Bowl-shaped Structures Research Articles

Bowl-Shaped Anthracene-Fused Antiaromatic Ni(II) Norcorrole: Synthesis, Structure, Assembly with C60, and Photothermal Conversion.

The synthesis of bowl-shaped antiaromatic molecules represents a formidable challenge, because the molecular distortion further destabilizes these already inherently reactive molecules. Here, we report the synthesis and properties of bowl-shaped fused anthrylnorcorroles that exhibit near-infrared (NIR) absorption reaching 1900 nm. The oxidation of meso-anthryldibromodipyrrin provides fused anthryldibromodipyrrin, which was converted to the fused mono- and bisanthrylnorcorroles through Ni(0)-mediated intramolecular coupling with a bis(dibromodipyrrin) Ni(II) complex. Single-crystal X-ray diffraction analyses revealed bowl-shaped structures for the fused mono- and bisanthrylnorcorroles, which enables them to act as suitable receptors for C60 with bonding constants of 2.89 × 103 M-1 and 1.59 × 103 M-1, respectively. The formation of a 1:1 complex between the fused monoanthrylnorcorrole and C60 was confirmed by single-crystal X-ray diffraction analysis. The effective expansion of the π-conjugation through the triple fusion of the norcorrole with the anthracene units substantially enhances the near-infrared absorption bands, which endows these anthrylnorcorroles with effective photothermal conversion.

Bowl-shaped PAHs as gas adsorbents: Hydrogen storage and binding of gaseous pollutants

Understanding the non-covalent interactions of various molecules with bowl-shaped carbon structures at a quantum-chemistry level is important for the design of new materials. In this work, adsorption of three important diatomic molecules (H2, CO, and HF) on a flat coronene molecule and bowl-shaped PAHs (corannulene, sumanene, and triazasumanene) was theoretically investigated. The considerable increase of the interaction energy (Eint) was found for all molecules inside the curved structures compared to coronene (the increase was up to 2 × ). It was shown that dispersion interactions play the main role in total attraction for H2 and CO molecules. For HF molecules, the importance of induction (Eind) and electrostatics (Eel) for adsorption was revealed. QTAIM and IGM analyses showed the existence of non-covalent interactions (H2, CO) and H-bonding (HF) between the adsorbate molecules and the adsorbents. The obtained results establish the potential use of the studied bowl-shaped carbon structures in gas adsorbent systems.

Diruthenium Tetracarboxylate-Catalyzed Enantioselective Cyclopropanation with Aryldiazoacetates.

A series of chiral bowl-shaped diruthenium(II,III) tetracarboxylate catalysts were prepared and evaluated in asymmetric cyclopropanations with donor/acceptor carbenes derived from aryldiazoacetates. The diruthenium catalysts self-assembled to generate C4-symmetric bowl-shaped structures in an analogous manner to their dirhodium counterparts. The optimum catalyst was found to be Ru2(S-TPPTTL)4·BArF [S-TPPTTL = (S)-2-(1,3-dioxo-4,5,6,7-tetraphenylisoindolin-2-yl)-3,3-dimethylbutanoate, BArF = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate], which resulted in the cyclopropanation of a range of substrates in up to 94% ee. Synthesis and evaluation of first-row transition-metal congeners [Cu(II/II) and Co(II/II)] invariably resulted in catalysts that afforded little to no asymmetric induction. Computational studies indicate that the carbene complexes of these dicopper and dicobalt complexes, unlike the dirhodium and diruthenium systems, are prone to the loss of carboxylate ligands, which would destroy the bowl-shaped structure critical for asymmetric induction.

Electrophilic C-H Borylation of Aza[5]helicenes Leading to Bowl-Shaped Quasi-[7]Circulenes with Switchable Dynamics.

