Search

International audience; This Letter reports the first characterization of nonfluorescent halloysite nanotubes (HNTs) by multiphoton microscopy via their endogenously generated second-harmonic (SH) resonance. The unveiled discovery that HNTs generate a SH signal in the nanoscale regime is supported by studies of the signal's propagation, polarization, and coherence properties and, finally, is directed toward the understanding of the origin of signal's generation from the nanoparticle's aluminosilicate skeleton. The study is significant, since it sheds light on halloysite nanotube technological applications in various domains, including alternative bioimaging, biosensing, and noninvasive biomedicine, as well as possibly nonlinear spectroscopy, optoelectronics, and many others.

This Article details the development of the iron-catalyzed conversion of olefins to radicals and their subsequent use in the construction of C-C bonds. Optimization of a reductive diene cyclization led to the development of an intermolecular cross-coupling of electronically-differentiated donor and acceptor olefins. Although the substitution on the donor olefins was initially limited to alkyl and aryl groups, additional efforts culminated in the expansion of the scope of the substitution to various heteroatom-based functionalities, providing a unified olefin reactivity. A vinyl sulfone acceptor olefin was developed, which allowed for the efficient synthesis of sulfone adducts that could be used as branch points for further diversification. Moreover, this reactivity was extended into an olefin-based Minisci reaction to functionalize heterocyclic scaffolds. Finally, mechanistic studies resulted in a more thorough understanding of the reaction, giving rise to the development of a more efficient second-generation set of olefin cross-coupling conditions.