Solvent-Free Synthesis of Nano Zirconium Phenylphosphonates with Molten Phenylphosphonic Acid

Nanosized α-zirconium phenylphosphonate particles were successfully prepared by the reaction between different zirconium sources and molten phenylphosphonic acid in the absence of solvent. The resultant nanoplates exhibit particle sizes in the range of 15 to 30 nm. The use of a topotactic anion exchange method starting from α-zirconium phosphate instead resulted in the generation of 15 to 180 nm plates, while also resulting in nanoparticles with a higher degree of crystallinity. The topotactic anion exchange of the phosphate groups by phenylphosphonate groups could be performed to completion when performed in molten phenylphosphonic acid. Characterization of both the final products as well as the individual steps in the anion exchange were performed by powder XRD, fast neutron activation analysis, TGA, FTIR spectroscopy, TEM, solid-state NMR and XPS.     

Enantioselective Synthesis of Polycyclic Aromatic Hydrocarbon (PAH)-Based Planar Chiral Bent Cyclophanes by Rhodium-Catalyzed [2+2+2] Cycloaddition

The enantioselective synthesis of polycyclic aromatic hydrocarbon (PAH)-based planar chiral cyclophanes was achieved for the first time by the rhodium-catalyzed intramolecular regio- and enantioselective [2+2+2] cycloaddition of tethered diyne-benzofulvenes followed by stepwise oxidative transformations. The thus synthesized planar chiral bent cyclophanes, that possess bent p-terphenyl- and 9-fluorenone-cores, were converted to 9-fluorenol-based ones with excellent ee values of >99 % by diastereoselective 1,2-reduction. These 9-fluorenol-based cyclophanes exhibited high fluorescence quantum yields, which were significantly higher than that of an acyclic reference molecule (78–82 % vs. 48 %). The bending effect on the chiroptical property was also examined, which revealed that the anisotropy factors (g_abs values) for electronic circular dichroism (ECD) of these 9-fluorenol-based planar chiral bent cyclophanes increase as the tether length becomes shorter.     

Elucidating structure and dynamics of crystalline α-zirconium phosphates intercalated with water and methanol by multinuclear solid-state MAS NMR: A comprehensive NMR approach

Solid-state NMR experiments on ²H, ³¹P, ¹³C, and ¹H nuclei, including ³¹P T₁, ¹H T₁, and ¹H T_1ρ measurements, as well as on the kinetics of proton-phosphorus cross-polarization have been performed to characterize the crystalline and amorphous α-zirconium phosphates, which were intercalated with D₂O and/or CD₃OD. The ¹³C{¹H} CP MAS NMR experiment performed for compound 1-CD ₃ OD (Zr (HPO₄)₂ ^. 0.2CD₃OD) with carbon cross-polarization via protons of phosphate groups has provided a prove that the methanol was intercalated into the interlayer spaces of this compound. The variable-temperature ²H solid-echo MAS NMR spectra of intercalated compounds demonstrated that the methanol molecules, in contrast to the mobile water, were immobile, keeping, however, free CD₃ rotations around the C₃-axis. It has been demonstrated that the intercalated species, D₂O and CD₃OD, do not affect the high-frequency motions of the phosphate groups. By utilizing local structural models that satisfy the constraints of the experimental data, it has been suggested that the immobile methanol molecules are located in the cavity between two neighboring layers of the zirconium phosphates. Thus, the present work illustrates the reliable criteria in a comprehensive NMR approach to structural and dynamic studies of such systems.     

Generic substitution policy,an incentive approach

Generic substitution policy has been adopted in several countries in order to control health expenditures. Using a model based on incentives, this work aims to analyze the response of doctors and pharmaceutical companies to the implementation of this policy. It is shown that after the implementation of GSP, the effort of doctor’s convincing the patient to take generics increase or decrease depending on his level of concern for patient well-being; pharmaceutical companies decrease the amount of detailing and the market share of generics tends to increase.     

Robustness of dual divergence estimators for models satisfying linear constraints

We consider new classes of estimators and test statistics for models satisfying linear constraints with unknown parameter. These procedures are based on minimization of divergences through duality techniques. We prove that, for various divergences, the new approach provides robust estimation and test procedures, unlike the empirical likelihood method. We give general results using the influence function approach, which we exemplify in detail in the case of the Cressie–Read divergences. It is found that the Hellinger distance is one of the divergences that leads to robust procedures.     

Convenient Synthesis of Cerpegin

A convenient procedure for the preparation of cerpegin is described.     

Design and synthesis of certain substituted cycloalkanecarboxamides structurally related to safinamide with anticonvulsant potential

Research on Chemical Intermediates - A series of novel safinamide derivatives were synthesized and biologically evaluated for their anticonvulsant activity against maximal electroshock seizure...