Ring Motif Research Articles

Crystal structure, Hirshfeld surface, and DFT studies of 4-((pyrrolidin-1-ylsulfonyl)methyl)aniline

The crystal structure investigation of the title compound 4-((pyrrolidin-1-ylsulfonyl) methyl)aniline (PSMA) C11H16N2O2S shows that the molecule is essentially coplanar with a dihedral angle of 26.70(14)°between the pyrrolidine and the benzene rings. A pair of strong N-H···O hydrogen bonds produces continuous two-dimensional sheets with R22(18) ring motifs. The crystal structure also features a weak C-H···π interaction resulting in a three-dimensional network. Density functional theory (DFT) calculations reveal that the experimental and calculated geometric parameters of the molecule are nearly the same. Hirshfeld surface analysis has been carried out to study the various intermolecular interactions responsible for the crystal packing. Theoretical calculations indicate an excellent correlation between the experimental and the simulated UV spectra.

Structural and Electrochemical Studies of Cobalt(II) and Nickel(II) Coordination Polymers with 6-Oxonicotinate and 4,4′-Bipyridine

The 6-oxonicotinate (6-Onic) salts of a one-dimensional cationic cobalt(II) or nickel(II) coordination polymers with 4,4′-bipyridine (4,4′-bpy), namely {[Co(4,4′-bpy)(H2O)4](6-Onic)2·2H2O}n (1) and {[Ni(4,4′-bpy)(H2O)4](6-Onic)2·2H2O}n (2), were prepared hydrothermally by reactions of cobalt(II) nitrate hexahydrate or nickel(II) nitrate hexahydrate, respectively, 6-hydroxynicotinic acid and 4,4′-bipyridine in a mixture of ethanol and water. In the hydrogen-bonded frameworks of 1 and 2, the one-dimensional polymeric chains of {[M(4,4′-bpy)(H2O)4]2+}n (M = Co, Ni), the 6-oxonicotinate anions and the lattice water molecules were assembled via strong intermolecular O–H···O and N–H···O hydrogen bonds and π–π interactions, leading to the formation of the representative hydrogen-bond ring motifs: trimeric R23(10) motif, the centrosymmetric tetrameric R24(8) and R24(12) motifs and the pentameric R45(12) motif. The isostructural coordination polymers 1 and 2 exhibited a different electrochemical behavior, as observed by cyclic voltammetry, which can be attributed to the nature of the metal ions (cobalt(II) vs. nickel(II)).

Synthesis, crystallization, XRD, Hirshfeld surface, vibrational spectra, and quantum chemical studies and Computational investigation of Caffeinium bisulfate: a new noncentrosymmetric form

Crystals of caffienium bisulfate were grown by solution growth technique. The vibrational spectra were scaled by adopting FT-IR and FT-Raman spectroscopy with the wide range, between 4000-400 cm−1. X-ray diffraction study exhibited that the functional group such as N-H….O hydrogen bonds played an effective role in generating hydrogen-bonded crystal packing, pre-dominant. The examined molecules showed an interconnection of anions, by the O-H…O hydrogen bonds, establishing a chain C (4) motif, extending along the b-axis of the unit cell. Further, anions have shown interaction with cations, through N-H…O hydrogen bond, resulting from a ring R1 2 (4) motif. The formed ring and chain motifs manifested an alternate hydrophilic stratum at z = ¼ and ¾. Geometrical optimization of tester molecule was done with Density Functional Theory (DFT) employing B3LYP function along with Hartree-Fock (HF) using 6-311++G(d,p) level basis set. Optimum molecular geometry and calculated database on the vibrational spectra were critically analyzed by comparing with experimental findings, resulting in a good correlating exhibited among them. Natural Bond Orbital (NBO) study revealed that hyper conjugation affinities and intermolecular charge transfer (ICT). An advanced technique such as HOMO-LUMO plot was performed to understand the chemical hardness, electro negativity and chemical efficacy of the tested molecules. The results showed that the occurrence of lower band gap value in the frontier orbital was responsible for the possible biological activities of the study materials. Bioinformatics analysis is applied for analyzing the biological activity of CAFSUL against Alzheimer's disease through computational methods. Communicated by Ramaswamy H. Sarma

Synthesis, crystal structure, crystal supramolecularity and Hirshfeld surface analysis of (E)-1-(2,5-dichlorothiophen-3-yl)-3-o-tolylprop-2-en-1-one

