Ternary chlorides of the trivalent late lanthanides

A comprehensive review on phase diagrams, crystal structures and thermodynamic properties of ternary chlorides formed in the systems ACl/LnCl₃ (A=Na, K, Rb, Cs) is presented. It continues an earlier review with the same contents on the lanthanides from La to Gd [1]. In both papers the author's own studies, published since 1985, together with original papers from other scientists are treated. With the three larger cations compounds of the composition A₃LnCl₆, A₂LnCl₅, ALn₂Cl₇ and beginning with holmium Cs₃Ln₂Cl₉ are formed. With sodium the compounds Na₃Ln₅Cl₁₈ (Ln=La to Sm) and NaLnCl₄ (Ln=Eu to Lu) also exist. The stability of a ternary chloride in a system ACl/LnCl₃ is given by the 'free enthalpy of synreaction', the formation of a compound from its neighbour compounds in its system. This must be negative. A surprising result is that the highest – melting compounds in the systems, A₃LnCl₆, are formed from ACl and A₂LnCl₅ with a loss of lattice energy, U. They exist as high-temperature compounds due to a sufficiently high gain in entropy at temperatures where the entropy term TΔS compensates the endothermic ΔH.     

Arylethyl (= Phenylethanoid) Glycosides and Oligosaccharide from the Stem of Cistanche tubulosa

Three new analogues of the arylethyl (= phenylethanoid) glycoside echinacoside ( 5 ), namely cistantubulosides A ( 1 ), B₁/B₂ ( 2a / 2b ), and C₁/C₂ ( 3a / 3b ), and one new oligosaccharide, cistantubulose A₁/A₂ ( 4a / 4b ), were isolated from the stems of Cistanche tubulosa (Schenk ) R. Wight , together with five known compounds, i.e., campneoside I, campneoside II ( 6 ), echinacoside ( 5 ), tubuloside, and cistanoside F. Among the compounds isolated, 2a / 2b, 3a / 3b, 4a / 4b , campneoside I, campneoside II ( 6 ), and cistanoside F each consisted of a pair of epimers. The structures of the new compounds were elucidated on the basis of spectral data.     

DFT‐based QSAR study and molecular design of AHMA derivatives as potent anticancer agents

A quantitative structure–activity relationship (QSAR) of 3‐(9‐acridinylamino)‐5‐hydroxymethylaniline (AHMA) derivatives and their alkylcarbamates as potent anticancer agents has been studied using density functional theory (DFT), molecular mechanics (MM+), and statistical methods. In the best established QSAR equation, the energy (E_NL) of the next lowest unoccupied molecular orbital (NLUMO) and the net charges (Q_FR) of the first atom of the substituent R, as well as the steric parameter (MR₂) of subsituent R₂ are the main independent factors contributing to the anticancer activity of the compounds. A new scheme determining outliers by “leave‐one‐out” (LOO) cross‐validation coefficient (q) was suggested and successfully used. The fitting correlation coefficient (R²) and the “LOO” cross‐validation coefficient (q²) values for the training set of 25 compounds are 0.881 and 0.829, respectively. The predicted activities of 5 compounds in the test set using this QSAR model are in good agreement with their experimental values, indicating that this model has excellent predictive ability. Based on the established QSAR equation, 10 new compounds with rather high anticancer activity much greater than that of 34 compounds have been designed and await experimental verification. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Spin crossover in iron(II) complexes with tris(pyrazol-1-yl)methane

Mononuclear iron(II) coordination compounds with tris(pyrazol-1-yl)methane (HC(Pz)₃) described as [Fe{HC(Pz)₃}₂]A₂ × nH₂O, where A = Cl⁻, Br⁻, I⁻, 1/2 SO₄²⁻, n = 0–7, were synthesized. The compounds were studied by static magnetic susceptibility measurements, IR and UV/Vis spectroscopy, and powder X-ray diffraction. The crystal and molecular structures of all compounds were determined by single crystal X-ray diffraction.     

