Synthesis,structural phase transition,and characterization of potassium hydrogen bis-dichloroacetate

Potassium hydrogen bis-dichloroacetate (1) was synthesized and separated as crystals. Differential scanning calorimetry (DSC) measurement reveals that this compound undergoes a reversible phase transition at about 259 K with a heat hysteresis of 23.5 K. Dielectric anomaly observed at 260 K in the heating process further confirms the phase transition. The room temperature X-ray single-crystal structure determination indicates that 1 crystallizes in the monoclinic crystal system with a centrosymmetric space group P2₁/c, and cell parameters are a =?6.240(1), b =?23.177(4), c =?7.335(1) Å, β =?106.938(1)°, V =?1014.8(3) ų, and Z =?4. In the low temperature phase, 1 also crystallizes in monolinic with space group P2₁/c, and cell parameters are a =?6.180(1), b =?22.988(2), c =?7.200(1) Å, β =?108.098(1)°, V =?972.4(1) ų, and Z =?4. The structural phase transition is dominating caused by the torsion of bond angles.     

Structural and vibrational investigation of 1, 2-<Emphasis Type="Italic">bis</Emphasis>(3, 4-dimethoxyphenyl) ethane-1, 2-dione (Veratril): experimental and theoretical studies

The molecular and crystal structures of 1,2-bis(3,4-dimethoxyphenyl)ethane-1,2-dione (TMBZ = tetramethoxybenzil) were determined by a single-crystal X-ray diffraction, ¹H NMR, and FT-IR spectroscopy. The compound TMBZ (C₁₈H₁₈O₆, M _r = 330.32) crystallized in the orthorhombic Fdd2 space group wherein: a = 39.145(4), b = 18.167(2), c = 4.3139(5) Å and β = 90°, Z = 8. The packing of the molecules in the crystal lattice is stabilized by intermolecular C–H?O contacts in the herringbone arrangement. The molecular geometry and harmonic frequencies of TMBZ in the ground state were calculated utilizing density functional (B3LYP) method with the 6-311++G(d, p)-basis set. The density functional theory optimized the geometric structure, and vibrational wave numbers of TMBZ in gas phase were compared with the experimental data. A complete assignment of the fundamentals was proposed based on the total energy distribution calculation.     

Synthesis,crystal structure,and hydrogen-bonded displacive-type structural phase transition of guanidine dichloroacetate

Guanidine dichloroacetate was synthesized and separated as crystals. Differential scanning calorimetry (DSC) measurement shows that this compound undergoes a reversible phase transition at about 275 K with a heat hysteresis of 28 K. Step-like dielectric anomaly observed at 274 K further confirms the phase transition. The single-crystal X-ray diffraction data suggested that these was a transition from a room-temperature phase with the space group of P2₁/n (a = 8.030(5), b = 12.014(9), c = 8.124(6) Å, β = 96.089(1)°, V = 779.3(1) Å³, and Z = 4) to a low-temperature one with the space group of P2₁/c (a = 7.941(2), b = 11.828(3), c = 10.614(2) Å, β = 130.985(1)°, V = 752.6(3) Å³, and Z = 4). The displacements of hydrogen bonds induce the structure phase transition.     

Synthesis,characterization, antimicrobial activity and ultrastructure of the affected bacteria of new quinoline compounds

The reaction on 8-hydroxy quinoline-7-aldehyde azo compounds (HL _n ) (where n = 1–5) with 4-amino-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one to obtain HL _n (where n = 6–10) have been characterized by means of TLC, melting point and spectral data, such as IR, ¹H NMR, mass spectra and thermal studies. The X-ray diffraction patterns of two starting materials 8-hydroxy quinoline-7-aldehyde (start 1), 4-amino-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one (start 2) and the ligands (HL_5,10) are investigated in powder form. All the ligands have been screened for their antimicrobial activity against four local bacterial species, two Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus) and two Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) as well as against four local fungi; Aspergillus niger, Alternaria alternata, Penicillium italicum and Fusarium oxysporium. The results show that the azo ligands (HL _n ) (where n = 1–5) have no antimicrobial activity against bacteria and fungi while most azomethine ligands (HL _n ) (where n = 6–10) are good antibacterial agents against E. coli and K. pneumoniae as well as antifungal agents against P. italicum and A. alternata. The results were compared to standard substances (start 1) and (start 2). Among the azomethine ligands, HL₁₀ was the most effective against the most microorganisms tested. The size of clear zone was ordered as p-(OCH₃ < CH₃ < H < Cl < NO₂) as expected from Hammett’s constant (σ ^R ). Also, the ultrastructure study of the affected bacteria confirmed that HL₈ is good antibacterial agent against E. coli and S. aureus.     

