Eu(fod) 3 binding on the 1 H‐NMR spectra of bis (2′‐ethylbenzoate)ethylene glycol podands

The complexing and selective binding constants of Eu(fod) 3 with bis (2′‐ethylbenzoate)ethylene glycol podands having one to four oxyethylene groups was observed on their 1 H‐NMR spectra at 250 MHz and 295 K in CDCl 3 . The Eu(fod) 3 interaction displayed the selective binding role of oxygen on H 2 C–O–CH 2 backbones with referring the 1 H chemical shifts. The estimated equilibrium constants, K a , of 1:1 ratio of interactions were in accordance with the Eu(fod) 3 ionic radii to bind the oxygen sites depending on the size and conformation of the esters. Esters having one or two ethyleneoxy groups gave mainly 2:2 complexes using ester sites. The minimum lanthanide‐podand ester distance displayed the maximum stability so that ester with four oxyethylene groups was found to bind the Eu(fod) 3 moderately, whereas ester with three oxyethylene groups showed a large induced chemical shift due to the stability of Eu 3+ complexes with larger ethyleneoxy groups. Copyright © 2012 John Wiley & Sons, Ltd.