ULTRASONIC SYNTHESIS OF NANOPARTICLES OF TWO NEW LANTHANUM(III) COMPLEXES

The ultrasonic method was used for the synthesis of two new nanosized eight coordinated lanthanum(III) nitrate complexes with formula La(NO3)3[P(O)(NC4H8NC(O)OEt)3]2 (1) and La(NO3)3[C6H5C(O)NHP(O)(NC5H9C(O)OEt)2]2 (2) were synthesized by. The two complexes were characterized by 1H, 13C, 31P{1H} NMR, FT–IR, UV-Visible, fluorescence, FE–SEM microscopy and elemental analysis. In both complexes, the two phosphoramides are attached to the central La(III) ion from the phosphoryl oxygen atom contributing in the O=P bond. The 31P{1H} NMR spectra illustrate that the 31P chemical shift of complex 1 appears at very much down field region (19.28 ppm)compared with that of 2 (9.46 ppm) indicating the phosphorus nulceos is much more deshielded in 1 than in 2. The 13C NMR spectrum of 2 presents two 2JP-C coupling constants equal to 4.4 and 4.6 Hz as well as one 3JP-C = 2.9 Hz are measured for the splitting of carbon atoms related to the endocylic CH2 groups with the phosphorus atom indicating the value of 3JP-C is smaller than those of 2JP-C. The FT-IR spectra indicate that the ν(P=O) of compounds 1 and 2 (1130 and 1165 cm-1) are weaker than those of their corresponding phosphoramide ligands (1200 for I and 1186 cm-1 for II) which are because ofcoordinative binding of oxygen loan pair in the P=O bonds to the La atoms. The UV-Visible 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 (3.09 and 2.99 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 about 40–60 and 70–90 nm respectively

کلیدواژه ها:

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