One‐Shot Double Elimination Process: A Practical and Concise Protocol for Diaryl Acetylenes

A variety of diaryl acetylenes were obtained in good yields when lithium hexamethyldisilazide was added to a solution of arylmethyl sulfone, aryl aldehyde, and chlorodiethylphosphate in THF. In this one‐shot process, a number of transformations such as aldol reaction, phosphorylation of aldolate, and double elimination of the resulting β‐substituted sulfone proceeded successively to afford the desired acetylenes. The one‐shot process was accelerated by the substitution of halogen atoms on the phenyl groups, and unsymmetrically substituted diaryl acetylenes were obtained without contamination of the dehalogenated products. Diaryl acetylenes with other substituents such as CF₃, ethoxycarbonyl, dimethylamino, TMS‐acetylene groups, as well as pyridinyl and thienyl moieties were also accessible with this method. However, methoxy‐substituted compounds were obtained in moderate yields under the same conditions, but the yields were increased when lithium diisopropylamide was used instead.     

Intercalation of Cyclic Amines into α-Titanium Phosphate

The intercalation of some amines (aniline, benzylamine, cyclohexylamine,piperidine, pyridine, pyrazine and piperazine) into -titaniumphosphate, Ti(HPO₄)_2×H₂O,has been investigated by the batch method and/or by exposing the host to thevapour of the amines. The changes in the interlayer distance of the solidduring the intercalation process was followed by X-ray powder diffraction.The new intercalates were characterised by chemical and thermal analysis.Materials with a monolaminar and/or bilaminar arrangement of amine moleculesin the phosphate interlayer region are obtained depending on the nature ofthe amine. Due to steric hindrance, saturated phases are not obtained forall amines studied. The thermal decomposition of the intercalates (nitrogenatmosphere), takes place in three stages: dehydration, removal of amines andcondensation of the hydrogenphosphate to pyrophosphate groups.     

Spectroscopic Studies on the Interaction of Tetramethylpyridylporphyrins and Cationic Clays

In the present work, the interaction between5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21H,23H-porphine (TMPyP) and its metallated form(CoTMPyP) with three cationic clays was investigatedby X-ray diffraction (XRD), UV-VIS and resonance Ramanspectroscopies. Sodium montmorillonites K10 and KSFand a synthetic fluorohectorite (FHT) containingdifferent macrocycle loadings, were prepared by an ionexchange reaction. In nonsaturated KSF and FHT, theCoTMPyP molecule assumes a flat orientation, relativeto the host layers, giving rise to at least twoabsorption bands in the Soret region (ca. 445 and 465 nm)assigned to adsorbed and intercalated CoTMPyP,respectively. For the delaminated K10 sample, a broadband centered around 456 nm, indicates a majorcontribution from the metalloporphyrin on the clayexternal surfaces. The electronic spectra of FHTsamples containing increasing amounts of CoTMPyPshow bands red shifted even when a small amount ofporphyrin is used, suggesting that the electroniclevels of the macrocycle are more affected by theinteraction with the clay than by the metalloporphyrindistortion inside the galleries. The resonance Ramanspectra obtained for all CoTMPyP samples presentedonly minor shifts in peak positions and band width,with the exception of the FHT saturated sample, wherethe bands are clearly broader when compared to otherloadings, suggesting that porphyrin aggregation isoccurring. In the case of TMPyP, the bands at ca. 430and 468 nm were assigned to nonprotonated andprotonated molecules, respectively. This assignment issupported by resonance Raman spectroscopy, which alsoshowed the ₂ mode (ca. 1550 cm^-1) to bethe most sensitive peak to protonation.     

Solvent intercalation in cobalt dimethylglyoximato complexes: A miniature host-guest system

When crystallized from appropriate solvents, the complex aqua-bis(dimethylglyoximato)nitrocobalt (III) may incorporate solvent molecules, thus forming a variety of mixed crystals. In the resulting host-guest crystals, the space groupP2_l/m and the packing motif of the pure host compound are retained. Lattice constantsa andb remain essentially unaltered upon intercalation, whereasc and the monoclinic angle depend largely on the clathrated guest. Space filling and intermolecular contacts are discussed.Dedicated to Professor Peter Paetzold at the occasion of his 60th birthday. A preliminary account of this work has been given at the Spring Meeting of the British Crystallographic Association, Newcastle upon Tyne, 1994.     

Molecular modeling of intercalation complexes of antitumor active 9-aminoacridine and a [d,e]-anellated isoquinoline derivative with base paired deoxytetranucleotides

Summary Intercalators are molecules capable of sliding between DNA base pairs without breaking up the hydrogen bonds between the DNA bases. On the basis of molecular mechanics calculations structural, models of B-DNA tetranucleotide intercalation complexes of some cytostatic active 9-aminoacridines and of a [d, e]-anellated isoquinoline derivative are presented. The drug complexes are stabilized by energetically favouredvan der Waals interactions and by selective hydrogen bonds between the side chains of the drugs and the DNA bases. Semiempirical quantum chemistry calculations revealed that the chromophoric system of the intercalators is able to form ,-charge-transfer interactions with the purine bases of the base paired deoxytetranucleotides. The theoretical findings are of interest for a more specific drug design of cytostatically active agents.

