Synthesis of water-soluble poly(p-phenyleneethynylene) in neat water under aerobic conditions via Suzuki-Miyaura polycondensation using a diborylethyne synthon

We report the synthesis, structure, and characterization of a novel ethyne synthon, 1,2-bis(4',4',5',5'-tetramethyl[1',3',2']dioxaborolan-2'-yl)ethyne (B2C2). We demonstrate the utility of B2C2 in the Suzuki-Miyaura polycondensation reaction, synthesizing a water-soluble poly(p-phenyleneethynylene) from [2,5-diiodo-1,4-bis(3-propoxy-sulfonicacid)benzene] sodium salt in neat water under an aerobic atmosphere.     

Host–:Guest Properties of the Aromatic Propellene 1,4- Bis(pyrazol-1'-yl)-2,3,5,6-tetrakis(3',5'-dimethylpyrazol-1'- yl)benzene

The structures of 1,4-bis(pyrazol-1'-yl)-2,3,5,6- tetrakis(3',5'-dimethylpyrazol-1'-yl) benzene 1, its monohydrate, 1a, four 1 : 2 host : guest complexes, 1b–1e (acetic, propionic, pentanoic, and (±)-2-methyl butyric acids) and a di-picrate salt, 1f, have been determined by X-Ray analysis. In all complexes, in the salt and in the monohydrate compound, the host molecules are hydrogen bonded to two centrosymmetric related guests and to the water molecule which is disordered over two positions to mimic the inclusion complexes. In all compounds, the host exhibits Ci symmetry having the lone pair on the N(2) atom of each pyrazole pointing alternately upwards (u) and downwards (d) from the benzene ring. 1H and 13C NMR spectra of the free host 1 and of the complexes are consistent with the ududud conformation and the stoicheiometry of the inclusion compounds.     

Reaction of 2- and 3-furylmethanephosphonates with esters

2- and 3-furylmethanephosphonates are acylated with ethyl formate, diethyl oxalate, and ethyl trifluoroacetate in toluene in the presence of sodium foil to afford five phosphorylated derivatives of furylacetic aldehyde, furylpyruvic acid, and 1,1,1-trifluoro-1-(2-furyl)propan-2-one. In a chloroform solution these compounds exist in the equilibrium with their enolic forms. When treated with sodium ethylate they form sodium salts which were isolated and characterized by ¹H, ¹³C, and ³¹P NMR spectroscopy. It was shown that in DMSO solutions sodium salts of formyl and oxalyl derivatives of 2-furylmethanephosphonate exist as mixtures of the carbanion and enolate forms. In the first case the carbanion form is predominant, while in the second one the enolate forms prevail. Sodium salt of formylated 3-furylmetanephosphonate exists only in the carbanion form, while the salt of 3-furylpyruvate is enolate. The alkylation of these salts with iodomethane proceeds at the carbon atom as well as at the oxygen one. First reaction pathway is often preferred.     

A simple and efficient method for synthesis of 5-substituted 2'-deoxyuridine nucleosides using metal-halogen exchange reaction of 5-iodo-2'-deoxyuridine sodium salt

Treatment of the sodium salt of 2'-deoxy-3', 5'-bis-O-(tert-butyldimethylsilyl)-5-iodouridine (3) with n-BuLi effected regioselective lithiation at the 5-position and the following reaction with various electrophiles afforded 5-substituted 2'-deoxyuridines including 1b, the precursor of stable spin-labeled 1a, in good yields.     

Studies on the constituents of Syringa species. XII. New glycosides from the leaves of Syringa reticulata (BLUME) HARA

Three new glycosides, 6'-O-alpha-D-galactopyranosylsyringopicroside (1), secologanoside 7-methyl ester (2) and (+)-lariciresinol 4'-O-beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranoside (3), were isolated from the leaves of Syringa reticulata. Their structures were established on the basis of chemical and spectral data. Compound 1 is the first naturally occurring iridoid di-glycoside having melibiose. Comparison of the spectral data of 2 and that previously recognized as secologanoside 7-methyl ester led to the conclusion that the recognized structure should be revised to the sodium salt of secoxyloganin (2').     

