Synthesis of tertiary α-amino phosphonate by one-pot three-component coupling mediated by LPDE

A very mild, efficient and simple method for the synthesis of tertiary α-amino phosphonates is reported by reaction of an aldehyde, a secondary amine and trialkylphosphite in ethereal solution of lithium perchlorate, LPDE, at ambient temperature with high yields.     

Preparation of novel structural nanosized Y2O3 powders and their catalytic activity on the decomposition of NH4ClO4

For the first time, novel structural nanosized Y₂O₃ powders were successfully synthesized by the n-butanol soft-template method. X-ray diffraction, transmission electron microscopy, scanning electron microscopy and Raman spectroscopy were used to characterize the products. The results indicate that these products (calcined at 700°C) were comprised of many Y₂O₃ nanomembranes, and the nanomembranes could change into nanorods when calcined at 1000°C. Interestingly, differential thermal analysis studies suggested that the nanosized Y₂O₃ crystals had intense catalytic activity on the thermal decomposition of ammonium perchlorate.     

An appreciation of the chemical approach of V. V. Boldyrev to the study of the decomposition of solids

Professor Vladimir V. Boldyrev has made numerous important contributions to a wide range of chemical topics, not only limited to studies of the decompositions of solids. Of particular value has been his emphasis on exploring, in detail, the chemical steps participating in the thermal reactions of solids by carefully designed experiments that rely on more observational evidence than the run-of-the-mill collection of overall kinetic data. Some of these major contributions to both the theory and the uses of solid-state reactions are identified here and discussed in relation to his illuminating and fundamental mechanistic studies of the thermal decompositions of silver oxalate, ammonium perchlorate, potassium permanganate and the dehydration of copper sulfate pentahydrate.     

Vibrational spectral studies of L-citrullinium perchlorate

Infrared and Raman spectra of L-citrullinium perchlorate crystals have been recorded at room temperature. The vibrational assignments of the observed wavenumbers are proposed on the basis of group theoretical analysis. The presence of carbonyl group indicates that the molecule exists in the ionic form. The shifting of stretching and bending wavenumbers indicates the presence of extensive hydrogen bonding in the crystal. The anion fundamentals however continue to be degenerated. This suggests that its symmetry is not affected in the crystal.     

Comparative ONIOM modeling of 1,3-butadiene polymerization using Nd(III) and Gd(III) Ziegler–Natta catalyst systems

On the base of structural and thermodynamic data using modern methods of quantum chemistry, a comparative theoretical study of the elementary acts of initiation and growth of a polymer chain during the polymerization of 1,3-butadiene was carried out. Ziegler–Natta catalysts based on Nd(III) and Gd(III) were used as polymerization initiators. It was shown that the higher stereospecificity of the action of gadolinium catalytic complexes in comparison with neodymium complexes is due to the increased stability of the anti-form of the π-allylic terminal structure of the growing polymer chain, and the reduced activity is due to the higher activation energy of the processes of initiation and chain growth.     

Raman spectra of crystalline iron perchlorate hexahydrate

Raman studies of crystalline iron perchlorate hexahydrate (Fe(ClO₄)₂·6H₂O) in the region of lattice and anion internal modes were carried out in the temperature range 80–385 K. The temperature‐dependent Raman results are consistent with those from previous works, showing that two phase transitions occur around 336 and 245 K. The transition at 336 K may be considered as an order–disorder transformation, while the one at 245 K is associated with the configurational disorder of the tetrahedron of the perchlorate ions. Copyright © 2008 John Wiley & Sons, Ltd.     

Effect of an aliphatic spacer group on the adsorption mechanism on the colloidal silver surface of L‐proline phosphonodipeptides

A comparative study of molecular structures of five L ‐proline (L ‐Pro) phosphonodipeptides: L ‐Pro‐NH‐C(Me,Me)‐PO₃H₂ (P1), L ‐Pro‐NH‐C(Me,iPr)‐PO₃H₂ (P2), L ‐Pro‐L ‐NH‐CH(iBu)‐PO₃H₂ (P3), L ‐Pro‐L ‐NH‐CH(PA)‐PO₃H₂ (P4) and L ‐Pro‐L ‐NH‐CH(BA)‐PO₃H₂ (P5) has been carried out using Raman and absorption infrared techniques of molecular spectroscopy. The interpretation of the obtained spectra has been supported by density functional theory calculations (DFT) at the B3LYP; 6–31 + + G** level using Gaussian 2003 software. The surface‐enhanced Raman scattering (SERS) on Ag‐sol in aqueous solutions of these phosphonopeptides has also been investigated. The surface geometry of these molecules on a silver colloidal surface has been determined by observing the position and relative intensity changes of the Pro ring, amide, phosphonate and so‐called spacer (−R) groups vibrations of the enhanced bands in their SERS spectra. Results show that P4 and P5 adsorb onto the silver as anionic molecules mainly via the amide bond (∼1630, ∼1533, ∼1248, ∼800 and ∼565 cm⁻¹), Pro ring (∼956, ∼907 and ∼876 cm⁻¹) and carboxylate group (∼1395 and ∼909 cm⁻¹). Coadsorption of the imine nitrogen atom and PO group with the silver surface, possibly by formation of a weaker interaction with the metal, is also suggested by the enhancement of the bands at 1158 and 1248 cm⁻¹. P1, P2 and P3 show two orientations of their main chain on the silver surface resulting from different interactions of the  C CH₃,  NH and  CONH fragments with this surface. Bonding to the Ag surface occurs mainly through the imino atom (1166 cm⁻¹) for P2, while for P1 and P3 it occurs via the methyl group(s) (1194–1208 cm⁻¹). The amide group functionality (CONH) is practically not involved in the adsorption process for P1 and P2, whereas the C_s P bonds do assist in the adsorption. Copyright © 2008 John Wiley & Sons, Ltd.