- Facile ring opening reaction of oxazolone enables efficient amidation for aminoisobutyric acid
-
Abstract: 4,4-Dimethyloxazolones derived from N-protected aminoisobutyric acid (AIB) are particularly known as poor electrophiles due to the steric hindrance around the carbonyl and not employed as useful intermediates for amidation whereas numerous examp
- Jo, Minmi,Won, Sun-Woo,Lee, Dong Guk,Yun, Jungeon,Kim, Sunhong,Kwak, Young-Shin
-
-
Read Online
- Gold nanoclusters protected by conformationally constrained peptides
-
The preparation and properties of a series of gold nanoclusters protected by thiolated peptides based on the α-aminoisobutyric acid (Aib) unit are described. The peptides were devised to form 0-3 C=O...H-N intramolecular hydrogen bonds, as required by their 310-helical structure. The monolayer-protected clusters (MPCs) were prepared, using a modified version of the two-phase Brust-Schiffrin preparation, and fully characterized with 1H NMR spectrometry, IR and UV-vis absorption spectroscopies, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The MPCs were obtained with core diameters in the range of 1.1-2.3 nm, depending on the reaction conditions. Structured peptides formed smaller clusters. The smallest MPC obtained is in agreement with the average formula Au38PeP18. The results showed that the chemical integrity of the peptide is maintained upon monolayer formation and that the average number of peptide ligands per gold cluster is typically 75-85% the value calculated for alkanethiolate MPCs of similar sizes. The IR and NMR spectra indicated that in the monolayer the peptides are involved in both intra- and interligand C=O-H-N hydrogen bonds.
- Fabris, Laura,Antonello, Sabrina,Armelao, Lidia,Donkers, Robert L.,Polo, Federico,Toniolo, Claudio,Maran, Flavio
-
p. 326 - 336
(2007/10/03)
-