• Crystal and molecular structure of ( E )−1-(2,5-dichlorothiophen-3-yl)−3-o-tolylprop-2-en-1-one. • 3D framework structure. • C–H•••O and C–H•••Cl, Cl•••Cl and S•••Cl interactions and crystal packing. • Hirshfeld surface analysis. • Energy frameworks analysis. • Dispersion energy contributions are the most important in stabilizing the crystal structure. The asymmetric unit of, C 14 H 10 Cl 2 OS, I , consists of one independent molecule with E configuration about the C C bond. The molecular structure composed of two aromatic rings, the 2,5-dichlorothiophenyl and the tolyl that are linked by the central –CO—CH CH– unit. The molecule is planar as indicated by the dihedral angle [4.27°] between the aromatic rings. The molecular structure is stabilized by two C—H•••O and one C—H•••Cl intramolecular hydrogen bonds forming S (5) S (5) S (6) ring motifs. In the crystal, the molecules are connected by C—H•••O/Cl, Cl•••Cl and S•••Cl interactions into a 3-dimensional supramolecular array. The Hirshfeld surface analysis revealed that the most significant interactions are: H•••H (25.7%), Cl•••H/H•••Cl (15.6%), C•••H/H•••C (15.3%), O•••H/H•••O (9.9%), C•••C (9.5%), amongst others. The calculated interaction energies indicate that the dispersion energy contributions are the most important in stabilizing the crystal structure. Crystal and molecular structure of ( E )-1-(2,5-dichlorothiophen-3-yl)-3-o-tolylprop-2-en-1-one are reported. Hirshfeld surface analysis and energy framework simulations are discussed.

Electrochemical Cobalt-catalyzed Cyclotrimerization of Alkynes to 1,2,4-Substituted Arenes

The transition-metal-catalyzed [2 + 2 + 2] cyclotrimerization of alkynes is one of the most straightforward routes for constructing six-membered ring motifs. Although this strategy possesses high a...

Crystal structure and Hirshfeld surface analysis of 3-[2-(3,5-di-methyl-phen-yl)hydrazinyl-idene]benzo-furan-2(3H)-one.

In the title compound, C16H14N2O2, the 2,3-di-hydro-1-benzo-furan ring system is essentially planar and makes a dihedral angle of 3.69 (7)° with the di-methyl-phenyl ring. The mol-ecular conformation is stabilized by an intra-molecular N-H⋯O hydrogen bond with an S(6) ring motif. In the crystal, mol-ecules are connected by C-H⋯π and π-π stacking inter-actions, forming a layer lying parallel to the (11) plane. One methyl group is disordered over two orientations, with occupancies of 0.67 (4) and 0.33 (4). Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (51.2%), O⋯H/H⋯O (17.9%), C⋯H/H⋯C (15.2%) and C⋯C (8.1%) contacts.

Crystal structure and Hirshfeld surface analysis of 2-{[(E)-(3-cyclo-butyl-1H-1,2,4-triazol-5-yl)imino]-meth-yl}phenol.

The title compound, C13H14N4O, was developed using the reaction of salicyl-aldehyde and 3-amino-5-cyclo-butyl-1,2,4-triazole in ethanol under microwave irradiation. This eco-friendly microwave-promoted method proved to be efficient in the synthesis of 2-{[(E)-(3-cyclo-butyl-1H-1,2,4-triazol-5-yl)imino]-meth-yl}phenol in good yields and purity. The title compound is a Schiff base that exists in the phenol-imine tautomeric form and adopts an E configuration. The three independent mol-ecules in the asymmetric unit (A, B and C) are not planar, the cyclo-butyl and the phenol-imine rings are twisted to each other making a dihedral angle of 67.8 (4)° in mol-ecule A, 69.1 (2)° in mol-ecule B and 89.1 (2)° in mol-ecule C. In each mol-ecule an intra-molecular O-H⋯N hydrogen bond is present, forming an S(6) ring motif. A Hirshfeld surface analysis was performed to investigate the contributions of the different inter-molecular contacts within the supra-molecular structure. The major inter-actions are H⋯H (53%), C⋯H (19%) and N⋯H (17%) for mol-ecule A, H⋯H (50%), N⋯H (20%) and C⋯H (20%) for mol-ecule B and H⋯H (57%), C⋯H (14%) and N⋯H (13%) for mol-ecule C.

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.

