|
KMID : 1059519990430060628
|
|
Journal of the Korean Chemical Society
1999 Volume.43 No. 6 p.628 ~ p.635
|
|
|
Chemical Equilibria of Lanthanides{Ln=Pr,Sm,Gd,Dy}-Macrocyclic Complexes with Auxiliary Ligands in CH3OH(Part ll): Study of the Coordination of Oxygen-Containing Bases
|
|
Byun Jong-Chul
Park Yu-Chul
Han Chung-Hun
|
|
|
Abstract
|
|
|
|
Direct preparative method of 2,6-diformyl-p-cresol and 2-hydroxy-3-hydroxy-5-methylbenzaldehyde from 2,6-bis(hydroxymethyl)-4-methylphenol using activated Mn(IV)O2, was described. Hexadentate compartmental Iigands, H4L[A] and H4L[B] were prepared by condensation reactions of 2-hydroxy-3-hydroxy methyl-5-methylbenzaldehyde with ethylenediamine and 1,3-diaminopropane respectively. By the reaction of macrocycle(H4[20]DOTA) with Ln(III) nitrate {Ln(III)=Pr, Sm, Cd, Dy }, discrete mononuclear Ln(III) complexes of the type [Ln(H2[20]DOTA)(Cl04)(H2O)]·3H20 were synthesized in the solid state. [Ln([20]DOTA)(N03)(H2O)](NO3)2·xH2O was placed in methanol for 2 days, and [Ln([20]DOTA)(N03)(CH30H)]2+ was formed, The equilibrium constants(K) for the substitution of coordinated CH3OH in the Ln-[20]DOTA complexes by various auxiliary ligand, La(=salicylic acid, p-chlorobenzoic acid, benzoic acid, acetic acid. 4-bromophenol) were determined spectroscopically at 25℃ and 0.1M NaCl04. The K values calculated were in the order of salicylic acid > p-chlorobenzoic acid > benzoic acic > acetic acid > 4-bromophenol, while pKa of auxiliary ligands was in the opposite trend.
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|