B-axis Direction Research Articles

2-(3-Methyl-2-oxoquinoxalin-1-yl)-N-(4-methyl-phen-yl)acetamide.

The quinoxaline moiety in the title mol-ecule, C18H17N3O2, is not quite planar and the p-tolyl group is rotationally disordered over two nearly equally populated sets of sites. In the crystal, N-H⋯O and C-H⋯O hydro-gen bonds form chains extending along the b-axis direction. Due to the disorder of the p-tolyl rings, short C⋯C distances are observed between adjacent chains.

Enanti-opure (S)-butan-2-yl N-(4-x-phen-yl)thio-carbamates, x = NO2, OCH3, F, and Cl.

The structures of (S)-butan-2-yl N-(4-nitro-phen-yl)thio-carbamate, C11H14N2O3S, (I), (S)-butan-2-yl N-(4-meth-oxy-phen-yl)thio-carbamate, C12H17NO2S, (II), (S)-butan-2-yl N-(4-fluoro-phen-yl)thio-carbamate, C11H14FNOS, (III), and (S)-butan-2-yl N-(4-chloro-phen-yl)thio-carbamate, C11H14ClNOS, (IV), all at 100 K, have monoclinic (P21) symmetry with two independent mol-ecules in the asymmetric unit. The Flack absolute structure parameters in all cases confirm the absence of inversion symmetry. The structures display N-H⋯S hydrogen bonds, resulting in R 2 2(8) hydrogen-bonded ring synthons connecting the two independent mol-ecules. Despite the ring synthon, the packing follows two distinct patterns, with (I) and (IV) 'pancaking' along the b-axis direction, while the other two 'sandwich' in layers perpendicular to the b axis. Crystal morphologies were determined theoretically via the BFDH (Bravais, Friedel, Donnay-Harker) model and agree qualitatively with the experimentally indexed results. One of the butyl substituent of (II) exhibits structural disorder.

Crystal structure and Hirshfeld surface analysis of (22 RS,23 SR,25 RS,26 SR)-23,25,5-trimethyl-21-(2,2,2-tri-fluoro-acet-yl)-5-aza-2(2,6)-piperidina-1,3(2,5)-di-furana-cyclo-hexa-phan-24-one.

The title compound, C20H21F3N2O4, features a main twelve-membered difuryl ring with which the furan rings make dihedral angles of 76.14 (5) and 33.81 (5)°. The dihedral angle between the furan rings is 42.55 (7)°. The six-membered nitro-gen heterocycle has a twist-boat conformation. In the crystal, pairs of mol-ecules are connected by inter-molecular C-H⋯O inter-actions, generating an R 2 2(14) ring motif. These pairs of mol-ecules form zigzag chains along the a-axis direction by means of C-H⋯F inter-actions. Furthermore, C-H⋯π and C-F⋯π inter-actions link the mol-ecules into chains along the b-axis direction, forming sheets parallel to the (001) plane. These sheets are also connected by van der Waals inter-actions.

Rac-1-(4-tert-Butyl-phen-yl)-5-ethyl-4-ferrocenyl-5-hy-droxy-1H-pyrrol-2(5H)-one.

The title compound, [Fe(C5H5)(C21H24NO2)], which is produced by the oxidation of 1-(4-tert-butyl-phen-yl)-2-ethyl-3-ferrocenyl-pyrrole, crystallizes as a racemic mixture in the centrosymmetric space group P21/n. The central heterocyclic pyrrole ring system subtends dihedral angles of 13.7 (2)° with respect to the attached cyclo-penta-dienyl ring and of 43.6 (7)° with the major component of the disordered phenyl group bound to the N atom. The 4-tert-butyl-phenyl group, as well as the non-substituted Cp ring are disordered with s.o.f. values of 0.589 (16) and 0.411 (16), respectively. In the crystal, mol-ecules with the same absolute configuration are linked into infinite chains along the b-axis direction by O-H⋯O hydrogen bonds between the hy-droxy substituent and the carbonyl O atom of the adjacent mol-ecule.

Synthesis, crystal structure and Hirshfeld surface analysis of the ortho-rhom-bic polymorph of 4-bromo-N-(4-bromo-benzyl-idene)aniline.

