Synthesis and Characterization of Donor–π‐Acceptor‐Based Porphyrin Sensitizers: Potential Application of Dye‐Sensitized Solar Cells

New porphyrin sensitizers based on donor–π‐acceptor (D‐π‐A) approach have been designed, synthesized, characterized by various spectroscopic techniques and their photovoltaic properties explored. N,N′‐Diphenylamine acts as donor, the porphyrin is the π‐spacer, and either carboxylic acid or cyanoacryclic acid acts as acceptor. All compounds were characterized by using ¹H NMR spectroscopy, ESI‐MS, UV–visible emission spectroscopies as well as electrochemical methods. The presence of aromatic groups between porphyrin π‐plane and acceptor group push the absorption of both Soret and Q‐bands of porphyrin towards the red region. The electrochemical properties suggests that LUMO of these sensitizers above the TiO₂ conduction band. Finally, the device was fabricated using liquid redox electrolyte (I^?/I₃^?) and its efficiency was compared with that of a leading sensitizer.     

Enantioselective synthesis of (S)-homocitric acid lactone and (R)-per-homocitric acid lactone involving organocatalysis

A concise enantioselective synthesis of (S)-homocitric acid lactone and its homolog, via an organocatalytic vinylogous Mukaiyama–Michael reaction of a silyloxy furan derivative and acrolein, is described.     

Dioxouranium(VI) and oxouranium(IV) fluorosulphates and double fluorosulphates of uranium(IV)

UO₂(SO₃F)₂, UO(SO₃F)₂, U(SO₃F)₄ and MU(SO₃F)₆, MMg, Zn have been prepared by reacting UO₂(O₂CCH₃)₂, U(O₂CCH₃)₄, U(O₂CCF₃)₄ and MU(O₂CCH₃)₆ with HSO₃F. The analysis of i.r. spectral data of UO₂(SO₃F)₂, UO(SO₃F)₂ and MU(SO₃F)₆ shows the presence of only one type of SO₃F group with reduced symmetry C_s. In U(SO₃F)₄, two SO₃F groups are bidentate, while the other two are monodentate. A sharp band at 925 cm^?1 in UO₂(SO₃F)₂ is diagnostic of UO₂²⁺. The diffuse reflectance spectra of UO(SO₃F)₂, U(SO₃F)₄ and MU(SO₃F)₆ reveal hexacoordination of U(IV), while the magnetic moments of these compounds support the existence of U(IV). UO₂(SO₃F)₂ and UO(SO₃F)₂ decompose thermally in a single step with the evolution of SO₂F₂ and formation of their respective sulphates.     

Preparation,Characterization and Applications of Electron-Beam Curing-Derived Monolithic Materials

Summary: Acrylate/methacrylate-based monoliths have been prepared via electron- beam (EB) initiated polymerization. These monolithic columns were found suitable for application in the analytical scale separation of various analytes such as proteins. Functionalization of the monolithic columns was accomplished via copolymerization of functional monomers. Selected examples of both synthesis and application will be summarized.     

Electron beam triggered, free radical polymerization-derived monolithic capillary columns for high-performance liquid chromatography

Monolithic capillary columns were prepared via electron beam triggered free radical polymerization within the confines of 0.2 and 0.1mm I.D. capillary columns using ethyl methacrylate and trimethylolpropane triacrylate as monomers as well as 2-propanol, 1-dodecanol and toluene as porogenic system. The influence of column diameter on reproducibility and separation performance was investigated. For evaluation, a protein standard consisting of five proteins in the range of 5800-66,000 g mol(-1) was used. Reproducibility was checked by determining the relative standard deviations in retention times, peak widths at half height, asymmetry and resolution. Excellent run-to-run reproducibility was found for both 0.2 and 0.1mm I.D. columns; batch-to-batch reproducibility was good for both column types. In order to enhance the non-polar character of the monolithic columns, lauryl methacrylate-based capillary columns were prepared. These were successfully used for the separation of proteins and a cytochrome c digest.     

Cu-mediated 1,3-dipolar cycloaddition of azomethine ylides with dipolarophiles: a faster access to spirooxindoles of potential pharmacological interest

CuI facilitated three-component reaction of isatin derivatives, l-proline and terminal alkynes containing an amide or ester functional group. The multi-component reaction (MCR) afforded a faster and practical synthesis of spirooxindole derivatives. A range of novel spirooxindoles were synthesized by using this straightforward and one-pot efficient methodology. A representative compound showed significant inhibition of PDE4B enzyme in vitro and good interactions with this protein in silico.     

