Propeller Configuration Research Articles

Synthesis, Crystal Structure, and Bioactivity of a Novel Iron(III) 18-Metallacrown-6 Complex

A macrocyclic hexanuclear iron(III) 18-metallacrown-6 compound, [Fe6(H2O)6 (abshz)6]·38H2O, has been prepared using a trianionic pentadentate ligand N-acetyl-5-bromosalicylhydrazidate (abshz3−) and characterized by X-ray diffraction. The crystal structure contains a neutral 18-member metallacrown ring consisting of six Fe(III) and six abshz3− ligands. The 18-member metallacrown ring is formed by the succession of six structural moieties of the type [Fe(III)-N-N]. Due to the meridional coordination of the ligand to the Fe3+ ion, the ligand enforces the stereochemistry of the Fe3+ ions as a propeller configuration with alternating Λ/Δ forms. The disc-shaped hexanuclear ring shows at its largest diameter about 7.27 Å at entrance and about 9.80 Å at the center of the cavity. Antibacterial screening data showed that the iron metallacrown has strong antimicrobial activity against Bacillus subtilis and Staphylococcus aureus.

An iron(III) 18-metallacrown-6 complex: synthesis, crystal structure, and bioactivity

A macrocyclic hexanuclear iron(III) 18-metallacrown-6 complex, [Fe6(C9H6BrN2O3)6(CH3OH)4(H2O)2] · 7CH3OH · 4H2O, has been prepared using a trianionic pentadentate ligand N-acetyl-5-bromosalicylhydrazidate, abshz3–, and characterized by X-ray diffraction. The crystal structure contains a neutral 18-membered metallacrown ring consisting of six Fe(III) and six abshz3– ligands. The 18-membered metallacrown ring is formed by combination of six structural moieties, [Fe(III)–N–N]. Due to meridional coordination of ligand to Fe3+, the ligand enforces the stereochemistry of the Fe3+ ions as a propeller configuration with alternating Δ/Λ forms. Methanol and water are linked with Fe1, Fe1A, Fe,3 and Fe3A. The ratios of methanol to water are 0.76 : 0.24 for Fe1 and Fe1A, and 0.30 : 0.70 for Fe3 and Fe3A, which results in four component crystals of metallacrown rings with ratio of 0.168 : 0.072 : 0.532 : 0.228. Antibacterial screening data showed that the iron metallacrown has moderate antimicrobial activity against Bacillus subtilis.

30-Membered decanuclear manganese metallacrown

A new macrocyclic decanuclear manganese(III) 30-metallacrowns-10, [Mn 10(ipbmshz) 8(dmpmshz) 2(DMF) 10]. 4DMF ( 1) has been prepared by supramolecular self-assembly and characterized by X-ray crystal diffraction, where ipbmshz 3− is N-(4-isopropylbenzoyl)-3-methylsalicylhydrazide, dmpmshz 3− is N-(2,2-dimethylpropanoyl)-3-methylsalicylhydrazide. The single-crystal structure shows that a novel ring formed by the succession of ten structural moieties of the type [Mn(III)–N–N] through hydrazide N–N groups bridging the ring Mn ions. The ligand enforces the Mn 3+ ions to form the stereochemistry of a propeller configuration with alternate…ΔΛΔΛ…-type chiral forms depending on the steric repulsions between the tail groups. The decanuclear systems measure ∼2.3 nm in diameter and ∼1.2 nm in thickness. The temperature-dependent magnetic properties have been studied and showed the presence of weakly antiferromagnetic couplings between Mn (III) ions.

