No abstract

Silver oxalate, one of the coordination polymer crystals, is a promising synthetic precursor for transformation into Ag nanoparticles without any reducing chemicals via thermal decomposition of the oxalate ions. However, its insoluble nature in solvents has been a great disadvantage, especially for systematic control of crystal growth of the Ag nanoparticles, while such control of inorganic nanoparticles has been generally performed using soluble precursors in homogeneous solutions. In this paper, we document our discovery of water-soluble species from the reaction between the insoluble silver oxalate and N,N-dimethyl-1,3-diaminopropane. The water-soluble species underwent low-temperature thermal decomposition of the oxalate ions at 30 °C with evolution of CO2 to reduce Ag+ to Ag0. Water-dispersible Ag nanoparticles have been successfully synthesized from the water-soluble species in the presence of gelatin via similar thermal decomposition at 100 °C. The gelatin-protected and water-dispersible Ag nanoparticles with a mean diameter of 25.1 nm appeared. In addition, antibacterial activity of the prepared water-dispersible Ag nanoparticles has been preliminarily investigated.

Metal oxalates (CO, ox) have been explored as promising precursors for the direct transformation of their oxalate moieties into metallic or metal oxide crystals via thermal decomposition without the formation of any byproducts due to releasing CO gas. The copper(ii) oxalate (Cu(ox)) crystal is a coordination polymer composed of an infinite coordination network with a thermal decomposition temperature around 300 °C; however, their insoluble nature in any solvents and relatively high decomposition temperature do not allow the solution-based syntheses of surface-modified metallic Cu nanocrystals (NCs) in the presence of various surfactants such as long-chain alkylamines and alkylcarboxylates which have been used for increasing the dispersibility of NCs in organic solvents. In this study, the insoluble nature of Cu(ox) is overcome by mixing Cu(ox) crystals and N,N-diethyl-1,3-diaminopropane (dedap) to form a discrete complex, [Cu(ox)(dedap)], whose structure is determined by X-ray crystallographic analysis. The obtained complex is well soluble in polar solvents and miscible with surfactants. Furthermore, it is decomposed at a moderate temperature of <170 °C with the evolution of CO gas; as a result, Cu NCs dispersible in organic solvents have been synthesized in suitable surfactants, such as the mixture of oleic acid, dodecylamine, and octylamine utilized as a reaction solvent. In addition, their potential application of the surface-modified Cu NCs as a conductive-ink has been preliminarily tested. The Cu film sintered at 280 °C exhibits a resistivity of 40 μΩ cm.

No abstract