Do aziridines require Lewis acids for cleavage with ionic nucleophiles?

A variety of activated aziridines were cleaved by sodium azide and sodium cyanide in aqueous acetonitrile at reflux, in the absence of any Lewis acid, to provide ring-opened products in quantitative yields. However, the reaction was sluggish in the ring opening of unactivated aziridines with sodium azide where the yields could be increased by adding 50 mol% CuCl₂·2H₂O. The reaction was used to synthesize chiral diamines.     

Donor substrate flexibility study of AtUGT89C1, a glycosyltransferase from Arabidopsis thaliana

AtUGT89C1, a glycosyltransferase from Arabidopsis thaliana, has shown interesting characteristics such as accepting diverse NDP-D/L-sugars as glycosyl donors. Genistein was used as a substrate to probe in vitro reactions in which different NDP-sugars were used as sugar donors. Among nine different NDP-D/L-sugars tested, AtUGT89C1 accepted five of them, including UDP-α-D-glu-cose, UDP-α-D-galactose, dTDP-β-L-rhamnose, GDP-β-L-fucose, and dTDP-α-2-deoxy-D-glucose and conjugated sugar moieties from the respective donors with the 7-hydroxyl position of genistein. Results showed the promiscuous nature of AtUGT89C1 toward donor and acceptor substrates, thus expanding the biotechnological application of this enzyme in the production of natural and unnatural flavonoid glycosides.     

A novel stability-indicating HPLC method for the determination of enantiomeric purity of eluxadoline drug: Amylose tris(3,5-dichlorophenyl carbamate) stationary phase

A simple and sensitive stability-indicating chiral HPLC method has been developed and validated per International Conference on Harmonization guidelines for the determination of enantiomeric purity of eluxadoline (Exdl). The impact of different mobile phase compositions and chiral stationary phases on the separation of Exdl enantiomer along with process- and degradation-related impurities has been studied. Homogeneity of Exdl and stable results of Exdl enantiomer in all degraded samples reveal the fact that the proposed method was specific (stability indicating). Amylose tris(3,5-dichlorophenyl carbamate) stationary phase column Chiralpak IE-3 (150 × 4.6 mm, 3 μm) provided better resolution with polar organic solvents than cellulose derivative, crown ether, and zwitterion stationary phases and nonpolar solvents. The mobile phase consisted of acetonitrile, tetrahydrofuran, methanol, butylamine, and acetic acid in the ratio of 500:500:20:2:1.5 (v/v/v/v/v). Isocratic elution was performed at a flow rate of 1.0 mL/min, column temperature of 35°C, injection volume of 10 μL, and UV detection of 240 nm. The United States Pharmacopeia (USP) resolution of the Exdl enantiomer was found to be more than 4.0 within a 65-min run time. Exdl enantiomer detector response linearity over the concentration range of 0.859–4.524 μg/mL was found to be R² = 0.9985. The limit of detection, limit of quantification, and average percentage recovery values were established as 0.283 μg/mL, 0.859 μg/mL, and 96.0, respectively.     

Coordination Cage-Based Emulsifiers: Templated Formation of Metal Oxide Microcapsules Monitored by In Situ LC-TEM

Metallo-supramolecular self-assembly has yielded a plethora of discrete nanosystems, many of which show competence in capturing guests and catalyzing chemical reactions. However, the potential of low-molecular bottom-up self-assemblies in the development of structured inorganic materials has rarely been methodically explored so far. Herein, we present a new type of metallo-supramolecular surfactant with the ability to stabilize non-aqueous emulsions for a significant period. The molecular design of the surfactant is based on a heteroleptic coordination cage ( CGA-3 ; CGA =Cage-based Gemini Amphiphile), assembled from two pairs of organic building blocks, grouped around two Pd(II) cations. Shape-complementarity between the differently functionalized components generates discrete amphiphiles with a tailor-made polarity profile, able to stabilize non-aqueous emulsions, such as hexadecane-in-DMSO. These emulsions were used as a medium for the synthesis of spherical metal oxide microcapsules (titanium oxide, zirconium oxide, and niobium oxide) from soluble, water-sensitive alkoxide precursors by allowing a controlled dosage of water to the liquid-liquid phase boundary. Synthesized materials were analyzed by a combination of electron microscopic techniques. In situ liquid cell transmission electron microscopy (LC-TEM) was utilized for the first time to visualize the dynamics of the emulsion-templated formation of hollow inorganic titanium oxide and zirconium oxide microspheres.     

Fluorescent Carbon Quantum Dots Functionalized by Poly L-Lysine: Efficient Material for Antibacterial,Bioimaging and Antiangiogenesis Applications

Journal of Fluorescence - This study illustrates the synthesis of functionalized carbon quantum dots (CQDs) by the one-pot pyrolysis method. The functionalization agent used in CQD synthesis was...     

Salp Swarm Optimization-Based Clustering Algorithm (SSOCA) in Adaptive FANET to Improve QoS for Disaster Response Operations

Wireless Personal Communications - Unmanned Aerial Vehicles (UAVs) are well appropriate devices for wireless communication in Flying Ad-hoc Networks deployed in several applications like disaster...     

Enantioselective total syntheses of (−)-clavaminol A and deacetyl (+)-clavaminol H

An efficient enantioselective approach to the syntheses of (?)-clavaminol A and deacetyl (+)-clavaminol H is presented, starting from n-decanol. The synthesis features Sharpless asymmetric dihydroxylation (AD), regioselective epoxide formation/opening and α-tosylation as key steps.     

Fine‐Tuning of Saponification‐Triggered Gelation by Strategic Modification of Peripheral Substituents: Gelation Regulators

A pioneering approach towards controlling the efficiency of saponification assisted gelation in ethyl ester based Zn^II‐complexes have been described. Using four new ester containing bis‐salen Zn^II complexes ( C1–C4 ) involving different para‐azo phenyl substituted ligands it has been clearly shown that gelation efficiency is greatly influenced by the electronic effects of the substituents (‐H ( C1 ), ‐CH₃ ( C2 ), ‐NO₂ ( C3 ), and ‐OCH₃ ( C4 )). Morphological, photophysical, and rheological investigations corroborated the experimental observations well and established that gelation efficiency was enhanced with electron‐withdrawing characteristics of substituents ( C4 < C2 < C1 < C3 ). This conclusion was also supported by DFT studies.