New cyanometalate building units: synthesis and characterization of [Re(CN)(7)]3- and [Re(CN)(8)]3-

Two new cyanorhenate complexes of potential utility in constructing magnetic and photomagnetic materials are reported. Reaction of (Bu4N)CN with [ReCl6]2- in acetonitrile affords yellow (Bu4N)3[Re(CN)7] (1), featuring the pentagonal bipyramidal complex [Re(CN)7]3-. The spectral and magnetic properties of 1 indicate that the complex has an S = 1/2 ground state with considerable anisotropy in the g tensor. In aqueous solution, 1 reacts with Mn2+ ions to generate the three-dimensional cyano-bridged solid [fac-Mn(H2O)3][cis-Mn(H2O)2][Re(CN)7].3H2O (2) containing diamagnetic [Re(CN)7]4-. Addition of KIO4 to the reaction solution, originally intended to prevent reduction of the rhenium during solid formation, instead yields white (Bu4N)3[Re(CN)8] (3). As crystallized in K3[Re(CN)8].2MeCN (4.2MeCN), the diamagnetic [Re(CN)8]3- complex adopts a nearly perfect square antiprismatic coordination geometry. In solution, this species behaves analogously to the isoelectronic [M(CN)8]4- (M = Mo, W) complexes, apparently converting to a dodecahedral geometry and photooxidizing under UV radiation to give paramagnetic [Re(CN)8]2-.     

Structural studies on 3-acetyl-1,5-diaryl and 3-cyano-1,5-diaryl formazan chelates with cerium(III), thorium(IV) and uranium(VI)

Summary Solid complexes of 3-acetyl-1,5-diaryl and 3-cyano-1,5-diaryl formazans were prepared and characterized by elemental analysis, IR, NMR, TGA and DTA analyses. Based on these studies, the suggested general formula for the complexes is [M(HL) _m (OH^–) _n or (NO ₃ ^– or Cl^–) _x ·(H₂O) _y or (C₂H₅OH orDMSO) _z , where HL=formazanM=Ce³⁺, Th⁴⁺, and UO ₂ ²⁺ ,m=1–2,n=0–3,x=0–3,y=0–4 andz=0–3. The metal ions are expected to have coordination numbers 6–8.

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Strukturuntersuchungen an 3-Acetyl-1,5-diaryl- und 3-Cyan-1,5-diaryl-formazan-Chelaten mit Cer(III), Thorium(IV) und Uran(VI)

Zusammenfassung Die hergestellten Chelate wurden mittels Elementaranalyse, IR, NMR, TGA und DTA charakterisiert. Darauf basierend wird die generelle Formel [M(HL) _m (OH^–) _n bzw. (NO ₃ ^– oder Cl^–) _x ·(H₂O) _y oder (C₂H₅OH bzw.DMSO) _z ] vorgeschlagen, wobei HL=Formazan,M=Ce³⁺, Th⁴⁺ oder UO ₂ ²⁺ ,m=1–2,n=0–3,x=0–3,y=0–4 undz=0–3. Die Metallionen haben Koordinationszahlen von 6–8.

     

Conductivity and FTIR studies on PEO-LiX [X: CF3SO3(-), SO4(2-)] polymer electrolytes

Polymer electrolytes based on poly(ethylene oxide)-lithium triflate (PEO-LiCF3SO3) and poly(ethylene oxide)-lithium sulphate (PEO-Li2S4) were prepared by using solution casting method. Measurements of conductivity and dielectric were carried out on these films as a function of frequency at various temperatures. It was observed that PEO-LiCF3SO3 polymer electrolytes have higher conductivity. The interaction between PEO and Li salts were studied by Fourier transform infrared (FTIR).     

Speciation of nitrogen - [N(3-)] and [N(2)(2-)] - in binary compounds

The nitrogen content of the binary compounds SrN = Sr(4)[N](2)[N(2)], Sr[N(2)], and Ba[N(2)] (prepared by high-pressure syntheses) was determined analytically by using the carrier gas hot extraction method. For handling of the air- and moisture-sensitive samples, a transfer chamber was constructed to protect the compounds against decomposition before being analyzed. Additionally, it was necessary to develop a method allowing controlled and variable heating of the electrode furnace to get analytical results with high precision and accuracy. By means of a suitable temperature program it was possible not only to verify the existence but also to quantify the two different nitrogen species ([N(3-)] and [N(2)(2-)]), and thus confirm the results of recent neutron diffraction studies.     

Spectral properties of substituted coumarins in solution and polymer matrices

The absorption and fluorescence spectra of substituted coumarins (2-oxo-2H-chromenes) were investigated in solvents and in polymer matrices. The substitutions involved were: (1) by groups with varying electron donating ability such as CH?, OCH? and N(CH?)?, mainly, but not exclusively, in positions 7 and (2), by either CHO or 4-PhNHCONHN=CH- in position 3. While the spectra of non-substituted coumarin-3-carbaldehyde has absorptions at approximately 305 and 350 nm, substitution at position 7 leads to remarkable changes in the shape of the absorption spectrum and shifts the absorption to a longer wavelength. Similarly, the replacement of the formyl group with a semicarbazide group substantially influences the shape of the absorption spectrum, and coumarins which have only N(CH?)? in position 7 experience small changes. These changes are associated with the increasing intramolecular charge transfer (ICT) character and increasing conjugation length of the chromophoric system, respectively, in the studied molecules. The fluorescence is almost negligible for derivatives which have H in this position. With increasing electron donating ability, and the possibility of a positive mesomeric (+M) effect of the substituent in position 7 of the coumarin moiety, the fluorescence increases, and this increase is most intense when N(CH?)? substitutes in this position, for both 3-substituted derivatives. Spectral measurements of the studied coumarins in polymer matrices revealed that the absorption and fluorescence maxima lay within the maxima for solvents, and that coumarins yield more intense fluorescence in polymer matrices than when they are in solution. The quantum yield of derivatives which have a dimethylamino group in position 7 in polymer matrices approaches 1, and the fluorescence lifetime is within the range of 0.5-4 ns. The high quantum yield of 7-dimethylamino derivatives qualifies them as laser dyes which have k(F) higher than k(nr) in the given medium. This is caused by stiffening of the coumarin structure in polar polymer matrices, such as PMMA and PVC, due to higher micro-viscosity than in solution and intermolecular dipole-dipole interaction between chromophore (dopant) and matrix.     

