Preparative Syntheses of Guanylate-Rich Oligonucleotides Using the Phosphotriester Method in Solution

Abstract

The guanylate-rich fragments: 150 mg d(G₄T₄), 180 mg d(T₄G₄), 350 mg d(T₄G₄T₄), 30 mg d(G₄T₄G₄), 85 mg d(T₄G₄T₄G₄)were synthesized using the triester method. By enzymatic ligation of aliquots the 36mer d(G₄T₄G₄T₄G₄T₄G₄T₄G₄) is obtained.     

Specificity of receptors for leukotrienes A4, B4, C4, D4, E4 and histamine on the guinea-pig lung parenchyma. Effect of FPL-55712 and desensitization of the myotropic activity

The novel metabolites of arachidonic acid, leukotriene (LT) A₄, B₄, C₄, D₄ and E₄ have potent myotropic activity on guinea-pig lung parenchymal strip . The receptors responsible for their action were characterized using desensitization experiments and the selective SRS-A antagonist, FPL-55712. During the continuous infusion of LTB₄, the tissues became desensitized to LTB₄ but were still responsive to histamine, LTA₄, LTC₄, LTD₄ and LTE₄. When LTD₄ was infused continuously, the lung strips contracted to LTB₄ and histamine but were no longer responsive to LTA₄, LTC₄, LTD₄ and LTE₄. Furthermore, FPL-55712 (10 ng ml⁻¹− 10 ug ml⁻¹) produced dose-dependent inhibitions of LTA₄, LTC₄, LTD₄ and LTE₄ without inhibiting the contraction to LTB₄ and histamine. On the basis of these results, it appears that the guinea-pig lung parenchyma may have one type of receptor for LTB₄ and another for LTD₄; LTA₄, LTC₄ and LTE₄ probably act on the LTD₄ receptor.     

Two star‐shaped tetranuclear Ru(II) complexes containing uncoordinated imidazole groups: synthesis,characterization, photophysical and pH sensing properties

Tetrapodal ligands H₄L¹ and H₄L² containing imidazole groups have been synthesized by the reaction of 1,10‐phenanthroline‐5,6‐dione with 1,2,4,5‐tetrakis[(4‐formylphenoxy)methyl]benzene and 1,2,4,5‐tetrakis[(3‐formylphenoxy)methyl]benzene, respectively, in presence of NH₄OAc. Two star‐shaped complexes [{Ru(bpy)₂}₄(μ₄‐H₄L¹)](PF₆)₈ and [{Ru(bpy)₂}₄(μ₄‐H₄L²)](PF₆)₈ (bpy = 2,2′‐bipyridine) have been prepared by refluxing Ru(bpy)₂Cl₂·2H₂O and each ligand in ethylene glycol. The deprotonated complexes [{Ru(bpy)₂}₄(μ₄‐L¹)](PF₆)₄ and [{Ru(bpy)₂}₄(μ₄‐L²)](PF₆)₄ have been obtained by the reaction of sodium methoxide with [{Ru(bpy)₂}₄(μ₄‐H₄L¹)](PF₆)₈ and [{Ru(bpy)₂}₄(μ₄‐H₄L²)](PF₆)₈, respectively, in methanol. The pH effects on the UV–vis light absorption and emission spectra of both complexes have been studied, and ground‐ and excited‐state ionization constants of both complexes have been derived. The photophysical properties of both complexes are strongly dependent on the solution pH. They act as proton‐induced off–on–off luminescent sensors through two successive deprotonation processes of imidazole groups, with a maximum on–off ratio of 8 in buffer solution at room temperature. Theoretical calculations for the highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LOMO) orbitals of bridging ligand are also presented for plausible explanations of the fluorescence changes. Copyright © 2015 John Wiley & Sons, Ltd.     

