Polyaniline nanostructure electrode: morphological control by a hybrid template

Journal of Solid State Electrochemistry - We report here a novel approach to the template-assisted electrochemical synthesis of vertically aligned polyaniline (PANI) nanostructure surface arrays....     

Diversity‐Oriented Synthesis of Intensively Blue Emissive 3‐Hydroxyisoquinolines by Sequential Ugi Four‐Component Reaction/Reductive Heck Cyclization

A convergent approach to highly functionalized 3‐hydroxyisoquinolines is reported. The key steps are an Ugi multicomponent reaction and a subsequent intramolecular reductive Heck reaction; these can also be performed as a one‐pot procedure. The structures display very interesting properties as blue‐fluorescence emitters. Photophysical studies on the absorption and static fluorescence indicate that the substitution pattern on the pyridyl part influences the optical properties only to a minor extent, unless the amide substituent becomes sterically demanding and leads to significant nonradiative deactivation. The donor substitution on the benzo core considerably enhances the fluorescence quantum yields and trimethoxy substitution causes a pronounced redshift of the emission bands. Protonation of the isoquinolyl nitrogen atom causes efficient static quenching of the fluorescence.     

Impact of agglomeration on crystalline product quality within the crystallization process chain

The quality of crystalline products, defined by e.g. purity or crystal size distribution (CSD), is primarily dominated by crystallization conditions but influenced by further downstream processes like solid‐liquid separation and drying also. Through uncontrolled agglomeration within the crystallization process chain the purity or CSD can be negatively affected. Therefore, in context of process optimization, missing knowledge of the impacts on the final product can lead to product batches out of specification. To increase the understanding of agglomeration and to provide insight into the relevance of holistic process optimization the agglomeration behavior of L‐alanine crystals is exemplarily quantified over the crystalline process chain. For the quantification the agglomeration degree (Ag) and the agglomeration degree distribution (AgD) are determined. The results show that the product quality achieved after crystallization is significantly affected by agglomeration during drying. Especially if washing after solid‐liquid separation is omitted, a broadening of the CSD is observed. Moreover, the evaluation by the AgD indicates that the final product can be ‐ despite similar characteristics of the CSD ‐ highly different. Consequently, it can be concluded that the characterization of the product quality by the CSD alone is insufficient and the quantification of agglomeration is essential for process optimization.     

Synthesis of aurachin D and isoprenoid analogues from the myxobacterium Stigmatella aurantiaca

Aurachins, a family of isoprenoid quinoline alkaloids isolated from the myxobacterium Stigmatella aurantiaca, possess multiple interesting bioactivities and were subject of intensive studies of biosynthesis. In this Letter, we describe the efficient few step total synthesis of the parent compound aurachin D and two isoprenoid analogues via Conrad–Limpach cyclization. The main antimicrobial and cytotoxic profiles of these derivatives were explored.     

Synthesis of rapamycin glycoconjugates via a CuAAC-based approach

The conversion of the C40 secondary hydroxyl group of rapamycin into the azido group was followed by copper catalyzed cycloaddition of the resulting azido-rapamcin with various unprotected propargyl O- and S-glycosides and a C-ethynyl derivative. This approach furnished a collection of triazole-bridged rapamycin glycoconjugates (14 examples) in 44–83% isolated yield.     

The Oxidation of Aldehydes to Methyl Esters using Trichloroisocyanuric Acid

Aldehydes are readily oxidized to methyl esters by a solution of methanol, pyridine, and trichloroisocyanuric acid in acetonitrile, acetone, or methylene chloride.