Solution and solid-state studies of a new supramolecular proton transfer salt and its VO₂ complex constructed with chelidamic acid and 3,4-diaminopyridine

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• 作者：Hadis Shams ; Zohreh Derikvand ; Michal Dusek&#8230
• 关键词：Chelidamic acid ; Proton transfer compound ; Potentiometric study ; Stability constant ; Crystal structure
• 刊名：Journal of the Iranian Chemical Society
• 出版年：2017
• 出版时间：April 2017
• 年：2017
• 卷：14
• 期：4
• 页码：811-822
• 全文大小：
• 刊物主题：Analytical Chemistry; Inorganic Chemistry; Physical Chemistry; Biochemistry, general; Organic Chemistry;
• 出版者：Springer Berlin Heidelberg
• ISSN：1735-2428
• 卷排序：14

文摘

The proton transfer compound (Hdap)(chelH)·2H₂O (1) and its related anionic complex (Hdap) [VO₂(chel)] (2), where chelH₂ = 4-hydroxypyridine-2,6-dicarboxylic acid (chelidamic acid) and dap = 3,4-diaminopyridine, were synthesized and characterized by elemental analysis, spectroscopy (IR, UV–Vis), thermal (TG/DTG) analysis and single-crystal X-ray diffraction. Compound 1 resulted from proton transfer between chelH₂ and dap in aqueous solution. In 1, two carboxylic acids of chelH₂ were deprotonated and the protons transferred to the nitrogen atoms of one chelidamate anion and one dap moiety. Compound 2 resulted from complexation of 1 and vanadyl sulfate. In the crystal structure of 2, the metal ion is five coordinated by one tridentate ligand (chel)2− and two O2− anions, with (Hdap)+ as a counter cation. In both structures, a complicated hydrogen-bonding network accompanied with π–π, C–O···π and C–H···π stacking interactions leads to formation of a 3D supramolecular network. In the following, solution studies have been performed by means of pH potentiometric titrations method as a power technique. This method was used for determination of protonation constants of chelH₂ and dap in their probable protonated forms and for calculation of equilibrium constants for the chelH₂–dap proton transfer system and the stoichiometry and stability constants of binary and ternary complexes of this system with VO2+ ion in aqueous solution. The stoichiometries of the most complex species in solution were compared with the corresponding crystalline complexes in the solid state.