NANOPARTICLES OF TWO NEW LANTHANUM(III) COMPLEXES: SYNTHESIS AND CHARACTERIZATION

The nanoparticles of two new lanthanum(III) nitrate complexes with formula La(NO3)3 [C6H5C(O)NHP(O)(NC4H8NC6H5)2]2 (1) and La(NO3)3[C6H5C(O)NHP(O)(NC4H8NC(O)OEt)2]2 (2) were synthesized by ultrasonic technique. The two complexes were characterized by 1H, 13C, 31P{1H} NMR, FT–IR, UV-Visible, fluorescence, FE–SEM microscopy and elemental analysis. The two complexes are eight coordinated in which the two phosphoramides are attached to the central La ion from the phosphoryl oxygen atom contributing in the O=P bond. The 31P{1H} NMR spectra reveal that the phosphorus chemical shift of complex 1 appears at slightly up field region (9.77 ppm) compared with that of 2 (10.37 ppm) confirming the P atom is slightly more shielded in 1 than in 2. The UVVisible spectra illustrate that the maximum absorption peaks are observed within the range of ~270–290 nm for both complexes 1 and 2 that can be related to the ligand to metal charge transfer (LMCT) or metal to ligand charge transfer (MLCT) transitions. Comparing the band gaps of complexes 1 and 2 (3.53 and 3.08 eV, respectively) measured from the fluorescence spectra reflects that the electron conductivity is easier in 2 due to its smaller gap. The FE-SEM images of complexes 1 and 2 indicate that the particles have spherical morphology and their average particle sizes are within the range of ~40–100 nm.

Keywords:

Lanthanum(III) complex , Nanoparticle , Ultrasonic synthesis , Phosphoramide , NMR , Fluorescence