130190-52-2Relevant academic research and scientific papers
Polycarboxylate diaza crown ethers derived from R,R-(+)-tartaric acid: synthesis and complexation of metal ions
Anantanarayan, Ashok,Fyles, Thomas M.
, p. 1338 - 1351 (2007/10/02)
The synthesis and complexation properties of polycarboxylate diaza crown ethers based on R,R-(+)-tartaric acid are described.Cesium carbonate mediated macrocyclization of a bis-tosylamide precursor with a bis-tosylate precursor provided the protected crown ethers.Photochemical deprotection of the tosylamides and hydrolysis of the carboxamides yielded dicarboxylic and tetracarboxylic acid derivatives of 1,10-diaza-18-crown-6.N-Methylenecarboxylate (N-acetate) derivatives were prepared by N-alkylation with bromoacetic acid.The synthetic and purification procedures developed provide samples of the ligands in a metal-free form.Acidity and stability constants for complexation of alkali metal, alkaline earth, late- and post-transition metal cations were determined by potentiometric titration.The ligands form complexes which show enhancement of stability by charge-charge and chelate interaction with the carboxylates.In comparison with crown ether polycarboxylates these aza crown ethers showed a selectivity for softer metal ions relative to alkali and alkaline earth metal ions.N-Methylenecarboxylate chelate ligands were found to bind almost all types of metal ions, due to a highly co-operative array of charge-charge, chelate and crown ether interactions.