Selective inclusion of DMF molecules within non-covalent cavity

[Me₄P]₄[Cu₄(mnt)₄]·2CH₃CN (1), [Me₄P]₄[Cu₄(mnt)₄]·2CH₃NO₂ (2), [Me₄P]₄[Cu₄(mnt)₄]·2DMF (3) and [Me₄P]₄[Cu₄(mnt)₄]·2C₃H₃N (4) (mnt = maleonitriledithiolate, [S₂C₂(CN)₂]²⁻) clusters are readily synthesized in several solvents like acetonitrile, nitromethane, N,N-dimethylformamide and acrylonitrile to provide respective solvent as guest within the non-covalent cavity of the cluster ion. The guest species is accommodated within non-covalent cavity that is generated by two adjacent {Cu₄(mnt)₄} cores bridging with tetramethylphosphonium cation through hydrogen bonding. These hydrogen bonds are not strong and when mixed solvents were used selective DMF binding takes place to yield only complex 3 over other complexes.     

Studies of the pyrolysis of tetraethylammonium tetrahydroborate

Tetraethylammonium tetrahydroborate, Et₄NBH₄, in suspension in refluxing decane-dodecane mixtures has been pyrolysed at temperatures between 175 and 190 °C. Et₃NBH₃, which is produced by partial decomposition of Et₄NBH₄, reacts with Et₄NBH₄ to give the intermediate Et₄NB₃H₈. Et₄NBH₄ and Et₃NBH₃ are also involved in the conversion of Et₄NB₃H_8. to (Et₄N)₂B₉H₉, (Et₄N)₂B₁₀H₁₀, Et₄NB₁₁H₁₄ and (Et₄N)₂B₁₂H₁₂ which are formed in varying proportions during the pyrolysis. A 1:1 Et₄NBH₄Et₃NBH₃ mixture gives the same mixture of final products in the same proportions as Et₄NBH₄ alone, but the reaction time is shorter.Results obtained under various conditions, for instance without solvent at 10⁻² torr (50% yield), are explained by the transfer of BH₃ groups occurring not only through Et₃NBH₃, but also by solid—solid reactions involving Et₄NBH₄. A more complete reaction of Et₃NBH₃ is obtained, giving quantitative yields, only when Et₃N is evacuated from the reaction mixture. Optimum conditions for the formation of each hydroborate are examined.     

Diazo complexes of osmium: preparation of binuclear derivatives with bis(aryldiazene) and bis(aryldiazenido) bridging ligands

Depending on experimental conditions and the nature of the phosphite, the reaction of OsH₂P₄ [P=P(OEt)₃ and PPh(OEt)₂] with bis(aryldiazonium) salts [N₂Ar-ArN₂](BF₄)₂ [Ar-Ar=4,4^′-C₆H₄-C₆H₄, 4,4^′-(2-CH₃)C₆H₃-C₆H₃(2-CH₃), 4,4^′-C₆H₄-CH₂-C₆H₄ and 1,5-C₁₀H₆] afford the cis and the trans binuclear [{OsHP₄}₂(μ-HNNAr-ArNNH)](BPh₄)₂1, 2 aryldiazene derivatives. These complexes 1, 2 further react with the mono(diazonium) (4-CH₃C₆H₄N₂)BF₄ salt to give the bis(aryldiazene) [{Os(4-CH₃C₆H₄NNH)P₄}₂(μ-HNNAr-ArNNH)](BPh₄)₄3, 4 derivatives. Binuclear bis(aryldiazenido) [{OsP₄}₂(μ-N₂Ar-ArN₂)](BPh₄)₂ (6) [P=P(OEt)₃; Ar-Ar=4,4^′-C₆H₄-C₆H₄, 4,4^′-C₆H₄-CH₂-C₆H₄] complexes were prepared by deprotonating with NEt₃ the nitrile-diazene [{Os(4-CH₃C₆H₄CN)P₄}₂(μ-HNNAr-ArNNH)](BPh₄)₄ (5) derivatives. The aryldiazenido compounds 6 react with HCl to give the new aryldiazene [{OsClP₄}₂(μ-HNNAr-ArNNH)](BPh₄)₂ (7) derivatives. The characterisation of the complexes by IR and ¹H, ³¹P, ¹⁵N NMR data is also discussed. The reaction of the hydride OsH₂(PPh₂OEt)₄ with mono(diazonium) salts was also studied and led exclusively to the mono(aryldiazene) [OsH(ArN NH)(PPh₂OEt)₄]BPh₄ (8) (Ar=C₆H₅, 4-CH₃C₆H₄) derivatives. Spectroscopic data (¹H, ³¹P, ¹⁵N NMR) on ¹⁵N-labelled derivatives suggest the presence of two isomers with the N-bonded and the π-bonded ArNNH ligand, respectively.     