The intrinsic relationship between helicenes and circulenes is of fundamental interest and importance in molecular engineering. Herein, electrophilic borylation of phenanthroline-derived aza[5]helicenes is presented, resulting in the incorporation of a boryl unit into two termini of helicenes to afford quasi-[7]circulenes. Their bowl-shaped structures were determined by X-ray diffraction. UV-vis absorption and fluorescence spectroscopy, as well as electrochemical measurements and DFT calculations, gave insight into their electronic properties. Variable-temperature NMR studies and DFT calculations revealed bowl-to-bowl inversion at room temperature and bowl-to-helix equilibria at elevated temperature, highlighting the important role of B ← N bond strength in tuning their dynamic properties.

Theoretical Study on the Structures, Electronic Properties, and Aromaticity of Thiophene Analogues of Anti-Kekulene

We predict the geometries, electronic properties, and aromaticity of thiophene analogues of anti-kekulene with six to nine thiophene rings 1–4, together with those of cyclobutadithiophenes (CDTs) and anti-kekulene as reference compounds, using density functional theory calculations. Investigation of the simplest reference compounds, CDTs, reveals that the local aromaticity of their thiophene rings is influenced by their fused position (b- or c-bond) to the four-membered ring (4MR). A thiophene ring fused at the b-position (b-TR) retains its aromatic character to some extent, whereas the aromatic character of one fused at the c-position is attenuated. The 4MR with two fused b-TRs retains a strong anti-aromatic character. Thiophene analogues of anti-kekulene with six to eight thiophene rings 1–3 favor bowl-shaped structures, in contrast to the planar structure of anti-kekulene, because of the shorter distances of the sulfur bridges. Compound 4, with nine thiophene rings, adopts a planar structure. The local aromaticity and anti-aromaticity of the thiophene ring and 4MR are significantly attenuated in 1–4 compared with the reference compounds, the CDTs and anti-kekulene. This can be attributed to the considerable contribution of the quinoidal electronic structure in 1–4. The present study provides new insight into the aromatic and electronic nature of systems containing cyclobutadienothiophene.

Wälzfestigkeit maschinell gehämmerter Oberflächenstrukturen im Zahnflankenanalogieversuch

Rolling-sliding contacts, such as the tooth flank contact, are tribological systems whose properties are determined by the interactions between the contacting bodies, the lubricant and the ambient medium. Innovative manufacturing processes are being used to reduce friction and increase the load-carrying capacity of highly loaded rolling-sliding contacts. For mixed friction conditions, bowl-shaped structures in particular, generated for example by laser machining, have led to improved running behavior. Similar to laser machining, machine hammer peening (MHP) also produces a deterministic surface structure that can exhibit improved tribological properties. In recent years, MHP has been used specifically to optimize the service life of highly stressed tools, e.g. in deep-drawing processes, and has been developed further in a targeted manner. In this report, the rolling strength of machine-hammered surfaces is evaluated using fatigue tests on a disk-on-disk test rig gear-typical contact conditions. The MHP can be used to increase the contact strength in a targeted manner, whereby the selection of the process parameters during surface hammering represent an important influencing factor. In particular, the surface can be pre-damaged by excessive impact energy as a result of the ram stroke.

Synergistic antibacterial photocatalytic and photothermal properties over bowl-shaped TiO2 nanostructures on Ti-19Zr-10Nb-1Fe alloy

As implant substitutes are increasingly applied to the clinic, the infection caused by implants has become one of the most common complications, and the modification of the antibacterial function of the implant can reduce such complications. In this work, a well-defined bowl-shaped nanostructure coating with photocatalytic and photothermal synergistic antibacterial properties was prepared on Ti-19Zr-10Nb-1Fe (TZNF) alloy. The coating is obtained by spin-coating and sintering TiO2 precursors templated from self-assembled microspheres of polystyrene-poly(4-vinylpyridine) (PS-P4VP) amphiphilic block polymer on TZNF alloy. PS-P4VP provides the bowl-shaped TiO2 nanostructures doped with C, N elements, reducing the band-gap of TiO2, which can absorb near-infrared (NIR) light to release reactive oxygen species and produce photothermal conversion. The bowl structure is expected to enhance the utilization of light via the reflection in the confined space. The bowl-shaped surface has 100% antibacterial rates after 30 min of NIR light irradiation. In addition to antibacterial properties, the bowl-shaped surface has better hydrophilicity and protein adsorption capacity. The amount of protein adsorbed on TZNF with the bowl-shaped structures was six times that of TZNF. Hence, the bowl-shaped nanostructure can promote the proliferation and adhesion of osteoblasts, the cell proliferation rate was increased by 10–30%.