Cs+ and Ba2+ Selective Transport by a Novel Self-Assembled Isoguanosine Ionophore Through Polymer Inclusion and Bulk Liquid Membranes

5'-(Tert-butyldimethylsilyl)-2',3'-O-isopropylidene isoguanosine(isoG 1) serves as a selective Cs⁺ carrier in liquid membrane transport. IsoG~1 is a lipophilic nucleoside that self-assembles via hydrogen bonds and cation-dipole interactions to form a stable decamer sandwich complex with Cs⁺. Using an acidic receiving phase, Cs⁺ transport through polymer inclusion membranes (PIMs) was observed at concentrations of isoG 1 below 21 mM. When isoG 1 was precomplexed with Cs⁺ to give the (isoG 1)₁₀-Cs⁺decamer, flux was observed above 21 mM carrier. The Cs⁺ flux increased with increasing carrier concentration of the precomplexed (isoG 1)₁₀-Cs⁺ decamer. The Cs⁺ transport selectivity by isoG 1 was investigated in the presence of sodium salt solutions of high concentration. Excellent Cs⁺ flux and selectivity over the other alkali metal cations was observed in PIMs and bulk liquid membranes (BLMs). In the absence of Cs⁺, this ionophore exhibitsgood Ba²⁺ selectivity in BLMs.     

阴离子碳菁染料的合成与聚集动力学研究

自从1938年,Scheibe^[1]发现了菁染料聚集体中的能量传递现象,人们对菁染料的聚集行为展开了大量的研究^[2,3].由于菁染料聚集体对乳剂具有特殊的增感作用,人们主要研究聚集体在乳剂中的增感机理^[4,5]以及菁染料聚集的溶剂效应与浓度效应^[6]等,而对于菁染料聚集的动力学行为研究较少.     

Surface interaction and self-assembly of cyclodextrins with organic dyes

The interaction of seven novel substituted merocyanine dyes, i.e. 1-methyl-4-[2-(3-methoxy-4-hydroxyphenyl)ethenyl)]pyridinium iodide, 1-methyl-4-[2-(3,5-dimethoxy-4-hydroxyphenyl)ethenyl)]pyridinium iodide, 1-methyl-4-[2-(4-dimethylaminophenyl)ethenyl)]pyridinium iodide, their quinoide forms as well as 1-methyl-4-[2-(3-methoxy-4-oxocyclohexadienilydene)ethylidene]-1,4-dihydropyridine, 1-methyl-4-[2-(3,5-dimethoxy-4-oxocyclohexadienilydene)ethylidene]-1,4-dihydropyridine, with α-CD, γ-CD as well as functionalized γ-cyclodextrin phosphate sodium salt is studied by the methods such as UV–Vis and fluorescence spectroscopy, linear-polarized infrared (IR-LD) spectroscopy of oriented colloids in nematic host, ¹H- and ¹³C-NMR spectroscopy, HPLC ESI tandem mass spectrometry, scanning electron and tunneling microscopy, powder X-ray diffraction as well as thermal methods. A formation of the 1D and 2D “supramolecular polymers” with nanosizes is found. The dyes are adsorbed on the CDs surface and form a hexagonal microcrystalline sub-structures. Remarkable fluorescence properties depending of the type of the substituent in the dyes, in solid-state are observed.     

Synthesis of 2',3'-Didehydro-2',3'-dideoxynucleosides by Reaction of 5'-Protected Nucleoside 2',3'-Dimesylates with Telluride Dianion: A General Route from Cis Vicinal Diols to Olefins

2',3'-Dimesylates of 5'-protected nucleosides are converted into the corresponding 2',3'-didehydro-2',3'-dideoxy compounds by treatment with telluride dianion in the form of the sodium or lithium salt. The method is well-suited to the preparation of unsaturated nucleosides that can be converted into compounds that are believed to be useful in the treatment of AIDS. The deoxygenation is general for vicinal dimesylates that have, or may adopt, a synperiplanar conformation. With straight chain compounds the reaction is stereospecific. In some cases, similar, but slower, deoxygenations can be performed with selenide dianion.     