A Novel 3D Platinum–Thallium Coordination Polymer having Strong Metal–Metal Interactions

A new three-dimensional platinum(II)–thallium(I) coordination polymer [{Pt(pda)(NHCOtBu)₂}₄Tl₄][Pt(CN)₄]₂·2H ₂ O (pda = 1,2-propyldiamine) has been prepared from the direct reaction of [Tl₂Pt(CN)₄] and [Pt(pda)(NHCOtBu)₂] in water, and its structure was characterized by X-ray diffraction analysis. The compound crystallizes in monoclinic, space group Pn, a = 11.567(2) Å, b = 11.570(2) Å, c = 37.677(8)Å, β = 94.64(3)°, V = 5025.8(17) Å³, Z = 2, R1 = 0.0679 and wR2 = 0.1574 [I >  2σ (I)], Goodness-of-fit on F ² = 1.055. The compound exhibits a novel 3D network structure consisting of [Pt(CN)₄]^2? connected 1D infinite Pt–Tl–Pt–Tl chains via strong Pt–Tl bonds.     

Synthesis and the structure of 1,2-bis(6-acetyl-2-methylbenzo[<Emphasis Type="Italic">b</Emphasis>]thiophen-3-yl)cyclopentene

New 1,2-dihetarylethene containing two 6-acetyl-2-methylbenzo[b]thiophene moieties linked by the cyclopentene bridge was synthesized. In a toluene solution, this compound exhibits photochromic properties. The X-ray diffraction study showed that the crystal structure also has properties characteristic of photochromic compounds, viz., the anti-parallel conformation of the molecule and the distance between the reaction centers equal to 3.729 Å.     

Blue Photoluminescent Dimeric Cu(I) Dithiophosphates Bridged by a Flexible Ligand 1,2-Bis(4-Pyridyl)Ethane

The title compound {Cu[S₂P(OC₂H₅)₂](bpe)} _n (1) is constructed from flexible ligand bpe (bpe = 1,2-bis(4-pyridyl)ethane) and the Cu[S₂P(OC₂H₅)₂], which was characterized by single crystal structure determination, elemental analysis, XRD, and IR spectra. X-ray diffraction studies revealed that polymeric compound 1 consists of dinuclear module to form 1-D chains with the intramolecular Cu···Cu interactions (ca. 2.63 Å). This interaction may show a profound influence on the observed blue luminescence emission spectrum for 1. Crystal data for 1 at 293(2) K: Space group P ? 1, a = 9.277(3), b = 10.504 (4), c = 31.801(1) Å, α = 92.849(3), β = 90.401(2), γ = 114.547(7)°, V = 2813.9(2) ų, Z = 2, R ₁ = 0.041.     

Synthesis,crystal structure,and thermodynamics of a high-nitrogen copper complex with <Emphasis Type="Italic">N</Emphasis>, <Emphasis Type="Italic">N</Emphasis>-bis-(1(2)H-tetrazol-5-yl) amine

