Synthesis of spiroheterocycles derived from benzo[f]chromanone

The syntheses of an important class of hitherto unreported spiro derivatives containing benzo[f]chromanone moiety involving very simple cyclocondensation reactions are described. Installation of pharmacologically active moieties like thiazolidine and thiazolidinone is achieved by taking simple reagents like ethylchloroacetate, 1, 2‐dibromo ethane and thioglycollic acid. J. Heterocyclic Chem., (2011).     

An unusual extraction behavior of americium (III) and dioxouranium (VI) from picric acid medium using 18-crown-6 as neutral oxodonor

The extraction behavior of Am³⁺ and UO₂ ²⁺ is investigated employing chloroform solution of 18-crown-6 as the organic phase and picrate solution at pH 3.0 as the aqueous phase. In contrast to the commonly observed behavior, the extraction of Am³⁺ is preferred to that of UO₂ ²⁺. This unusual separation behavior is investigated as a function of several variable parameters such as crown ether concentration, picric acid concentration, inert electrolyte concentration, nature of diluent etc. Thermodynamic parameters are also evaluated.     

Extension of the Method of Quasilinearization and Rapid Convergence

An extension of the method of quasilinearization has been applied to first-order nonlinear initial-value problems (IVP for short). It has been shown that there exist monotone sequences which converge rapidly to the unique solution of IVP.     

Evidence for the decay D0-->K(-)pi(+)pi(-)e(+)nu(e)

Using a 281 pb{-1} data sample collected at the psi(3770) with the CLEO-c detector, we present the first absolute branching fraction measurement of the decay D0-->K(-)pi(+)pi(-)e(+)nu(e) at a statistical significance of about 4.0 standard deviations. We find 10 candidates consistent with the decay D0-->K(-)pi(+)pi(-)e(+)nu(e). The probability that a background fluctuation accounts for this signal is less than 4.1 x 10{-5}. We find B(D0-->K(-)pi(+)pi(-)e(+)nu(e)) = [2.8{-1.1}{+1.4}(stat)+/-0.3(syst)]x10{-4}. By restricting the invariant mass of the hadronic system to be consistent with K1(1270), we obtain the product of branching fractions B(D{0}-->K{1}{-}(1270)e{+}nu{e})xB(K1-(1270)-->K{-}pi{+}pi{-})=[2.5{-1.0}{+1.3}(stat)+/-0.2(syst)]x10{-4}. Using B(K1-(1270)-->K{-}pi{+}pi{-})=(33+/-3)%, we obtain B(D{0}-->K{1}{-}(1270)e{+}nu{e})=[7.6{-3.0}{+4.1}(stat)+/-0.6(syst)+/-0.7]x10{-4}. The last error accounts for the uncertainties in the measured K1-(1270)-->K{-}pi{+}pi{-} branching fractions.     

Inverse scattering problem with Levinson formula for eigenparameter-dependent discrete Sturm–Liouville equation

In this paper, an inverse scattering problem for discrete Sturm–Liouville equation with eigenparameter-dependent boundary condition is investigated. In quest of finding scattering function and the main equation of this problem, the uniqueness of the kernel is proven. Also, an appropriate Levinson-type formula based on the continuity of scattering function is given.     

Potential candidates for hyperhalogens: a comparative study of BO2, AlO2, and VO3 species

Recent work has shown that BO(2) which is a superhalogen with an electron affinity of 4.46 eV, can be used as building block of a new class of molecules/clusters whose electron affinities can exceed that of BO(2). This class of molecules was named hyperhalogens and the concept was illustrated by focusing on Au(BO(2))(2). Here we explore other superhalogens besides BO(2) to see if they too can be used to form hyperhalogens. We have chosen to focus on AlO(2) which is valence isoelectronic with BO(2) as well as VO(3) which involves a transition metal atom. The results obtained using density functional theory show unexpected behavior: Although AlO(2) and VO(3) are both superhalogens such as BO(2), only Na(BO(2))(2) is a hyperhalogen while Na(AlO(2))(2) and Na(VO(3))(2) are not. The origin of this anomalous result is traced to the large binding energy of the dimers of AlO(2) and VO(3).     

Chromatographic separation of carrier free 90Y from 90Sr using a diglycolamide based resin for possible pharmaceutical applications

N,N,N',N'-tetraoctyl diglycolamide (TODGA) has been used as the stationary phase in an extraction chromatography resin (XCR) material prepared for evaluating the uptake and the separation behaviour of (90)Y and (90)Sr from acidic feeds. Chromosorb-W was used as the solid support material while the feed solution was usually 4M HNO(3). The batch uptake studies have suggested almost no Sr(II) uptake while Y(III) uptake increased with acidity up to 4M HNO(3) beyond which a decrease in the K(d,w) values were observed. Column studies were carried out and breakthrough profiles were obtained for both Y(III) and Sr(II). No breakthrough of Y(III) was noticed even when >50 column volumes of the feed (carrier free (90)Y at 4 M HNO(3)) was passed through the column while about 20 column volumes were required for the breakthrough of Y(III) when the feed contained 1 g/L Y in 4 M HNO(3) spiked with (90)Y tracer. The reusability of the column was also studied which indicated in the deterioration of the column performance as shown by the sharp fall in the breakthrough volumes and was attributed to the probable leaching of the reagent from the support material. The role of absorbed dose was also investigated for Y(III) uptake. Separation of carrier free (90)Y tracer was carried out by loading the column with (90)Sr and eluting with 0.01M solutions of HNO(3) as well as EDTA. The purity of the product was ascertained by half-life method.     

Iodo-cyclizations: novel strategy for the total syntheses of polyrhacitide A and epi-cryptocaryolone

Highly stereoselective total syntheses of polyrhacitide A and epi-cryptocaryolone have been achieved in 11 steps with high overall yield of 24% and 28%, respectively, following a recently developed strategy for the construction of trans-2,6-disubstituted-3,4-dihydropyrans. In this report, the versatility of iodo-cyclization for the total syntheses of polyrhacitide A and epi-cryptocaryolone is demonstrated.     

Interactions of a Mn atom with halogen atoms and stability of its half-filled 3d-shell

Using density functional theory with hybrid exchange-correlation potential, we have calculated the geometrical and electronic structure, relative stability, and electron affinities of MnX(n) compounds (n = 1-6) formed by a Mn atom and halogen atoms X = F, Cl, and Br. Our objective is to examine the extent to which the Mn-X interactions are similar and to elucidate if/how the half-filled 3d-shell of a Mn atom participates in chemical bonding as the number of halogen atoms increases. While the highest oxidation number of the Mn atom in fluorides is considered to be +4, the maximum number of halogen atoms that can be chemically attached in the MnX(n)(-) anions is 6 for X = F, 5 for X = Cl, and 4 for X = Br. The MnCl(n) and MnBr(n) neutrals are superhalogens for n ≥ 3, while the superhalogen behavior of MnF(n) begins with n = 4. These results are explained to be due to the way different halogen atoms interact with the 3d electrons of Mn atom.