Intramolekulare Diels-Alder-Additionen in 6-(But-3-enyl)-6-methyl-cyclohexa-2,4-dien-1-on-Systemen; eine neue Synthese von Twistanderivaten

Alkylation of the sodium salt of mesitol with 2-bromomethyl-buta-1,3-diene ( 7 ) in benzene and subsequent refluxing of the reaction mixture gave 7% 2-methylene-3-butenyl-mesitylether ( 8 ), 12% 5-methylene-1,3,8-trimethyl-tricyclo[4,3,1,0^3,7]-8-decen-2-one ( 9 ) and 44% 9-methylene-1,3,5-trimethyl-tricyclo[4,4,0,0^3,8]-4-decen-2-one ( 10 ), a twistane derivative. The same procedure, when applied to the sodium salt of 2,6-dimethyl-4-methoxyphenol, gave in 73% yield a 26:18:54 mixture of 2,6-dimethyl-4-methoxyphenyl-(2-methylene-3-butenyl)-ether ( 11 ), 1,3-dimethyl-8-methoxy-5-methylene-tricyclo[4,3,1,0^{3, 7}]-8-decen-2-one ( 12 ), and 1,3-dimethyl-5-methoxy-9-methylene-tricyclo[4,4,0,0^{3, 8}]-4-decen-2-one ( 13 ). The tricyclic ketones 9 and 10 , or 12 and 13 , were also obtained on heating 8 or 11 respectively at 176° in decane solution. Alkylation of the sodium salt of 2,6-dimethylphenol with 3-butenylbromide in boiling toluene gave 1,3-dimethyl-tricyclo[4,3,1,0^3,7]-8-decen-2-one ( 17 ) as the only tricyclic product in 8% yield. The structures of the twistane derivatives 10 and 13 as well as those of the ketones 9, 12 and 17 were mainly deduced from spectroscopic data. Furthermore, the ketones 10 and 13 could be converted to the twistane derivatives 20 and 22 , possessing C₂-symmetry. On the other hand, compounds 9 and 17 gave only the asymmetric derivatives 18 and 21 .     

Dissociation constants of phosphoric acid at 25°C and the ion pairing of sodium with orthophosphate ligands at 25°C

The first and second acidity constants of phosphoric acid were determined in a 0.70 ionic strength solution of both a sodium and a potassium ion background salt at 25°C. These experimentally determined constants were compared to literature values as well as values calculated from a theoretical model. Assuming negligible ion pairing of the phosphate ligand with the potassium ions, the stability constants of the NaHPO ₄ ^- and NaH₂PO ₄ ⁰ complexes were determined to be 1.3±0.3 and 0.49±0.07 (mol-L^–1), respectively. These constants were used to model the speciation of orthophosphate in a background of a sodium salt from pH 3 to 10.     

Synthesis of N'-[4'-Benzo(15-Crown-5)]-4-Tolylaminoglyoxime and N'-[4'-Benzo(15-Crown-5)]-4-Chlorophenylaminoglyoxime and Their Complexes with Copper (II), Nickel (II) and Cobalt (II)

N'-[4'-benzo(15-crown-5)]-4-tolylaminoglyoxime (H₂L¹),the sodium chloride salt of H₂L¹ (H₂L¹...NaCl),N'-[4'-benzo(15-crown-5)]-4-chlorophenylaminoglyoxime(H₂L²) and the sodium chloride salt of H₂L² (H₂L²...NaCl)have been prepared from p-chlorophenylchloroglyoxime,p-tolylchloroglyoxime, 4'-aminobenzo[15-crown-5] and sodiumbicarbonate or sodium bicarbonate and sodium chloride. Nickel (II),cobalt (II) and copper (II) complexes of H₂L and H₂L...NaClhave a metal-ligand ratio of 1 : 2 and the ligand coordinatesthrough the two N atoms, as do most of the vic-dioximes. Their IR spectra and elemental analyses are given, together with¹H NMR spectra of the ligands.     