The crystal structure of the title compound, C13H9Br2N [systematic name: (E)-N,1-bis-(4-bromo-phen-yl)methanimine], is a second polymorph (Form II) crystallizing in the ortho-rhom-bic space group Pccn. The first polymorph (Form I) crystallizes in the monoclinic space group P21/c [Bernstein & Izak (1975 ▸). J. Cryst. Mol. Struct. 5, 257-266; Marin et al. (2013 ▸). J. Mol. Struct. 1049, 377-385]. The mol-ecule is disordered about an inversion center situated in the middle of the C=N bond, similar to the situation in the monoclinic polymorph: the C=N bond length is 1.243 (7) Å. In the crystal, mol-ecules stack along the b-axis direction and are linked by C-H⋯π inter-actions. The inter-atomic contacts in the crystal for both polymorphs were studied by Hirshfeld surface analysis and have notable differences. The solid-state fluorescence spectrum of Form II shows an emission peak at ca 469 nm. The two-photon absorption coefficient measured from the open aperture Z-scan technique is 1.3 × 10 -11 m W-1, hence, Form II shows optical limiting behaviour.

Directional Migration and Rapid Coalescence of Au Nanoparticles on Anisotropic ReS2.

Interfacial atomic configuration and its evolution play critical roles in the structural stability and functionality of mixed zero-dimensional (0D) metal nanoparticles (NPs) and two-dimensional (2D) semiconductors. In situ observation of the interface evolution at atomic resolution is a vital method. Herein, the directional migration and structural evolution of Au NPs on anisotropic ReS2 were investigated in situ by aberration-corrected transmission electron microscopy. Statistically, the migration of Au NPs with diameters below 3 nm on ReS2 takes priority with greater probability along the b-axis direction. Density functional theory calculations suggest that the lower diffusion energy barrier enables the directional migration. The coalescence kinetics of Au NPs is quantitatively described by the relation of neck radius (r) and time (t), expressed as . Our work provides an atomic-resolved dynamic analysis method to study the interfacial structural evolution of metal/2D materials, which is essential to the study of the stability of nanodevices based on mixed-dimensional nanomaterials.

2-Ethyl-4-methyl-1H-imidazol-3-ium bromide.

In the title mol-ecular salt, C6H11N2 +·Br-, the components are linked by N-H⋯Br⋯H-N hydrogen bonds into C(8)chains of alternating cations and anions propagating in the b-axis direction; these chains are cross-linked in the c-axis direction by weak C-H⋯Br hydrogen bonds.

Green synthesis, X-ray crystallography, DFT and Hirshfeld analysis of C-2 symmetric 1,3-bis(4-ethylphenyl)triaz-1-ene

A green synthesis of the novel symmetrical title molecule 1,3-bis(4-ethylphenyl)triazene (3) was achieved by self-coupling of 4-ethylaniline at room temperature via diazotization under 4.5–5.0 pH in water in excellent yield and purity. The structure of 3 was inferred by spectroscopic data, elemental analysis and corroborated by single crystal X-ray crystallography. It crystallizes in monoclinic I 2/a space group. In crystal structure, the intermolecular N–H···N hydrogen bonds link the molecules into infinite chains along the b-axis direction in which they are highly effective in the stabilization of the structure. The Hirshfeld surface analysis confirms the importance of H-atom contacts in establishing the packing. The large number of H···H and H···C/C···H interactions suggest that van der Waals interactions and hydrogen bonding play the major roles in the crystal packing. The evaluation of the electrostatic, dispersion and total energy frameworks indicates that the stabilization is dominated via the dispersion energy contribution. The HOMO and LUMO energies are −0.19401 and −0.5546 respectively.

Self-assembly of new cobalt complexes based on [Co (SCN)4], synthesis, empirical, antioxidant activity, and quantum theory investigations

The cobalt (II) complexes have been synthesized from the reaction of the cationic entities (3,4-dimethylaniline (1) and histamine (2)) with metallic salt CoCl2⋅6H2O and thiocyanate ion (SCN−) as a ligand in H2O/ethanolic solution and processing by the evaporation crystal growth method at room temperature to get crystals. The synthesized complex has been fully characterized by single-crystal X-ray diffraction. UV–Visible, FTIR spectroscopy, TGA analysis, and DFT circulations were also performed. The crystal structural analysis reveals that the solid (1) {[Co(SCN)4] (C8H12N)3}·Cl crystallizes in the monoclinic system with the space group P21/n and the solid (2) {[Co(SCN)4](C5H11N3)2}·2Cl crystallizes in the monoclinic space group P21/m. Metal cations are joined into corrugated chains parallel to the b-axis direction in (1) and (2) by four thiocyanate anions. The crystal structures of (1) and (2) were calculated using XRPD data, indicating that they are closely connected to the DRX mono-crystal results. Different interactions pack the system into a ring formed by N–H⋯Cl and N–H⋯S hydrogen bonds. C–H⋯π and the π⋯π stacking of anilinuim ring for (1) and N–H⋯S intermolecular interactions for (1) and (2) increase the crystals' robustness. Hirshfeld surface analysis cum 2D fingerprint plots visualize the main intermolecular interactions with their contributions in the solid-state phase. The molecular geometries of both complexes obtained from the crystal structure were used for quantum chemical calculation. Here, frontier orbital analysis and electrostatic potential illustrate the chemical reactivities of metal–organic complexes. QTAIM and NCI analysis reveal the strength of interactions at the electronic level.

