Enhanced stability of platinized silicon substrates using an unconventional adhesion layer deposited by CSD for high temperature dielectric thin film deposition

Almost all platinized substrates manufactured presently use an TiO₂ adhesion layer to improve the adhesion between the SiO₂ and the Pt. These substrates however are stable till only 800 °C. We show that simply by replacing the TiO₂ with Al₂O₃, the stability of the electrodes can be increased to 1000 °C and more. These substrates can be used for high temperature depositions which standard platinized substrates cannot withstand. Further we show that dielectric thin films of BaTiO₃ and (Ba,Sr)TiO₃ crystallized at higher temperatures show almost a threefold increase in permittivity on these high temperature stable platinized silicon substrates.The large increase in permittivity is attributed to an increase in grain size at high temperatures. PACS 61.82.Fk; 68.35.Np; 68.60.Dv; 77.55.+f; 81.20.Fw     

Dimethylmetall-tropolonate des galliums,indiums und zinns

The reaction of GaMe₃ and InMe₃ (Me = CH₃) with equimolar amounts of α-tropolone forms dimethylgallium tropolonate and dimethylindium tropolonate, respectively, in high yields. Both compounds are monomeric in solution, almost planar 7-/5-ring bicyclic structures of C_2v symmetry can be discussed. According to the X-ray structure determination of Me₂GaTrop (Trop = C₇H₅O₂) this compound is dimeric in the solid state and crystallizes in the monoclinic space group P2₁/c with 4 formula units (2 dimers) per unit cell. Me₂SnTrop₂ is formed by the interaction of Me₂SnCl₂ with LiTrop in a $\text{1}\text{2}$ molar ratio. This ditropolonate is monomeric not only in solution but also in the solid state. The compound crystallizes in the triclinic space group P$\text{1}$ (Z = 4), and the molecules have a cis-structure of approximate C₂-symmetry. The vibrational and NMR spectra of all compounds were measured and are partly assigned.     

Generation of fluorescent adducts of malondialdehyde and amino acids: toward an understanding of lipofuscin

Lipofuscin is a yellow-brown, highly fluorescent pigment that undergoes an age-related progressive accumulation in animal cells, mainly in postmitotic cells. It is a heterogeneous, high-molecular weight material associated with proteins, lipids and nucleic acids. Lipofuscin is implicated in many aspects of human health, including aging, oxidative stress, macular degeneration, lipid peroxidation, atherosclerosis, dementia (Alzheimer's Disease) and diseases associated with prions. Although the fluorescent properties of lipofuscin have long been recognized, neither histologists nor chemists have yet isolated the pigments themselves or characterized their optical properties. We have prepared lipofuscinlike species by reacting malondialdehyde (MDA) with cysteine (Cys). MDA:Cys adducts 3:2 and 2:2 are two of those that have been identified among the many that were present in the reaction. Whereas previous attempts to synthesize lipofuscinlike species resulted in compounds that were either nonfluorescent or emitted principally in the blue, the MDA:Cys adducts reported in this study are not only fluorescent but also emit over a broader range.     

Elucidating the structure of surface acid sites on γ-Al2O3

Differential pair distribution function analysis was applied to resolve, with crystallographic detail, the structure of catalytic sites on the surface of nanoscale γ-Al(2)O(3). The structure was determined for a basic probe molecule, monomethylamine (MMA), bound at the minority Lewis acid sites. These active sites were found to be five-coordinate, forming distorted octahedra upon MMA binding. This approach could be applied to study the interaction of molecules at surfaces in dye-sensitized solar cells, nanoparticles, sensors, materials for waste remediation, and catalysts.     

Triazine‐based Organic Polymer‐catalysed Conversion of Epoxide to Cyclic Carbonate under Ambient CO2 Pressure

In this work we have achieved epoxide to cyclic carbonate conversion using a metal‐free polymeric catalyst under ambient CO₂ pressure (1.02 atm) using a balloon setup. The triazine containing polymer (CYA‐ANIS) was prepared from cyanuric chloride (CYA?Cl) and o‐dianisidine (ANIS) in anhydrous DMF as solvent by refluxing under the N₂ gas environment. The presence of triazine and amine functional groups in the polymer results in the adsorption of CO₂ up to 7 cc/g at 273 K. This inspired us to utilize the polymer for the conversion of a series of functionalised epoxides into their corresponding cyclic carbonates in the presence of tetrabutyl ammonium iodide (TBAI) as co‐catalyst. The product has wide range of applications like solvent in lithium ion battery, precursor for polycarbonate, etc. The catalyst was efficient for the conversion of different mono and di‐epoxides into their corresponding cyclic carbonates under atmospheric pressure in the presence of TBAI as co‐catalyst. The study indicates that epoxide attached with electron withdrawing groups (like, CH₂Cl, glycidyl ether, etc.) displayed better conversion compared to simple alkane chain attached epoxides. This is mainly due to the stabilization of electron rich intermediates produced during the reaction (e. g. epoxide ring opening or CO₂ incorporation into the halo‐alkoxide anion). This catalyst mixture was capable to maintain its reactivity up to five cycles without losing its activity. Post catalytic characterization clearly supports the heterogeneous and recyclable nature of the catalyst.     

Mechanochemical Synthesis of Functionalized Quinolines by Iodine Mediated Oxidative Annulation

An iodine‐mediated environmentally benign synthesis of multi‐substituted quinoline derivatives is developed using a solvent‐free mechanochemical process. Appropriately designed and easily accessible protecting group‐free aniline derivatives were used for the oxidative annulation reaction, and a series of quinoline derivatives with variable functionalities were synthesized up to 89 % isolated yield. Importantly, the activator iodine remains in the quinoline molecule and promotes further functionalizations. The present methodology is beneficial with regard to operational simplicity and mild reaction conditions.