Synthesis and Reactivity of 1-Hydroxyherquline A.

Herein, we present the synthesis of 1-hydroxyherquline A and describe its reactivity discovered during its attempted conversion to herquline A, a long-sought natural product target in the synthetic chemical community. The strategic installation of the C1 hydroxyl group enabled the key aza-Michael addition-mediated N10-C2 bond formation and eventually access to 1-hydroxyherquline A, the most advanced herquline A congener reported to date. Our attempted reductive transformation of 1-hydroxyherquline A to herquline A was challenged by the extremely strained bowl-shaped pentacyclic structures of key precursors that prevented either radical formation at C1 or protonation (or hydrogenation) from the desired face. These discoveries regarding the innate chemical reactivities of advanced intermediates toward herquline A may prove useful in efforts toward this formidable target.

Miniatured Fluidics-Mediated Modular Self-Assembly of Anticancer Drug–Amino Acid Composite Microbowls for Combined Chemo-Photodynamic Therapy in Glioma

A particulate carrier with the ability to load a combination of therapeutic molecules acting via diverse modes to initiate cancer cell ablation would help heighten anticancer therapeutic outcomes and mitigate harmful side effects due to high doses of mono drug therapy. Moving a step closer, herein, we have developed doxorubicin-curcumin-amino acid-based composite microbowls (CMBs) following miniaturized fluid flow-based self-assembly. The CMBs were further exploited as dual chemo-photodynamic therapeutic agents in C6 glioma cells cultured in both two-dimensional (2D) monolayer and as three-dimensional (3D) spheroids. These CMBs showed synergistic and visible (blue)-light-sensitive cell-killing effects in both C6 cells and 3D spheroids. Furthermore, these bowl-shaped structures also demonstrated good stability and excellent in vitro cytocompatibility in C6 glioma cells. Our results indicated that CMBs with asymmetric cavities could potentially be used as a combinatorial drug carrier enabling simultaneous chemo- and phototherapy for effective cancer treatment. The use of blue light, from the visible part of the electromagnetic system, to generate the phototherapeutic effect further advocates for the ease and widespread applicability of the systems.

Formation of deep-drawing in an open-die by pulsed-magnetic field pressure

The deep-drawing process is considered one of the most important metal processing processes, which is used to form sheet metal of bowl-shaped structures in the field of mechanical engineering, aviation and rocket engineering under tension and compression without changing the sheet thickness. The present work is to evaluate the formability of an aluminum alloy sheet using an open-die in deep drawing process, an attractive manufacturing technique using electromagnetic force (Lorentz) to form metal parts. This work investigates the history of deformation (displacement, deformation, strain rate) in the process of electromagnetic deep drawing in an open-die using a numerical model. The research methods are the finite element method (FEM) associated with the boundary element method (BEM) using LS-DYNA software for the analysis of electromagnetic, mechanical and thermal solvers. Results analysis of the deformable solid thickness in the process of deformation showed that the thickness increased in the marginal zone and reached 1.77 mm. Further, the thickness in the middle zone decreased by 0.23 mm and decreased by 0.35 mm in the central zone. The plastic deformation of the workpiece gradually increased from zero to 26% for the middle zone, 31% for the marginal zone and 46% for the central zone.

Subbiliazine: A Contracted Phthalocyanine Analog.

The direct borylation of two bis(pyrazolylimino)isoindoline chelates with BF3 and base under dry conditions results in the formation of two boron adducts. These are ring-contracted analogs of biliazine and can be considered as subbiliazines, as they have bowl-shaped structures similar to subphthalocyanine. Additionally, a new iminooxoisoindoline BF2 complex was made from hydrolysis of the free base in the presence ofBF3. The electronic structures of the free bases and subbiliazines were probed by density functional theory (DFT) and time-dependent DFT (TDDFT) methods.