Modeling aspects of hydrodesulfurization by molybdenum hydride compounds: Desulfurization of thiophene and benzothiophene and C-S bond cleavage of dibenzothiophene

The molybdenum hydride complexes Mo(PMe₃)₅H₂ and Mo(PMe₃)₄H₄ are capable of cleaving the C-S bonds of thiophene, benzothiophene and dibenzothiophene. For example, Mo(PMe₃)₅H₂ reacts with thiophene to give the η⁵-thiophene and butadiene-thiolate complexes, (η⁵-C₄H₄S)Mo(PMe₃)₃ and (η⁵-C₄H₅S)Mo(PMe₃)₂(η²-CH₂PMe₂). These complexes are also obtained from the reaction between Mo(PMe₃)₄H₄ and thiophene under photochemical conditions, whereas at elevated temperatures thiophene is desulfurized to liberate but-1-ene. Similarly, Mo(PMe₃)₄H₄ desulfurizes benzothiophene at elevated temperatures to liberate ethylbenzene, while the arylthiolate complex Mo(PMe₃)₄(SC₆H₄Et)H₃ is obtained photochemically. Furthermore, Mo(PMe₃)₄H₄ cleaves the C-S bond of dibenzothiophene to give [η⁶,κ¹-C₆H₅C₆H₄S]Mo(PMe₃)₂H.     

Synthesis and biological activities of leukotriene F4 and leukotriene F4 sulfone

Leukotriene F₄ (LTF₄ and LTF₄ sulfone have been synthesized and their biological activities determined in the guinea pig. LFT₄ displayed comparable activity to LTD₄ on guinea pig trachea and parenchyma but was less active on the ileum. When injected intravenously into the guinea pig, LTF₄ induced a bronchoconstriction (ED₅₀ 16 μg Kg⁻¹) which was blocked by indomethacin and FPL-55712 and was 50–100 X less potent than LTD₄ in this assay. LTF₄ sulfone was approximately 2–5 times less active than LTF₄ and . When injected into guinea pig skin with PGE₂ (100 ng); LTF₄ and LTF₄ sulfone (10–1000 ng) induced changes in vascular permeability. The order of potency in this assay was LTE₄ sulfone = LTD₄ = LTD₄ sulfone > LTE₄ > LTF₄ = LTF₄ sulfone.     

Synthesis and thermal stability of Zr(BH4)4 and Zr(BD4)4 produced by mechanochemical processing

Zirconium tetrahydroborate Zr(BH₄)₄ and its deuteride compound Zr(BD₄)₄ were successfully synthesized by mechanochemical reaction between NaBH₄ or NaBD₄ and ZrCl₄, reaching yields of 55% and 46%, respectively. The influence of the synthesis parameters on the yield of Zr(BH₄)₄ was analyzed. The composition of the ZrCl₄:NaBH₄ starting mixture and the use of LiBH₄ instead of NaBH₄ as reactive show a clear effect on the Zr(BH₄)₄ yield. Instead, milling atmosphere does not affect the amount of the obtained product. FTIR analysis of atmosphere inside of milling vial allows to determine the formation of diborane during milling from Zr(BH₄)₄ decomposition. Thermal stability of pure Zr(BH₄)₄ and its deuterated compound was studied by combined gas-phase FTIR and DSC measurements under flowing Ar. We found that Zr(BH₄)₄/Zr(BD₄)₄ melt at about 305/303 K, decompose at about 430 K from the gas-phase and show evolution of B₂H₆/B₂D₆ under heating.     