Syntheses and crystal structures of 4-(4-meth-oxy-phen-yl)piperazin-1-ium 4-methyl-benzoate monohydrate and bis-[4-(4-meth-oxy-phen-yl)piperazin-1-ium] benzene-1,2-di-carboxyl-ate.

Co-crystallization of N-(4-meth-oxy-phen-yl)piperazine with 4-methyl-benzoic acid and with benzene-1,2-di-carb-oxy-lic acid yields the salts 4-(4-meth-oxy-phen-yl)piperazin-1-ium 4-methyl-benzoate monohydrate, C11H17N2O+·C8H7O2 -·H2O (I), and bis-[4-(4-meth-oxy-phen-yl)piperazin-1-ium] benzene-1,2-di-carboxyl-ate, 2C11H17N2O+·C8H4O4 2- (II). These salts both crystallize with Z' = 2, in space groups P and Pna21, respectively. In compound (I), a combination of four O-H⋯O, four N-H⋯O, one C-H⋯O and one C-H⋯π(arene) hydrogen bonds link the six independent components into complex sheets, within which the two piperazine rings, the two anions, and the two water mol-ecules are related by an approximate, non-crystallographic translation along the b-axis direction. In compound (II), sheets containing R 4 4(18) and R 10 12(38) rings are formed by the combined action of eight independent N-H⋯O hydrogen bonds. Comparisons are made with the structures of some related compounds.

Macroscopic Polarization Change of Mononuclear Valence Tautomeric Cobalt Complexes Through the Use of Enantiopure Ligand.

The crystallization of a complex having electron transfer properties in a polar space group can induce the polarization switching of a crystal in a specific direction, which is attractive for the development of sensors, memory devices, and capacitors. Unfortunately, the probability of crystallization in a polar space group is usually low. Noticing that enantiopure compounds crystallize in Sohncke space groups, this paper reports a strategy for the molecular design of non-ferroelectric polarization switching crystals based on the use of intramolecular electron transfer and chirality. In addition, this paper describes the synthesis of a mononuclear valence tautomeric (VT) cobalt complex bearing an enantiopure ligand. The introduction of enantiomer enables the crystallization of the complex in the polar space group (P21 ). The polarization of the crystals along the b-axis direction is not canceled out and the VT transition is accompanied by a change in the macroscopic polarization of the polar crystal. Polarization switching via electron transfer is realized at around room temperature.

Synthesis and crystal structure of ebastinium hydrogen fumarate.

The structure of ebastinium hydrogen fumarate {systematic name: 1-[4-(4-tert-butyl-phen-yl)-4-oxobut-yl]-4-(di-phenyl-meth-oxy)piperidin-1-ium (E)-3-carb-oxy-1-hy-droxy-prop-2-en-1-olate}, C32H40NO2 +·C4H3O4 -, a 1:1 salt formed in the reaction between ebastine and fumaric acid is presented. All examined crystals were found to be twinned by pseudo-merohedry. The structure is extensively disordered, with over half (20 out of 35) its non-hydrogen atoms modelled as lying over two sets of sites. In the crystal, cation-anion pairs are linked by a strong N-H⋯O hydrogen bond [N⋯O = 2.697 (11) Å]. These units inter-act via weaker C-H⋯O and C-H⋯π contacts to form layers lying parallel to the bc plane. The hydrogen fumarate anions are linked by a very short O-H⋯O hydrogen bond [O⋯O = 2.5402 (17) Å], augmented by weak C-H⋯O contacts into pairs of R 2 2(6) ring motifs to form chains that extend parallel to the b-axis direction. Comparisons to similar crystal structures are presented.