Burn-back Equations for High Volumetric Loading Single-grain Dual-thrust Rocket Propellant Configuration

Dual-thrust mode is adopted in solid propellant rocket propulsion through tailoring of burning area, nozzle, rocket motor chamber, propellant type, multiple propellant blocks. In the present study, mathematical formulation has been evolved for generation of burning surface area with web burnt for a simple central blind hole in a solid cylindrical propellant geometry with proper partial inhibition on external and lateral surfaces. The burn-back equation has been validated by static firing and parametric study was conducted to understand effect of various control geometrical parameters. The system is utilised for high volumetric loading, single propellant, single composition, single-chamber, single nozzle dual-thrust mode of burning profiles in rocket application. Defence Science Journal, 2011, 61(2), pp.165-170 , DOI:http://dx.doi.org/10.14429/dsj.61.41

Esterification and isolation of the carboxylic acid with salicyl-bis-hydrazide via coordination of iron(III) 18-metallacrown-6 complex

The trianionic heptadentate ligand, (Z)-3-(5′-bromosalicylhydrazinocarbonyl) propenoic acid ((Z)-H4bshcpa), has been synthesized in good yield and reacted with FeCl3 · 6H2O to produce [FeIII 6(C12H8N2O5Br)6(H2O)2(CH3OH)4] · 8H2O · 8CH3OH. The complex has been characterized by single-crystal X-ray diffraction. In the self-assembly process the ligand was esterified and transferred into (Z)-methyl 3-(5′-bromosalicylhydrazinocarbonyl) propenoate ((Z)-H3mbshcp). In the crystal structure, the neutral Fe(III) complex contains an 18-membered metallacrown ring consisting of six Fe(III) and six trianionic ligands. The 18-membered metallacrown ring is formed by six structural moieties of the type [Fe(III)–N–N]. Due to the meridional coordination of the ligands to Fe3+, the ligands enforce stereochemistry of the Fe3+ ions as a propeller configuration with alternating Λ/Δ forms. The metallacrown can be treated with SnCl2 to obtain purified ester. In addition, we have also obtained reduced esterified ligand, methyl 3-(5′-bromosalicylhydrazinocarbonyl) propanoate (H3mbshcp), with Zn powder as reductant.

Path Planning for Lock Entering Maneuvers Using Nonlinear Programming

Abstract This paper presents a path planning method for lock entering maneuvers that is based on nonlinear programming. Fairway boundaries, lock walls and the input saturation of the thrust devices of the vessel are accounted for as inequality constraints in the optimization. The environmental constraints are modeled as polygons or constructive solid geometry objects. Each of the methods is used to compute a path for a typical inland vessel with a bow thruster and a rudder and propeller configuration.

2,2′-Dimethyl-5,5′-dipropan-2-yl-4,4′-(phenylmethylene)diphenol

In the title mol­ecule, C27H32O2, the aromatic rings are in a propeller configuration. In the crystal, mol­ecules are linked through O—H⋯O hydrogen bonds forming a two-dimensional network which develops parallel to (010). Futhermore, weak C—H⋯π inter­actions involving the two substituted rings build up a three-dimensional network.

Influence of propeller wake sheet on rudder gap flow and gap cavitation

The characteristics of the flow over the rudder’s pintle gap are investigated by using the particle image velocimetry (PIV) technique. The propeller and rudder models are scaled down to 1/28.5. Highly accelerated leakage outflows are separated at the discontinuities of the gap and generate strong cavitation at the suction side of the rudder. In the rudder and propeller configuration, the propeller wake sheet ahead of the gap entrance region starts to induce leakage flow over the lower pintle gaps of the suction side. The gap flow has a velocity magnitude as high as 0.4 U 0 in the high leakage flow condition, where the wake sheet locates over the gap entrance. The cross-flow of the propeller wake sheet interferes the gap entrance region and triggers gap cavitation. As the propeller wake sheet moves downstream and weakens, the gap flow velocity decreases over the gap entrance.

