Fine-Tuning Ligand-Receptor Design for Selective Molecular Recognition of Dicarboxylic Acids

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• 作者：Arnau Arbuse ; Carmen Anda ; Ma Angeles Martí ; nez ; Javier P&eacute ; rez-Miró ; n ; Carlos Jaime ; Teodor Parella ; Antoni Llobet
• 刊名：Inorganic Chemistry
• 出版年：2007
• 出版时间：December 10, 2007
• 年：2007
• 卷：46
• 期：25
• 页码：10632 - 10638
• 全文大小：384K
• 年卷期：v.46,no.25(December 10, 2007)
• ISSN：1520-510X

文摘

The host-guest interaction between the hexaaza macrocyclic ligand 3,7,11,18,22,26-hexaazatricyclo[26.2.2.2^13,16]tetratriaconta-1(31),13(34),14,16(33),28(32),29-hexaene (P3) and three rigid dicarboxylic acids (isophthalic acid,H₂is; phthtalic acid, H₂ph; and terephthalic acid, H₂te) has been investigated using potentiometric equilibrium methodsand NMR spectroscopy including the measurement of intermolecular nuclear Overhauser effects (NOEs) and self-diffusion coefficients (D). Ternary complexes are formed in aqueous solution as a result of hydrogen bond formationand Coulombic interactions between the host and the guest. In the [(H₆P3)(is)]⁴⁺ complex, those bonding interactionsreach a maximum yielding a log K₆^R of 4.74. Competitive distribution diagrams and total species distribution diagramsare used to illustrate the main features of these systems. In particular, a selectivity of over 89% at p[H] = 5.0 isobtained for the complexation of the is versus the te substrates. The recognition capacity of P3 over dicarboxylicacids (da) is compared to the related hexaaza macrocycle Me₂P3 (7,22-dimethyl-3,7,11,18,22,26-hexaazatricyclo[26.2.2.2^13,16]tetratriaconta-1(30),13,15,28,31,33-hexaene) that binds da with a lesser strength, and it is not selective.Theoretical calculations performed at molecular dynamics level have also been carried out and point out that theorigin of selectivity is mainly due to the capacity of the P3 ligand receptor to adapt to the geometry of the dicarboxylicacid to form relatively strong hydrogen bonds.