N-(2,3,5,6-Tetrafluoropyridin-4-yl)formamide.

The title compound, C6H2F4N2O, displays amide bond lengths of 1.218 (3) Å and 1.366 (3) Å for the C=O and C-N bonds, respectively. The Cp-N-C-O (p = pyridine) torsion angle of 179.0 (2)° indicates an anti-conformation for the grouping. Inter-molecular hydrogen bonding is observed between the amine N-H group and the carbonyl O atom, which generates chains of mol-ecules propagating along the b-axis direction.

Investigation on crystal structure, spectral FT-IR analysis, DFT and molecular docking studies of a novel complex with the N′-(pyridin-2-ylmethylene)nicotinohydrazide

The chemical preparation, crystal structure, spectroscopic characterization and elemental analysis of the Zn(II) complex with the tetradentate ligand N′-(pyridin-2-ylmethylene)nicotinohydrazide [Zn(C12H9N4O)H2O]ClO4 are reported. The Zn(II) cations are pentacoordinated, in a square pyramid fashion, by three nitrogen atoms from the organic ligand and two oxygen atoms, one of the organic molecule and the other of the water molecule. In the atomic arrangement, the organic ligands and the penta-coordinated Zn centers link each other to give a 1-D corrugated chain with the molecular formula [Zn(C12H11N4O2)H2O]n running along the b-axis direction between which the perchlorate anions intercalate by establishing C/O…H…O hydrogen bonds with these chain to form a three-dimensional network. The vibrational absorption bands were identified by infrared spectroscopy. Intermolecular interactions were investigated via Hirshfeld surfaces and electronic properties such as HOMO and LUMO energies were derived. In order to determine modes of interactions of the title compound with HIV-1 Protease 1HSG protein, molecular docking simulations were performed at molecular level.

Synthesis and crystal structure of 2-(2-hy-droxy-phen-yl)-1,3-bis-(4-meth-oxy-benz-yl)-1,3-diazinan-5-ol.

The redetermined structure of 2-(2-hy-droxy-phen-yl)-1,3-bis-(4-meth-oxy-benz-yl)-1,3-diazinan-5-ol, C26H30N2O4, at 173 K has ortho-rhom-bic (Pbca) symmetry. It was previously described by Bolte et al. [ Private Communication (refcode EWICEV). CCDC, Cambridge, England]. The title compound resulted from the condensation reaction between 1,3-bis-{[(4-meth-oxy-phen-yl)meth-yl]amino}-propan-2-ol and 2-hy-droxy-benzaldehyde in CH3OH. The structure exhibits disorder. One of the 4-meth-oxy-benzyl groups, the hy-droxy group bonded to the 1,3-diazinan ring, and the methyl group of the meth-oxy residue are disordered over two orientations, with occupancies of 0.807 (3)/0.193 (3), 0.642 (5)/0.358 (5), and 0.82 (4)/0.18 (4), respectively. The dihedral angles between the mean planes of the central 1,3-diazinan-5-ol and the 4-meth-oxy-phenyl rings (both occupancy components of the disordered ring) are 88.65 (13), 85.79 (14) and 83.4 (7)°. The crystal packing is sustained by C-H⋯O and O-H⋯π inter-actions, giving rise to infinite chains running along the b-axis direction.

Ethyl 2-[4-(4-meth-oxy-benz-yl)-3-methyl-6-oxopyridazin-1-yl]acetate.

In the title mol-ecule, C17H20N2O4, the inner part of the ester substituent is nearly perpendicular to the di-hydro-pyridazine ring, forming a dihedral angle of 83.21 (7)°. In the crystal, inversion dimers are formed by pairwise C-H⋯O inter-actions with the dimers connected into chains extending along the b-axis direction by C-H⋯π(ring) inter-actions. The chains are connected by π-stacking inter-actions to give corrugated layers parallel to the ab plane. The terminal ethyl group is disordered over two two sets of sites with the major component having a site occupancy factor of 0.715 (10).

