N,N-Diethyl-diaminopropane-copper(ii) oxalate self-reducible complex for the solution-based synthesis of copper nanocrystals

Abstract

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.

Size-Tunable Continuous-Seed-Mediated Growth of Silver Nanoparticles in Alkylamine Mixture via the Stepwise Thermal Decomposition of Silver Oxalate

“…We have previously reported the synthesis of monodisperse silver (Ag) and copper (Cu) NPs by a self-redox reaction via the thermal decomposition of the alkylamine-coordinated metal oxalate (M­(ox)) complex in an alkylamine medium. − An example of this mechanism involves Ag 2 (ox), a coordination polymer crystal with poor solubility in all solvents. Ag 2 (ox) thermally decomposes at 200 °C and transforms into bulk Ag 0 metal with vigorous CO 2 evolution by a self-redox mechanism, without the addition of any reducing agent (eq ).…”

“…Therefore, [(alkylamine)­Ag I (μ-ox)­Ag I (alkylamine)] formed a homogeneous liquid reaction medium by mixing with a small amount of surfactant, and thermally decomposed with the evolution of CO 2 gas generated by the thermal decomposition of the oxalate ion at temperatures above the decomposition temperature. Consequently, Ag NPs with a narrow size distribution were obtained via the thermal decomposition of the Ag 2 (ox) moiety of [(alkylamine)­Ag I (μ-C 2 O 4 )­Ag I (alkylamine)] at 150 °C …”

“…Consequently, Ag NPs with a narrow size distribution were obtained via the thermal decomposition of the Ag 2 (ox) moiety of [(alkylamine)Ag I (μ-C 2 O 4 )Ag I (alkylamine)] at 150 °C. 51 In this paper, we report the size-tunable synthesis of Ag NPs via the thermal decomposition of Ag 2 (ox) in a small amount of alkylamine mixture with a high concentration of Ag (1.5 × 10 −1 to 2.4 × 10 1 M) keeping constant reaction volume using a theoretical approach based on the LaMer model. The size of the Ag NPs was tuned by continuous-seed-mediated growth via the stepwise decomposition of Ag 2 (ox) by modifying a previously reported method.…”

Ambient Aqueous-Phase Synthesis of Copper Nanoparticles and Nanopastes with Low-Temperature Sintering and Ultra-High Bonding Abilities

“…Therefore, studies utilizing inexpensive copper as nanoinks for circuit-forming materials and bonding materials instead of silver nanoparticles have expanded 30–34 because the thermal conductivity of bulk copper is 398 W·m −1 ·K −1 . To date, various methods, such as hydrazine reduction 2,35,36 , polyol reduction 37–41 , thermal decomposition 42 , and electrochemical reduction 30 , have been proposed for the synthesis of copper nanoparticles (NPs) with low-temperature sintering ability. Despite extensive efforts by researchers, the above-mentioned methods require the use of polymers and surfactants to control the diameter of copper NPs and prevent aggregation in organic solvents.…”

Synthesis of copper nano/microparticles via thermal decomposition and their conversion to copper oxide film

“…They synthesized 40 g of monodisperse iron oxide (magnetite) nanocrystals by heating iron-oleate complex slowly in 1-octadecene up to 320 °C. Various copper complexes such as copper-oleate [ 11 – 13 ], copper cupferrate [ 14 ], copper oxalate [ 15 , 16 ], copper acetylacetonate [ 17 , 18 ], bis(salicylaldiminato)copper(II) [ 19 ], N,N-diethyl-diaminopropane-copper(II) oxalate [ 20 ], copper-bis(1(2)H-tetrazol-5-yl)amine [ 21 ], bis(triphenylphosphine)copper(I) 2-(2-(2-methoxyethoxy)ethoxy)acetate [ 22 ], and copper(II) dialkylamino alkoxide [ 23 ] were thermally decomposed to produce copper nanoparticles in solvent or solvent-free media.…”