Novel 18-membered hexanuclear manganese metalladiazamacrocycle

The novel macrocyclic hexanuclear manganese(III) 18-Metallacrowns-6, [Mn 6[(amshz) 6(DMA) 5(H 2O)]·3DMA·H 2O ( 1), has been synthesized by a self-assembly and characterized, where amshz 3− is N-acetyl-4-methyl-salicylhydrazide. The ring is formed by the succession of six structural moieties of the type [Mn(III) N N] through hydrazide N N groups bridging the ring Mn ions. The ligand enforces the metal ions to form the stereochemistry of a propeller configuration with alternate …ΔΛΔΛ…-type chiral forms. The disc molecule offers a oval cavity with an entrance diameter ∼6.7 Å, inner largest diameter ∼9.6 Å and height ∼4.6 Å. The magnetic properties of the metallacrown are characterized by a weak antiferromagnetic exchange interaction, with the value of μ eff = 12.10 μ B at 300 K between the Mn 3+ ion spins with S = 2 in the cyclic system.

Thermomechanical modeling of regressing heterogeneous solid propellants

A numerical framework based on the generalized finite element method (GFEM) is developed to capture the coupled effects of thermomechanical deformations and thermal gradients on the regression rate of a heterogeneous solid propellant. The thermomechanical formulation is based on a multiplicative split of the deformation gradient and regression of the heterogeneous solid propellant is simulated using the level set method. A spatial mesh convergence study is performed on a non-regressing solid heterogeneous propellant system to examine the consistency of the coupled thermomechanical GFEM solver. The overall accuracy (spatial and temporal) of the coupled thermomechanical solver for regressing solid propellants is obtained from a periodic sandwich propellant configuration, where the effects of thermomechanical deformations on its regression rate is investigated. Finally, the effects of thermomechanical deformations in a regressing two-dimensional heterogeneous propellant pack are studied and time-average regression rates are reported.

Synthesis, Crystal Structure and Bioactivities of a Novel Propeller Shaped Manganese Complex with the Ligand N′‐Benzylidenesalicylhydrazide

AbstractA new propeller shaped mononuclear manganese(III) complex of the general formula: [MnL3(H2O)], where HL is N′‐benzylidenesalicylhydrazide, was synthesized and characterized. The crystal structure of the title compound was characterized by X‐ray single crystal diffractometry, which belongs to a triclinic system with space group P‐1, cell dimensions of a=11.6411 Å, b=12.728 Å, c=16.346 Å, α=110.357°, β=96.555°, γ=108.996°, V=2075.2 Å3, Z=2 and Dcalc=1.265 g/cm3. In this complex, the metal ion is in an octahedral coordination environment, enforcing the stereochemistry of the ligands as a propeller configuration. Antibacterial screening data indicate that the complex has stronger antibacterial activity against the tested microorganisms than the ligand.

Synthesis, crystal structure and esterification of a novel iron(III) 18-metallacrown-6 complex

The trianionic heptadentate ligand, ( Z)-3-(5′-chlorosalicylhydrazinocarbonyl) propenoic acid, has been synthesized and reacted with FeCl 3·6H 2O, to produce the complex [Fe III 6(C 12H 8N 2O 5Cl) 6(H 2O) 4(CH 3OH) 2]·8H 2O·4CH 3OH. In the self-assembly process the ligand was esterified and transferred into ( Z)-methyl 3-(5′-chlorosalicylhydrazinocarbonyl) propenoate. In the crystal structure, the neutral Fe(III) complex contain a 18-membered metallacrown ring consisting of six Fe(III) and six trianionic ligands. The 18-membered metallacrown ring is formed by the succession of six structural moieties of the type [Fe(III)–N–N]. Due to the meridional coordination of the ligands to the Fe 3+ ions, the ligands enforce the stereochemistry of the Fe 3+ ions as a propeller configuration with alternating Λ/Δ forms. The metallacrown can be treated with SnCl 2 or Zn powder to obtain purified ester.

