Synthesis and spectroscopic characterization of aryloxide derivatives of titanium(IV) and zirconium(IV)

Homo- and heteroleptic aryloxides of the type MX_4–x(OAr)_x [M = Ti^IV, Zr^IV; X = OPrⁱ, Cl; x = 1,2,3,4; OAr = OC₆H₄Prⁱ-4(OAr¹), OC₆H₃Me-2-Prⁱ-5(OAr²), OC₆H₃Me-5-Prⁱ-2(OAr³), OC₆H₂Me₃-2,4,6(OAr⁴), OC₆H₃Bu^t₂-2,4(OAr⁵), OC₆H₃Bu^t₂-2,6(OAr⁶)] have been prepared either by alkoxo–aryloxo or chloro-aryloxo exchange reactions in benzene or tetrahydrofuran. All these new derivatives have been characterized by elemental analyses, spectroscopic (i.r., ¹H-, ¹³C-n.m.r.) studies and molecular weight measurements. The FAB mass spectral studies of four representative derivatives Support a dimeric nature for [Ti(OC₆H₃Me-5-Prⁱ-2)₄], [TiCl₂(OC₆H₃Me-5-Prⁱ-2)₂], and [Zr(OC₆H₃Bu^t₂-2,4)₄(thf)], whereas the derivative [ZrCl(OC₆H₃Bu^t₂-2,4)₃(thf)] is monomeric.     

Effect of pretreatment of molasses and posttreatment of fermented broth in industrial production of ethanol

The aim of preclarification is to minimize sludge going to yeast separators. This purpose is partially fulfilled. However, it has been measured during the plant trial runs that preclarification does not noticeably improve fermentation. The aim of postclarification is to minimize sludge going to distillation. This purpose is well served as noted from the fact that cycle run of distillation columns using postclarification is three times longer (9–12 mo) as compared to the normal one (3–4 mo).     

Concise Stereoselective Total Synthesis of (4R, 6R)-Lactone Moiety Analog of Mevinoline and Compactin

A simple and highly efficient synthetic route has been developed for analogue of HMGCo A reductase inhibitor (1). The strategy utilizes S-Corey–Bakshi–Shibata (CBS) reduction, FeCl₃-catalyzed C-H insertion of ethyl diazoacetate.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]     

Cobalt(II)–metformin complexes containing α‐diimine/α‐diamine as auxiliary ligand: DNA binding properties

The cobalt(II) complexes [Co(Cl)₂(met)(o‐phen)] ( 1 ), [Co(Cl)₂(en)(met)] ( 2 ) and [Co(Cl)₂(met)(opda)] ( 3 ) (met = metformin, o‐phen = ortho‐phenanthroline, en = ethylenediamine, opda = ortho‐phenylenediamine) were synthesized and characterized using liquid chromatography–mass spectrometry, elemental analysis, molar conductance measurements, thermal analysis, infrared spectroscopy, magnetic moment measurements, electronic spectroscopy and X‐ray diffraction. The metal centre was found to be in an octahedral geometry. UV–visible absorption, fluorescence and viscosity measurements were conducted to assess the interaction of the complexes with calf thymus DNA. The complexes showed absorption hyperchromism in UV–visible spectra with DNA. The binding constants from UV–visible absorption studies were 1.38 × 10⁵, 2.1 × 10⁵ and 3.1 × 10⁵ M^?1 for 1 , 2 and 3 , respectively, and Stern–Volmer quenching constants from fluorescence studies were 0.146, 0.176 and 0.475, respectively. Viscosity measurements revealed that the binding of the complexes with DNA could be surface binding, mainly due to groove binding. The activities of the complexes in DNA cleavage decrease in the order 3 > 2 > 1 . The complexes were docked into DNA topoisomerase II using Discovery Studio 2.1 software.     

Dimethyl selenide complexes of copper,gallium and indium halides as potential precursors for selenium-containing chalcopyrite semiconducting materials

The coordination chemistry of copper, gallium and indium halides with the simplest possible selenoether i.e. Me₂Se was investigated with the aim to use the resulting complexes as precursors for selenium-containing chalcopyrite semiconducting materials. An optimized general procedure for the high yield synthesis is described and the influence of a halide ion on the structure and solubility of these metal halide dimethyl selenide complexes are discussed. These complexes were characterized by the elemental analysis, FT-IR and ¹H NMR spectroscopy as well as single crystal X-ray structures, the later study showing them to be monomeric for gallium halides, mono- or dimeric for indium halides and either an ion-pairs or 2-D extended structure in the case of copper halides.     

HPLC quantification of the HIV-1 protease inhibitor saquinavir in brain and testis of mice

A rapid, reliable HPLC method with UV detection (240 nm) was developed and validated for quantitation of saquinavir in mice brain and testis. Saquinavir and the internal standard were isolated from homogenized tissue matrices using liquid-liquid extraction procedure and were then analyzed using an isocratic mobile phase by reversed-phase liquid chromatography. The lower limit of quantification was 50 ng/g for both brain and testis. A linear dynamic range of 50-5000 ng/g for both brain and testis was established. This HPLC method was validated with between-batch precision of 0.5-4.4 and 1.5-5.5% for brain and testis, respectively. The between-batch accuracy was 94.7-105.9% and 97.5-105.0% for brain and testis, respectively. The present method was applied for tissue distribution studies of the novel drug delivery systems of saquinavir in mice.     

First total synthesis of (+)-crassalactone A

A simple and highly efficient first total synthesis of cytotoxic (+)-crassalactone A starting from (R)-mandelic acid is described. The strategy involves the osmium tetroxide-catalyzed cis-hydroxylation and the stereoselective addition of ethyl lithiopropiolate to a chiral aldehyde intermediate as key steps.     

A Novel Redundant Binary Number to Natural Binary Number Converter

Redundant binary number appears to be appropriate for high-speed arithmetic operation, but the delay and hardware cost associated with the conversion from redundant binary (RB) to natural binary (NB) number is still a challenging task. In the present investigation a simple approach has been adopted to achieve high speed with lesser hardware and power saving. A circuit level approach has been adopted to implement the equivalent bit conversion algorithm (EBCA) (Kim et al. IEEE Journal of Solid State Circuits 36:1538-1544, 2001, 38:159-160, 2003) for RB to NB conversion. The circuit is designed based on exploration of predictable carry out feature of EBCA algorithm. This implementation concludes a significant delay power product and component complexity advantage for a 64-bit RB to NB conversion using novel carry-look-ahead equivalent bit converter.     

Incoherently coupled two component screening photovoltaic solitons in two-photon photorefractive materials under the action of external field

The existence of incoherently coupled two-component steady state photovoltaic solitons in biased two-photon photorefractive materials due to two-photon photorefractive effect has been investigated. In the steady state regime, these incoherently coupled solitons can propagate in bright–bright, dark–dark and bright–dark configurations. The most important finding is that, with the application of electric field, it is possible to generate solitons and control them in those media where soliton formation was hitherto prohibited. Dynamic evolution of these solitons has been examined using numerical simulations, which show that these solitons are stable.