Two new supramolecular metal diphosphonates: Synthesis, characterization, crystal structure and inhibiting effects on metallic corrosion

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• 作者：Khodayar Gholivand^a ; ^{gholi_kh@modares.ac.ir" class="auth_mail" title="E-mail the corresponding author} ; Rouhollah Yaghoubi^a ; Alireza Farrokhi^b ; Shahram Khoddami^c
• 关键词：Metal phosphonates ; Crystal structures ; Corrosion ; Inhibition ; Layered materials
• 刊名：Journal of Solid State Chemistry
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：243
• 期：Complete
• 页码：23-30
• 全文大小：2714 K

文摘

Two new divalent metal(II) aminodiphosphonates with layered structure, namely, Cu(H₃L¹)₂·2H₂O (1), [H4L¹=methyl-N(CH₂PO₃H₂)₂] and Cd₂(H₂L²)₄(2), [H₄L²=n-propyl-N(CH₂PO₃H₂)₂] were synthesized and characterized. The Cu(II) ions in complex 1 are octahedrally coordinated by four oxygen atoms from two chelating ligands and two phosphonate oxygen atoms from two neighboring Cu(H₃L¹)₂ units. The Cu(H₃L¹)₂ units are interconnected by bridging phosphonate groups, forming a 2-D metal phosphonate layer. The structure of complex 2 contains two unique Cd(II) ions octahedrally-coordinated by six phosphonate oxygen atoms from four H₂L² diphosphonate anions. Corrosion inhibition performances of 1 and 2 were also compared with each other in order to study the effect of combinations of externally added Cd/H₄L² and Cu/H₄L¹ (1:1 ratio) on corrosion rates of carbon steel. It was found that at pH 3.0, Cd/H₄L² or Cu/H₄L¹ combinations do not have noticeable corrosion inhibition efficiency for carbon steel. In contrast, at pH 7.0, higher corrosion inhibition efficiency was achieved for Cd/H₄L². Physical characterizations such as scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were applied to study the corrosion specimens and film material.