Iron(iii) coordination induced novel 18-metallacrown-6 complex: esterification and isolation of the ligand

The trianionic heptadentate ligand, (Z)-3-(salicylhydrazinocarbonyl) propenoic acid ((Z)-H(4)shcpa) (1), has been synthesized in good yield and reacted with FeCl(3).6H(2)O, to produce the complex [Fe(III)(6) (C(12)H(9)N(2)O(5))(6)(H(2)O)(2)(CH(3)OH)(4)] x 6CH(3)OH (2). The complex has been characterized by single-crystal X-ray diffraction. In the self-assembly process the ligand was esterified and transferred into (Z)-methyl 3-(salicylhydrazinocarbonyl) propenoate ((Z)-H(3)mshcp) (3). In the structure, the neutral Fe(III) complex contains a 18-membered metallacrown ring consisting of six Fe(III) and six trianionic ligands. The 18-membered metallacrown ring is formed by the succession of six structural moieties of the type [Fe(III)-N-N]. Due to the meridional coordination of the ligands to the Fe(3+) ions, the ligands enforce the stereochemistry of the Fe(3+) ions as a propeller configuration with alternating Lambda/Delta form. The metallacrown can be treated with SnCl(2) to obtain purified ester. In addition, we have also obtained reduced esterified ligand, methyl 3-(salicylhydrazinocarbonyl) propanoate (H3mshcp) (4) with another reductant Zn powder.

Investigation of the Magnetic Field in a Pulsed Plasma Thruster

The magnetic field between the electrodes of an 80 J ablative pulsed plasma thruster was both measured and determined analytically. This was done to better understand the acceleration process and assess the accuracy of the analytical method. The measurements at different positions in both breech-fed and side-fed propellant configurations were performed using a shielded induction probe of 1 mm in diameter. To calibrate the probe, a Helmholtz coil was built. The magnetic field was calculated using the law of Biot-Savart and assuming a current sheet thickness of 3 mm. The measured magnetic field showed an overall peak at 0.7 T. It was possible to confirm the induced current loop formed between the electrodes at the time when the overall current passes through zero. The comparison between the magnetic field model and the measurements at the propellant surface of a breech-fed thruster showed reasonably good accordance.

Total impulse improvement of coaxial pulsed plasma thruster for small satellite

Research and development on pulsed plasma thruster (PPT) for small satellites has been conducted in Tokyo Metropolitan University (TMU). A PPT with coaxial electrode and PTFE cavity has been considered to gain larger impulse bit than that of parallel plate PPT. In this paper, the objectives are development of the PPTs with large impulse bit and large total impulse, to apply to a propulsion system for a small satellite. The electrodes and the propellant configuration were considered. As a result, divergent nozzle and larger cathode diameter improved thrust performances and larger impulse bit from 300 to 800 μNs was achieved. And the current reversal was appeared remarkable as its operation accumulated. Then, propellant-feeding mechanism was considered to improve its total impulse. With exchange of five propellants in each 20,000 shots, total impulse of 40 Ns was obtained. These results indicate that the PPT developed in TMU would provide various missions for a small satellite.

A novel 18-membered metallacrown containing a double-azathiacrown

A new type of 18-metallacrown-6, [Fe6(H2O)6L6] (L = 1-(2-hydroxy-benzoyl)-thiosemicarbazide), has been prepared and characterized. The backbone of this metal-organic assembly is the double-azathiacrown, which is formed by six repeating units of the five-membered rings [Fe–S–C–N–N]. It is the first metal complex containing a double-azathiacrown. Due to the meridional coordination of the ligand to the Fe3+ ion, the ligand enforces the stereochemistry of the Fe3+ ions as a propeller configuration with alternating Λ/Δ forms. Antibacterial screening data showed that the metallacrown has strong antimicrobial activity against Escherichia coli and Staphylococcus aureus.

Synthesis, characterization and bioactivity of a novel iron(III) 18-metallacrown-6 complex with S-donor ligands

The reaction of 4-salicyloyl thiosemicarbazide (H 3st) ( 1) with FeCl 3 · 6H 2O in methanol solution gives a novel 18-metallacrown-6 [Fe(st)(H 2O)] 6 · 21H 2O ( 2). The structure containing S–Fe bonds was determined for 2 by using X-ray crystallography. The ring of the metallacrown was consisted of six interlink [Fe–N–N] repeated units. And the ligand enforces the metal ions to form the stereochemistry as a propeller configuration with alternation Λ/ Δ form. The largest diameters of the disc-shaped hexanuclear ring are about 7.44 Å at entrance, 9.91 Å at the central of the cavity, respectively. The structural integrity and stability of the metallacrown ring were studied by electronspray ionization ESI-MS and UV–Vis spectroscopy. The results show that it is stable and soluble in methanol. Antibacterial screening data show that the complex 2 weakened dramatically the antibacterial activity of the ligand H 3st.

