Electrospray ionization tandem mass spectrometry for poly(propylene oxide) starting and end group analysis

Electrospray ionization tandem mass spectrometry was applied to study poly(propylene oxide) obtained in the presence of potassium hydride. It was found that the polyether chains possess different starting groups, i.e. those situated at the beginning of the polymer backbone. These were isopropoxy, hydroxy, methoxy and allyloxy groups when the polymerization was stopped by the addition of methyl iodide. Each macromolecule was terminated by the methoxy group in this case. Copyright 1999 John Wiley & Sons, Ltd.     

Heterocyclic carbene complexes of nickel, palladium, and copper(I) as effective catalysts for the reduction of ketones*

Carbene complexes of nickel, palladium, and copper(I) effectively catalyze the reduction of aromatic ketones under the influence of 2-propanol in the presence of potassium hydroxide. Bis(1,3-dimethylbenzimidazol-2-ylidene)copper(I) iodide and the polymeric complex of crown-biscarbene with copper(I) iodide show the highest catalytic efficiency.     

Metalation of toluene and cumene with alkali metal-crown ether complexes

Metalation of toluene and isopropylbenzene with alkali metal-crown ether complexes led to the corresponding α-metalated alkylbenzenes. Treatment of the latter in succession with solid carbon dioxide, water, and hydrochloric acid gave carboxylic or dicarboxylic acids in 65–78% yield. Metalation of isopropylbenzene with sodium or potassium crown ether complexes above 90°C was accompanied by cleavage of the polyether ring with formation of organometallic compounds which then reacted with isopropylbenzene to produce 2-sodio(potassio)-2-phenylpropane and open-chain oligoether.     

Über das Fluoreszenzthermochrome Acetonitrilo-Kupferjodid mit Dibenzo-18-Krone-6

About the Fluorescence Thermochromism of Acetonitrile Copper Iodide with Dibenzo-18-Crown-6 Copper iodide reacts in actonitrile solution with dibenzo-18-crown-6 to form a compound,(CuJ)₄(CH₃CN)₄(db-18-c-6), which fluoresces yellow at 298K, but pink at 77 K. It decomposes at 55.3°C. (5 Torr) by lost of acetonitrile and a heterogeneous mixture of copper iodide and polyether results. In absence of dibenzo-18-crown-6, copper iodide forms with acetonitrile a heterogeneous mixture of copper iodide and polyether results. In absence of dibenzo-18-crown-6, copper iodide forms with acetonitrile a solvate CuJ. CH₃CN. It also shows fluorescence thermochromism (yellow at 298 K, but green at 77 k) but decomposes at 0°C and 760 Torr. The luminescences pectra of the macrocyclic polyether complex at 298 K is redshifted. This probably results from intersection between the crown and the acetonitrile copper iodide.     

Supramolecular self-assembly of inclusion complexes of a multiarm hyperbranched polyether with cyclodextrins

A new class of crystalline inclusion complexes of a multiarm hyperbranched polyether combined with various cyclodextrins (CDs) was successfully prepared. Using self-condensing ring-opening polymerization, a kind of multiarm polyether with a hyperbranched poly(3-ethyl-3-oxetanemethanol) core and multiple linear poly(ethylene glycol) (PEG) arms was obtained. It has been found that this kind of hyperbranched polyether can be dissolved in water. Adding alpha-CDs to the multiarm hyperbranched polyether solution, molecular recognition results in the formation of crystalline inclusion complexes based on the noncovalent interactions between the linear PEG arms of the polyether particles and the alpha-CDs. These multiarm polyether inclusion complexes have been well characterized. Interestingly, quite different from inclusion complexes of CDs and linear polymeric guests, the complexes of the multiarm hyperbranched polyether with alpha-CDs show a novel lamellar morphology. The experimental results validate that the resultant lamellar crystals have a juxtaposed structure. In addition, the formation mechanism of these inclusion complexes of a multiarm polyether with alpha-CDs has also been well described. Besides the role of displacement of associated water molecules and the presence of hydrogen bonding between CDs in channel structure CD inclusion complexes, the noncovalent intermolecular forces between CDs and polymers also play an important role in the formation of complex architectures.     

氮杂冠醚与碱金属离子配位反应的研究

滴定量效法是研究反应热化学和热力学的重要手段之一．用这种方法对冠醚与金属离子的配位反应热力学性质进行研究一直受到很大关注【且S习．但是对氨杂冠林，尤其是一系列结构相似的氨杂冠醚体系进行系统的热力学性质研究的报导不多．前文K则曾报导了用自组装的消定量热计对银（I）－a吹体系和铜（11）·N，N’一问位取代革基乙二胺体系的配位反应热化学研究结果·本文报导从（对位取代革基）k杂15冠5卜RPW15CS，R＝CIZH；CHa；CHso）与碘化钠和碘化钾在25T、无水乙过溶液中进行配位反应的消定量效研究结果．讨论了配体上取代基的电…     

Oxidation potentials of platinum(II) bromide and iodide complexes

The reactions of platinum(II) bromide and iodide complexes with potassium permanganate have been studied by potentiometric titration. The main regularities of the effect of complexation on the reduction properties of the central metal atom and ligands have been found.     

