%0 Journal Article
%T Synthesis, Characterization of La(III), Nd(III), and Er(III) Complexes with Schiff Bases Derived from Benzopyran-4-one and Thier Fluorescence Study
%A Aida L. El-Ansary
%A Nora S. Abdel-Kader
%J International Journal of Inorganic Chemistry
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/901415
%X The Schiff bases, L1, L2, and L3, are synthesized from the condensation of 5,7-dihydroxy-6-formyl-2-methylbenzopyran-4-one (L) with 2-aminopyridine (1), p-phenylenediamine (2), and o-phenylenediamine (3). The prepared Schiff bases react with lanthanum (III), neodymium (III), and erbium (III) nitrate to give complexes with stoichiometric ratio (1£¿:£¿1) (ligand£¿:£¿metal). The binuclear complexes of Er(III) with L3 and the three metal ions with L2 are separated. The complexes have been characterized by elemental analysis, molar conductance, electronic absorption, and infrared, 1H-NMR spectral studies. The presence of hydrated and coordinated water molecules is inferred from thermogravimetric analysis. Thermal degradation studies show that the final product is the metal oxide. The luminescence properties of the Nd(III) and Er(III) complexes in dimethylformamide (DMF) solutions were investigated. 1. Introduction The coordination chemistry of lanthanide (III) ions is rapidly increasing, owing to the relevance of these compounds in basic and applied research in different scientific areas ranging from chemistry to material science to the life science [1¨C8]. Lanthanide coordination compounds are the subject of intense research efforts owing to their unique structures and their potential applications in advanced materials such as Ln-doped semiconductors [9], magnetic [10, 11], catalytic [12], fluorescent [13, 14], and nonlinear optical materials [15, 16]. It has been shown that ligands containing both nitrogen and oxygen donor atoms are good building blocks for the formation of various lanthanide coordination compounds [17¨C24]. Schiff bases continue to occupy an important position as ligands in metal coordination chemistry [25], even almost a century since their discovery. Schiff base metal complexes have played a key role in the development of coordination chemistry, resulting in an enormous number of publications, ranging from pure synthetic work to modern physicochemical and biochemically relevant studies of metal complexes [26]. The lanthanide cations can promote Schiff base condensation and can give access to complexes of otherwise inaccessible ligands. It is essential to design appropriate ligands to optimize the luminescence properties of lanthanide ions by facilitating the well-known light conversion process, which show to be efficient ligand-to-metal energy transfer process [27]. In view of this, we have designed a series of Schiff bases, which can enhance the luminescence properties of lanthanide ions. In the present work, the complexes of rare earth
%U http://www.hindawi.com/journals/ijic/2012/901415/