Adsorption of Triton X-100 and cetyltrimethylammonium bromide mixture with ethanol at nylon-6–solution interface with regard to nylon-6 wettability: II. Work of adhesion and activity of surfactants at interfaces

On the basis of the values of the surface tension of the aqueous solutions of the Triton X-100 and CTAB mixture with ethanol, the surface tension of nylon-6 and the nylon-6–solution interfacial tension, the activity of the surfactant mixture and ethanol at the nylon-6–solution interface was calculated and compared to that at the solution–air one. For these calculations, the Sprow and Prausnitz equation was applied. The obtained values of the activity were used for the calculations of the work of adhesion of the solution to the polymer surface. The values of the work of adhesion obtained in this way were compared to those determined from the Young–Dupre equation by using the contact angle values of the aqueous solutions of the TX-100 and CTAB mixture with ethanol measured on the nylon-6 surface. The changes of the work of adhesion determined from the Young–Dupre equation were also considered as a function of the surface tension of the solution, its polar component and the interfacial interaction parameter.     

Studies on the Reaction of Substituted 6-Nitrocoumarin with Anilines

Greatat'tentionhasbeenpaidtocoumarinsfortheirmulti-activityagainstseveraldiseasessuchascancer,AIDS.Inordertoobtainsomemoreeffectiveanti-tumorcompounds,wedesignedaseriesofcoumarinderivativeswithanovelretinoidsstructure.WhenweattemptedtosynthesisaSchiffbaseofnitrosubstituted3-acetylcoumarins,however,itissurprisinglyfoundthatanewreactionoccurredandasmallersizedSchiffbasewasobtained.'H-NMR,"C-NMR,MSandelementalanalysisshowedthatthenewcompoundwasaheterocyclicringfissionproductI(Schemel).Othe…     

Enhanced β phase of polyvinylidene fluoride with addition of polyamide 6: role of interfacial interactions

In this study, the polymer blends composed of polyvinylidene fluoride (PVDF) and polyamide 6 (PA6) were prepared via precipitation method, and then, the effects of PA6 on the crystallization behavior of PVDF, including the polymorphism and crystallization kinetice, were systematically investigated. For this aim, time-resolved Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimeter were utilized to study the influence of PA6 on crystallization behavior of PVDF. Furthermore, the morphologic images from scanning electron microscopy also supply the corresponding evidences. The results obtained shows that PA6 is immiscible with PVDF, while the PA6 component could form polar environment around the PVDF segment which is conducive to the formation of β phase of PVDF. In addition, calorimetric studies via DSC on the non-isothermal crystallization behavior and non-isothermal crystallization kinetics demonstrated conclusively that PA6 segments could effectively hinder the subsequent PVDF crystallization process because of the interfacial hydrogen bonds and incompatibility between PVDF and PA6.     

SrIrIn6 – An Intergrowth of SrIrIn4 with Indium Slabs

The indium-rich intermetallic compound SrIrIn₆ was synthesized from the elements in a sealed tantalum ampoule at 1173 K, followed by slow cooling for crystal growth. SrIrIn₆ crystallizes with a new structure type which was characterized by X-ray powder and single crystal diffraction: Pmma, a = 852.34(2), b = 434.54(5), c = 1059.18(6) pm, wR₂ = 0.0178, 884 F² values, and 32 variables. The SrIrIn₆ structure shows two basic building units: (i) Ir@In₉ tricapped trigonal prisms (261–292 pm Ir–In) and (ii) distorted bcc In@In₈ cubes (301 to 329 pm In–In). The strontium cations fill cages within the complex three-dimensional [IrIn₆] network and have coordination number 13 (Sr@In₁₃) in form of a tricapped pentagonal prism. The SrIrIn₆ structure can be described as a simple intergrowth variant of SrIrIn₄ (LaCoAl₄ type) with indium slabs. The crystal chemical similarities with the structures of SrIrIn₄, SrIr₂In₈ and Eu₃Ir₂In₁₅ are discussed.     

