Ring Interactions Research Articles

Supramolecular construction of a cyclobutane ring system with four different substituents in the solid state

Methods to form cyclobutane rings by an intermolecular [2 + 2] cross-photoreaction (CPR) with four different substituents are rare. These reactions are typically performed in the liquid phase, involve multiple steps, and generate product mixtures. Here, we report a CPR that generates a cyclobutane ring with four different aryl substituents. The CPR occurs quantitatively, without side products, and without a need for product purification. Generally, we demonstrate how face-to-face stacking interactions of aromatic rings can be exploited in the process of cocrystallization and the field of crystal engineering to stack and align unsymmetrical alkenes in CPRs to afford chiral cyclobutanes with up to four different aryl groups via binary cocrystals. Overall, we expect the process herein to be useful to generate chiral carbon scaffolds, which is important given the presence of four-membered carbocyclic rings as structural units in biological compounds and materials science.

Enhanced magnetocaloric effect in a mixed spin-(1/2, 1) Ising–Heisenberg two-leg ladder with strong–rung interaction

The magnetic and magnetocaloric properties of the mixed spin-(1/2,1) Ising-Heisenberg model on a two-leg ladder with dimer-rung alternation are exactly examined under an adiabatic demagnetization process using the transfer-matrix formalism. We notify that the magnetization curve of the model exhibits plateaux as a function of the applied magnetic field and cyclic four-spin Ising interaction at certain rational fractions of the saturation value. We precisely investigate the ability of cooling/heating of the model nearby the critical points at which discontinuous ground-state phase transition occurs. It is evidenced that the model manifests an enhanced magnetocaloric effect in a proximity of the magnetization steps and jumps, accompanying with the plateaux and jumps of correlation function of the dimer spins. We conclude that not only the cooling/heating capability of the model could be pleasantly demonstrated by the applied magnetic field variations, but also a typical cyclic four-spin Ising interaction plays essential role to determine an efficiency of the magnetocaloric effect of the model.

Crystal structure, Hirshfeld surface analysis and inter-action energy calculation of 1-decyl-2,3-di-hydro-1H-benzimidazol-2-one.

The title mol-ecule, C17H26N2O, adopts an L-shaped conformation, with the straight n-decyl chain positioned nearly perpendicular to the di-hydro-benzimidazole moiety. The di-hydro-benzimidazole portion is not quite planar as there is a dihedral angle of 1.20 (6)° between the constituent planes. In the crystal, N-H⋯O hydrogen bonds form inversion dimers, which are connected into the three-dimensional structure by C-H⋯O hydrogen bonds and C-H⋯π(ring) inter-actions. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯H (75.9%), H⋯C/C⋯H (12.5%) and H⋯O/O⋯H (7.0%) inter-actions. Based on computational chemistry using the CE-B3LYP/6-31 G(d,p) energy model, C-H⋯O hydrogen bond energies are -74.9 (for N-H⋯O) and -42.7 (for C-H⋯O) kJ mol-1.

Synthesis, Crystal structure, Hirshfeld surface Analysis and computational approach of new 2-methylbenzimidazo[1,2-a]pyrimidin-4(1H)-one

• A newly benzimidazole derivative has been synthesized and characterized. • Its structural is confirmed by XRD and compatible with DFT findings. • The compound exhibited promising NLO properties. • Molecular docking and molecular dynamics studies were performed for the compound. The present article describes the synthesis of the new compound 2-methylbenzimidazo[1,2- a ]pyrimidin-4(1 H )-one. The electronic and spatial structure of this molecule was studied theoretically and experimentally. The title molecule, C 11 H 9 N 3 O, is slightly twisted and bowed based on the recent crystallographic study, while the DFT-B3LYP study shows that the title compound is fully planar in the gas phase. This discrepancy between the experimentally determined geometry and the B3LYP optimized one may be due to the crystal packing. In the crystal, a layer structure is formed by N—H•••N and C—H•••O hydrogen bonds together with π-stacking and C—H•••π(ring) interactions. However, the Hirshfled surface analysis showed that the most important intermolecular interaction for the title compound is the H•••H contact. Based on the wide biological interest, molecular docking and molecular dynamics studies were performed for the above titled compound with the poly(ADP-ribose)polymerase (PARP) enzyme target and the result shows that there is a good binding affinity and stability in PARP complex system.

