ABSTRACT
This paper presents a feasible and reliable phase transfer protocol for polyoxyethylene alkyl amine surfactant (AMIET)-coated gold nanoparticles (AuNPs) in aqueous media to chloroform using a pH-triggered method, through the liquid-liquid interface. In the initial stage, the colloidal aqueous dispersion is destabilized by pH adjustment towards the isoelectric pH of the nanoparticle, which promotes the separation of the particles from water. We further explored a mechanistic view of this phase transfer phenomenon, considering the orientation of hydrophilic and hydrophobic moieties depending on the nature of the surrounding solvent. It was proposed that the AMIET molecules bound to the AuNPs undergo conformational changes through phase transfer. Ultraviolet visible absorption spectra before and after the phase transfer reveal that the original morphology and dispersion states of the particles were preserved.
Subject(s)
Gold , Metal Nanoparticles , Gold/chemistry , Hydrophobic and Hydrophilic Interactions , Metal Nanoparticles/chemistry , Solvents/chemistry , Water/chemistryABSTRACT
2-(Bromomethyl)-1-sulfonylaziridines were converted into novel 3-sulfonamido-2,3,4,5-tetrahydro-1,5-benzothiazepines upon treatment with 2-aminothiophenol in THF in the presence of K2CO3. Starting from 3-substituted 2-(sulfonyloxymethyl)aziridines, a regio- and stereocontrolled synthesis of trans-2-phenyl- and trans-4-(phenyl or propyl)-3-sulfonamido-2,3,4,5-tetrahydro-1,5-benzothiazepines was developed in good yields via two different reaction pathways, depending on the nature of the sulfonyloxy group.
Subject(s)
Aziridines/chemical synthesis , Thiazepines/chemical synthesis , Aziridines/chemistry , Magnetic Resonance Spectroscopy , Stereoisomerism , Thiazepines/chemistryABSTRACT
A racemic [2]rotaxane, composed of an asymmetric rotor and an asymmetric axle, formed a diastereomer with an amino acid derivative, and showed an optical response for the chiral recognition.
Subject(s)
Amino Acids/chemistry , Rotaxanes/chemistry , Molecular Structure , StereoisomerismABSTRACT
A 25 membered crownophane with two hydroxy and two amide groups around the cavity has been reported for the first time to be able to include carbonic acid formed from both carbon dioxide and water molecules to give a stable 1:1 complex at room temperature.