Linear free energy relationships between stability of complex and basicity of ligand: VII. The copper(II)-heteronuclear aromatic base-aminoacid ternary systems

The formation constants of ternary mixed ligand complex compounds formed from Cu(II)-2,2′-bipyridyl (bipy) with N-(para-substituted phenyl) glycines (pRPhG), Cu(II)-1,10-phenanthroline (phen) with N-(meta-substituted phenyl) glycines (mRPhG), Cu(II)-bipy/phen with some α-aminoacids (αA) have been determined by pH method at 25°C in the presence of 0.10 M NaClO₄. It was found that linear free energy relationships do exist between the stability of ternary complex compounds and the base strengths of the ligands in all four ternary systems investigated. The stability of the ternary complex compounds was discussed in terms of ΔlogK_M and log X values. It was found again that linear relationships exist between Δ log K_M, log X and pK₂ in the Cu(II)-phen-mRPhG ternary system.     

Facile synthesis of highly functionalized novel pyrazolopyridones using oxoketene dithioacetal and their anti-HIV activity

A series of novel 3-amino-4,5-dihydro-6-methyl-4-oxo-N-aryl-1H-pyrazolo[4,3-c]pyridine-7-carboxamide have been synthesized starting from various oxoketene dithioacetals. The cyclocondensation reaction of 2-(bis(methylthio)methylene)-3-oxo-N-arylbutanamide 2a–w with cyanoacetamide using NaOiPr as base under reflux condition afforded novel highly functionalized pyridone 3a–w derivatives. Further, [3?+?2] cyclocondensation reaction of pyridones with hydrazine in the presence of alcohol was yielded pyrazolopyridones (23 nos) 4a–w with excellent yields. All newly synthesized compounds were evaluated for in vitro anti-HIV activity using MTT method. Most of these compounds have showed moderate to potent activity against HIV-1 (III_B) and HIV-2 (ROD) strains with an IC₅₀ ranging from >18 IC₅₀[µg/ml] to <100 IC₅₀[µg/ml]. Among them, compounds 4j and 4v were identified as the most promising compound for both types of HIV strains. (IC₅₀?=?18?µg/ml). Three compounds 4l, 4m, and 4p have been found potent anti-HIV 1 and 2 activity against MT-4 cells.     

Initiation of Radical Chain Reactions of Thiol Compounds and Alkenes without any Added Initiator: Thiol‐Catalyzed cis/trans Isomerization of Methyl Oleate

A kinetic study of the dodecanethiol‐catalyzed cis/trans isomerization of methyl oleate (cis‐ 2 ) without added initiator was performed by focusing on the initiation of the radical chain reaction. The reaction orders of the rate of isomerization were 2 and 0.5 for 1 and cis‐ 2 , respectively, and an overall kinetic isotope effect k_H/k_D of 2.8 was found. The initiation was shown to be a complex reaction. The electron‐donor/‐acceptor (EDA) complex of dodecanethiol ( 1 ) and cis‐ 2 formed in a pre‐equilibrium reacts with thiol 1 to give a stearyl and a sulfuranyl radical through molecule‐assisted homolysis (MAH) of the sulfur–hydrogen bond. Fragmentation of the latter gives the thiyl radical, which catalyzes the cis/trans isomerization. A computational study of the EDA complex, MAH reaction, and the sulfuranyl radical calculated that the activation energy of the isomerization was in good agreement with the experimental result of E_A=82 kJ M ^?1. Overall, the results may explain that the thermal generation of thiyl radicals without any initiator is responsible for many well‐known thermally initiated addition reactions of thiol compounds to alkenes and their respective polymerizations and for the low shelf‐life stability of cis‐unsaturated thiol compounds and of mixtures of alkenes and thiol compounds.     