Chemical Synthesis and Immunological Evaluation of a Pentasaccharide Bearing Multiple Rare Sugars as a Potential Anti‐pertussis Vaccine

With the infection rate of Bordetella pertussis at a 60‐year high, there is an urgent need for new anti‐pertussis vaccines. The lipopolysaccharide (LPS) of B. pertussis is an attractive antigen for vaccine development. With the presence of multiple rare sugars and unusual glycosyl linkages, the B. pertussis LPS is a highly challenging synthetic target. In this work, aided by molecular dynamics simulation and modeling, a pertussis‐LPS‐like pentasaccharide was chemically synthesized for the first time. The pentasaccharide was conjugated with a powerful carrier, bacteriophage Qβ, as a vaccine candidate. Immunization of mice with the conjugate induced robust anti‐glycan IgG responses with IgG titers reaching several million enzyme‐linked immunosorbent assay (ELISA) units. The antibodies generated were long lasting and boostable and could recognize multiple clinical strains of B. pertussis, highlighting the potential of Qβ‐glycan as a new anti‐pertussis vaccine.     

Sunitinib LC–MS/MS Assay in Mouse Plasma and Brain Tissue: Application in CNS Distribution Studies

Sunitinib malate is a multi-targeted tyrosine-kinase inhibitor, currently in clinical trials for glioma. Previously developed methods for preclinical studies in species such as mice have either employed high-performance liquid chromatography (HPLC) or did not describe a detailed analytical method, which could be employed by other preclinical laboratories. In this paper, we have developed and validated a simple, sensitive high-performance liquid chromatography tandem mass-spectrometric method (LC–MS/MS) for the determination of sunitinib concentration in mouse plasma and brain tissue homogenate using dasatinib-free base as the internal standard. A single step liquid–liquid extraction method was used for both the matrices. Since sunitinib exhibits light-induced E/Z isomerism, all sample preparation was done in light-protected conditions. Separation was performed on a ZORBAX Eclipse XDB C18 column 4.6 × 50 mm, 1.8 μm. The mobile phase consisted of 20 mM ammonium formate (with 0.1 % formic acid): acetonitrile (70:30, v/v) pumped isocratically at a flow rate of 0.25 mL min^?1 with a total run-time of 13 min. The retention times of sunitinib and dasatinib were 7.8 and 5.5 min, respectively. The calibration curve was linear over the range from 1.95 to 500 ng mL^?1 in both plasma and brain tissue homogenate with 1.95 ng mL^?1 as the lower limit of quantification (LLOQ) for both the matrices. Inter- and intra-day accuracy and precision was <15 % for low QC, med QC and high QC and <20 % for LLOQ. The method was applied to a pharmacokinetic study in FVB wild-type mice to determine the plasma and brain concentrations after a single oral sunitinib malate dose of 20 mg kg^?1.     

Efficient Catalytic Activity of Transition Metal Ions in Vilsmeier–Haack Reactions with Acetophenones

Vilsmeier–Haack (VH) formylation reactions with acetophenones are sluggish in acetonitrile medium even at elevated temperatures. However, millimolar concentrations of transition metal ions such as Cu(II), Ni(II), Co(II), and Cd(II) were found to exhibit efficient catalytic activity in Vilsmeier–Haack Reactions with acetophenones. Reactions are accelerated remarkably in the presence of transition metal ions. The VH reactions followed second order kinetics and afforded acetyl derivatives under kinetic conditions also irrespective of the nature of oxychloride (POCl₃ or SOCl₂) used for the preparation of VH reagent along with DMF. On the basis of UV–vis spectroscopic studies and kinetic observations, participation of a ternary precursor [M(II) S (VHR)] in the rate‐limiting step has been proposed to explain the mechanism of the metal ion–catalyzed VH reaction.     

First stereoselective total synthesis of (+)-dodoneine

The first stereoselective total synthesis of the natural product (+)-dodoneine is described involving a Crimmins aldol reaction and a Horner-Wadsworth-Emmons olefination as the key steps.