Dimethyl(2-oxo-2-ferrocenylethyl)sulfonium iodide—a useful synthetic equivalent of ferrocenoylcarbene in the synthesis of ferrocene-containing cyclopropanes

The reaction of 1-ferrocenyl-3-thiabutan-1-one with methyl iodide in acetonitrile at room temperature gave dimethyl(2-oxo-2-ferrocenylethyl)sulfonium iodide, which was characterized by spectral data (¹H NMR, ¹³C NMR, IR) and X-ray crystallographic analysis. This salt reacted with a base (sodium hydride) in acetonitrile yielding a stabilized ylide—dimethylsulfonium ferrocenoylmethylide, which was in turn, submitted to reactions with seven conjugated enones. The obtained results showed that this methodology is potentially a new and useful approach to ferrocene-containing cyclopropanes.     

Correlation between Thermodynamic Behavior and Structure in the Complexation of Modified β-Cyclodextrins and Bile Salts

Complex stability constants (K _S), standard molar enthalpy changes (ΔH ⁰) and entropy changes (ΔS ⁰) for the inclusion complexation of two cyclodextrin dimers, 6,6′-{2,2′-diselenobis[2-(benzoylamino)ethylamino]}-bridged bis(β-cyclodextrin) (1) and o-phenylenediseleno bridged bis(β-cyclodextrin)s (3), and their monomer analogs, 6-deoxy-6-{[2-(2,3-dihydro-3-oxo-1,2-benzisoselenazol-2-yl)ethyl]amino}-β-cyclodextrin (2) and mono[6-(phenylseleno)-6-deoxy]-β-cyclodextrin (4), with two bile salt guests, sodium cholate (CA) and sodium deoxycholate (DCA), were determined at 25°C in Tris buffer solutions (pH 7.4) at 298.15?K by means of isothermal titration microcalorimetry (ITC). The interactions and binding modes between the host cyclodextrins and the guest bile salts were further studied by ROESY spectroscopy. The thermodynamic parameters obtained, together with the ROESY spectra, were used to examine the correlations between thermodynamic behavior and binding modes of the host–guest complexation. The results indicate that the length, structure and conformation of the tethers linked to the cyclodextrins determine the binding modes and the binding abilities between hosts and guests to a great extent, leading to a reversion in binding ability when comparing the corresponding dimer and its monomer analog.     

Studies on silicic acid and its salts: XV. 29Si NMR study of sodium silicate in solution

The ²⁹Si NMR study of aqueous solution of sodium silicate of mole ratio SiO₂ to Na₂O equals one shows that the degree of polymerization of sodium silicate decreases with the decrease of the concentration, but the concentration of monosilicate anion increases, and that the lower the salt concentration, the faster is the rate of increase of the anionic concentration. The effect of SiO₂/Na₂O mole ratio and the concentration of sodium silicate on chemical shifts and spin-lattice relaxation time, T₁, of Si species and the effect of salt on degree of polymerization of sodium silicate in solution were also investigated.     

The short-term cycling properties of Na/PVdF/S battery at ambient temperature

The Na/PVdF/S cells were composed of solid sodium, sulfur, and polyvinylidene fluoride–hexafluoropropene (PVdF) gel polymer electrolyte. The PVdF polymer electrolyte was prepared form tetraglyme plasticizer and NaCF₃SO₃ salt, and its electrochemical properties were studied using CV and impedance analysis. The interfacial resistance between sodium and polymer electrolyte increase with storage time, which might be associated with passivation layer. Solid-state sodium/sulfur cell using a PVdF gel polymer electrolyte has been tested. The Na/PVdF/S cell with 0.288 mA cm^?2 shows a high discharge capacity of 392 mAh g^?1 and 36 mAh g^?1 after 20 cycles. The cycle performance of Na/GPE/S cell operating at 25 °C is worse than Na/S cell at a high temperature.     

Luminescence properties of three structures built from 3‐cyano‐4‐dicyanomethylene‐5‐oxo‐4,5‐dihydro‐1H‐pyrrol‐2‐olate and alkaline metals (Na,K and Rb)