Preparation and in vitro investigations of triphenyl[ω‐(tetrahydro‐2H‐pyran‐2‐yloxy)alkyl]tin(IV) compounds

The reaction of SnPh₃Li with X(CH₂)_n O–THP (THP = tetrahydro‐2H ‐pyran‐2‐yl; n  = 3, 4, 6, 8, 11; X = Cl, Br) afforded organotin(IV) compounds with the general formula Ph₃Sn(CH₂)_n O–THP ( 1 – 5 ). The tetraorganotin(IV) compounds were characterized using multinuclear NMR and infrared spectroscopies and high‐resolution mass spectrometry. Anticancer activity of the synthesized compounds was tested in vitro against the A2780 (ovarian), A549 (lung), HeLa (adenocarcinoma) and SW480 (colon) tumour cell lines with SRB assay. The in vitro investigations revealed that when a shorter chain was present a higher activity was achieved; however compounds 1 – 5 were found to be less active than cisplatin. In addition, the most active compound, 1 , enters A2780 cells and causes apoptosis by triggering both intrinsic and extrinsic caspase pathways.     

Facile Synthesis of Novel 3‐(4‐phenylisothiazol‐5‐yl)‐2H‐chromen‐2‐one Derivatives as Potential Anticancer Agents

A series of 3‐(4‐phenylisothiazol‐5‐yl)‐2H‐chromen‐2‐one ( 6a – l ) derivatives has been efficiently synthesized by straightforward sequential reactions. Tandem Vilsmeier Hack reaction/cyclization/bromination/Suzuki cross‐coupling reactions were successfully applied to the preparation of title compounds in good‐to‐high yields. In the synthetic sequences, 3‐chloro‐3‐(2‐oxo‐2H‐chromen‐3‐yl)acrylaldehydes ( 2 ) were found to react with ammonium thiocyanate to yield the corresponding 3‐(isothiazol‐5‐yl)‐2H‐chromen‐2‐ones ( 3 ). These derivatives were brominated with N‐bromo succinamide to yield the corresponding regioselective 3‐(4‐bromoisothiazol‐5‐yl)‐2H‐chromen‐2‐one ( 4 ). Finally, compound 4 was treated with various phenyl/pyrazole/7H –pyrrolo[2,3‐d]pyrimidinyl boronic acids 5a – l in the presence of K₂CO₃ and Pd catalyst in dimethylformamide to yield the corresponding title derivatives 6a – l . All the synthesized compounds were characterized by analytical and spectral studies. All the final compounds were screened against different cancer cell lines (A549, PC3, SKOV3, and B16F10), and among these compounds, 6b , 6g , 6h , and 6l displayed moderate cytotoxic activity against the tested cell lines.     

Heterocycles. CLXIX. Barriers to rotation in some N,N-Dimethyl-N′-heteroaryl,N,N-Diethyl-N′-heteroaryl-substituted formamidines and N,N-Dimethyl-N′-heteroaryl-substituted acetamidines

The free energies of the rotational barriers, ΔG*, about ?CH? NMe₂ bond in N′-heteroaryl N,N-dimethylformamidines (A), about ?CH? NEt₂ bond in N-heteroaryl N,N-diethylformamidines (B), and about ?C(Me)? NMe₂ bond in N′-heteroaryl N,N-dimethylacetamidines (C) have been found to be in the range 17.5–20.1 kcal/mole for type A, 18.8–21.6 kcal/mole for type B and 13–14 kcal/mole or below for type C of compounds, respectively. The compounds of the types A and B exist in the forms IIa, IIIa, IV, V, and VI, while the compounds of the type C exist in the forms IIb and IIIb.     

Drug–Membrane Interaction on Immobilized Liposome Chromatography Compared to Immobilized Artificial Membrane (IAM), Liposome/Water,and Octan‐1‐ol/Water Systems

The objective of this study was to investigate drug–membrane interaction by immobilized liposome chromatography (ILC; expressed as lipophilicity index log K_s) and the comparison with lipophilicity indices obtained by liposome/H₂O, octan‐1‐ol/H₂O, and immobilized artificial membrane (IAM) systems. A set of structurally diverse monofunctional compounds and drugs (nonsteroidal anti‐inflammatory drugs and β‐blockers) were selected in this study. This set of solutes consists of basic or acidic functionalities which are positively or negatively charged at physiological pH 7.4. No correlation was found between log K_s from ILC and lipophilicity indices from any of the other membrane model systems for the whole set of compounds. For structurally related compounds, significant correlations could be established between log K_s from ILC and lipophilicity indices from IAM chromatography and octan‐1‐ol/H₂O. However, ILC and liposome/H₂O systems only yield parallel partitioning information for structurally related large molecules. For hydrophilic compounds, the balance between electrostatic and hydrophobic interactions dominating drug partitioning is different in these two systems.     