C–C Activation to BNB-Embedded Indenophenanthrenes. Electronic Structure and Reactivity

The BNB-embedded indenophenanthrenes 3 have been synthesized by reduction of LBX2 (2; L represents a BN phenanthrene ligand and X = Br, Cl) with 2 equiv of potassium graphite under ambient conditions. The formation of 3 very likely goes through an aminoborylene intermediate, which underwent an intramolecular insertion into a C–C bond to close the polycyclic structure. DFT calculations disclosed the delocalized BNB 3c-2e interaction in the BNBC2 five-membered ring of 3. Treatment of 3a with IPr (1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) selectively led to the coordination of IPr to one of two boron atoms, the structure of which has been confirmed by an X-ray single-crystal analysis.

Biantennary Alkyl Triazole Glycosides by Double‐click‐Coupling for Water‐in‐Oil‐Emulsification

AbstractA series of biantennary sugar‐based surfactants reflecting glyco‐glycero‐lipids, in which the ester linkage of the surfactant antipodes was replaced by a triazole, has been synthesized and investigated on their emulsifying potential for water‐in‐oil systems related to hydrofuel. The results suggest beneficial interactions of the triazole with fossil‐derived diesel, whereas corresponding interactions appear to destabilize emulsions in ester‐based biodiesel. The highest emulsion stability was observed for 1,3‐linked glycerol‐isomers, where the glucose‐based ATG outperformed the corresponding xylose‐analogue exhibiting a significantly higher Krafft temperature. Molecular modeling results relate this behavior to chromonic interactions of the triazole rings.

Blood backspatter interaction with propellant gases

The theoretical results of the present work reveal a significant interaction of the oncoming vortex ring of propellant muzzle gases with backward blood spatter. It is shown that there is even possibility that a blood droplet from the backspatter will fully turn around by a powerful vortex ring and land behind a victim. Such a predicted outcome is confirmed by experimental data of fully reversed drop trajectories observed in the experiments conducted in the second part of this work [N. Sliefert, G. Li, J. B. Michael, A. L. Yarin, “Experimental and numerical study of blood backspatter interaction with propellant gases,” Phys. Fluids 33, 043319 (2021)]. A parametric study is conducted here to investigate the totality of the outcomes of the vortex ring interaction with the backward blood spatter and the corresponding deflections and landing locations of blood drops. Furthermore, a secondary vortex ring is introduced here to reveal a continuous effect of the propellant gas.

Thermochromic and highly tunable color emitting bis-tolane based liquid crystal materials for temperature sensing devices

The luminescent compounds based on the D-π-A system consisting of substituted pyrrole as acceptor, π conjugated bis-tolane and -OMe, -N(CH3)2, -N(Ph)2 at termini acting as donors have been synthesized. On heating, all the compounds exhibited distinct mesomorphic behavior depending upon donating groups and substituents at the acceptor unit. These luminescent liquid crystals exhibited emission from blue, green to reddish orange with high quantum efficiency in solid as well in solutions state. We discovered the rarely reported three membered ring interactions between the Br at alpha position of pyrrole and acetylene bond and their impact on luminescence efficiency via single crystal structure of 2Br–CN–N(CH3)2 and 2Br–CN–N(Ph)2. Furthermore, the thermochromic behavior of these LLCs compounds has been explored, especially CN–N(Ph)2, its reddish orange emission changed to blue at 240 °C–250 °C in pure state, while in dimethyl silicone polymer (PDMS) film, it switched to blue at 200 °C and completely vanished at 240 °C. These simple and highly emissive compounds display outstanding thermochromic properties above 200 °C, thus will be potentiality valuable for high temperature sensing devices.

Crystal structure and Hirshfeld surface analysis of (3S,3aR,6aS)-3-(1,3-diphenyl-1H-pyrazol-4-yl)-5-(4-meth-oxy-phen-yl)-2-phenyl-3,3a,4,5,6,6a-hexa-hydro-2H-pyrrolo-[3,4-d][1,2]oxazole-4,6-dione.

In the title compound, C33H26N4O4, the two fused five-membered rings and their N-bound aromatic substituents form a pincer-like motif. The relative conformations about the three chiral carbon atoms are established. In the crystal, a combination of C-H⋯O and C-H⋯N hydrogen bonds and C-H⋯π(ring) inter-actions leads to the formation of layers parallel to the bc plane. A Hirshfeld surface analysis indicates that the most significant contributions to the crystal packing are from H⋯H (44.3%), C⋯H/H⋯C (29.8%) and O⋯H/H⋯O (15.0%) contacts.