Synthesis, crystal structure, and a molecular modeling approach to identify effective antiviral hydrazide derivative against the main protease of SARS-CoV-2

In the fall of 2019, a new type of coronavirus took place in Wuhan city, China, and rapidly spread across the world and urges the scientific community to develop antiviral therapeutic agents. In our effort we have synthesized a new hydrazide derivative, (E)-N'-(1-(4-bromophenyl)ethylidene)-2-(6-methoxynaphthalen-2-yl)propanehydrazide for this purpose because of its potential inhibitory proprieties. The asymmetric unit of the title molecule consists of two independent molecules differing noticeably in conformation. In the crystal, the independent molecules are linked by N—H···O and C—H···O hydrogen bonds and C—H···π(ring) interactions into helical chains extending along the b-axis direction. The chains are further joined by additional C—H···π(ring) interactions into the full 3-D structure. To obtain a structure-activity relationship, the DFT-NBO analysis is performed to study the intrinsic electronic properties of the title compound. Molecular modeling studies were also conducted to examine the binding affinity of the compound for the SARS-CoV-2 main protease enzyme and to determine intermolecular binding interactions. The compound revealed a stable binding mode at the enzyme active pocket with a binding energy value of -8.1 kcal/mol. Further, stable dynamics were revealed for the enzyme-compound complex and reported highly favorable binding energies. The net MMGBSA binding energy of the complex is -37.41 kcal/mol while the net MMPBSA binding energy is -40.5 kcal/mol. Overall, the compound disclosed the strongest bond of ing the main protease enzyme and might be a good lead for further structural optimization.

Precise Determination of Offset between Optical Axis and Re-Chain Direction in Rhenium Disulfide.

ReS2 is a group-VII chalcogenide with a crystal structure that has inversion symmetry only. Due to the low symmetry, it has in-plane anisotropy, and the two vertical orientations are not equivalent. The in-plane anisotropy leads to optical birefringence that can be observed by using polarized optical microscopy. We found ReS2 crystals with domains of inequivalent vertical orientations but with the same Re-chain directions. Polarized Raman spectroscopy was used to determine the vertical orientations and the b-axis (Re-chain) directions of the domains, and high-resolution scanning transmission electron microscopy measurements confirmed that the Re-chain directions of the two types of the neighboring domains are exactly parallel. From polarized optical reflectivity measurements of the two types of domains, we found that the optical slow axis is not along the b-axis as previously believed but is tilted by ∼2.4° from the b-axis of the crystal. This offset makes the two neighboring domains with parallel Re-chains optically inequivalent and enables one to observe optical contrast between the two types of domains in polarized optical microscopy. We propose a quick and easy method to determine the crystallographic orientations of such domains by using polarized optical microscopy only.

Synthesis, crystal structure, and photoluminescence of the new nitridoboroaluminosilicate phosphor (Sr0.93Eu0.07)11B2(Al0.275Si0.725)40N59

Single crystals of a new nitride, (Sr0.93Eu0.07)11B2(Al0.275Si0.725)40N59, were synthesized by heating a mixture of binary nitride powders at 2030 ​°C under nitrogen gas at 0.85 ​MPa. The fundamental X-ray diffraction reflections from a single crystal were indexed with the monoclinic cell parameters a ​= ​5.6836(4) Å, b ​= ​46.772(3) Å, c ​= ​5.6845(4) Å, and β = 118.028(2)° and diffuse streaks were observed between the reflections. The crystal structure was analyzed based on a statistical average structural model with space group Cm. The structure was determined to comprise (Al/Si)N4 tetrahedra and BN3 planar triangles forming a three-dimensional framework by sharing nitrogen atoms with Sr/Eu atoms located in the cage portions of the framework. Stacking faults in the b-axis direction and disordered atomic arrangements along the [1 0 1] direction on the a-c plane were observed by scanning transmission electron microscopy. These single crystal grains were found to emit red light when irradiated with near ultraviolet or blue light, with a maximum emission wavelength of 616 ​nm and a full width at half-maximum value of 106 ​nm in response to 450 ​nm light.

Crystal structures of dimetal terephthalate di-hydroxides, M 2(C8H4O4)(OH)2 (M = Co, Ni, Zn) from powder diffraction data and DFT calculations.

The crystal structure of poly[di-hydroxido(μ6-terepthalato)dizinc], [Zn2(C8H4O4)(OH)2] n , was solved and refined using synchrotron powder data, and the structures of the isostructural Co and Ni analogues were refined using laboratory powder X-ray data. The structure of [Co2(C8H4O4)(OH)2] n has been reported previously in space group C2/m, which yields disordered terephthalate anions. Doubling the c-axis of that cell results in an ordered model in space group C2/c. The octa-hedral MO6 coordination polyhedra of the metal cations share edges, forming chains running parallel to the b-axis direction. These chains share corners (hydroxyl groups), forming layers lying perpendicular to the a-axis direction.