Supramolecular architectures of mononuclear nickel(II) and homobinuclear copper(II) complexes with the 5,5′-dimethyl-2,2′-bipyridine ligand: Syntheses, crystal structures and Hirshfeld surface analyses

Two new compounds based on one mononuclear nickel(II) and one homobinuclear copper(II) complexes respectively and of general formula [Ni(dmbpy)2(CH3COO)]ClO4 (1) and [Cu2(dmbpy)2(CH3COO)3]ClO4 (2) with dmbpy = 5,5′-dimethyl-2,2′-bipyridine, were synthesized by hydrothermal treatment. Both were influenced by the coordinated acetate ion molecule. The crystal and molecular structures of (1) and (2) were determined by single crystal X-ray diffraction method and both compounds were additionally characterized by means of elemental and thermogravimetric analysis, FT-IR spectroscopy, powder X-ray diffraction and UV–visible. The mononuclear complex (1) shows a distorted octahedral geometry around the metal ion. On the other hand, the copper(II) compound crystallizes as an homobinuclear system, in which each of the metal ions is located into the N2O3 coordination spheres adopting a distorted square pyramidal geometry. In (2) the intramolecular distance between two copper atoms is of the order of Cu1-Cu2 = 3.38 (2) Å. In both crystals packing of these two complexes, H-bonding, π⋯π, and C-H⋯π interactions are operative in forming supramolecular motifs. Complex (1) displays two 1D chains that lead to form R88(42) ring motifs, repetition of which generates a 2D supramolecular network. These chains interacts with the neighbouring ones via intermolecular C-H···π and π···π stacking interactions, leading to the formation of a 3D-stacking network (2D+1D→3D). Formation of a 2D supramolecular sheet in the solid state structure of (2) is facilitated by the C–H⋯O, C–H⋯π and π⋯π interactions (1D+1D→2D). Hirshfeld surface analysis and theoretical calculations were carried out on the two compounds. The results clearly show that C–H···O, C–H··· π and π···π stacking interactions play a paramount role in the stabilization of the supramolecular architecture of (1) and (2). In addition, absorption spectra reveal their semi-conductive nature (4.19 eV for (1)·and 4.43 eV for (2)).

Crystal structure and Hirshfeld surface analysis of (Z)-2-{[(2,4-di-methyl-phen-yl)imino]-meth-yl}-4-methyl-phenol.

The title compound, C16H17NO, is a Schiff base that exists in the enol-imine tautomeric form and adopts a Z configuration. The mol-ecule is non-planar, with the twisted rings making a dihedral angle of 39.92 (4)°. The intra-molecular O-H⋯N hydrogen bond forms an S(6) ring motif. In the crystal, mol-ecules are linked by C-H⋯π inter-actions and very weak π-π stacking inter-actions also help to consolidate the crystal packing. A Hirshfeld surface analysis was performed to investigate the contributions of different inter-molecular contacts within the supra-molecular structure. The major contributions are from H⋯H (65%), C⋯H (19.2%) and O⋯H (6.6%) inter-actions.

Crystal structure and Hirshfeld surface analysis of (3aSR,6RS,6aSR,7RS,11bSR,11cRS)-2,2-dibenzyl-2,3,6a,11c-tetra-hydro-1H,6H,7H-3a,6:7,11b-di-epoxy-dibenzo[de,h]isoquinolin-2-ium tri-fluoro-methane-sulfonate.

In the cation of the title salt, C30H28NO2 +·CF3O3S-, the four tetra-hydro-furan rings adopt envelope conformations. In the crystal, pairs of cations are linked by dimeric C-H⋯O hydrogen bonds, forming two R 2 2(6) ring motifs parallel to the (001) plane. The cations and anions are connected by further C-H⋯O hydrogen bonds, forming a three-dimensional network structure. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (47.6%), C⋯H/H⋯C (20.6%), O⋯H/H⋯O (18.0%) and F⋯H/H⋯F (9.9%) inter-actions.

Crystal structure and Hirshfeld surface analysis of (Z)-2-amino-4-(2,6-di-chloro-phen-yl)-5-(1-hy-droxy-ethyl-idene)-6-oxo-1-phenyl-1,4,5,6-tetra-hydro-pyridine-3-carbo-nitrile.

The mol-ecular conformation of the title compound, C20H15Cl2N3O2, is stabilized by an intra-molecular O-H⋯O hydrogen bond, forming an S(6) ring motif. The central pyridine ring is almost planar [maximum deviation = 0.074 (3) Å]. It subtends dihedral angles of 86.10 (15) and 87.17 (14)°, respectively, with the phenyl and di-chloro-phenyl rings, which are at an angle of 21.28 (15)° to each other. The =C(-OH)CH3 group is coplanar. In the crystal, mol-ecules are linked by inter-molecular N-H⋯N and C-H⋯N hydrogen bonds, and N-H⋯π and C-H⋯π inter-actions, forming a three-dimensional network. The most important contributions to the crystal packing are from H⋯H (33.1%), C⋯H/H⋯C (22.5%), Cl⋯H/H⋯Cl (14.1%), O⋯H/H⋯O (11.9%) and N⋯H/H⋯N (9.7%) inter-actions.