Synthesis, X-ray, spectroscopic characterization, Hirshfeld surface analysis, DFT calculation and molecular docking investigations of a novel 7-phenyl-2,3,4,5-tetrahydro-1H-1,4- diazepin-5-one derivative

The tetrahydrodiazepine ring in the title molecule, C11H12N2O, adopts a twisted envelope conformation. In the crystal, inversion dimers are formed by NH⋯O hydrogen bonds which are connected into corrugated layers by NH⋯O hydrogen bonds and CH⋯π(ring) interactions. However, the Hirshfeld surface analysis indicated that the most important intermolecular interaction for the title compound is the H⋯H contact. Moreover, the DFT-B3LYP study showed that the title compound should have a slightly different geometry in the gas phase with respect to that in the solid phase. The antitumor activity of the novel tetrahydrodiazepine derivative is investigated by investigating its binding affinity into the active site of Checkpoint Kinase Chk1/SB218078. Docking outputs reveal moderate Checkpoint Kinase inhibition by tetrahydrodiazepine derivative.

Crystal structures of two hydrazide derivatives of mefenamic acid, 3-(2,3-di-methyl-anilino)-N'-[(E)-(furan-2-yl)methyl-idene]benzohydrazide and N'-[(E)-benzyl-idene]-2-(2,3-di-methyl-anilino)benzo-hydrazide.

The conformation about the central benzene ring in the mol-ecule of (I), C20H19N3O2, is partially determined by an intra-molecular N-H⋯O hydrogen bond. In the crystal, chains parallel to the c axis are generated by inter-molecular N-H⋯O hydrogen bonds with the chains assembled into a three-dimensional network structure by inter-molecular C-H⋯O hydrogen bonds and C-H⋯π(ring) inter-actions. The mol-ecule of (II), C22H21N3O, differs from (I) only in the substituent at the hydrazide N atom where a phenyl-methyl-ene moiety for (II) is present instead of a furan-methyl-ene moiety for (I). Hence, mol-ecules of (I) and (II) show similarities in their mol-ecular and crystal structures. The conformation of the central portion of the mol-ecule of (II) is also therefore partially determined by an intra-molecular N-H⋯O hydrogen bond and inter-molecular N-H⋯O hydrogen bonds form chains parallel to the c axis. Likewise, the chains are connected into a three-dimensional network by C-H⋯O hydrogen bonds and C-H⋯π(ring) inter-actions.

Tripartite Motif 22 (TRIM22) protein restricts herpes simplex virus 1 by epigenetic silencing of viral immediate-early genes.

Intrinsic resistance is a crucial line of defense against virus infections, and members of the Tripartite Ring Interaction Motif (TRIM) family of proteins are major players in this system, such as cytoplasmic TRIM5α or nuclear promyelocytic leukemia (PML/TRIM19) protein. Previous reports on the antiviral function of another TRIM protein, TRIM22, emphasized its innate immune role as a Type I and Type II interferon-stimulated gene against RNA viruses. This study shows that TRIM22 has an additional intrinsic role against DNA viruses. Here, we report that TRIM22 is a novel restriction factor of HSV-1 and limits ICP0-null virus replication by increasing histone occupancy and heterochromatin, thereby reducing immediate-early viral gene expression. The corresponding wild-type equivalent of the virus evades the TRIM22-specific restriction by a mechanism independent of ICP0-mediated degradation. We also demonstrate that TRIM22 inhibits other DNA viruses, including representative members of the β- and γ- herpesviruses. Allelic variants in TRIM22 showed different degrees of anti-herpesviral activity; thus, TRIM22 genetic variability may contribute to the varying susceptibility to HSV-1 infection in humans. Collectively, these results argue that TRIM22 is a novel restriction factor and expand the list of restriction factors functioning in the infected cell nucleus to counter DNA virus infection.

Effect of π···π Interactions of Donor Rings on Persistent Room-Temperature Phosphorescence in D4-A Conjugates and Data Security Application.

