Crystallization-Induced Dynamic Resolution of Fox Chiral Auxiliary and Application to the Diastereoselective Electrophilic Fluorination of Amide Enolates

A highly efficient crystallization-induced dynamic resolution (CIDR) of <i>trans</i>-<b>Fox</b> (fluorinated oxazolidine) chiral auxiliary is reported. This chiral auxiliary was used for highly diastereoselective (>98% <i>de</i>) electrophilic fluorination of amide enolates. After removal of the chiral auxiliary, highly valuable enantiopure α-fluorocarboxylic acids and β-fluoroalcohols are obtained

Experimental investigation of the thermal emission cross-section of nano-resonators using hierarchical Poisson-disk distributions

Effective cross-sections of nano-objects are fundamental properties that determine their ability to interact with light. However, measuring them for individual resonators directly and quantitatively remains challenging, particularly because of the very low signals involved. Here, we experimentally measure the thermal emission cross-section of metal-insulator-metal nano-resonators using a stealthy hyperuniform distribution based on a hierarchical Poisson-disk algorithm. In such distributions, there are no long-range interactions between antennas, and we show that the light emitted by the metasurface behaves as the sum of cross-sections of independent nanoantennas, enabling direct retrieval of the single resonator contribution. The emission cross-section at resonance is found to be of the order of $\mathbf{\lambda_0^2/3}$, a value that is nearly three times larger than the theroretical maximal absorption cross-section of a single particle but remains smaller than the maximal extinction cross-section. This measurement technique can be generalized to any single resonator cross-section, and we also apply it here to the extinction cross-section

Three-Dimensional Self-Assembling of Gold Nanorods with Controlled Macroscopic Shape and Local Smectic B Order

We describe a method of controlled evaporation on a textured substrate for self-assembling and shaping gold-nanorod-based materials. Tridimensional wall features are formed over areas as large as several square millimeters. Furthermore, analyses by small-angle X-ray scattering and scanning electron microscopy techniques demonstrate that colloids are locally ordered as a smectic B phase. Such crystallization is in fact possible because we could finely adjust the nanoparticle charge, knowledge that additionally enables tuning the lattice parameters. In the future, the type of ordered self-assemblies of gold nanorods we have prepared could be used for amplifying optical signals