Open AccessThermodynamics of Self‐Assembly of Dicarboxylate Ions with Binuclear Lanthanide Complexes
Author(s) -
Sørensen Thomas Just,
Hill Leila R.,
Faulkner Stephen
Publication year - 2015
Publication title -
chemistryopen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 29
ISSN - 2191-1363
DOI - 10.1002/open.201500060
Subject(s) - europium , chemistry , aqueous solution , lanthanide , potentiometric titration , isophthalic acid , inorganic chemistry , medicinal chemistry , stereochemistry , ion , organic chemistry , polyester , terephthalic acid
Self‐assembly of a range of carboxylic acids (benzoic acid, dinicotinic acid, nicotinic acid, and isophthalic acid) with the europium complex of 5‐nitro‐α,α′‐bis(DO3Ayl)‐ m ‐xylene (where DO3A is 1,4,7,10‐tetraazacyclododecane‐1,4,7‐triacetic acid) has been explored to establish the thermodynamics of binding in a range of solvent systems and in a range of aqueous buffer solutions. In this system, profound effects are observed as a consequence of competition by the hydroxide ion, which outcompetes even dinicotinate at high pH. In the case of isophthalate, which binds most strongly, and dinicotinate, both enthalpic and entropic contributions to binding have been identified. The europium complex with 5‐nitro‐α,α′‐bis(DO3Ayl)‐ m ‐xylene is found to have a solution structure significantly different from the related europium complex of 5‐amino‐α,α′‐bis(DO3Ayl)‐ m ‐xylene. It is found that phosphate binds strongly to the europium complex of the nitro derivate but not to the europium complex of amino derivative. Lactate, citrate, and pyruvate also bind strongly to 5‐nitro‐α,α′‐bis(Eu⋅DO3Ayl)‐ m ‐xylene, and it is concluded that the solution structure of this binuclear lanthanide complex is significantly different from that of the amino‐substituted complex.