The structures of three salts of 3‐cyano‐4‐dicyanomethylene‐5‐oxo‐4,5‐dihydro‐1H‐pyrrol‐2‐olate with alkali metals (Na, K and Rb) are related to their luminescence properties. The Rb salt, rubidium(I) 3‐cyano‐4‐dicyanomethylene‐5‐oxo‐4,5‐dihydro‐1H‐pyrrol‐2‐olate, Rb⁺·C₈HN₄O₂⁻, is isomorphous with the previously reported potassium salt. For the Na compound, sodium(I) 3‐cyano‐4‐dicyanomethylene‐5‐oxo‐4,5‐dihydro‐1H‐pyrrol‐2‐olate dihydrate, Na⁺·C₈HN₄O₂⁻·2H₂O, two independent sodium ions, located on inversion centers, are coordinated by four water molecules each and additionally by two cyano groups for one and two carbonyl groups for the other. The luminescence spectra in solution are unaffected by the nature of the cation but vary strongly with the dielectric constant of the solvent. In the solid state, the emission maxima vary with structural features; the redshift of the maximum luminescence varies inversely with the distance between the stacked anions.     

Sodium-tolerant matrix for matrix-assisted laser desorption/ionization mass spectrometry and post-source decay of oligonucleotides

A mixture of 2',4',6'-trihydroxyacetophenone in acetonitrile and aqueous triammonium citrate solution in a 1:1 molar proportion (0.2 M concentration) was found to be a good matrix for the detection of synthetic oligodeoxynucleotide samples. A high proportion of volatile solvent as well as the high salt content ensure fast co-crystallization of the matrix, co-matrix and analyte molecules. Matrix-assisted laser desorption/ionization (MALDI) mass spectra obtained in negative ion reflectron mode from samples prepared with this protocol show deprotonated molecules [M - H](-), rather than sodium adducts, as the most abundant ions even when up to 50 mM of sodium chloride is present in the sample. The matrix is shown to be effective for low mass modified single nucleotides as well as for longer oligodeoxynucleotides (up to 18mer). Post-source decay (PSD) mass spectra can also be obtained by increasing the laser fluence. Simple sequence information such as the identity and localization of a deleted base or the 5'/3' orientation can then easily be obtained. The calibration method and mass accuracy required are discussed depending on the type of information required.     

Composite host lattices of 4,4′‐sulfonyldibenzoate water/boric acid in two tetrapropylammonium inclusion compounds

Two novel inclusion compounds of 4,4′‐sulfonyldibenzoate anions and tetrapropylammonium cations with different ancillary molecules of water and boric acid, namely bis(tetrapropylammonium) 4,4′‐sulfonyldibenzoate dihydrate, 2C₁₂H₂₈N⁺·C₁₄H₈O₆S²⁻·H₂O ( 1 ), and bis(tetrapropylammonium) 4,4′‐sulfonyldibenzoate bis(boric acid), 2C₁₂H₂₈N⁺·C₁₄H₈O₆S²⁻·2H₃BO₃ ( 2 ), were prepared and characterized using single‐crystal X‐ray diffraction. In the two salts, the host 4,4′‐sulfonyldibenzoic acid molecules, which are converted to the corresponding anions under basic conditions, can be regarded as proton acceptors which link different proton donors of the ancillary molecules of water or boric acid. In this way, an isolated hydrogen‐bonded tetramer is constructed in salt 1 and a ribbon is constructed in salt 2 . The tetramers and ribbons are then packed in a repeating manner to generate various host frameworks, and the tetrapropylammonium guest counter‐ions are contained in the cavities of the host lattices to give the final stable crystal structures. In these two salts, although the host anion and guest cation are the same, the difference in the ancillary small molecules results in different structures, indicating the significance of ancillary molecules in the formation of crystal structures.     

Conformation and ortho steric effects in a series of 2-(pyrazol-1-yl)quinolines

Nine 2-(pyrazol-1-yl)-4-methylquinolines bearing substituents on the pyrazole 3- or 5-positions (H, Me, Et, i-Pr, t-Bu) were regioselectively synthesized either using the direct condensation of 2-chloro-4-methylquinoline and sodium salt of 3(5)-substituted pyrazoles or by treatment of 2-hydrazino-4-methylquinoline with an appropriate β-ketoaldehyde. The ¹H and ¹³C chemical shifts were discussed taking into account the preferred conformation about the C-2-N-1′ bond as calculated by the AM1 Hamiltonian. It appears that 5-ethyl and 5-isopropyl substituted derivatives present short C-H-N-1 interactions. Ortho steric effects appear to be responsible for these conformations.