Dinickel(II), dizinc(II) and dilead(II) complexes of a pyridazine-containing Schiff-base macrocycle

The study of the mid-late first row transition metal co-ordination chemistry of the pyridazine-containing Schiff-base macrocycle L1 [derived from the (2 + 2) condensation of 3,6-diformylpyridazine and 1,3-diaminopropane] has been completed. Transmetallation reactions of [Pb₂(4 + 4)](ClO₄)₄ (1) under appropriate conditions have led to the formation of the following complexes, [Ni₂L1(NCS)₂(SCN)₂] (3), [{Pb₂L1}₂(μ³-OH)₂](ClO₄)₆ (4), and [Zn₂L1(CH₃CN)₄](ClO₄)₄ (5 · 4CH₃CN), all of which have been structurally characterised. The analogous triflate salt of 5, [Zn₂L1](CF₃SO₃)₄ (6), can only be obtained by template reaction, as transmetallation of 1 with Zn(CF₃SO₃)₂ · 6H₂O gave 5, albeit in reduced yield. Attempts to synthesise pure [Fe₂L1(CH₃CN)₄](ClO₄)₄ (7) using the transmetallation procedure, from either [Pb₂(4 + 4)](ClO₄)₄ or [Zn₂L1(CH₃CN)₄](ClO₄)₄, were unsuccessful. The electrochemical studies carried out on [Zn₂L1](ClO₄)₄ (5) revealed multiple reduction processes and associated oxidations, but no processes corresponding to oxidation of 5.     

Fluorophosphates from Solid‐State Synthesis and Electrochemical Ion Exchange: NaVPO4F or Na3V2(PO4)2F3?

Vanadium‐based fluorophosphates are promising sodium‐ion battery cathode materials. Different phases of NaVPO₄F and Na₃V₂(PO₄)₂F₃ are reported in the literature. However, experiments in this work suggest that there could be confusions about the single‐phase NaVPO₄F in solid‐state synthesis. Here, systematic investigation of the mechanism underlying structural and compositional evolution of solid‐state synthesis (NaF:VPO₄ = 1:1) is determined by in situ and ex situ X‐ray diffraction and electrochemical measurements. Three reactions—3NaF + 3VPO₄ → Na₃V₂(PO₄)₂F₃ + VPO₄ (up to 500 °C), Na₃V₂(PO₄)₂F₃ + VPO₄ → Na₃V₂(PO₄)₃ + VF₃↑ (600–800 °C), and 2Na₃V₂(PO₄)₃ → 2(VO)₂P₂O₇ + Na₄P₂O₇ + amorphous products (above 800 °C)—are validated by in situ XRD and thermogravimetric analysis/differential scanning calorimetry. None of the products reported in this work is consistent with single‐phase NaVPO₄F at any temperature. It is speculated that the assignments of I4/mmm and C₂/c NaVPO₄F from solid‐state synthesis are incorrect, which are instead multiphase mixtures of Le Meins' Na₃V₂(PO₄)₂F₃, unreacted VPO₄, and hexagonal Na₃V₂(PO₄)₃. Liquid‐electrolyte‐based electrochemical ion exchange of LiVPO₄F produces a tavorite NaVPO₄F structure, which is very different from Le Meins' family of Na₃Al₂(PO₄)₂F₃ polymorphs.     

New palladacyclopentadiene complexes containing an N,P-donor setting. Crystal structure of [Pd{C4(COOMe)4}(o-Ph2PC6H4CHNPr)]

The synthesis of palladacyclopentadiene derivatives with the mixed-donor bidentate ligands o-Ph₂PC₆H₄CHNR (N^∧P) has been achieved. The new complexes of general formula [Pd{C₄(COOMe)₄}(o-Ph₂PC₆H₄CHNR)] [R=Me (1), Et (2), ⁱPr (3), ^tBu (4), NHMe (5)] have been prepared by reaction between the precursor [Pd{C₄(COOMe)₄}]_n and the corresponding iminophosphine. The polymer complex [Pd{C₄(COOMe)₄}]_n also reacts with pyridazine (C₄H₄N₂) to give the insoluble dinuclear complex [Pd{C₄(COOMe)₄}(μ-C₄H₄N₂)]₂ (6), which has been successfully employed as precursor in the synthesis of pyridazine-based palladacyclopentadiene complexes. The reaction of 6 with tertiary phosphines yielded complexes containing an N,P-donor setting of formula [Pd{C₄(COOMe)₄}(C₄H₄N₂)(L)] (L=PPh₃ (7), PPh₂Me (8), P(p-MeOC₆H₄)₃ (9), P(p-FC₆H₄)₃ (10)). The new complexes were characterized by partial elemental analyses and spectroscopic methods (IR, ¹H, ¹⁹F and ³¹P NMR). The molecular structure of complex 3 has been determined by a single-crystal diffraction study, showing that the iminophosphine acts as chelating ligand with coordination around the palladium atom slightly distorted from the square-planar geometry.     

