Nanocrystalline Ag from Supramolecular Stabilization of Metals in 4‐tert‐Butylcalix[4]arene Lattices

Abstract

Competition between intermolecular forces is a prime method for directing the formation of self-assembled structures without resorting to the use of covalently modified host molecules. In this study, we demonstrate how the competition between hydrogen bonding, coordinate bonding, and van der Waals interactions guides the formation of a complex crystalline clathrate based on a Ag-ethylenediamine coordination complex and 4-tert-butylcalix[4]arene. Owing to the coordinative flexibility of Ag and the stabilizing interactions with the calixarene framework, a four-coordinate Ag complex is included in the structure. Subsequent removal of the amine by heating the crystalline inclusion compound results in reduction of the Ag+ ion such that metallic Ag nanocrystals are formed, thus indicating that this self-assembly approach is a viable method for obtaining simple calixarene frameworks loaded with silver. In the light of the experimental evidence, we comment on how this process relates to the reduction of silver in other systems.

The Role of Calix[n]arenes and Pillar[n]arenes in the Design of Silver Nanoparticles: Self-Assembly and Application

“…Also, there are a series of articles reporting unsubstituted p-tert-butylcalix[n]arenes as AgNP stabilizers. A unique approach to the synthesis of AgNPs was developed [54] AgNPs based on calix [6]arene CA-12 with diameters of about 7 nm are capable of interacting with sanguinarine (antitumor, antibacterial, antioxidant and anti-inflammatory drugs) [55]. The nanoparticle-sanguinarine complex has shown to lower toxicity towards two cell lines (normal CHO and cancerous A549).…”