3-[2(4)-Pyrimidinyl]coumarins and their condensed analogs

3-Pyrimidinylcoumarins have been synthesized by interacting 2- and 4-pyrimidinylacetonitriles with substituted salicylic aldehydes, but 9-pyrimidinylpyrano[2,3-f]chromene-4,8-diones were obtained with 8-formyl-7-hydroxychromones. Modification of the corresponding 7-hydroxycoumarins was carried out by acylation and aminomethylation.     

Excited state absorption dynamics in metal cluster polymer [WS4Cu3I(4-bpy)3]n solution

The nonlinear absorptive property of a novel metal cluster [WS(4)Cu(3)I(4-bpy)3]n in DMF solution is studied by using an open-aperture Z-scan technique with picosecond and nanosecond laser pulses at the wavelength of 532 nm. The experimental results show that the cluster has strong nonlinear absorption under the 8 ns pulse excitation and a relatively weak nonlinear absorptive property under the picosecond pulse excitation. The picosecond pump-probe response of the metal cluster is similar to that of C60 solution, which implies that the nonlinear mechanisms are the same for the two materials. By using the rate-equation model, the experimental data are theoretically simulated; several optical parameters of the cluster, especially the lifetime of the higher excited singlet state of the cluster, are obtained.     

Poly[3-(5-octyl-thienylene-vinyl)-thiophene]: a side-chain conjugated polymer with very broad absorption band

A novel polythiophene derivative, poly[3-(5-octyl-thienylene-vinyl)-thiophene] (POTVT) with conjugated thienylene vinyl side-chain, was synthesized, and the POTVT film shows a very broad absorption band-width covering from 300 nm to 700 nm after thermal annealing at 130 degrees C for 10 min.     

Reactions of atomic oxygen [O(3P)] with polymer films

The reactions of polymer films with oxygen atoms are reviewed. Emphasis is on work from this laboratory on polybutadienes having different amounts of 1,4 or 1,2 double bonds and their polyalkenamer homologues, on a polyimide (Kapton), and on a series of polyolefins with increasing fluorine content ranging from polyethylene (PE) to polytetrafluoroethylene (PTFE). Interest in this topic stems from a need to understand the mechanism(s) of surface erosion, or etching, that occurs in organic polymers when exposed to the low Earth orbital (LEO) environment, where ground-state atomic oxygen [O(³P)] is the most abundant constituent. The major findings for O atom reactions with the polyalkenamers were: (1) etch rates increase with decrease in -CH=CH-unsaturation, starting with 1,4-polybutadiene and reaching the maximum rate with PE or ethylene-propylene rubber; (2) in polybutadienes having both 1,4 and 1,2 double bonds, the rate of O(³P)-induced etching is lower the higher the 1,2 content; and (3) the reactions are confined to the polymer surface. Relative etch rates for various commercial polymer films (e.g., Kapton, Teflon, PE) exposed to O(³P) downstream from a low-pressure, radio-frequency O₂ plasma were compared with corresponding literature data for films exposed to O(³P) either during a Space Shuttle flight or in the plasma glow (where many species besides O(³P) are present). The use of O₂ discharge reactors – whether exposures are conducted “out of the glow” or “in the glow” – cannot serve as a routine, ground-based simulation of exposures of a polymer to the LEO environment. ESCA analysis of the surfaces of Kapton and other polymers, before and after reaction with O(³P), showed that there is a steady-state competition between surface recession and oxidation. In a series of fluorine-containing polyolefins exposed to O(³P), the maximum oxygen uptake increased regularly with decrease in fluorine content, ranging from a minimum in PTFE to a maximum in PE.     

5-(4-氟苯基)-N-1-(3-羟基金刚烷基)-7-三氟甲基吡唑并[1,5-a]嘧啶-3-酰胺的合成及其抗肿瘤活性

以乙氧基甲叉基氰乙酸乙酯和对氟苯乙酮为起始原料,设计并合成了新化合物5-(4-氟苯基)-N-1-(3-羟基金刚烷基)-7-三氟甲基吡唑并[1,5-a]嘧啶-3-酰胺(7),其结构经~1H NMR,IR和HR-MS(ESI)表征。采用MTT法测定了其对人乳腺癌细胞(Bcap-37)、人宫颈癌细胞(He La229)、人肝癌细胞(QGY-7701)和人肺癌细胞(A549)体外抗肿瘤细胞的增殖活性。结果表明:7对受试细胞的抑制活性较好,其IC_(50)值分别为23.9μmol·L~(-1),29.8μmol·L~(-1),31.4μmol·L~(-1)和21.7μmol·L~(-1)。     

7-Aryl-3-(hydroxymethyl)-5-oxo-1,2,3,5-tetrahydro[1,2,4]triazolo[1,5-a]pyridine-6,8-dicarbonitriles: Synthesis and Predicted Biological Activity

Russian Journal of General Chemistry - Aminomethylation of 1,6-diamino-4-aryl-2-oxo-1,2-dihydropyridine-3,5-dicarbonitriles under the action of excess of formaldehyde in ethanol has led to the...