Thiophenolate clusters as potential nanosized building blocks for zinc-based nanocomposite materials: synthesis and characterization

The synthesis, the spectroscopic and structural characterization of different thiophenolate-capped zinc clusters are reported and described. In particular, different reactions of 4-chlorobenzenethiol with zinc salts yield the clusters [Me₄N][Et₃NH][Zn₄(μ-S-C₆H₄-Cl)₆(S-C₆H₄-Cl)₄] (2a), [Et₃NH]₂[Zn₄(μ-S-C₆H₄-Cl)₆(S-C₆H₄-Cl)₄] (2b), and [Me₄N]₂[Zn₄(μ-S-C₆H₄-Cl)₆(S-C₆H₄-Cl)₄] (2c), and also the thiophenolate derivative [Et₃NH]₂[Zn₄(μ-S-C₆H₅)₆(S-C₆H₅)₄] (1b) was obtained.The nanosized thiophenolate-capped clusters were investigated by ¹H and ¹³C NMR, elemental analysis, and electrospray ionization (ESI) mass spectrometry. NMR experiments provided insights into the dynamic behaviour of the clusters. The thermal decomposition patterns of 2c were analyzed in air as well as in nitrogen, indicating the formation of zinc oxide and metallic zinc, respectively. The X-ray structure of 2a revealed that the cluster core consists of an adamantane-like framework analogous to those realized in many other M₄(SR)₁₀ metal complexes.     

Supramolecular coordination polymers of silver(I) with 2-isocyanopyridine or 1,2-phenylenediisocyanide

The silver(I) complexes [Ag{C₅H₄N(NC)}]_n(BF₄)_n (1), [Ag{C₅H₄N(NC)}₂]_n(BF₄)_n (2), [Ag{C₆H₄(NC)₂}]_n(BF₄)_n (3), and [Ag{C₆H₄(NC)₂}₂]_n(BF₄)_n (4) have been synthesized using different Ag:L ratios of 2-isocyanopyridine (or 2-pyridylisocyanide, CNPy-2) or 1,2-phenylenediisocyanide ligands. The polymeric complex 2 has been characterized by X-ray diffraction revealing a polymeric chain structure. Breaking the polymeric structure of [Ag{C₆H₄(NC)₂}]_n(BF₄)_n (3) with acetonitrile, the dimeric complex [Ag{(CN)₂C₆H₄)}(NCMe)₂]₂(BF₄)₂ (5) is formed, which has been also characterized by X-ray diffraction.     

Thallium(III) complexes of the metalloligands [Pt2(μ-S)2(PPh3)4] and [Pt2(μ-Se)2(PPh3)4]

Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with the diarylthallium(III) bromides Ar₂TlBr [Ar = Ph and p-ClC₆H₄] in methanol gave good yields of the thallium(III) adducts [Pt₂(μ-S)₂(PPh₃)₄TlAr₂]⁺, isolated as their salts. The corresponding selenide complex [Pt₂(μ-Se)₂(PPh₃)₄TlPh₂]BPh₄ was similarly synthesised from [Pt₂(μ-Se)₂(PPh₃)₄], Ph₂TlBr and NaBPh₄. The reaction of [Pt₂(μ-S)₂(PPh₃)₄] with PhTlBr₂ gave [Pt₂(μ-S)₂(PPh₃)₄TlBrPh]⁺, while reaction with TlBr₃ gave the dibromothallium(III) adduct [Pt₂(μ-S)₂(PPh₃)₄TlBr₂]⁺[TlBr₄]⁻. The latter complex is a rare example of a thallium(III) dihalide complex stabilised solely by sulfur donor ligands. X-ray crystal structure determinations on the complexes [Pt₂(μ-S)₂(PPh₃)₄TlPh₂]BPh₄, [Pt₂(μ-S)₂(PPh₃)₄TlBrPh]BPh₄ and [Pt₂(μ-S)₂(PPh₃)₄TlBr₂][TlBr₄] reveal a greater interaction between the thallium(III) centre and the two sulfide ligands on stepwise replacement of Ph by Br, as indicated by shorter Tl-S and Pt?Tl distances, and an increasing S-Tl-S bond angle. Investigations of the ESI MS fragmentation behaviour of the thallium(III) complexes are reported.     

