Thermodynamics and hydration of the europium complexes of a nitrogen heterocycle methane-1,1-diphosphonic acid.

Journal Article · Sat Jan 01 04:00:00 EST 2000 · J. Chem. Soc., Dalton Trans.

DOI:https://doi.org/10.1039/b004038j· OSTI ID:942935

Jensen, M P; Beitz, J V; Rogers, R D; Nash, K L

The enthalpies for formation of five Eu{sup 3+} complexes with N-piperidinomethane-1,1-diphosphonic acid (H{sub 4}pmdp) have been determined by titration calorimetry in 2 M (Na,H)ClO4 media at 25 {sup o}C. Both protonation enthalpies and entropies, and the structure of H{sub 4}pmdp in the solid state indicate protonation of the piperidine nitrogen to give a zwitterion in the free ligand. Luminescent lifetime measurements show that the formation of the 1:1 and 1:2 Eu:L complexes of a variety of methane-1,1-diphosphonic acids liberates an average of 3.3 {+-} 0.1 water molecules per ligand from the Eu inner hydration sphere. The number of water molecules in the inner coordination sphere and the thermodynamic parameters of the complexes suggest that the structure of the Eu{sup 3+}-pmdp complexes and the strength of the Eu{sup 3+}-pmdp bonds are similar to those of other methane-1,1-diphosphonic acids despite the presence of the piperidine ring. However, the complexation entropies argue for weaker solvation of the Eu-pmdp complexes probably due to the hydrophobic character of the piperidine ring.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 942935
• Report Number(s): ANL/CHM/JA-36063
• Journal Information: J. Chem. Soc., Dalton Trans., Journal Name: J. Chem. Soc., Dalton Trans. Journal Issue: 2000; ISSN 0300-9246; ISSN JCDTBI
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
EUROPIUM COMPLEXES
FORMATION HEAT
HYDRATION
LIGANDS
LUMINESCENCE
MOLECULAR STRUCTURE
PIPERIDINES
SOLVATION
THERMODYNAMICS