Ion Selective Electrode Determination of Free Versus Total Fluoride Ion in Simple and Fluoroligand Coordinated Hexafluoropnictate (PnF<Subscript>6</Subscript><Superscript>−</Superscript>, Pn = P,As, Sb,Bi) Salts

Interpretation of the results of determinations of free fluoride (F_f⁻) and total fluoride (F_t⁻) obtained with fluoride ISE while conducting elemental chemical analysis of bulk material of newly synthesized inorganic fluoride compounds is of crucial importance for the purpose of determination of purity and stoichiometry of these compounds. Knowledge of the properties and behavior of these compounds in aqueous media is therefore essential. Observations are presented on the determinations of the amounts of F_t⁻ and F_f⁻ in fluorinated compounds, in the particular hexafluoropnictate salts (PnF₆⁻, Pn = P, As, Sb, Bi) as found in aqueous media and in some compounds with XeF₂, AsF₃ ligands. A critical look at the determined amounts of F_f⁻, F_t⁻and calculated amounts of bound fluoride (F_b⁻) is provided.     

Structural Diversity and Magnetic Properties of Hybrid Ruthenium Halide Perovskites and Related Compounds

There has been a great deal of recent interest in extended compounds containing Ru³⁺ and Ru⁴⁺ in light of their range of unusual physical properties. Many of these properties are displayed in compounds with the perovskite and related structures. Here we report an array of structurally diverse hybrid ruthenium halide perovskites and related compounds: MA₂RuX₆ (X=Cl or Br), MA₂MRuX₆ (M=Na, K or Ag; X=Cl or Br) and MA₃Ru₂X₉ (X=Br) based upon the use of methylammonium (MA=CH₃NH₃⁺) on the perovskite A site. The compounds MA₂RuX₆ with Ru⁴⁺ crystallize in the trigonal space group and can be described as vacancy‐ordered double‐perovskites. The ordered compounds MA₂MRuX₆ with M⁺ and Ru³⁺ crystallize in a structure related to BaNiO₃ with alternating MX₆ and RuX₆ face‐shared octahedra forming linear chains in the trigonal space group. The compound MA₃Ru₂Br₉ crystallizes in the orthorhombic Cmcm space group and displays pairs of face‐sharing octahedra forming isolated Ru₂Br₉ moieties with very short Ru–Ru contacts of 2.789 Å. The structural details, including the role of hydrogen bonding and dimensionality, as well as the optical and magnetic properties of these compounds are described. The magnetic behavior of all three classes of compounds is influenced by spin–orbit coupling and their temperature‐dependent behavior has been compared with the predictions of the appropriate Kotani models.     

Synthesis,characterization, in vitro antimicrobial and cytotoxic evaluation of Co(II), Ni(II), Cu(II) and Zn(II) complexes derived from bidentate hydrazones

Co(II), Ni(II), Cu(II) and Zn(II) complexes have been synthesized from hydrazone ligands (HL¹–HL⁴) obtained by condensation reaction of 6-chlorothiochroman-4-one with benz hydrazide/nicotinic hydrazide/isonicotinic hydrazide/p-toluic hydrazide. The synthesized compounds (1–20) were characterized by physicochemical procedures, i.e. (FTIR, ¹H NMR, ¹³C NMR, mass, ESR, UV–Vis), TGA/DTA, powder XRD, elemental analysis (CHN), magnetic susceptibility and molar conductance measurements. The various data suggested bidentate nature (NO) of hydrazones, which coordinate with central metal ions via nitrogen of azomethine (–C=N–) group and deprotonated carbonyl oxygen in the enolized form, resulting in octahedral complexes. Low values of molar conductance suggested their non-electrolytic nature. Thermal decomposition pattern of complexes confirms the metal oxides as end product. In vitro antimicrobial activity of hydrazones and their metal complexes were evaluated against two gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus); two gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli); and two fungal strains (Candida albicans and Aspergillus niger) by serial dilution method, and it was found that the metal complexes were highly active as compared to hydrazones. Among all the compounds, complexes 11, 13, 14 and 19 were found most efficient antimicrobial agent. The anticancer activity of (1–20) compounds was performed on human cancer cell lines A549 (lung), DU145 (prostate) and SW620 (colorectal) by MTT assay using paclitaxel as reference drug. The cytotoxicity results suggested compounds [Cu(L²)₂(H₂O)₂] 11 as most potent against A549, DU145 and SW620 cancer cell lines with IC₅₀ values of 3.46, 18.21 and 7.61 µM. Furthermore, compounds (9, 10, 11, 12) were also investigated on A549 cell line for their ROS generation and mitochondrial membrane potential loss and suggested that complex [Cu(L²)₂(H₂O)₂] 11 has highest ROS production and induction of apoptosis by mitochondrial depolarization in cancer cells.

