In order to get a better control of the initial complexation between metallic ions and calixarenes, we undertook the synthesis of calixarene-based metallic complexes. The variations in the composition might result from different initial complexations between Au( III), Ag( I) and calixarenes. Such non-homogeneous structure might come from aggregation of small clusters with different compositions. However, the proportions of gold and silver were not constant from one NP to another and the NP structure appears non-homogeneous with domains containing more gold atoms and others more silver atoms. were obtained with a mean size of 3.5 nm. In the case of the reduction of ethanolic solution containing both Au( III) and Ag( I) salts in the presence of C8, alloyed Au–Ag NPs. 5 For a metal/calixarene ratio of 10, the reduction of metallic salts, AgClO 4 or HAuCl 4, in the presence of C8 in ethanolic solution leads to the formation of small spherical NP, homogeneous in size (diameter <5 nm). Lately, we reported the radiolytic synthesis of mono and bimetallic gold–silver nanoparticles (NPs) stabilised by octa(hydroxyl)-octa(mercaptobutoxy)calixarenes ( C8, Chart 1). Calixarenes-based NPs have already been the subject of several reviews. Among the ligands, macrocycles such as calixarenes have attracted attention due their conformational behaviour, functionalisation tunability, host-guest properties as well as non-toxicity, biological mimics and surface accessibility. But, the NP surface and its interactions with the environment and/or the ligands play an important role for applications. Towards that goal, the use of ligands, capping agents or supports is often required. However, their properties depend on their size, shape and morphology, parameters which need to be controlled. Introduction In the last decades, research involving metal nanoparticles (NP) has seeped into many domains: material science, analytical chemistry, biochemistry… Indeed, due to their unique properties, metal NPs find applications in different fields, for instance catalysis, optics, sensing or medicine. We show that the radiolytic reduction of these complexes leads to the formation of small bimetallic nanoparticles with an alloyed structure, as evidenced by XPS, HR-TEM and STEM/HAADF-EDX measurements.

In this paper, we report the first synthesis and characterisations of bimetallic gold( I)–silver( I) calixarene complexes.

Xps peak sulphur s2p