Synthesis of 1,2-Diphenylpyrazolidin-4-ol and its Derivatives

Summary. A synthesis of 1,2-diphenylpyrazolidin-4-ol via direct heterocyclization of 1,2-diphenylhydrazine with 1-chloro-2,3-epoxypropane, its O-epoxypropyl-, O-ethyl-, and O-benzylderivatives are described. Novel hydrazone derivatives with pyrazolidine units were also synthesized. The compounds were characterized by spectroscopic methods as well as elemental analyses.     

Synthesis of highly textured superconducting NdBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7-<Emphasis Type="Italic">y</Emphasis></Subscript> thin films by two aqueous sol-gel dip coating techniques

Today, the deposition of coated conductors on a variety of substrates is often performed using a vacuum or low pressure technique. However, obtaining uninterrupted deposition at high speed, increasing flexibility in composition and attaining independence of geometric constraints of the substrates are areas in which vacuum techniques will need sustained development in order to answer industrial demands. The development of the next generation of deposition methods, based on deposition under atmospheric environment and from aqueous precursor solutions is a real challenge. This work describes the deposition of thin NdBa₂Cu₃O_7-y layers on SrTiO₃ single crystals based on a new sol-gel dip coating process using aqueous precursor solutions. Two inorganic aqueous sol-gel routes were investigated, a metal nitrate–citric acid based and a metal acetate–triethanol amine based solution. Using detailed thermal analysis, it is shown that adjusting the different parameters during thermal treatment can be used to control the morphology of the films. Also special attention is given to the microstructure of the thin film because of its relevance to the superconducting transport properties of the coated conductor system.     

Determination of 19-norandrosterone in CCQM-P68. NIST results using an isotope dilution liquid chromatography/tandem mass spectrometry method

The US National Institute of Standards and Technology (NIST) participated in an international interlaboratory study under the auspices of the Consultative Committee for Amount of Substance (CCQM) for the determination of 19-norandrosterone (19-NA) in urine, the principal metabolite of nandrolone and certain other synthetic testosterone substitutes banned for use by the World Antidoping Agency (WADA). Prior to this study, NIST developed a candidate reference measurement procedure based upon isotope dilution liquid chromatography/tandem mass spectrometry. This method was applied to a urine sample distributed to the participants in the study by the Australian National Measurement Institute, Pymble, Australia (NMIA). The NIST results were in very good agreement with those from the other participants, all of whom used methods based upon gas chromatography/mass spectrometry. All known significant sources of uncertainty were evaluated, resulting in a relative expanded uncertainty of less than 5% (coverage factor k = 2).     

Electrical Conductance Studies in Aqueous Solutions of Glutaric Acid,Disodium Glutarate and Sodium Hydrogen Glutarate

Conductivity measurements of glutaric acid and disodium glutarate in dilute aqueous solutions were performed in the 288.15 to 323.15 K temperature range. The limiting equivalent conductances of glutarate anions, λ ^o(HGlut⁻,T) and λ ^o(1/2Glut²⁻,T), and the dissociation constants of glutaric acid, K ₁(T) and K ₂(T), were derived by the use of the Onsager and the Quint and Viallard conductivity equations. The applied molecular model was successfully confirmed by analyzing the conductivities of sodium hydrogen glutarate at 298.15 K.     

Sphericities of Double Cosets,Double Coset Representations,and Fujita’s Proligand Method for Combinatorial Enumeration of Stereoisomers

The concepts of double coset representations and sphericities of double cosets are proposed to characterize stereoisomerism, where double cosets are classified into three types, i.e., homospheric double cosets, enantiospheric double cosets, or hemispheric double cosets. They determine modes of substitutions (i.e., chirality fittingness), where homospheric double cosets permit achiral ligands only; enantiospheric ones permit achiral ligands or enantiomeric pairs; and hemispheric ones permit achiral and chiral ligands. The sphericities of double cosets are linked to the sphericities of cycles which are ascribed to right coset representations. Thus, each cycle is assigned to the corresponding sphericity index (a _d , c _d , or b _d ) so as to construct a cycle indices with chirality fittingness (CI-CFs). The resulting CI-CFs are proved to be identical with CI-CFs introduced in Fujita’s proligand method (S. Fujita, Theor. Chem. Acc. 113 (2005) 73–79 and 80–86). The versatility of the CI-CFs in combinatorial enumeration of stereoisomers is demonstrated by using methane derivatives as examples, where the numbers of achiral plus chiral stereoisomers, those of achiral stereoisomers, and those of chiral stereoisomers are calculated separately by means of respective generating functions.     

Adsorption and structure formation of the weak polyelectrolytic diblock copolymer,PVP-<Emphasis Type="Italic">b</Emphasis>-PDMAEMA

This paper reports on the pH-dependent adsorption of weak the polyelectrolytic diblock copolymer poly(2-vinylpyridine)-block-poly(dimethylaminoethyl methacrylate), (PVP-b-PDMAEMA). Aqueous PVP-b-PDMAEMA solutions have been adsorbed on alkaline pretreated silicon substrates. Altogether two copolymers differing in block ratio and molecular weight were used for the investigations. While the electrical charge of both samples in solution was investigated by electrophoretic measurements, the adsorbed polymer layers were studied with ellipsometry and atomic force microscopy (AFM). Depending on pH the electrical charge of both blocks of the diblock copolymer varied. Three different regimes have been identified. Under acidic conditions at pH<5, both blocks are mainly positively charged. At medium pH between 5 and 8, only the PDMAEMA block is positively charged. At pH>8, both blocks are nearly uncharged and a polymer precipitation occurred in solution. Each of these pH regimes was characterized by a specific adsorption behaviour leading to two adsorption maxima at acidic and alkaline pH values, while at medium pH a plateau in the adsorbed amount was observed. Moreover, the structures of the polyelectrolytes formed on the substrate after adsorption were specific to each of the three pH regimes.     