Crystal Structure of Borophosphate with 6_1 Screw Axis Helices

1 INTRODUCTION Most materials with nonlinear optical pro- perties and electro-optical applications are either borates or phosphates. LBO(LiB3O5), KTP(KtiO- PO4), BBO(b-BaB2O4) and KDP(KH2PO4) are well- known commercially and extensively used for different optical elements. In recent years, the compounds combined both borate and phosphate groups have been synthesized and structurally characterized with quite different anionic partial structures. In particular, the use of hydrot…     

Reactions of 3а,6a-diaza-1,4-diphosphapentalene with activated acetylenes

The reaction of cyclohexane-annulated 3 a,6a-diaza-1,4-diphosphapentalene (DDP) with di-tert-butyl acetylenedicarboxylate (DBAD) affords the 1,3-dipolar cycloaddition product of the acetylene moiety to the phosphorus and sp²-carbon atoms of DDP in 90% yield. No individual products were isolated in the reaction of DDP with dimethyl acetylenedicarboxylate (DMAD). In the three-component DDP–DMAD–carbazole system (1: 2: 1), a product was generated in 73% yield via successive reactions, including the 1(P),3(C)-dipolar cycloaddition of DMAD to DDP, the addition of the second equivalent of DMAD to the three-coordinate phosphorus atom of the intermediate, and the NH addition of carbazole at the unsaturated C=C bond of the second DMAD moiety. The structures of the reaction products were established by X-ray diffraction.     

A Conformational Study on the Interaction of Saporin-S6 with Phospholipid Vesicles

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Coordination polymers of zinc with (η6-benzenecarboxylate) chromium tricarbonyl

Different coordination polymers were obtained by the reaction of (benzoic acid) chromium tricarbonyl with zinc acetate in the presence of various organic dipyridyl linkers. Depending on the nature of the linker either monomeric or polymeric compounds were obtained. Reactions of (benzoic acid) chromium tricarbonyl with zinc acetate and bidentate pyridine based ligands 4,4'-bipyridine (4,4'-bipy), 1,2-bis(4-pyridyl)ethane (bpe), 1,3-bis(4-pyridyl)propane (tmdp), and 2,2'dipyridylamine (DPA) afforded the novel coordination polymers [Zn[{η(6)-C(6)H(5)COO}Cr(CO)(3)](2)(4,4'-bipy)](n), [Zn[{η(6)-C(6)H(5)COO}Cr(CO)(3)](2)(bpe)](n), [Zn[{η(6)-C(6)H(5)COO}Cr(CO)(3)](2)(tmdp)}](n), and the monomeric complex [Zn[{η(6)-C(6)H(5)COO}Cr(CO)(3)](2)(DPA)]. The solid state structures of all compounds were determined by single crystal X-ray diffraction. By using 1,3-bis(4-pyridyl)propane as a linker a chiral infinite helical structure was formed in the solid state. Thermogravimetric analysis (TGA) studies showed that upon heating the carbonyl groups of the {η(6)-C(6)H(5)COO}Cr(CO)(3) anion were lost before the organic ligand sphere was thermally decomposed.     

Reaction of Cytisine with 4″-Substituted Dibenzo-18-crown-6 Sulfonylchlorides

Sulfamides were synthesized via the reaction of cytisine with 4,4(5)-dibenzo-18-crown-6-disulfonyl-, 4-sec-butyl-4(5)-dibenzo-18-crown-6-sulfonyl-, and 4-acetyl-4(5)-dibenzo-18-crown-6-sulfonylchlorides. The structures of the prepared compounds were confirmed by PMR.     

