Nanoporous gold assemblies of calixarene-phosphine-capped colloids

Abstract

COMMUNICATIONAlexander Katz et al. Nanoporous gold assemblies of calixarene-phosphine-capped colloids

Microwave-assisted multicomponent synthesis of julolidines using silica-supported calix[4]arene as heterogeneous catalyst

“…Once determined that a solvent-free reaction was the best condition to obtain 1[(±)-T+C], we further investigated what the minimum amount of catalyst CX4SO 3 HSi(n) required to achieve the maximum reaction yield. The 1[(±)-T+C] yield decreased to 57% and 56% when the amount of CX4SO 3 HSi(n) was increased from 0.5 mol% to 1.0 mol% and 2.0 mol% (Table 2, entries 5- 7). By using the microwave irradiation and different power (50, 100, 200 and 300 W), the 1[(±)-T+C] yield decreased to 92%, 87%, 85% and 70% when the power was increased from 50 W, 100 W, 200 W and 300 W (Table 2, entries 5 and 8-10).…”

“…2 In the last years, research interest in calix [n]arene chemistry has increased dramatically due to their applications in several fields of chemistry, such as gels and films with fluorescent properties, 3 molecular recognition, 4 self-assembling systems, 5 mechanically interlocked molecules, 6 and nanoporous materials. 7 The application of calix [n]arenes as organocatalysts in organic synthesis has become very popular. 8 On the other hand, the application of calix [n]arenes as a heterogeneous catalyst for the chemical transformations remains largely unexplored.…”

Resorcin[4]arene-based multidentate phosphate ligands with superior binding affinity for nanocrystal surfaces

“…Macrocyclic ligands have been considered for nanocrystals before, but past research was mostly focused on noble metal nanocrystals, featuring soft ligands. [26][27][28][29] In addition, their binding to the nanocrystal surface was not thoroughly studied. Therefore, 1 and 2 present the first systematic effort in macrocyclic ligand design for a wider class of nanocrystals.…”

Synthesis and Electrochemical Stability of Ultrahigh Aspect Ratio Nanoporous Gold after Calixarene-Phosphine Ligand Removal

“…Although functionalization of the nanoporous gold surface with calixarene-phosphine ligands can be advantageous for certain applications (e.g., providing binding sites for small molecules via synthetically tailorable calixarene cavities), the removal of the calixarene-phosphine ligands is also of importance to provide more access to the underlying metal surface and to enable further adjustment of the surface chemistry of the pores. Originally, we suggested that removal of calixarene-phosphine ligands from its surface should be possible without compromising the integrity of the nanoporous gold scaffold, and supported this hypothesis with data that demonstrated nanosized patches of ligand removal via beam damage under the high-energy electron beam of a scanning transmission electron microscope …”

“…We also assess the electrochemical stability of the resulting nanoporous gold, which lacks protective organic ligands. Typically coarsening and sintering of gold is observed under reducing electrochemical conditions, , which is problematic for long-term stability in electrochemical applications . We have investigated whether the resulting nanoporous gold may exhibit greater robustness under these conditions.…”