Organic room-temperature phosphorescence (RTP) materials with persistent RTP (PRTP) have attracted huge interest in inks, bioimaging, and photodynamic therapy. However, the design principle to increase the lifetime of organic molecules is underdeveloped. Herein, we show donor(D4)–acceptor(A) molecules (TOEPh, TOCPh, TOMPh, TOF and TOPh) with similar orientation of donor rings in aggregates that cause a large number of noncovalent interactions. We observed that TOEPh, TOCPh, TOMPh and TOF showed PRTP, whereas TOPh showed only phosphorescence emission (ΦP = ∼11%) with no PRTP property at ambient conditions. The spectroscopic and single-crystal X-ray analyses confirm the molecular assembly via J-aggregation with a face-to-face orientation of the donor rings. The crystal structure analysis (TOEPh, TOCPh, TOMPh, TOF) reveals that moderate π···π interactions (3.706 to 4.065 Å) between the donor rings cause the enhancement of the phosphorescence lifetime (26 to 245 ms), whereas the short phosphorescence lifetime (12 ms) of TOPh was observed because of the absence of π···π interactions. We found that TOEPh shows a long lifetime (245 ms) as compared to other derivatives because of the presence of ethoxy (−OEt) groups that enables spin–orbit coupling caused by strong lone pair (O)···π interactions present in the molecule. Utilizing the PRTP feature of TOEPh and the fluorescence emission of TOPh, we have shown data security applications in poly(methyl methacrylate).

Occurrence of Morpholine in Central Nervous System Drug Discovery

Developing drugs for the central nervous system (CNS) requires fine chemical modifications, as a strict balance between size and lipophilicity is necessary to improve the permeability through the blood-brain barrier (BBB). In this context, morpholine and its analogues represent valuable heterocycles, due to their conformational and physicochemical properties. In fact, the presence of a weak basic nitrogen atom and of an oxygen atom at the opposite position provides a peculiar pKa value and a flexible conformation to the ring, thus allowing it to take part in several lipophilic–hydrophilic interactions, and to improve blood solubility and brain permeability of the overall structure. In CNS-active compounds, morpholines are used (1) to enhance the potency through molecular interactions, (2) to act as a scaffold directing the appendages in the correct position, and (3) to modulate pharmacokinetic/pharmacodynamic (PK/PD) properties. In this perspective, selected morpholine-containing CNS drug candidates are discussed to reveal the active pharmacophores accountable for the (1) modulation of receptors involved in mood disorders and pain, (2) bioactivity toward enzymes and receptors responsible for neurodegenerative diseases, and (3) inhibition of enzymes involved in the pathology of CNS tumors. The medicinal chemistry/pharmacological activity of morpholine derivatives is discussed, in the effort to highlight the importance of morpholine ring interactions in the active site of different targets, particularly reporting binding features retrieved from PDB data, when available.

Crystallographic and spectroscopic characterization of 2-[(7-acetyl-4-cyano-6-hy-droxy-1,6-dimethyl-8-phenyl-5,6,7,8-tetra-hydro-isoquinolin-3-yl)sulfan-yl]-N-phenyl-acetamide.

In the title mol-ecule, C28H27N3O3S, the heterocyclic portion of the tetra-hydro-iso-quinoline unit is planar and an intra-molecular N-H⋯N hydrogen bond and a C-H⋯π(ring) inter-action help to determine the overall conformation. In the crystal, a layer structure with the layers parallel to (10) is generated by O-H⋯O and C-H⋯O hydrogen bonds.

Synthesis and characterization of Fe(III), Pd(II) and Cu(II)-thiazole complexes; DFT, pharmacophore modeling, in-vitro assay and DNA binding studies