A new high-nitrogen complex [Cu(Hbta)₂]·4H₂O (H₂bta = N,N-bis-(1(2)H-tetrazol-5-yl) amine) was synthesized and characterized by elemental analysis, single crystal X-ray diffraction and thermogravimetric analyses. X-ray structural analyses revealed that the crystal was monoclinic, space group P2(1)/c with lattice parameters a = 14.695(3) Å, b = 6.975(2) Å, c = 18.807(3) Å, β = 126.603(1)°, Z = 4, D _c = 1.888 g cm^?3, and F(000) = 892. The complex exhibits a 3D supermolecular structure which is built up from 1D zigzag chains. The enthalpy change of the reaction of formation for the complex was determined by an RD496–III microcalorimeter at 25 °C with the value of ?47.905 ± 0.021 kJ mol^?1. In addition, the thermodynamics of the reaction of formation of the complex was investigated and the fundamental parameters k, E, n, \( \Updelta S_{ \ne }^{{{\uptheta}}} \), \( \Updelta H_{ \ne }^{{{\uptheta}}} \), and \( \Updelta G_{ \ne }^{{{\uptheta}}} \) were obtained. The effects of the complex on the thermal decomposition behaviors of the main component of solid propellant (HMX and RDX) indicated that the complex possessed good performance for HMX and RDX.     

Effect of alkali metal salts on decomposition of ionic liquid like organic salt

N ¹,N ¹,N ²,N ²-tetramethylethane-1,2-diamine-based ionic salts (TMEDA), N ¹,N ¹,N ¹,N ²,N ²,N ²-hexamethylethane-1,2-diaminium dicyanamide (HMEDA-(DCA)₂) were prepared following the quaternization and subsequent ion exchange. The chemical structure of the HMEDA-(DCA)₂ was confirmed using ¹³C NMR spectrum and elemental analysis. The corresponding viscosity of its 60 wt% solution was found to be lower than 5 cP at room temperature, which was critical for propellant application. The ignition delay of 40 wt% HMEDA-(DCA)₂ solution was decreased to 20–30 ms dramatically using alkali metal salts, Li(CH₃COO), Mg(CH₃COO)₂, and Ca(CH₃COO)₂ as a co-catalyst when white fume nitric acid was utilized as an oxidizer.     

Dynamic clustering threshold reduces conformer ensemble size while maintaining a biologically relevant ensemble

Representing the 3D structures of ligands in virtual screenings via multi-conformer ensembles can be computationally intensive, especially for compounds with a large number of rotatable bonds. Thus, reducing the size of multi-conformer databases and the number of query conformers, while simultaneously reproducing the bioactive conformer with good accuracy, is of crucial interest. While clustering and RMSD filtering methods are employed in existing conformer generators, the novelty of this work is the inclusion of a clustering scheme (NMRCLUST) that does not require a user-defined cut-off value. This algorithm simultaneously optimizes the number and the average spread of the clusters. Here we describe and test four inter-dependent approaches for selecting computer-generated conformers, namely: OMEGA, NMRCLUST, RMS filtering and averaged-RMS filtering. The bioactive conformations of 65 selected ligands were extracted from the corresponding protein:ligand complexes from the Protein Data Bank, including eight ligands that adopted dissimilar bound conformations within different receptors. We show that NMRCLUST can be employed to further filter OMEGA-generated conformers while maintaining biological relevance of the ensemble. It was observed that NMRCLUST (containing on average 10 times fewer conformers per compound) performed nearly as well as OMEGA, and both outperformed RMS filtering and averaged-RMS filtering in terms of identifying the bioactive conformations with excellent and good matches (0.5 < RMSD < 1.0 Å). Furthermore, we propose thresholds for OMEGA root-mean square filtering depending on the number of rotors in a compound: 0.8, 1.0 and 1.4 for structures with low (1–4), medium (5–9) and high (10–15) numbers of rotatable bonds, respectively. The protocol employed is general and can be applied to reduce the number of conformers in multi-conformer compound collections and alleviate the complexity of downstream data processing in virtual screening experiments.     

X-ray and computational structural study of neutral <Emphasis Type="Italic">bis</Emphasis>(<Emphasis Type="Italic">N,N,N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-tetramethylthiophosphoramidoyl)-methylamine

The structure of bis(N,N,N′,N′-tetramethylthiophosphoramidoyl)-methylamine 1 has been determined by single-crystal X-ray diffraction. The compound 1 crystallizes in the monoclinic system, with a space group P2₁/c, a = 11.836(2) Å, b = 11.659(2) Å, c = 12.796(5) Å and β = 95.28(3)°, V = 1758.3(5) Å³ and Z = 4. The X-ray crystallographic data have been assessed by semi-empirical and ab-initio density functional theory and by Hartree–Fock molecular orbital methods. A comparative study of the results of the different methods is given.     

