Light-Induced Ostwald Ripening of Organic Nanodots to Rods
摘要:
Ostwald ripening allows the synthesis of 1D nanorods of metal and semiconductor nanoparticles. However, this phenomenon is unsuccessful with organic it-systems due to their spontaneous self-assembly to elongated fibers or tapes. Here we demonstrate the uses of light as a versatile tool to control the ripening of amorphous organic nanodots (ca. 15 nm) of an azobenzene-derived molecular assembly to micrometer sized supramolecular rods. A surface confined dipole variation associated with a low-yield (13-14%) trans-cis isomerization of the azobenzene moiety and the consequent dipole-dipole interaction in a nonpolar solvent is believed to be the driving force for the ripening of the nanodots to rods.
Copper Nitrate Mediated Regioselective [2+2+1] Cyclization of Alkynes with Alkenes: A Cascade Approach to Δ<sup>2</sup>-Isoxazolines
作者:Mingchun Gao、Yingying Li、Yuansheng Gan、Bin Xu
DOI:10.1002/anie.201503393
日期:2015.7.20
An efficient method for the regioselective synthesis of pharmacologically relevant polysubstituted Δ2‐isoxazolines is based on the copper‐mediated direct transformation of simple terminal alkynes and alkenes. The overall process involves the formation of four chemical bonds with inexpensive and readily available copper nitrate trihydrate as a novel precursor of nitrile oxides. The reaction can be easily