Characterization of Push-Pull-Type Benzo[X]quinoline Derivatives (X = g or f): Environmentally Responsive Fluorescent Dyes with Multiple Functions.

Benzo[X]quinoline (X = g or f: BQX) derivatives bearing bis-trifluoromethyl and amine groups have been designed as push-pull-type fluorescent dyes. Through the synthesis of BQX derivatives from 2,7-diaminonaphthalene, linear-type (BQL) and angular-type (BQA) structural isomers were obtained. X-ray structures of single crystals from six given BQX derivatives revealed that the BQL and BQA series adopt planar- and bowl-shaped structures. In the fluorescence spectra, interestingly, the BQL series emitted in the near-infrared region over 700 nm in polar solvents. Based on the visible absorptions and base properties related to the amine moiety, the ammonia responsiveness was investigated using an ion-exchange reaction by the BQX-HCl salt. By exploiting the environmentally responsive fluorescence probe, cell imaging through confocal laser microscopy was conducted using HeLa and 3T3-L1 cells, emitting specific lipid droplets. The results indicate that BQX derivatives have multiple functions and may be applied in materials chemistry and biochemistry.

Stacking interactions in cavity-containing molecular structures built from acylphloroglucinols: a computational study

Computational studies of cavity-containing molecular structures built from acylphloroglucinol units had shown that the bowl-shaped structures are likely the deepest and most tightly-textured bowls that can be obtained from hydroxybenzenes, and that tube-shaped structures exhibit tight texture with alternatingly higher and lower levels of the benzene rings of the building units. Because of the mutual positions of the aromatic rings in the walls of the cavity, stacking interactions can be expected to play significant roles. The current work presents the results of a computational study in which the previously calculated bowl-shaped and tube-shaped structures were recalculated using the same DFT/B3LYP/6-31 + G(d,p) level of theory, with the inclusion of the Grimme correction to take stacking interactions into account. The energy lowering and the changes in other molecular properties − with respect to the results of calculations without the Grimme correction − are analysed in terms of the shapes of the structures (bowl- or tube-shaped), the number and types of monomeric units constituting it, the symmetry type, and the conformer type. The results confirm the significance of the stacking interactions for cavity-containing structures built from acylphloroglucinols.

Tube-shaped molecular structures built from acylphloroglucinols: an ab initio and DFT study

Molecular structures containing a cavity encounter a variety of applications, from hosts to ions or to smaller molecules to building units for nanomaterials. Previous computational studies of bowl-shaped structures built from acylphloroglucinol (ACPL) units had shown that ACPLs can form the deepest cavities among hydroxybenzenes. The current work considers tube-shaped structures built from ACPL units. To ensure that the two rims have equal size, the orientations of the even-number units are alternated, so that each rim contains alternating RCO and OH-only groups from neighbouring units. Tubes with 4 and 6 units and different R chains have been calculated at the HF/6-31G(d,p) and DFT/B3LYP/6-31+G(d,p) levels. In each rim, the space between two consecutive RCO groups contains three consecutive intramolecular hydrogen bonds (IHBs). The computable properties of the calculated tubes are analysed in detail, with particular attention to the tubes’ geometric features (including the size of the hollow inner part) and to the characteristics and roles of the IHBs. It is inferred that the characteristics of these tubes (including the tight texture of their ‘walls’, the electron-richness of their cavities, and the possibility of expanding their size through the addition of more monomeric units) suggest potential interest for practical applications.