Synthesis,spectroscopic characterization,crystal structures,and theoretical studies of (<Emphasis Type="Italic">E</Emphasis>)-2-(2,4-dimethoxybenzylidene)thiosemicarbazone and (<Emphasis Type="Italic">E</Emphasis>)-2-(2,5-dimethoxybenzylidene)thiosemicarbazone

Two thiosemicarbazones, (E)-2-(2,4-dimethoxybenzylidene)thiosemicarbazone (24-MBTSC (1)) and (E)-2-(2,5-dimethoxybenzylidene)thiosemicarbazone (25-MBTSC (2)), derived from 2,4-dimethoxybenzaldehyde and 2,5-dimethoxybenzaldehyde, respectively, with thiosemicarbazide have been synthesized and their structures were characterized by elemental analyses, FT-IR, ¹H NMR spectroscopy, and X-ray single-crystal diffraction analysis. Molecular orbital calculations have been carried out for 1 and 2 by using an ab initio method (HF) and also density functional method (B3LYP) at 6-31G basis set. Compound 1 crystallizes in the monoclinic system, space group P2₁/c, with a = 8.1342(5) Å, b = 18.1406(10) Å, c = 8.2847(6) Å, β = 109.7258(17)°, V = 1150.75(12) Å³, and Z = 4, whereas compound 2 crystallizes in the orthorhombic system, space group Pbca, with a = 11.0868(6) Å, b = 13.1332(6) Å, c = 15.9006(8) Å, V = 2315.2(2) Å³, and Z = 8. The compounds 1 and 2 displays a trans-configuration about the C=N double bond.     

Synthesis,crystal structure and fungicidal activity of 1-(4-chlorophenyl)-2-(5-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)-4-phenyl-4H-1,2,4-triazol-3-ylthio)ethanone

A novel bis-heterocyclic compound was synthesized and characterized. The crystal structure of the title compound (C₂₂H₂₀ClN₅OS, Mr = 437.94) has been determined by single-crystal X-ray diffraction. The crystal is of triclinic, space group P-1 with a = 8.646 (2), b = 9.148 (3), c = 14.540 (4) Å, α = 94.422 (4), β = 98.500 (4), γ = 102.823 (4)°, V = 1101.8 (5) Å³, Z = 2, F(000) = 312, Dc = 1.320 g/cm³, μ = 0.2900 mm^?1, the final R ₁ = 0.041000 and wR ₂ = 0.1160 for 2675 observed reflections with I > 2σ(I). A total of 5623 reflections were collected, of which 3866 were independent (R _int = 0.019000). The fungicidal activity of title compound was determined, the results showed the title compound displayed moderate fungicidal activity against G. zeae Petch, Phytophthora infestans (Mont.) de Bary, Botryosphaeria berengeriana f. sp. piricola (Nose) koganezawa et Sakuma, Fusarium oxysporum f.sp. cucumerinum, and Cercospora arachidicola.     

Synthesis,spectral and thermal studies on dicarboxylate-bridged palladium(II) coordination polymers. Part II

The synthesis and thermal behavior of the new [Pd(fum)(bipy)] _n ·2nH₂O (1), [Pd(fum)(bpe)] _n ·nH₂O (2) and [Pd(fum)(pz)] _n ·3nH₂O (3) {bipy = 4,4′-bipyridine, bpe = 1,2-bis(4-pyridyl)ethene and pz = pyrazine} fumarate complexes are described in this work as well their characterization by IR and ¹³C CPMAS NMR spectroscopies. TG curves showed that the compounds released organic ligands and lattice water molecules in the temperature range of 46–491 °C. In all the cases, metallic palladium was identified as the final residue.     