Graphic abstract

The synthesized compounds (1–20) were screened for in vitro cytotoxicity against A549 (lung), DU145 (prostate), SW620 (colorectal) human cancer cell lines. Copper complex (11) was found to be the most active antitumor agent which enhance ROS production and MMP loss on A549 cells.

     

Oxygen‐Controlled Catalysis by Vitamin B12‐TiO2: Formation of Esters and Amides from Trichlorinated Organic Compounds by Photoirradiation

An oxygen switch in catalysis of the cobalamin derivative (B₁₂)‐TiO₂ hybrid catalyst for the dechlorination of trichlorinated organic compounds has been developed. The covalently bound B₁₂ on the TiO₂ surface transformed trichlorinated organic compounds into an ester and amide by UV light irradiation under mild conditions (in air at room temperature), while dichlorostilbenes (E and Z forms) were formed in nitrogen from benzotrichloride. A benzoyl chloride was formed as an intermediate of the ester and amide, which was detected by GC‐MS. The substrate scope of the synthetic strategy is demonstrated with a range of various trichlorinated organic compounds. A photo‐duet reaction utilizing the hole and conduction band electron of TiO₂ in B₁₂‐TiO₂ for the amide formation was also developed.     

Crystal structure and ionic conductivity of the series A2Bi24Mo8X2O68 (A = Ca, Sr and Ba and X = Cr and W) in the Bi2O3?MoO3 system

A series of A₂Bi₂₄Mo₈X₂O₆₈ compounds, Ca₂Bi₂₄Mo₈Cr₂O₆₈ (CBMC), Sr₂Bi₂₄Mo₈Cr₂O₆₈ (SBMC), Pb₂Bi₂₄Mo₈Cr₂O₆₈ (PBMC) and Ba₂Bi₂₄Mo₈W₂O₆₈ (BBMW) have been synthesized by the solid-state method and characterized by single crystal X-ray diffraction. The compounds index into the monoclinic P2/c system with a=11.687(4) ?, 5.784(2) ?, 24.728(9) ?, 101.911(6)°, Z=1; 11.673(6) ?, 5.775(3) ?, 24.670(2) ?, 101.757(8)°, Z=1; 11.638(3) ?, 5.790(1) ?, 24.655(6) ?, 101.716(4)°, Z=1 and 11.718(6) ?, 5.818(3) ?, 24.716(12) ?, 101.835(9)°, Z=1 for CBMC, SBMC, PBMC and BBMW, respectively. The structures were solved by direct methods and refined to R indices of 0.081, 0.065, 0.080 and 0.079 respectively. These compounds are isostructural with Bi₂₆Mo₁₀O₆₉ and the structure consists of columns of [Bi₁₂O₁₄] along the b-axis, surrounded by Mo/Cr/WO₄ tetrahedra. a.c. impedance studies indicate higher values of ionic conductivity for the tungsten-substituted compounds. Supplementary material The crystal data of CBMC, SBMC, PBMC and BBMW have been deposited at the Fachinformationszentrum Karlsruhe (FIZ) with the numbers CSD 415143, CSD 415145, CSD 415144 and CSD 415142, respectively.     

