Abstract: In this paper, syntheses and properties of solid tertiary coordination compounds of the title compound (1-2-4-acid, ANSH) with rare earths and o-phenanthro-line (Phen) were studied.The four coordination compounds obtained were confirmed as [RE(ANS)₂· Phen] Cl·xH₂O, for La and Nd, x= 1, for Eu, x = 2, for Ho, x = 5. Comparison of their IRspectra with that of ANSH, three conclusions can be drawn:1) intermolecular H-bond of ligand ANSH is ruptured accompanying formation of coordination compound, 2) proton dissociation of sulfonic acid group occurred,3) OHgroup probably participated in coordination.The characteristic ¹H NMRshifts belonging to Phen shifted to high field in the coordination compounds. This shows the participation of N-atom in Phen in coordination with REion, which in turn decreases both the aromaticity of Phen and descreening action of π-electron cloud in benzene ring. The fluorescence spectra showed the decreasing of aromaticity of Phen after coordination. The thermogram shows the higher thermal stability of coordination compounds. Different 2θ and I/I₀ values in the X-ray diffraction pattern show the formation and the similarity of new coordination compounds. The coordination compounds obey activation type electric conduction pattern, so that they are a good class of semiconducting materials.

Key words: 1-Amino-2-Naphthol-4-Sulfonic acid(ANSA), o-Phenanthroline (Phe.n), Rare earth ternary complexes