crystal packing is determined by π-π inter-actions and C-H⋯O contacts. The results of DFT calculations at the B3LYP/6-31G* level of theory provided an explanation of the unusually large dihedral angle between the chromone moiety and the phenyl group. The electrostatic potential map on the mol-ecular surface was calculated in order to determine the potential binding sites to receptors.