Two novel rare earth coordination compounds, (E)-N-hexadecyl-4-(2-4'-dimethylaminophenyl) ethenyl pyridinium 1,6-bis-(1'-phenyl-3'-methyl-5'-pyrazolone- 4')hexanedione [1,6] lanthanum-dysprosium (Ⅲ) have been synthesized and characterized by elemental analysis. UV-Vis, IR, ^1H NMR, TG-DTA analysis, X-ray power diffraction and molar conductivity. The comparison of the surface pressure-area isothems of the comlexes with those of hemicyanine bromide and iodide is made. The Langmuir film-forming properties of the metal complexes are superior to the hemicyanine bromide and iodide. Second-harmonic generation from monolayer film of the dysprosium complex shows that the second-order molecular hyperpolarizability to be 4.8×10^-^4^8C m^3 V^-^2.

Key words: ULTRAVIOLET SPECTROPHOTOMETRY, INFRARED SPECTROPHOTOMETRY, ELEMENTAL ANALYSIS, NMR SPECTROMETRY, RARE EARTH METAL COMPLEX, DIFFERENTIAL THERMAL ANALYSIS, LANTHANUM COMPLEX, DYSPROSIUM COMPLEX