The structures, morphologies, and photophysical properties of multiluminescent layered lanthanide-phosphono-carboxylate nanoparticles

A new family of layered metal(III)-phosphono-carboxylate nanostructures (M=Y, Eu, Tb, Er, and Yb) was hydrothermally synthesized and their structures and morphologies were characterized by X-ray powder diffraction and TEM. 4-Bis(phosphonomethyl)amino]caproic acid and 4- bis(phosphonomethyl)amino]undecanoic acid, with general formula (H(2)O(3)PCH(2))(2)NR (R=C(5)H(10)COOH(P2CAPR) and C(10)H(22)COOH(P2UND), respectively) were used as building blocks for the preparation of novel layered hybrid materials in which the inorganic layers were composed of MO(7) or MO(8) polyhedra and PO(3)C tetrahedra. The interlayer region was occupied by carboxyalkyl chains. These layered compounds were easily dispersed as stable solutions in alkylamine/water upon ultrasonication. These dispersions were constituted of rectangular elongated nanoparticles (NPs), which showed a distribution of sizes ranging from 20-500 nm. These new materials had interesting photophysical properties because they were multiluminescent compounds. These properties gave rise to several emission bands, which were spread over the broad spectroscopic region, from the near-UV up to the near-IR regions. Each emission band had a specific lifetime, which ranged from the sub-ps to the ms scale.