Variation inRhizobium leguminosarum response to short term application of NH4NO3 to nodulatedPisum sativum L.

Summary This study was conducted to determine the effect of short term application of NH₄NO₃ on nodule function and to determine whether the rhizobial isolate used was a significant factor in this effect. Pea plants were inoculated with 10 differentRhizobium leguminosarum isolates and grown for 3 weeks in N-free medium before addition of 0, 1, 2 or 5 mM NH₄NO₃ for 2 to 7 days. Acetylene reduction and leghemoglobin content decreased with increasing exposure time to NH₄NO₃ and with increasing concentration of NH₄NO₃. NH ₄ ⁺ and NO ₃ ⁻ depletion from the nutrient medium were assayed in plants exposed to 5 mM NH₄NO₃ and mean uptake rates were similar for each ion. There were significant differences among isolates in the rate of decrease of C₂H₂ reduction with increasing NH₄NO₃ concentration (C₂H₂ reduction responsiveness to NH₄NO₃) 4 and 7 days after addition of NH₄NO₃ but no differences after 2 days of exposure to NH₄NO₃. There were significant differences among isolates in NH ₄ ⁺ depletion from the nutrient medium but these differences were not correlated with the differences observed in C₂H₂ reduction. Ranking of the isolates for C₂H₂ reduction responsiveness to NH₄NO₃ applied to plants with nodules was different from that obtained when NH₄NO₃ was applied at seeding. Isolates with varying sensitivity to NH₄NO₃ may be useful tools for determining the mechanisms responsible for inhibition of symbiotic N₂ fixation by combined nitrogen. NRCC paper no. 25863.     

C-ansa-zirconocene complexes with O/S donor ligands: Novel homoleptic six coordinate 4-mercaptophenolate complex of Zr(IV)

New C-ansa-zirconocene complexes containing methoxythiophenolate and mercaptophenolate ligands have been synthesized and characterized. The reaction of (HSC₆H₄-n-OMe) (n = 2, 3 or 4) with [Zr{(t-Bu)HC(η⁵-C₅Me₄)(η⁵-C₅H₄)}Me₂] (1) led to the formation of monosubstituted complexes [Zr{(t-Bu)HC(η⁵-C₅Me₄)(η⁵-C₅H₄)}Me(κ,S-SC₆H₄-n-OMe)] (n = 2 (2); n = 3 (3)) and the disubstituted complex [Zr{(t-Bu)HC(η⁵-C₅Me₄)(η⁵-C₅H₄)}(κ,S-SC₆H₄-4-OMe)₂] (4). The complexes [Zr{(R)HC(η⁵-C₅Me₄)(η⁵-C₅H₄)}(κ,O-OC₆H₄-4-SH)₂] (R = t-Bu (6); R = CH₂CHCH₂ (7)) and [Zr(η⁵-C₅H₄)₂(OC₆H₄-n-SH)₂] (n = 3 (9); n = 4 (10)) have been synthesized using the corresponding dimethyl zirconocene and mercaptophenol. However, the reaction of [Zr{(t-Bu)HC(η⁵-C₅Me₄)(η⁵-C₅H₄)}Cl₂] (11) with 4-mercaptophenol in the presence of NEt₃ led to the formation of the first example of a homoleptic six-coordinate mercaptophenolate complex of zirconium, namely [HNEt₃]₂[Zr(κ,O-OC₆H₄-4-SH)₆] (12). Complex 12 can be obtained in higher yield by the reaction of ZrCl₄ with six equivalents of 4-mercaptophenol and NEt_3. The reaction of 12 with [Zr(η⁵-C₅H₄)₂Cl₂] gave the unexpected disubstituted complex [Zr(η⁵-C₅H₄)₂(OC₆H₄-4-SH)₂] (10). The molecular structures of 4 and 12 have been determined by single-crystal X-ray diffraction studies.     