Structure,bioactivity and theoretical study of 1-cyano-<Emphasis Type="Italic">N</Emphasis>-p-tolylcyclo-propanecarboxamide

A novel cyclopropane derivative, 1-cyano-N-p-tolylcyclopropanecarboxamide (C₁₂H₁₂N₂O, Mr = 200.24) was synthesized and its structure was studied by X-ray diffraction, FTIR, ¹H and ¹³C NMR spectrum and MS. The crystals are monoclinic, space group P2_1/c with a = 7.109 (4), b = 13.758 (7), c = 11.505 (6) Å, α = 90.00, β = 102.731 (8), γ = 90.00 °, V = 1097.6 (9) ų, Z = 4, F(000) = 312, D _c  = 1.212 g/cm³, μ = 0.0800 mm^?1, the final R = 0.0490 and wR = 0.1480 for 1,375 observed reflections with I > 2σ(I). A total of 6,109 reflections were collected, of which 2,290 were independent (R _int = 0.0290). Theoretical calculation of the title compound was carried out with HF/6-31G (d,p), B3LYP/6-31G (d,p), MP2/6-31G (d,p). The full geometry optimization was carried out using 6-31G(d,p) basis set, and the frontier orbital energy. Atomic net charges were discussed, and the structure-activity relationship was also studied. The preliminary biological test showed that the synthesized compound is bioactive against the KARI of Escherichia coli.     

Gas electron diffraction and quantum chemical study of the structure of a 2-nitrobenzenesulfonyl chloride molecule

A combined gas electron diffraction and quantum chemical (B3LYP/6-311+G**, B3LYP/cc-pVTZ, B3LYP/cc-pVTZ, midix (Cl), and MP2/cc-pVTZ) study of the structure of a 2-NO₂-C₆H₄-SO₂Cl molecule is performed. It is found experimentally that at a temperature of 345(5) K the gas phase contains two conformers of the C ₁ symmetry. Conformer I with a nearly perpendicular arrangement of the S-Cl bond with respect to the benzene ring plane (the C(NO₂)-C-S-Cl torsion angle is 84(3)°) is contained predominantly (69(12)%). In conformer II, the S-Cl bond is located near the benzene ring plane (the C(NO₂)-C-S-Cl angle is 172(3)°). The following experimental internuclear distances (Å) are obtained for conformer I: r _h1(C-H) = 1.064(15), r _h1(C-C)_av = 1.397(3), r _h1(C-S) = 1.761(6), r _h1(S-O)_av = 1.426(4), r _h1(S-Cl) = 2.043(5), r _h1(N-O)_av = 1.222(4), r _h1(C-N) = 1.485(16). In both conformers, the NO₂ group is turned by more than 30° relative to the benzene ring plane.     

New hybrids of clozapine and haloperidol and their isosteric analogues: synthesis,X-ray crystallography,conformational analysis and preliminary pharmacological evaluation