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Molecular Modeling von Interkalationskomplexen antitumoraktiver 9-Aminoacridine sowie eines [d, e]-anellierten Isochinolinderivates mit basengepaarten Desoxytetranukleotiden

Zusammenfassung Interkalatoren sind Moleküle, die in der Lage sind, sich zwischen DNA-Basenpaare einzulagern, ohne die Wasserstoffbrücken zwischen den DNA-Basen aufzubrechen. Auf der Basis von molekülmechanischen Rechnungen werden Tetranukleotid-Interkalationskomplexe von verschiedenen zytostatisch aktiven 9-Aminoacridinen und von einem [d, e]-anellierten Isochinolinderivat präsentiert. Die Komplexe werden durch energetisch günstigevan der Waals-Interaktionen sowie durch selektive Wasserstoffbrückenbindungen zwischen den Seitenketten der Wirkstoffe und den DNA-Basen stabilisiert. Semiempirische quantenchemische Rechnungen ergaben, daß der Chromophor der Interkalatoren in der Lage ist, ,-charge-transfer Wechselwirkungen mit den Purinbasen der basengepaarten Desoxytetranukleotide auszubilden. Die theoretischen Ergebnisse sind für ein spezifischeres Wirkstoffdesign zytostatisch aktiver Verbindungen von Interesse.

     

Surface modification of carbon anodes for secondary lithium battery by fluorination

Recent results on the surface modification of petroleum cokes and their electrochemical properties as anodes of secondary lithium batteries are summarized. The surface of petroleum coke and those heat-treated at 1860-2800 °C were fluorinated by elemental fluorine (F₂), chlorine trifluoride (ClF₃) and nitrogen trifluoride (NF₃). No surface fluorine was found except only one sample when ClF₃ and NF₃ were used as fluorinating agents while surface region of petroleum coke was fluorinated when F₂ was used. Transmission electron microscopic (TEM) observation revealed that closed edge of graphitized petroleum coke was destroyed and opened by surface fluorination. Raman spectra showed that surface fluorination increased the surface disorder of petroleum cokes. Main effect of surface fluorination with F₂ is the increase in the first coulombic efficiencies of petroleum cokes graphitized at 2300-2800 °C by 12.1-18.2% at 60 mA/g and by 13.3-25.8% at 150 mA/g in 1 mol/dm³ LiClO₄-ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1, v/v). On the other hand, main effect of the fluorination with ClF₃ and NF₃ is the increase in the first discharge capacities of graphitized petroleum cokes by ∼63 mAh/g (∼29.5%) at 150 mA/g in 1 mol/dm³ LiClO₄-EC/DEC.     

Thermodynamic properties of lithium chloride ammonia complexes for application inahigh-lifthigh temperature chemical heat pump

Ammonia absorption by and desorption from lithium chloride at different pressures has been studied using high-pressure differential scanning calorimetry, for application in a high-lift high temperature chemical heat pump. The measurements were performed under isobaric as well as under isothermal circumstances. Clausius–Clapeyron plots were constructed and used to calculate the thermodynamic parameters and to determine the stability regions of the different complexes. Controversies in literature as to the real existing phases are resolved.     

Hygrometric Determination of Water Activities and Osmotic and Activity Coefficients of NH4Cl–LiCl–H2O at 25°C

The mixed aqueous electrolyte system of ammonium and lithium chlorides has been studied by the hygrometric method at 25°C. The relative humidities of this system are measured at total molalities from 0.3 to 6 mol-kg^{– 1} for different ionic-strength fractions y of NH₄Cl with y = 0.33, 0.50, and 0.67. The data obtained allow the deduction of new water activities and osmotic coefficients. The experimental results are compared with the predictions of the ECA (extended composed additivity) law proposed in our previous work. The Zdanovskii–Stokes–Robinson (ZSR), the Robinson–Stokes (RS), Reilly–Wood–Robinson (RWR), the Pitzer, and the Lietzke–Stoughton (LS II) models are also compared with our results. Predictions made using these models are, in general, consistent with our results. From these measurements, new Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture for different ionic-strength fractions.     

四苯基卟啉在改性磷酸锆层间的插入及荧光增强

近年来,出于节约一次性能源的考虑,人们已经加大对太阳能等天然资源的利用,致力于模拟天然光合作用的研究[1￣3],而光合作用中的捕光复合物又称为光子天线。光子天线中往往存在一种或几种猝灭剂,猝灭剂吸收光子后产生激发态的能量可以在不同分子或者同一分子的不同生色团之间转移,转移出能量的一方为能量给体,另一方为能量受体。