Exploring the adsorption and sensing behavior of the M-Nx-B36-x (M=Fe, Ni, and Cu; x=0, 3) bowl-shaped structures upon CO, NO, O2, and N2 molecules: A first-principles study

Designing a novel metal-doped material is the abiding quest to remove toxic gases from the atmosphere using sensors based on 2D nanomaterials. Experimental observation of the finite-size of B 36 borophene on one side and theoretical investigation of the potential of B 36 as support for transition metals (Sc–Zn) on the other side, motivated this study to explore the electronic and chemical properties of B 36 as support for M = Fe, Ni, and Cu atoms towards the adsorption of O 2 , N 2 , NO, and CO molecules. In addition, the N-doped configuration as a result of the substitution of three N atoms with three B atoms in the central ring of B 36 moiety of the M − B 36 (M = Fe, Ni, and Cu) clusters to improve their gas sensing behavior is also considered. It is found that, M − B 36 clusters can bear their stability upon N-doping. Also, the impact of N-doping on the electronic structure of the M − B 36 (M = Fe, Ni, and Cu) clusters before and after gas adsorption is discussed by analyzing the adsorption energy (E ads ), the change of HOMO-LUMO gap (E g ), and density of state (DOS) plots. Among the six studied clusters, namely M-N x -B 36-x (M = Fe, Ni, and Cu; x = 0, 3), it is revealed that Cu–B 36 , Fe–N 3 –B 33 , Ni–N 3 –B 33 , and Cu–N 3 –B 33 clusters could be recommended as a promising gas sensing material for the O 2 , CO, NO, and N 2 gases, respectively. The E ads for the most stable configurations were calculated to be in the range of −0.32 to −3.31 eV for O 2 , N 2 , NO, and CO adsorption over M-N x -B 36-x clusters. Also, E g of Fe–N 3 –B 33 and Ni–N 3 –B 33 clusters significantly reduces the E g (in the range of 15–36%). Thus, the electrical conductivity of Fe–B 36 and Ni–B 36 clusters is meaningfully increased by N-doping toward CO and NO adsorption. It is expected that the potential of the M-N x -B 36-x clusters in the gas sensing can provide a new route to design boron-based gas sensors for gas detection. • O 2 , N 2 , NO, and CO adsorption on M − B 36 (M = Fe, Ni, and Cu) clusters has been investigated. • The effect of N-doing on the O 2 , N 2 , NO, and CO adsorption is also studied. • The N-doping increases the sensing behavior of metalized borophene. • Boron-based sensors can be applied in gas separation.

Bowl-shaped structures in a Pleistocene clastic carbonate wedge on the Island of Rhodes, Greece

Bowl-shaped structures are for the first time reported from the Greek Island of Rhodes. They occur in Pleistocene deposits of the Cape Arkhangelos Formation in the Rhodes Synthem. The regularity of their three-dimensional appearance is the argument for a biological origin. This gives the reason to assign the structures to Piscichnus waitemata for which we issue a formal diagnosis. They were formed on a clastic carbonate wedge that built into a coastal, steep-sided basin. Associate trace fossils are Thalassinoides suevicus and Bichordites monastiriensis.

Five- and six-member bowl-shaped structures from acylphloroglucinols: an ab initio and DFT study.

Molecular structures containing bowl-shaped cavities are interesting for purposes such as hosting molecules or metal ions. Acylphloroglucinols are derivatives of phloroglucinol (1,3,5-trihydroxybenzene) containing a CRO group. A previous study had considered bowl-shaped structures consisting of 3 or 4 identical acylphloroglucinol units linked by methylene bridges, selecting representative R chains and including also a structure with phloroglucinol units. The presence of three 'binding' levels between neighbouring units (consecutive hydrogen bonds in the lower rim, the methylene bridges at intermediate level, and another set of hydrogen bonds in the upper rim) makes these bowls 'deeper' than bowls from other hydroxybenzenes. The current study considers larger bowls, consisting of 5 and 6 identical units, to investigate how the molecular properties change with the increase in the size of the bowl. The monomeric units are the same as in the previous study, and the levels of theory are the same as in the previous study, to enable meaningful comparisons. Like in the previous study, two conformers are considered for each bowl, differing by the orientation of the OH groups in the lower rim. Calculations were performed at the HF/6-31G(d,p) and DFT/B3LYP/6-31+G(d,p) levels with fully relaxed geometry, complemented by single-point MP2/HF/6-31G(d,p) calculations. The results show that the Cnv symmetry (with n being the number of constituting monomers) is maintained for 5-member bowls, while 6-member bowls do not show C6v symmetry but only C2v symmetry. The molecular properties of the calculated bowls are analysed in detail and also compared with the properties of the previously calculated 4- and 5-member bowls. Graphical abstract Bowls built from acylphloroglucinol units have three levels of intermonomer linkages: hydrogen bonds in the bottom rim, methylene bridges at intermediate level, and other hydrogen bonds in the upper rim. They are the deepest bowls that can be built from hydroxybenzene units.