Classification of heavy-metal fluorides. Fluorides with cation arrangement ofβ-K2UF6 type

Cation arrangement in some complex fluoride structures with U⁴⁺, Th⁴⁺, and Zr⁴⁺ dgering in composition, symmetry, and unit cell parameters is analyzed. In all structures investigated, we have isolated (using the CAS-PAN technique) a common structural fragment: planar close-packed cation nets (3³4² + 3⁶) characteristic of the high-symmetry -K₂UF₆ structure chosen as the standard. The whole set of close-filled cation planes is described. A cation-anion fragment — columns or ribbons of high-valent cation polyhedra — has been isolated which determines the main structural peculiarities.Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Institute of Crystallography, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 5, pp. 126–132, September–October, 1993.Translated by T. Yudanova     

Crystal and Molecular Structure of an Inclusion Complex of p-tert-Butylcalix[6]arene with Toluene

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The Studies of the Reactions of 2, 4, 6-Triphenylpyrylium Tetrafluoroborate with Amino Acids

The reactions of triphenylpyrylium salt 1 with various amino acids were explored and compared. The reactions with most α-amino acids yielded decarboxylation products 2 viadecarboxylation. The reactions with glutamic acid, lysine and ACC (1-aminocyclopropyl-carboxylic acid) gave triphenylpyridine 8, dimer 9 and acid 5a-ace, respectively. The reactionswith β and γ-amino acids yielded triphenylpyridine by intramolecular elimination.     

Synthesize of 2, 6-Di-O-acetyl Sucrose by Regioselective Acetylation with Dibutyltin Oxide

2,6-Di-O-acetyl sucrose was regioselective synthesized by using dibutyltin oxide in about 60% yield. The structure of acetyl derivative was elucidated by ^1H NMR, ^13C NMR,2D-NMR and MS spectral data.     

Crystalline Morphology and Crystallization Characteristics of In-situ Blends of Anionic Polyamide 6 with Noncrystallizable Semiaromatic Polyamide Copolymer

A noncrystallizable semiaromatic polyamide copolymer(NSAP) was dissolved in molten caprolactam, and PA6/NSAP blends were produced in-situ via the anionic ring-opening polymerization of caprolactam. The presence of a single loss tangent(tanδ) peak measured by means of dynamic mechanical analysis(DMA) proves the miscibility between PA6 and NSAP in the blends. It was found that there existed drastic changes in the crystallographic form and crystallization kinetics for the in-situ blends, e.g., when 20% NSAP was added, nearly all crystallites existed in the γ form and the crystallization could hardly occur upon cooling even at a rate of 2.5 ℃/min. Moreover, cold crystallization appears during the subsequent heating, and its melting point is 40 ℃ lower than that of the virgin system. On the other hand, the size of the spherulites only decreases modestly. It is suggested that the introduction of irregular stiff segments originated from NSAP into PA6 macromolecule chain, which resulted from transamidation during the polymerization play a dominant role in the drastic change of crystallization kinetics and the resultant morphology of the in-situ blends.     

Spectroscopic investigation of interaction of 6-methoxyflavanone and its β-cyclodextrin inclusion complex with calf thymus DNA

The interaction of 6-methoxyflavanone (6MF, 6-methoxy-2-phenyl-4H-1-benzopyran-4-one) with calf thymus DNA (ctDNA) was investigated by absorption spectroscopy, fluorescence spectroscopy, and cyclic voltammetry in the presence and absence of ??-cyclodextrin (??-CD) acting as capping agent. Molecular modelling was used to optimise the study of 6MF-??-CD and 6MF-DNA interactions. Enhancement in the fluorescence intensity of 6MF was observed due to the formation of 1 : 1 complex with ??-CD. In the presence and absence of DNA, 6MF showed different characteristics such as hyperchromic effect, red shift of absorption spectra and fluorescence quenching of 6MF due to binding between 6MF and ctDNA. The nature of the binding group was found to be different for the 6MF-ctDNA and 6MF-ctDNA-??-CD systems. An increase in fluorescence intensity was observed for the 6MF-ctDNA system while varying the concentration of ??-CD due to encapsulation of a part of 6MF in cyclodextrin. The results are compatible with the possibility of the interaction of dihydrobenzopyran-4-one moiety of 6MF with ctDNA as well as with ??-CD. Cyclic voltammetric studies confirmed the binding interaction between 6MF and ctDNA in the absence and presence of ??-CD and molecular modelling explains the site of the interaction of 6MF with cyclodextrin and ctDNA.     

