Paper Title
Size-Controlled Synthesis of Platinum Nanoparticles using A Macrocycle

Abstract
A simple and one-pot synthesis of platinum nanoparticles (PtNPs) through the reaction of an aqueous mixture of a platinum salt (K2[PtCl4]) and a macrocycle, cucurbit[7]uril (CB7) [1-3], in the presence of an alkaline (NaOH) solution at room temperature was achieved without introducing any type of traditional reducing agents and/or outside energy sources (Scheme 1). Further, we could manipulate the particle size (Fig. 1) by just changing the experimental conditions such as reaction concentration (Table 1). The size of the PtNPs was observed as < 1 nm at pH = 12, which suggests the inclusion mechanism. However, the particle size of PtNPs, was 1-3 nm at different conditions, which suggests the capping mechanism for the well-dispersed nanoparticles (Scheme 1). Therefore, we demonstrated that macrocycle, e.g., cucurbituril [3, 5], not only is able to act as a protecting agent but also can act as reducing agent for the preparation of platinum nanoparticles with tunable size at ambient conditions. Therefore, we consider this method to be a facile and significant general method [6-8] for the preparation of metal nanoparticles in the water medium. Keywords - Macrocyle, Nanoparticle, Platinum, TEM.