Contraction of guinea pig uterus by synthetic leukotrienes

Synthetic leukotrienes (LT) C₄ and D₄ elicited concentration-dependent contractions of the guinea pig uterus between 10^?8-10^?6M, whereas LTE₄ appeared 1000-fold weaker. The potencies of LTC₄ and LTD₄ were similar to that of acetylcholine and PGF_2α but weaker than that of PGE₂. The maximal contractions elicited by LTC₄ and LTD₄ were 66.0 ± 2.1% and 63.8 ± 4.6% that elicited by acetylcholine. FPL 55712 (10^?5M) antagonized the uterine contractile activity of LTD₄, while meclofenamic acid at 10^?5M but not at 10^?6M also antagonized the LTD₄-induced contration. Radioimmunoassay of the uterine tissue bathing fluid following LTD₄ indicated the variable presence of low concentrations of PGE₂, PGF_2α and TXB₂. These results demonstrate the LTC₄ and LTD₄ possess significant uterine contractile activity, which may only partially be mediated indirectly via prostaglandin products.     

Supramolecular architectures based on di-, tri- and tetrameric complexes with N,N′-diacylhydrazide ligands

Five new complexes, [Co₃(HL₁)₂(Py)₈]·4CH₃OH (1), [Ni₃(HL₁)₂(Py)₄]₂·2DMF (2), [Co₃(H₂L₂)₂(Py)₈]·2NO₃ (3), [Ni₂(HL₂)(Py)₆] (4) and [Cu₄(HL₂)₂(Py)₄]·4DMF (5) (H₄L₁ = N-propionyl-4-hydroxysalicylhydrazide, H₄4-hopshz; H₅L₂ = N-(3-carboxy-cis-2-propenoyl)-4-hydroxysalicylhydrazide, H₅4-hocpshz) have been obtained from two N,N′-diacylhydrazide ligands and characterized by elemental analysis, FT-IR, X-ray diffraction and antimicrobial activities. These di-, tri-, and tetrameric complexes are connected into three-dimensional supramolecular architectures with interesting topologies through O-H?O, C-H?O and C-H?π interactions. 1-3 are linear trimeric complexes with the ligands triply-deprotonated. Topological analysis indicates that they exhibit 2D (4,4), 3D (6,8)-connected (3³4⁹5²6)(3⁴4¹²5⁷6⁴7) and 8-connected (4²⁵6³) net, respectively. 4 and 5 possess dimeric and tetrameric structures, which are extended into 7-connected (3³4¹³5³6) and 4-connected (4,4) net, respectively.     

Synthesis and antioxidant activities of 2-oxo-quinoline-3-carbaldehyde Schiff-base derivatives

A series of 2-oxo-quinoline-3-carbaldehyde Schiff-base derivatives 4a₁–4n₂ were designed and synthesized based on the 2-oxo-quinoline structure core as novel antioxidants. In vitro antioxidant activities of these compounds were evaluated and compared with commercial antioxidants ascorbic acid, BHT and BHA, employing DPPH assay, ABTS⁺ assay, O₂^? assay and OH assay. The results showed that IC₅₀ of most compounds were lower than standard value 10 mg/mL, indicating good antioxidant activities of these compounds. In addition, in vitro antioxidant activities screening revealed that 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities of compounds 4b₂, 4e₁, 4e₂ and 4g₂, 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) cation (ABTS⁺) radical scavenging activities of compounds 4a₁, 4e₁, 4e₂, 4f₁, 4f₂, 4g₁, 4g₂, 4h₁, 4h₂, 4k₁, 4k₂, 4n₁ and 4n₂, superoxide anion radical scavenging activities of 4b₁, 4e₁, 4f₂, 4j₁, 4k₁, 4k₂, 4m₁, 4m₂, and 4n₂, and hydroxyl radical scavenging activity of almost all the compounds except 4f₁, 4f₂, 4j₂, 4l₁ and 4l₂ were better than that of the commercial antioxidant butylated hydroxytoluene (BHT).