Study on kinetics and mechanism of mononuclear rare earth metal complexes in promoting the hydrolysis of p-nitrophenyl phosphate (NPP)

✍ Scribed by Huakuan Lin; Qiang Liu; Hai Lin

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 532 KB
• Volume: 259
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/j.molcata.2006.02.040

✦ Synopsis

Two novel tripodal ligands, N,N ,N -tri-(3 -phenylpropionic acid-2 -yl-)-1,3,5-triaminomethylbenzene (L1), N,N ,N -tri-(4 -methylvaleric acid-2 -yl-)-1,3,5-triaminomethylbenzene (L2) have been synthesized. The hydrolytic kinetics of p-nitrophenyl phosphate (NPP) catalyzed by complexes of L1, and L2 with La(III) and Gd(III) have been studied in aqueous solution at 298 K, I = 0.10 mol dm -3 KNO 3 at pH 6.7-8.2, respectively. In the study it is found that the catalytic effect of GdL2 was the best in the four complexes for hydrolysis of HPNP. Its k LnLH -1 , k LnL and pK a are 0.0198 mol -1 dm 3 s -1 , 0.0000187 mol -1 dm 3 s -1 and 7.76, respectively. This paper expounds the result from the structure of the ligands and the properties of the metal ions, and deduces the catalysis mechanism.