The Rapid Synthesis of π-Extended Azacorannulenes

In this account we describe our recent development of rapid syntheses of π-extended azacorannulenes. The key to successful synthesis is the use of polycyclic aromatic azomethine ylides, which exhibit extremely high reactivity in sequential 1,3-dipolar cycloadditions with alkenes and alkynes followed by oxidation to form fused pyrroles. This efficient construction of the polycyclic pyrrole structure has led to the rapid synthesis of various π-extended azacorannulenes, which are characterized by their extended π-surface and highly curved, bowl-shaped structures. The present study provides useful insights toward the bottom-up synthesis and property elucidation of heteroatom-containing fullerenes and their fragment molecules.

Relationship between bowl-shaped clastic injectites and parent sand depletion: implications for their scale-invariant morphology and composition

Abstract Three-dimensional seismic reflection data provide a means to assess the impact of injection on parent sands, and to quantify the character of the resulting injectite networks. The morphology of a series of large injectite structures hosted in the Paleocene Lower Lista Formation were mapped using broadband 3D seismic data from the North Sea to investigate their relationship with parent sands. Fourteen bowl-shaped structures were identified within the Lista Formation in the study area (60–85 m in height, and 200–900 m in width). Sand is absent (below resolution) below these large-scale bowls, suggesting that the parent sand is the underlying Maureen Formation and that sand ‘welds’ formed, rather than sand-prone channelized deposits within the Lista Formation. Identification of injectite networks can be ambiguous, which impacts geological model development. Observations from exhumed systems and core offer high-resolution insights into the complexity of injectite networks. To advance our understanding of this scale gap, we argue for injectites being scale invariant in their shape and grain size. This permits the application of outcrop-scale knowledge to seismic-scale interpretation. The demonstrable depletion of parent sands, and their scale invariance, can be applied to basin-fills worldwide to reduce uncertainties of the impact of sand injectites on hydrocarbon reservoirs.

Dicyclopenta[ghi,pqr]perylene as a Structural Motif for Bowl-Shaped Hydrocarbons: Synthetic and Conformational Studies.

Dicyclopenta[ghi,pqr]perylene (DCPP) is a substructural fragment on the surface of C70 yet not on C60. Unlike its intensely investigated buckybowl cousins, corannulene and sumanene, DCPP is largely ignored due to the lack of synthetic accessibility. This communication describes the first preparation of a DCPP derivative from bay substituted perylene bis(4-(trifluoromethyl)phenyl)methanol as the key cyclization precursor. Further incorporation of indeno substitutions at peri positions was accomplished through Suzuki-Heck benzannulation. DCPP derivatives 4 adopts a planar structure in crystal. On the contrary, indeno DCPP 5 and bis-indeno DCPP 6 adopt the bowl-shaped conformation in both the solid state and solution. Density functional theory (DFT) calculation reveals that the lowest-energy conformations of 4, 5, and 6 are all bowl-shaped. Nevertheless, small bowl-to-bowl inversion barrier for 4 (3.4 kcal/mol) is overcome by the crystal packing force, which leads to its observed planar structure. However, the bowl-shaped structures of 5 and 6 are affirmed by DFT calculation with intermediate and high bowl-to-bowl inversion barriers (10.4 and 18.5 kcal/mol, respectively).