New pharmacologically active complexes were prepared from Pd (II), Fe (III), and Cu (II)ions with 2-amino-6-oxo-3-(piperidinylamidino)-4-(4methoxyphenyl)-6,7-dihydro-pyrano[2,3-d]-5,7thiazol ligand (MPTP). The ligand acted as neutral bidentate with the metals via NH and NH2 groups. FT-IR spectra, CHN-analysis, TGA, UV–Vis, molar conductance and 1H &13C NMR spectra were used to characterize the new compounds. Also stability constant of MPTP-complexes was identified in solution and pH-profile indicates high stability of complexes. Computational study was implemented to extract significant features for MPTP and its complexes. In addition to, essential maps were demonstrated over formulated chk-file. In-silico assay was executed by two different approaches over compounds to evaluate their biological behavior and degree of interaction with biological systems, before practical application. MPTPPd complex displayed priority in interaction with amino acid residues and drug-like feature. In-vitro assay was then carried out for compounds against different microbes and MPTPPd and MPTPCu showed high antimicrobial activity. Also, their cytotoxic behavior was examined against MCF-7, HCT-116, and HepG2 carcinoma cell lines, high cytotoxicity was clearly recorded with MPTPPd and MPTPCu complexes. Furthermore, antioxidant activity was examined and the complexes exhibited high reactivity with trapping free radicals. The interaction of metal chelates with DNA was detected by gel electrophoreses, viscosity and spectral studies. Spectrophotometric titration and viscosity studies expose that each of tested complex is an avid binder to DNA. This may be due to enhanced hydrophobic & electrostatic interaction of aromatic rings. Finally, such complexes may be considered as a promising bioactive agents.

The role of sulfur interactions in crystal architecture: experimental and quantum theoretical studies on hydrogen, halogen, and chalcogen bonds in trithiocyanuric acid–pyridine N-oxide co-crystals

Hydrogen, halogen, chalcogen bonds and π interactions of the trithiocyanuric acid ring are responsible for crystal structure architecture and have been classified according to the QTAIM approach as closed-shell interactions.

Vortex ring-tube reconnection in a viscous fluid

The vortex ring-tube reconnection in a viscous fluid was investigated using a proposed vortex-in-cell method combined with a large eddy simulation model (LVIC). This method was verified using simulations of the Taylor–Green vortex flow at the Reynolds numbers (Re) 200 and 2000. The results show that the present method can capture the small-scale vortex structures in turbulent flows well. Besides, a Lagrangian method for passive scalar transport was successfully developed to track the vortex dynamics. The LVIC was then applied to three simulations of the interaction of a vortex ring at ReΓr(Γ/ν)=10000 and a vortex tube at ReΓt=1000, 5000, and 10 000. At ReΓr=10000 and ReΓt=1000, the effects of the tube on the ring are trivial while the ring breaks it into two parts and entrains them. The flow’s energy spectrum remains unchanged with time, the small-scale vortices are not generated, and the ring’s motion plays a key role in the flow. Moreover, the helicity distribution on the vortices is negligible. At ReΓr=10000 and ReΓt=5000, the tube breaks into two parts, and the leaving part of the tube interacts forcefully with the ring to form the small-scale vortices at the high wavenumbers. The population of small-scale vortex structures increases with time, and the large-scale vortices are twisted after the impingement. At ReΓr=10000 and ReΓt=10000, the impingement of the ring on the tube leads to their breakdown and reconnection. A part of the ring interacts with the leaving part of the tube to form a secondary ring, while the rest replaces the leaving part to reconnect the tube. The population of small-scale vortex structures and helicity distribution increase in this flow stage because of the interaction of the secondary ring wake and connection vortices. However, after the reconnection, the population and helicity distribution on the vortex structures significantly decrease. The smallest-scale vortex structure and the most effective mixing occur with ReΓr=10000 and ReΓt=5000.

Numerical Simulation of U-Shaped Metal Rings in a Wind-Sand Environment

The interaction of U-shaped rings used for power transmission hardware with a wind-sand field is simulated numerically. A standard turbulence model is used in synergy with an Eulerian-Lagrangian approach. The results show that the wind pressure on the windward side of the U-shaped ring is the highest, a negative pressure zone appears on both sides of the U-shaped ring, while a Kármán Vortex Street is created on its leeward side. There are three possible regimes of motion for the sand grains in the wind field. Sand grains with size below 0.125 mm can follow the airflow directly into the contact area of two U-shaped rings. When the sand size is about 0.1 mm, the number of sand grains that are blown into the contact area attains a maximum. Through the simulation of U-shaped rings in the wind-sand field, the dynamics of such processes are explained in detail, thereby providing relevant information for the subsequent protection and design of connecting hardware used for power transmission.

Interactions of aromatic rings in the crystal structures of hybrid polyoxometalates and Ru clusters

Computational analysis for π–π interaction energies of {(arene)Ru}2+ containing complexes and relative group 5 hybrid polyoxometalates reveals different frameworks. Some perspectives on πOF materials processing and crystal engineering were discussed.