Counterions effect on uracil-silver coordination

• Published in: Inorganica Chimica Acta 2019-05, Vol.490, p.246-253
• Main Authors: Tahirbegi, I. Bogachan, Pérez, Yolanda, Mir, Mònica, Samitier, Josep
• Format: Article
• Language: English
• Subjects: Complex formation; Coordination complex; Coordination compounds; Cyanide process; Electrodeposition; Electrometallization; Electroplating; Low cost; Metal complex; NMR spectroscopy; Silver; Silver compounds; Silver electrodeposition; Toxicity; Uracil
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2019.03.028

In this work, we studied a hitherto unknown phenomenon on the diverse structures formation of silver uracil complex due to the presence of different alkaline counterions. The distinct structuration of this complex clearly impact on the efficiency and deposition yields of silver electroplating. [Display omitted] •Uracil based electroplating is a harmless and low cost silver deposition method.•The unknown behavior of base solutions in the of Ag-uracil complex was studied.•The counterions key role in the complexetion and deposition of Ag was studied.•Counterions forms different structures, resulting in different Ag deposition yields.•Complexes were characterised by FT-IR, UV–vis, DRUV–vis, multi-nuclear NMR and CV. Cyanide based silver electroplating is a low-cost reliable and well-established process for metal deposition. However, delicate handling during the process is needed because of the high toxicity of cyanide, for the persons and the environment. Uracil based silver electrodeposition got the attention of this field, because of its low cost and non-toxic nature. However, little is known about the silver complexation with uracil and the process behind the silver electroplating. In this work, we studied a hitherto unknown phenomenon on the diverse structure’s formation of silver uracil coordination complex due to the presence of different alkaline counterions. The distinct structuration of this complex clearly impacts on the efficiency and deposition yields of silver electroplating. We demonstrate the unknown key role that play hydroxide counterions in the uracil-silver coordination, and the different molecular structures created on the basis of the used counterion. The hydroxide counterion determines monomeric and polymeric complex formation with silver, which affects the solubility of the uracil silver complex and its subsequent electrodeposition. The different molecular complexes were characterized by FT-IR, UV–vis, DRUV–vis and multi-nuclear NMR spectroscopy and the silver electrodeposition by cyclic voltammetry and TOF-SIMS. This study sheds some light in the improvement of silver electroplating process.