Complexation of 6-Deoxy-6-(aminoethyl)amino-β-cyclodextrin with Sodium Cholate and Sodium Deoxycholate

In order to study its guest binding and the inclusion phenomena, 6-deoxy-6-(aminoethyl)amino--cyclodextrin (CDN) was synthesised and its binding properties examined. The complexation phenomena of sodium cholate (NaC) and sodium deoxycholate (NaDC) with CDN has been monitored by the NMR method using ¹³C chemical shift data. The method of continuous variation Job's method has been used to determine the stoichiometry of these supramolecular complexes. The Job's plot confirms the 1 : 1 supramolecular complex for NaC: CDN and the 1 : 2 supramolecular complex for NaDC: CDN. The interaction of NaC and NaDC with CDN has been obtained through two-dimensional Rotational Nuclear Overhauser Effect Spectroscopy (ROESY) NMR. Equilibrium constants were also obtained from ¹³C chemical shift data (C-1, C-3 & C-4) at different pH values (7, 9, & 11).     

Conjugates of polyhedral boron compounds with carbohydrates 6. Synthesis of glycoconjugates of closo-ortho-carborane with β-lactosylamine and β-d-galactopyranosylamine derivatives as galectin bi- and trivalent ligands

Five glycoconjugates were obtained from ortho-carboranylacetic acid and β-actosylamine or β-d-galactopyranosylamine derivatives with the terminal amino group in the spacer. The glycoconjugates have different lengths of the spacer (9 to 15 atoms) and contain two or three βlactosylamine residues or one, two, or three β-d-galactopyranosylamine residues.     

An alternate method of treating competition kinetics: reaction of OH radical with IrBr3−6

Carbonate competition is often used to indirectly measure rates of OH reactions by pulse radiolysis. The product CO⁻₃ ion has an optical absorption maximum near 600 nm with a conveniently large extinction coefficient. The standard data treatment, which involves a reciprocal concentration plot, works well provided the reaction is complete at the time of measurement, and the pulse size is reproducible. An alternate method, referred to as ‘elimination of time as independent variable’, is based on a treatment given in Benson’s Foundations of Chemical Kinetics. This method, which involves a log–log plot of the reactant concentrations rather than a reciprocal plot, will be described and compared to the standard method. We are currently using a Febetron 706 to study several reactions of iridium halide complexes, in particular a reaction in which OH oxidizes IrBr³⁻₆ to the −2 ion, for which k=1.4×10⁹ M⁻¹ s⁻¹ was found using either the standard or the alternate competition method.     

Metal complexes of phytohormones. Part IV. Interactions of tetrakis-μ-acetato dirhodium(II) with 6-furfurilaminopurine, 6-benzylaminopurine, 6-furfurilaminopurine riboside and 6-benzylaminopurine riboside

Summary Interactions of tetrakis--acetato-dirhodium(II) with purine-derived ligands of biological interest such as the cytokinins 6-furfurilaminopurine (K), 6-benzylaminopurine (BAP), 6-furfurilaminopurine riboside (KR) and 6-benzylaminopurine riboside (BAPR) have been studied by means of magnetic susceptibility measurements at room temperature, i.r. and electronic spectroscopy and thermogravimetric analysis 11 metal:ligand adducts were obtained with all ligands; in addition 12 adducts were obtained with KR and BAPR. The most plausible structure for the 11 adducts is a polymeric bridging one, involving both axial positions of the Rh^II dimer and two N-sites of the purine moiety; for the 12 adducts only one N-site is involved.