Crystal structure and Hirshfeld surface analysis of (3Z)-7-meth-oxy-3-(2-phenyl-hydrazinyl-idene)-1-benzo-furan-2(3H)-one.

In the title compound, C15H12N2O3, pairs of mol-ecules are linked into dimers by N-H⋯O hydrogen bonds, forming an R 2 2(12) ring motif, with the dimers stacked along the a axis. These dimers are connected through π-π stacking inter-actions between the centroids of the benzene and furan rings of their 2,3-di-hydro-1-benzo-furan ring systems. Furthermore, there exists a C-H⋯π inter-action that consolidates the crystal packing. A Hirshfeld surface analysis indicates that the most important contacts are H⋯H (40.7%), O⋯H/H⋯O (24.7%), C⋯H/H⋯C (16.1%) and C⋯C (8.8%).

Crystal structures of three N-acyl-hydrazone isomers.

The crystal structures of three isomers of (E)-4-chloro-N-{2-[2-(chloro-benzyl-idene)hydrazin-yl]-2-oxoeth-yl}-benzene-sulfonamide, namely, (E)-4-chloro-N-{2-[2-(2-chloro-benzyl-idene)hydrazin-yl]-2-oxoeth-yl}-benzene-sulfonamide (I), (E)-4-chloro-N-{2-[2-(3-chloro-benzyl-idene)hydrazin-yl]-2-oxoeth-yl}-benzene-sul-fon-amide (II) and (E)-4-chloro-N-{2-[2-(4-chloro-benzyl-idene)hydrazin-yl]-2-oxo-eth-yl}-benzene-sulfonamide (III), with the general formula C15H13Cl2N3O3S are described, with the chloro group in ortho, meta and para positions in the benzyl-idene benzene ring. All the three isomeric compounds crystallize in the centrosymmetric triclinic P space group with one mol-ecule each in the asymmetric unit and two mol-ecules in the unit cell. The dihedral angles between the two phenyl rings are 11.09 (14), 53.79 (18) and 72.37 (11)° in (I), (II) and (III), respectively. The central part of the mol-ecule (-C-N-N=C-) is almost linear with C-N-N-C torsion angles of 179.1 (2), -169.5 (3) and 178.5 (2)° for (I), (II) and (III), respectively. In all the three crystals, the mol-ecules form inversion dimers with R 2 2(8) ring motifs, which are further augmented by C-H⋯O inter-actions.

Crystal structure and Hirshfeld surface analysis of dimethyl 5-[2-(2,4,6-trioxo-1,3-diazinan-5-yl-idene)hydrazin-1-yl]benzene-1,3-di-carboxyl-ate 0.224-hydrate.

In the crystal, the whole mol-ecule of the title compound, C14H12N4O7·0.224H2O, is nearly planar with a maximum deviation from the least-squares plane of 0.352 (1) Å. The mol-ecular conformation is stabilized by an intra-molecular N-H⋯O hydrogen bond, generating an S(6) ring motif. In the crystal, mol-ecules are linked by centrosymmetric pairs of N-H⋯O hydrogen bonds, forming ribbons along the c-axis direction. These ribbons connected by van der Waals contacts, forming sheets parallel to the ac plane. There are also inter-molecular van der Waals contacts and and C-H⋯π inter-actions between the sheets. A Hirshfeld surface analysis indicates that the most prevalent inter-actions are O⋯H/H⋯O (41.2%), H⋯H (19.2%), C⋯H/H⋯C (12.2%) and C⋯O/ O⋯C (8.4%).

Crystal structure and Hirshfeld surface analysis of ethyl 6'-amino-2'-(chloro-meth-yl)-5'-cyano-2-oxo-1,2-di-hydro-spiro-[indoline-3,4'-pyran]-3'-carboxyl-ate.