New Steroids and a New Alkaloid from the Gorgonian Isis minorbrachyblasta: Structures,Cytotoxicity, and Antilarval Activity

Two new polyoxygenated steroids, (1α,3β,7α,11α,12β)‐gorgost‐5‐ene‐1,3,7,11,12‐pentol 12‐acetate ( 1 ) and 11‐O‐acetyl‐22‐epihippuristanol ( 2 ), and a new alkaloid, 2,3,5,6,11,11b‐hexahydro‐2‐hydroxy‐1H‐indolizino[8,7‐b]indole‐2‐carboxylic acid ( 3 ), together with three known compounds, 22‐epihippuristanol ( 4 ), hippuristanol ( 5 ), and tryptamine ( 6 ), were isolated from the EtOH/CH₂Cl₂ extracts of the South China Sea gorgonian Isis minorbrachyblasta. The structures of the new compounds were determined by spectroscopic methods. Compound 1 showed weak cytotoxicity against A549, HONE1, and HeLa cancer cell lines and strong antilarval activity towards Bugula neritina larvae with an EC₅₀ value of 5.8 μg/ml. Compound 5 showed moderate cytotoxicity against A549, HONE1, and HeLa cell lines, and the epimer mixture 4 / 5 (weight ratio 3 : 2) exhibited potent cytotoxicity against A549 and HONE1 cell lines with IC₅₀ values of 4.2 and 4.8 μg/ml, which indicated that epimers 4 and 5 might have a synergistic effect on their cytotoxicity against A549 and HONE1 cell lines.     

Effects of cis/trans-Configuration and Ligand Substitution of the Cyanidometal Bridge on Metal to Metal Charge Transfer Properties in Mixed Valence Complexes

To investigate the effects of cis/trans-configuration of the cyanidometal bridge and the electron donating ability of the auxiliary ligand on the cyanidometal bridge on metal to metal charge transfer (MMCT) in cyanidometal-bridged mixed valence compounds, two groups of trinuclear cyanidometal-bridged compounds cis/trans-[Cp(dppe)Fe(μ-NC)Ru(4,4’-dmbpy)₂(μ-CN)Fe(dppe)Cp][PF₆]_n (n=2 ( cis/trans - 1[PF₆]₂ ), 3 ( cis/trans - 1[PF₆]₃ ), 4 ( cis/trans - 1[PF₆]₄ )) and cis/trans-[Cp(dppe)Fe(μ-NC)Ru(bpy)₂(μ-CN)Fe(dppe)Cp][PF₆]₃ ( cis/trans - 2[PF₆]₃ ) were synthesized and fully characterized. The experimental results indicate that for these one- and two-electron oxidation mixed valence compounds, the trans-configuration compounds are more beneficial for MMCT than the cis-configuration compounds, and increasing the electron donating ability of the auxiliary ligand on the cyanidometal bridge is also conductive to MMCT. Moreover, compounds cis/trans - 1[PF₆]_n (n=3, 4) and cis/trans - 2[PF₆]₃ belong to localized compounds by analyzing the experimental characterization results, supported by the TDDFT calculations.     

Solid-Phase Reagent for Analgin and Ascorbic Acid on the Basis of a Copper(II) Complex with Tetrabenzotetraazacyclohexadecine Immobilized by Adsorption on Silica Gel

The reactions of a number of natural organic reducing agents with a copper(II) complex with tetrabenzo[b, f, j, n][1, 5, 9, 13]tetraazacyclohexadecine adsorbed on silica were examined. A solid-phase reagent was proposed for the sorption–spectrophotometric determination of Analgin and ascorbic acid (c _min= 0.91 and 0.06 mg/L, respectively) and for the visual test determination of the above compounds (c _min= 0.50 and 0.025 mg/sample, respectively).     

Copper induced single electron transfer trifluoromethylation of organic halides with 3-oxo-ω-fluorosulfonylperfluoropentyl iodide

Treatment of ICF₂CF₂OCF₂CF₂SO₂F (1) with organic halides in the presence of copper powder in a co-solvent DMF/HMPA(V/V= 1:1) gave the corresponding trifluoromethylated compounds in good to excellent yields. A copper induced single electron transfer reaction mechanism is proposed.