Synthesis of 2,8,12,18-tetrabutyl-3,7,13,17-tetramethyl-5-{3-[11-(pyridin-4-yloxy)-3,6,9-trioxaundecyloxy]phenyl}-porphyrin and study on the effect of its molecular conformation on physicochemical properties

2,8,12,18-Tetrabutyl-3,7,13,17-tetramethyl-5-{3-[11-(pyridin-4-yloxy)-3,6,9-trioxaundecyloxy] phenyl}porphyrin was synthesized, and its complexation with zinc and potassium cations in the system toluene-methanol (5:1) was studied by spectrophotometric titration and ¹H NMR spectroscopy. Spatial preorganization of the meso-aryl substituent due to complex formation of potassium cation with the polyether fragment accelerates the reaction of zinc with the title compound approximately threefold. A probable scheme of the interaction was proposed, and formation constants of the corresponding complexes were determined.     

Phase diagram of an iodine-potassium iodide-water-ethanol system at 25°C

Phase equilibriums are studied in the isothermal-isobaric sections of the phase diagram of a fourcomponent iodine-potassium iodide-water-ethanol system at 25°C and atmospheric pressure. The compositions of the solvent at which it exhibits the greatest ability to dissolve iodine are established. It is shown that in all the investigated sections, there is three-phase eutonic equilibrium with potassium iodide and crystalline iodine as the solid phases. It is revealed that in the sections containing 30 and 50% of ethanol, potassium iodide serves as the salting in agent for crystalline iodine, due to the formation of polyiodide complexes of various composition in the studied system.     

Methyl isobutyl ketone extraction of iodide complexes from sulphuric acid-potassium iodide media and back-extraction into an aqueous phase

The methyl isobutyl ketone extraction of 15 elements (Cu, Ag, Zn, Cd, In, Tl, Ge, Sn, As, Sb, Bi, Se, Te, Mo and Pd) as iodide complexes from 0.1-5 M sulphuric acid/0.01-0.5M potassium iodide media has been studied. At the optimum potassium iodide concentrations, and a 1:2 v v ratio of organic to aqueous phase, Cu(II), Ag, Cd, In(III), Tl(III), Sb(III), Bi, Te(IV) and palladium(II) are completely extracted in a single step from 1-5M sulphuric acid. All these elements except palladium are also quantitatively extracted from 0.05-0.5M iodide/2M sulphuric acid. Zn, Sn(IV) and As(III) are completely extracted at high acid and iodide concentrations, and at the highest concentrations of acid and iodide investigated, Ge is partly extracted and Mo(VI) is slightly extracted. The extraction of Se(IV) is incomplete because of its reduction to the elemental state by iodide. The back-extraction of the elements has also been investigated and the forms in which they are extracted and potential analytical separations and interferences are discussed.     

Proton-ionizable crown compounds. 3. Synthesis and structural studies of macrocyclic polyether ligands containing a 4-pyridone subcyclic unit

New proton-ionizable macrocyclic polyether ligands containing the 4-pyridone subcyclic unit have been prepared by reacting 4-THP blocked-2,6-pyridinedimethanol with various oligoethylene glycol ditosylates. The 18-crown-6 ligand containing the 4-pyridone subcyclic unit, 4 , forms stable complexes with alkali metal and organic ammonium cations. The crystal structure of 4 proves the 4-pyridone structural unit. The crystal structure of the potassium thiocyanate complex of 4 is also reported and shows the complex to contain the 4-hydroxypyridine unit.     

Specific features of using phosphate adsorption method for removing base catalyst from polyethers

Regular trends in variation of the solubility of potassium phosphates in the polyether-water system depending on the physicochemical parameters of the process and kind of the polyether were examined. The residual solubility of potassium dihydrogen phosphate was studied in relation to the temperature, water content, and kind of the polyether being purified.     

Evaluation of noncovalent interactions between peptides and polyether compounds via energy-variable collisionally activated dissociation

Energy-variable collisionally activated dissociation (CAD) was used to analyze noncovalent interactions of protonated peptide/polyether complexes in a quadrupole ion trap complexes were formed with a series of four polyether host molecules and thirteen peptide molecules. Comparison of dissociation thresholds revealed correlations between the gas-phase basicities of the peptides and polyether molecules and the onset of dissociation. The dissociation thresholds of complexes containing the tripeptides or pentapeptides were inversely proportional to the gas-phase basicities of the sites of protonation of the peptides. Intramolecular hydrogen bonding of the pentapeptides affected the observed dissociation thresholds as well. The dissociation thresholds also scaled proportionally to the gas-phase basicities of the polyethers in the complexes, and the importance of the conformational flexibility of the polyether ligand was confirmed for one of the histidine-containing tripeptide complexes.     