The mol-ecular conformation of the title compound, C17H14ClN3O4, is stabilized by an intra-molecular C-H⋯O contact, forming an S(6) ring motif. In the crystal, the mol-ecules are connected by N-H⋯O hydrogen-bond pairs along the b-axis direction as dimers with R 2 2(8) and R 2 2(14) ring motifs and as ribbons formed by inter-molecular C-H⋯N hydrogen bonds. There are weak van der Waals inter-actions between the ribbons. The most important contributions to the surface contacts are from H⋯H (34.9%), O⋯H/H⋯O (19.2%), C⋯H/H⋯C (11.9%), Cl⋯H/H⋯Cl (10.7%) and N⋯H/H⋯N (10.4%) inter-actions, as concluded from a Hirshfeld surface analysis.

Structural, Hirshfeld surface studies and computation of interaction energies of 4-Amino-N-(3-chloropyrazin-2-yl)benzene-1-Sulfonamide organic compound

Present paper reports the study of single crystal X-ray diffraction of the compound 4-Amino-N-(3-chloropyrazin-2yl)benzene-1-sulfonamide which crystallizes in an orthorhombic crystal system with the space group Pbca having precise unit cell parameters a = 11.5260(19)Å, b = 9.6270(16)Å, c = 22.099(5)Å, Z = 8 and V = 2452.1(8)Å3. The structure was solved by direct methods and was refined by full-matrix least-squares based on F2. After subsequent cycles of refinement, the structure was converges to the Goodness-of-Fit (S) = 1.33. The molecule was adopted as a non-planar structure with a dihedral angle of 89.95°. In the crystal, molecules are held together through intermolecular N–H…O and C–H…O interactions. The nitrogen (N) atom of pyrazine ring has exhibited trifurcated intramolecular relations through C–H…N, N…C, and N…O incorporating S(5), S(6), and S(7) ring motifs, respectively. The intermolecular interactions were analyzed, and their percentage of contribution towards crystal packing was computed using Hirshfeld surface analysis. Also, interaction energies between the different pairs of molecules were analyzed, visualized and estimated using the energy density model of B3LYP/6-31G(d,p).

Crystal structure and mol-ecular docking study of (E)-2-{[(E)-2-hy-droxy-5-methyl-benzyl-idene]hydrazinyl-idene}-1,2-di-phenyl-ethan-1-one.

The title compound, C22H18N2O2, is a Schiff base that exists in the phenol-imine tautomeric form and adopts an E configuration with respect to the C=N bond. The mol-ecular structure is stabilized by an O-H⋯N hydrogen bond, forming an S(6) ring motif. In the crystal, pairs of C-H⋯O hydrogen bonds link the mol-ecules to form inversion dimers. Weak π-π stacking inter-actions along the a-axis direction provide additional stabilization of the crystal structure. The mol-ecule is non-planar, the aromatic ring of the benzaldehyde residue being nearly perpendicular to the phenyl and 4-methyl-phenol rings with dihedral angles of 88.78 (13) and 82.26 (14)°, respectively. A mol-ecular docking study between the title mol-ecule and the COVID-19 main protease (PDB ID: 6LU7) was performed, showing that it is a potential agent because of its affinity and ability to adhere to the active sites of the protein.

Solid-Phase Synthesis of an Insect Pyrokinin Analog Incorporating an Imidazoline Ring as Isosteric Replacement of a trans Peptide Bond.

A facile solid-phase synthetic method for incorporating the imidazoline ring motif, a surrogate for a trans peptide bond, into bioactive peptides is reported. The example described is the synthesis of an imidazoline peptidomimetic analog of an insect pyrokinin neuropeptide via a cyclization reaction of an iminium salt generated from the preceding amino acid and 2,4-diaminopropanoic acid (Dap).

Crystal structure and Hirshfeld surface analysis of 5,7-diphenyl-1,2,3,5,6,7-hexa-hydro-imidazo[1,2-a]pyridine-6,6,8-tricarbo-nitrile methanol mono-solvate.

In the title compound, C22H17N5·CH4O, the imidazolidine ring of the 1,2,3,5,6,7-hexa-hydro-imidazo[1,2-a]pyridine ring system is a twisted envelope, while the 1,2,3,4-tetra-hydro-pyridine ring adopts a twisted boat conformation. In the crystal, pairs of mol-ecules are linked by O-H⋯N and N-H⋯O hydrogen bonds via two methanol mol-ecules, forming a centrosymmetric R 4 4(16) ring motif. These motifs are connected to each other by C-H⋯N hydrogen bonds and form columns along the a axis. The columns form a stable mol-ecular packing, being connected to each other by van der Waals inter-actions. A Hirshfeld surface analysis indicates that the most significant contributions to the crystal packing are from H⋯H (43.8%), N⋯H/H⋯N (31.7%) and C⋯H/H⋯C (18.4%) contacts.