title: Synthesis, structure and optical properties of rare-earth benzene carboxylates.
abstract: Two series of rare-earth isophthalates of the general formula, [M(2)(H(2)O)][{C(6)H(4)(COO)(2)}(2){C(6)H(4)(COOH)(COO)}(2)].H(2)O, M=La (I), Pr (Ia), and Nd (Ib) and [M(2)(H(2)O)(2)][{C(6)H(4)(COO)(2)}(3)].H(2)O, M=Y (II), Gd (IIa), and Dy (IIb) have been prepared by the reaction of the corresponding trivalent lanthanide salts and isophthalic acid under mild hydrothermal conditions. The La (I), Pr (Ia) and Nd (Ib) have MO(9) polyhedra connected to the isophthalate anions forming a two-dimensional structure, whereas Y (II), Gd (IIa) and Dy (IIb) have MO(7) and MO(8) polyhedral units connected to the isophthalate anions forming a different, but related two-dimensional structure. Both the structures are stabilized by hydrogen bonding and pi...pi/CH...pi interactions. Partial substitution of Eu and Tb (2 and 4%) at the La (I) and Y (II) sites give rise to characteristic red/pink or green luminescence, indicating a ligand-sensitized metal-centered emission. The Nd (Ib) compound shows interesting UV and blue emission through an up-conversion process.
authors.affiliation: Framework Solids Laboratory, Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560 012, India.
authors.forename: Partha
authors.initials: P
authors.lastname: Mahata
authors.forename: K V
authors.initials: KV
authors.lastname: Ramya
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Natarajan
mesh_terms: D001554:Benzene / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry*; D018360:Crystallography, X-Ray / Q000379:methods; D005682:Gadolinium / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D028581:Lanthanoid Series Elements / Q000737:chemistry; D008024:Ligands; D008670:Metals / Q000737:chemistry; D008674:Metals, Rare Earth / Q000737:chemistry*; D008968:Molecular Conformation; D055095:Optics and Photonics; D010777:Photochemistry / Q000379:methods; D017785:Photons; D013055:Spectrophotometry, Infrared / Q000379:methods; D014466:Ultraviolet Rays