Schizophrenia is a debilitating mental disorder which affects approximately 1% of the world’s population. Clozapine is an atypical antipsychotic showing unmatched effectiveness in the control of treatment-resistant schizophrenia. Unlike typical antipsychotics, clozapine does not induce extrapyramidal side effects (EPS), tardive dyskinesia or elevate prolactin levels. However, clozapine can induce a potentially fatal blood disorder, agranulocytosis, in 1–2% of patients, severely limiting its clinical use. The model for antipsychotic activity under investigation is based on obtaining a clozapine-like profile with preferential dopamine D₄ and serotonin 5-HT_2A receptor affinity. Profiled herein are three unique members of a series of prospective antipsychotic agents. Compound (I) originated from the structural hybridization of the commercial therapeutics, clozapine and haloperidol, whilst compounds (II) and (III) possess an alternative tricyclic nucleus derived from JL13; a clozapine-like atypical antipsychotic developed by Liégeois et al. These compounds have been synthesized and characterized by means of elemental analysis, IR, ¹H and ¹³C-NMR spectroscopy, MS and X-ray diffraction. Compound (I) crystallizes in space group P(?1) with a = 10.5032(1), b = 10.6261(2), c = 12.6214(3) Å, α = 81.432(1)°, β = 83.292(1)°, γ = 61.604(1)°, Z = 2, V = 1223.62(4) Å³, C₂₈H₂₉ClN₄O, M _r = 473.00, D _c = 1.284 Mg/m³, μ = 0.185 mm^?1, F(000) = 500, R = 0.0506 and wR = 0.1304. Compound (II) crystallizes in the monoclinic space group P2₁/c with a = 10.8212(2), b = 9.3592(2), c = 22.9494(5) Å, β = 106.471(1)°, Z = 4, V = 2228.88(8) Å³, C₂₅H₂₅ClN₄O₂, M _r = 448.94, D _c = 1.338 Mg/m³, μ = 0.202 mm^?1, F(000) = 944, R = 0.0529 and wR = 0.1129. Compound (III) crystallizes in the monoclinic space group P2₁/c with a = 10.5174(2), b = 9.3112(2), c = 24.2949(5) Å, β = 98.666(1)°, Z = 4, V = 2352.03(8) Å³, C₂₅H₂₄Cl₂N₄O₂, M _r = 483.38, D _c = 1.365 Mg/m³, μ = 0.306 mm^?1, F(000) = 1008, R = 0.0478 and wR = 0.1067. The solid state conformations of (I), (II) and (III) exhibit the characteristic V-shaped buckled nature of the respective dibenzodiazepine and pyridobenzoxazepine nuclei with the central seven-membered heterocycle in a boat conformation. The molecules of (I) form a head-to-tail dimeric motif stabilized by hydrogen bonding. The results of a conformational analysis of compounds (I)–(III) investigating the effect of environment (in vacuo and aqueous solution) are presented. These analogues were tested for in vitro affinity for the dopamine D₄ and serotonin 5-HT_2A receptors and their comparative receptor binding profiles to clozapine and JL13 are reported.     

Power consumption for an agitated vessel equipped with pitched blade turbine and short baffles

Power characteristics for an agitated vessel equipped with planar short baffles of length L and pitched blade turbine of pitch β are presented in the paper. The studies were carried out in the vessel of inner diameter D = 0.6 m, where the baffles were located in the distance p from the vessel bottom (p + L = H). Torque was measured using strain gauge method within the turbulent regime of the flow of Newtonian liquid in the agitated vessel. The effects of the pitch β and geometrical parameter p/H on the power number Ne were determined mathematically. The results showed that, for the assumed value of the angle β, the function Ne = f (L/H) decreases with the decrease in the baffle length L (i.e. with the increase in the parameter p). Moreover, for the assumed value of the baffle length L, the function Ne = f (β) increases with the increase in the angle β of the inclination of the impeller blade.     

Saw-sedge <Emphasis Type="Italic">Cladium mariscus</Emphasis> as a functional low-cost adsorbent for effective removal of 2,4-dichlorophenoxyacetic acid from aqueous systems

For the first time in the published literature, a study is described concerning the use of the saw-sedge Cladium mariscus (C. mariscus) for adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous systems. Among the experiments carried out, the elemental composition of C. mariscus was determined (C = 48.0 %, H = 7.1 %, N = 0.95 %, S = 0.4 %), FTIR spectroscopic analysis was performed to confirm the chemical structure of the adsorbent, and porous structure parameters were measured: BET surface area (A _BET  = 0.6 m²/g), total pore volume (V _p  = 0.001 cm³/g) and average pore size (S _p  = 6.6 nm). It was shown that the effectiveness of removal of 2,4-D from aqueous systems using C. mariscus depends on parameters of the process: contact time, system pH, mass of sorbent, and temperature. Maximum adsorption was attained for a solution at pH = 3. Further increase in the alkalinity of the tested systems led to a reduction in the effectiveness of the process. The kinetic of adsorption of 2,4-D by C. mariscus was also determined, and thermodynamic aspects were investigated. The experimental data obtained correspond to a pseudo-second-order kinetic model of type 1. Additionally the negative values obtained for ΔHº indicate that the process is exothermic, and the negative values of ΔGº show it to be spontaneous. As the temperature of the system increases the spontaneity of adsorption is reduced, in accordance with the exothermic nature of the process.