Synthesis of chalcone‐based fluorescent polymers: Diels‐Alder reaction of chalcones and their polymerization through ROMP

Ring opening metathesis polymerization (ROMP) was carried out on Diels‐Alder adducts formed from reactions between chalcones and cyclopentadiene. Most of the chalcones gave predominantly endo‐adducts and the exo‐adducts were obtained in good yields from reacting cyclopentadiene with furfurylidine acetone and N,N,diethylaminobenzylidine‐(4‐hydroxy)acetophenone. These exo‐adducts were subjected to ROMP using Grubbs catalyst, bis(tricyclohexylphosphine)benzylidinedichloride. The monomers and polymers were characterized using spectroscopic techniques like FT‐IR, ¹HNMR. The polymers were characterized using TGA, DSC, and GPC. The polymers were found to possess fluorescent properties and poly[2‐(4‐diethylamino)phenyl‐3,5‐divinylcyclopentyl](4‐hydroxyphenyl) methanone was found to have good emissive property at two wavelengths. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1521–1531, 2008     

Electronic transition-moment variation in the B 2ϵ+−X 2Пr system of the AsO molecule

The spectrum of AsO was excited in a quartz discharge tube and the relative band intensities were measured by using photographic photometry. It was found that the electronic transition moment varies as R_e(r) = constant x (1–0.575r) in the range $\text{1.46}\text{A}\text{?}\text{< r < 1.66}\text{A}\text{?}$. Smoothed relative band strengths are derived for the 11 bands.     

Influence of oxygen deficiency on the thermoelectric power of Y1Ba2Cu3O7-x

In this paper we report measurements of the thermoelectric power on a series of Y₁Ba₂Cu₃O_7-x specimens with varying amounts of oxygen deficiency obtained by changing the cooling rate of the sintered specimens. The specimens have been characterized by X-ray diffraction measurements, electric resistivity and oxygen contents. The temperature variation of the thermopower reveals a peak just before the onset of superconducting transition. We examine possible theoretical explanations of this anomaly. In particular we argue that this anomaly is associated with the pairing fluctuations in the normal state close toT _c . We present some theoretical results in support of this conclusion.     

The tilted-plate method for introducing carrier fringes of extension in Moiré interferometry

Experimental Techniques -     

A stereoconvergent synthesis of (+)-4-demethoxydaunomycin

Sharpless kinetic asymmetric epoxidation on (±)-2-(l-hydroxyethyl)-5,8-dimethoxy-3,4-dihydronaphthalene (8) followed by LAH reduction gave R-2-(S-l-hydroxyethyl)-2hydroxy-5,8-dimethoxy-1,2,3,4-tetrahydronaphthalene and the undesired antipode. The former was converted to R-(-)-2-acetyl-2 hydroxy-5,8-dimethoxy-l,2,3,4-tetrahydronapthalen[R-(-)-5],while the latter was epimerized and recycled. R-(-)-5 has been exploited for the synthesis of(+)-4-demethoxydaunomycin     

The reaction of cycloalkanonhydrazones with mercaptoacetic acid. Synthesis of novel N-aminospirothiazolidinones

Cycloalkanone hydrazones undergo condensation with mercaptoacetic acid to give predominantly the spirothiazolidinones. The structures of the products have been established on the basis of physico-chemical data. These compounds have shown promising antibacterial and antifungal activity.     

Modern preparation methods of oriented thick films of superconducting cuprates

Modern trends in the development of methods of manufacturing biaxially textured large-grained coatings ～ 100 μm thick based on superconducting rare-earth-barium cuprate elements, as well as bismuth-containing high-temperature superconductors, are considered. It is shown that the formation of a symmetric artificial surface relief makes it possible to control the mutual orientation of crystallites on polycrystalline metal substrates with high efficiency. In this case, the fraction of superconductor crystallites with an angle of mutual misorientation <5% may be as high as 75–90%. The high efficiency of this method of forming oriented films of multicomponent oxide phases indicates that it can be used to fabricate new-generation superconducting composite materials.     

Synergistic solvent extraction of cerium(III) with mixtures of thenoyltrifluoroacetone and dialkyl sulfoxides

Synergism in the extraction of Ce(III) from thiocyanate solutions has been investigated using mixtures of 2-thenoyltrifluoroacetone (HTTA) and bis-2-ethylhexyl sulfoxide (B2EHSO) or di-n-octyl sulfoxide (DOSO) in benzene. A very high synergistic enhancement of the order of 10⁵ has been observed. If a mixture of both dialkyl sulfoxides (B2EHSO+DOSO) is used, an additional synergistic effect is found due to the formation of a mixed, solvated complex when both reagents are added to the metal chelate. These extraction data have been analyzed theoretically with the aid of a computer by taking into account complexation of the metal in the aqueous phase by inorganic ligands and plausible complexation in the organic phase. The equilibrium constants of the various product species have been deduced by non-linear regression analysis.