Sorption of iodine-containing vapor onto chitosan

The kinetics of sorption of vapor over aqueous and aqueous-alcoholic solutions of potassium iodide and potassium iodine–iodide and over crystalline iodine onto chitosan powder or film was studied. The vapor diffusion coefficients in the initial and final sorption steps were calculated from the data obtained. For all the chitosan–sorbate vapor systems studied, the mass transfer relationships are not described by Fick’s law and are characterized by anomalous sorption kinetics. The properties of chitosan powder after the uptake of the sorbate vapor were evaluated by electronic and IR spectroscopy, X-ray diffraction, and differential thermal and thermal gravimetric analysis. Sorption of iodine-containing vapor onto the polymer is accompanied by complexation of the components. The iodine–chitosan complexes are stable in storage and resistant to heat treatment. The results obtained served as a basis for developing a procedure for preparing kinetically and thermally stable powdered iodinated chitosan derivatives.     

Complexes of macrocyclic polyethers with some potassium monoethyl benzeneazophosphonates

Complexes of the potassium monoethyl ester of [-(4-benzeneazoanilino)-N-benzyl]phosphonic acid, [-(4-benzeneazoanilino)-N-4-hydroxybenzyl]phosphonic acid and [-(4-benzeneazoanilino)-N-4-methoxybenzyl]phosphonic acid with dibenzo- 18-crown-6 and dibenzo-24-crown-8 have been studied. The new complexes were identified and characterized on the basis of elemental and thermogravimetric analysis, conductivity measurements, and UV, IR and ¹H NMR spectra. The results obtained were compared with those obtained for the corresponding sodium monoalkyl benzeneazophosphonate complexes. It has been observed that the formation of salt complexes is controlled by a combination of factors, including the metal cation size in relation to the polyether hole, size and charge density of the anion, as well as the choice of the reaction solvent.     

Hydrogen-bonding interactions in gas-phase polyether/ammonium ion complexes

Hydrogen bonds are among the most important interactions involved in selective complexation in host-guest chemistry. In this study a variety of hydrogen-bonded crown ether/ammonium ion complexes are generated in the gas phase by association reactions between an amine substrate and a polyether, one of which is initially protonated, and stabilized by many collisions in the chemical ionlzation source of a triple quadrupole mass spectrometer or in a quadrupole ion trap. The nature of the hydrogen-bonding interactions of the ion complexes are evaluated by comparison of their collision-activated dissociation spectra. After collisional activation, those complexes that are weakly bound dissociate to form intact protonated polyether molecules and/or ammonium ions by simple cleavages of the hydrogen-bond association interactions. In contrast, those complexes strongly bound by multiple hydrogen bonds dissociate not only to the protonated polyether and/or ammonium ions but also by extensive covalent bond cleavage of the protonated ether skeleton.This latter type of dissociation behavior suggests that the polyether/ammonium ion complexes may be sufficiently strongly bound that surpassing the high barrier to decomposition results in formation of internally excited polyether molecules that may then undergo subsequent fragmentation by skeletal cleavages. Moreover, complexes involving multiple hydrogen bonds may have slower dissociation kinetics, allowing competition from fast dissociation processes that have substantial energy barriers.     

Proton-ionizable crown compounds. 4. New macrocyclic polyether ligands containing a triazole subcyclic unit

A series of macrocyclic polyether (crown) ligands containing the proton-ionizable s-triazole subcyclic unit were prepared by reacting the 1-THP blocked 3,5-bis(chloromethyl)-1H-1,2,4-triazole with various oligoethylene glycols. The starting bis(chloromethyl)triazole is a vessicant and must be used with caution. Triazolo-18-crown-6 ( 5 ) formed stable complexes with barium, strontium, copper and benzylammonium cations but not with potassium or lithium. The crystal structure of 5 showed the triazole proton to be on nitrogen 3 which is outside the macroring cavity.     

Thermal properties of barium complexes used for depositing thin films of YBa2Cu3O7 superconductors

The thermal properties of several barium containing complexes are compared by using thermogravimetric analysis and solids probe mass spectrometry. The properties of complexes containing flourinated and non-fluorinated β-diketonates with and without the presence of a polyether to occupy additional barium coordination sites are compared. Barium complex thermal properties are heavily dependent on the structure of the β-diketones and polyether comprising the complex. Barium complexes containing fluorinated ligands are better suited for chemical vapour deposition of barium than complexes containing non-fluorinated ligands because they efficiently evolve vapours containing barium at lower temperatures.     

State of Water in Hydration Spheres of Potassium Iodide

Ion hydration has been studied for potassium iodide solutions with concentrations from 0 to 51 wt.% at temperatures from 288.15 to 308.15 K based on ultrasonic measurements and molar adiabatic compressibility data. For hydration complexes, structural characteristics have been determined. The structure of noncoordinated water plays a significant role even in concentrated solutions. An electrostatic ion field has a strong effect on the temperature dependence of the molar volume of hydration water. A method for the precise determination of the total solvation boundary is presented.     

A study of the hydration of potassium halides by adiabatic compression

A strict approach to determine the adiabatic compressibility of a solvent at constant entropy of the solution is developed. It is shown that the apparent adiabatic compressibility of a solute is not strictly equal to the pressure derivative of the apparent molar volume of a solute at constant entropy of a solution in the general case. With this approach, the equation for hydration numbers and adiabatic compressibility of hydrate complexes is obtained thermodynamically correctly. Parameters of the hydration of potassium chloride, bromide, and iodide are found.