4-(2,2′:6′,2′′-Terpyridyl)benzyltriphenylphosphonium bromide

In the title compound, C40H31N3P+·Br−, the 4-(2,2′:6′,2"-terpyridine)benzyl group is in a slightly twisted conformation with a dihedral angle between the benzyl ring and the central pyridyl ring of 28.87 (5)°. The dihedral angles between the two outer and the inner pyridyl rings are only 4.04 (4) and 7.17 (5)°, respectively. The three phenyl groups are in a propeller configuration typical for this type of triphenyl­phospho­nium compound. The title compound exhibits large voids filled with diffuse solvent mol­ecules of 252.5 Å3 (13.9% of the unit-cell volume), which stretch as channels parallel to the c axis. The packing of the structural components is governed by C—H⋯Br hydrogen bonds, and C—H⋯π as well as π–π stacking inter­actions [the closest centroid-to-centroid distance is 3.843 (2) Å], to form a three-dimensional supra­molecular structure.

Synthesis, characterization and bioactivity of a novel 18-metallacrown-6: [Mn(pcshz)(CH 3OH)] 6 · 4CH 3OH · 4H 2O

The reaction of N-propionyl-5-chlorosalicylhydrazide (H 3pcshz) with Mn(OAc) 2 · 4H 2O in methanol solution gives a novel 18-metallacrown-6 [Mn(pcshz)(CH 3OH)] 6 · 4CH 3OH · 4H 2O ( 1). The structure of 1 has been determined by X-ray diffraction and it crystallizes in the monoclinic system and space group P2(1)/ n. The ring of the metallacrown is consisted of six interlink [Mn–N–N] repeated units through hydrazide N–N group bridging the ring manganese ions. And the ligand enforces the metal ions to form the stereochemistry as a propeller configuration with alternation Λ/ Δ form. The largest diameters of the disc-shaped hexanuclear ring are about 8.82 Å at entrance, 9.83 Å at the central of the cavity, respectively. The solution integrity and stability of the metallacrown was studied by electrospray ionization (ESI)-MS and UV–Vis spectroscopy. The results show it is soluble and stable in methanol. Antibacterial screening data indicate the forming of the complex weakens dramatically the antibacterial activity of the ligand H 3pcshz except for Eschericha coli.

Two novel 18-metallacrown-6 complexes: Synthesis, structural characterization and bioactivity

Two new macrocyclic hexanuclear metal(III) 18-metallacrowns-6, [Mn6(acshz)6(H2O)6]·18H2O (1) and [Fe6(acshz)6(CH3OH)6]·6CH3OH·6H2O (2), have been synthesized and characterized, where acshz3− is N-acetyl-5-chlorosalicylhydrazidate. These crystal structures contain neutral 18-membered metallacrown rings consisting of six metal(III) ions and six acshz3− ligands. The ring is formed by the succession of six structural moieties of the type [M(III)–N–N] through hydrazide N–N groups bridging the ring metal ions. The ligand enforces the metal ions to form the stereochemistry of a propeller configuration with alternate Λ/Δ or Δ/Λ forms. The largest diameters of the hexanuclear rings are about 6.97Å at the entrance and 9.53Å at the centre of the cavity for 1; and 7.94 and 10.24Å for 2, respectively. The solution integrity and stability of the metallacrowns were confirmed using electrospray ionization ESI-MS and UV–Vis spectroscopy in methanol. Antibacterial screening data indicate the formation of the metallacrown 1 reduces the antimicrobial activity of the ligand H3acshz hugely, while metallacrown 2 has strong antimicrobial activity against Bacillus subtilis (B. subtilis).