Synthesis,structure, and thermal decomposition of a novel one-dimensional chain complex of manganese(II) with 2,2-diphenic acid and 1,10-phenanthroline

A novel one-dimensional (1D) chain coordination polymer [Mn₂(2,2′-dipha)₂(phen)]_n has been synthesized by hydrothermal reaction, and characterized by elemental analysis, IR spectroscopy, TGA, and X-ray diffraction. Orange crystals crystallized in the monoclinic system, space group C2/c with a = 19.393(7) Å, b = 19.183(7) Å, c = 19.729(7) Å, β = 90.826(6)°, V = 7338(5) ų, Z = 8. In the crystal structure, one manganese atom is six-coordinated with four carboxylate oxygen atoms from one pentadentate 2,2′-dipha ligand and two tetradentate 2,2′-dipha ligands, and with two nitrogen atoms of one phen ligand, giving a slightly distorted octahedral geometry. The other manganese atom is five-coordinated with five oxygen atoms from two tetradentate 2,2′-dipha ligands and two pentadentate 2,2′-dipha ligands and has a trigonal bipyramidal environment. The TGA curve shows that the compound is stable below 310°.     

Quantitative analysis of conformational exchange contributions to 1H-15N multiple-quantum relaxation using field-dependent measurements. Time scale and structural characterization of exchange in a calmodulin C-terminal domain mutant

Multiple-quantum spin relaxation is a sensitive probe for correlated conformational exchange dynamics on microsecond to millisecond time scales in biomolecules. We measured differential 1H-15N multiple-quantum relaxation rates for the backbone amide groups of the E140Q mutant of the C-terminal domain of calmodulin at three static magnetic field strengths. The differential multiple-quantum relaxation rates range between -88.7 and 92.7 s(-1), and the mean and standard deviation are 7.0 +/- 24 s(-1), at a static magnetic field strength of 14.1 T. Together with values of the 1H and 15N chemical shift anisotropies (CSA) determined separately, the field-dependent data enable separation of the different contributions from dipolar-dipolar, CSA-CSA, and conformational exchange cross-correlated relaxation mechanisms to the differential multiple-quantum relaxation rates. The procedure yields precise quantitative information on the dominant conformational exchange contributions observed in this protein. The field-dependent differences between double- and zero-quantum relaxation rates directly benchmark the rates of conformational exchange, showing that these are fast on the chemical shift time scale for the large majority of residues in the protein. Further analysis of the differential 1H-15N multiple-quantum relaxation rates using previously determined exchange rate constants and populations, obtained from 15N off-resonance rotating-frame relaxation data, enables extraction of the product of the chemical shift differences between the resonance frequencies of the 1H and 15N spins in the exchanging conformations, deltasigma(H)deltasigma(N). Thus, information on the 1H chemical shift differences is obtained, while circumventing complications associated with direct measurements of conformational exchange effects on 1H single-quantum coherences in nondeuterated proteins. The method significantly increases the information content available for structural interpretation of the conformational exchange process, partly because deltasigma(H)deltasigma(N) is a signed quantity, and partly because two chemical shifts are probed simultaneously. The present results support the hypothesis that the exchange in the calcium-loaded state of the E140Q mutant involves conformations similar to those of the wild-type apo (closed) and calcium-loaded (open) states.     

Swelling behavior of ionically cross-linked polyampholytic hydrogels in varied salt solutions

Ionically cross-linked polyampholytic hydrogels were synthesized by redox copolymerization of acrylamide and an ionic complex of (N,N-diethylamino)ethyl methacrylate and acrylic acid (designated as PADA hydrogel). The swelling behavior of the hydrogels in water indicated that a minimal equilibrium swelling ratio is found when the molar ratio of anionic/cationic monomers was 1.55. In NaCl solution, the hydrogels exhibited the typical swelling behavior of conventional polyampholytic gels. Their equilibrium swelling ratios increased with an increase in the NaCl concentration. In solutions of multivalent ions (CaCl₂ and trisodium citrate solutions), the equilibrium swelling ratios of the hydrogels increased first and were then followed by a decrease with an increase in salt concentration. Interestingly, an unexpected abrupt swelling phenomenon was observed when the fully swollen hydrogels in salt solution were transmitted to pure water. The unique swelling behavior of PADA hydrogels depends not only on the molar ratio of the anionic/cationic monomers but also on the valency of the ions.     

Bioaccumulation study of acrylates in algae (<Emphasis Type="Italic">Chlorella kessleri</Emphasis>) by Py-GC and Py-GC/MS

Acrylate monomers methylmethacrylate (MMA) and cyclohexylmethacrylate (CHMA) bioaccumulation has been determined in aquatic organism, algae (Chlorella kessleri). Algae were collected in amount of 0.4 mg and directly injected to the pyrolytical cell. In algae bodies accumulated monomers were analysed by pyrolysis gas chromatography (Py-GC) and pyrolysis gas chromatography coupled with mass spectrometry (Py-GC/MS). Traces of the accumulated monomers in algae body can be determined after 1-, 2-, 3-weeks of incubation. Maximum content of MMA was determined after 3-week of experiment, contrariwise in the case of CHMA after 2-week exposition. Relationship with pyrolysis temperature has also been studied.