Nicolas Kerbellec

Structural and Luminescent Properties of Micro- and Nanosized Particles of Lanthanide Terephthalate Coordination Polymers

Reaction in water between rare earth ions (Ln = Y, La-Tm, except Pm) and the sodium salt of terephthalic acid leads to a family of lanthanide-based coordination polymers of general formula [Ln2(C8H4O4)3(H2O)4] n with Ln = La-Tm or Y. The isostructurality of the compounds with the previously reported Tb-containing polymer is ascertained on the basis of their X-ray powder diffraction diagrams. The coordination water molecules can be reversibly removed without destroying the crystal structure for compounds involving one of the lighter lanthanide ions (La-Eu). For compounds involving one of the heavier lanthanide ions (Tb-Tm) or yttrium, a structural change occurs during the drying process. X-ray diffraction data show this new anhydrous phase corresponding to the linking of pairs of Er(III) ions through mu-carboxylate bridges. Porosity profiles calculated for the anhydrous phases of Tb(III) and Er(III) show the presence of channels with very small sections. The luminescent properties of all the compounds have been recorded and the two most luminescent polymers, namely, the europium- and the terbium-containing ones, have been studied in more detail. Tb(III)-containing compounds display large quantum yields, up to 43%. Polyvinylpyrrolidone nanoparticles doped with [Ln2(C8H4O4)3(H2O)4] n (Ln = Eu, Tb, Er) have also been synthesized and characterized. The encapsulation of the coordination polymers results in somewhat reduced luminescence intensities and lifetime, but the nanoparticles can be dispersed in water and remain unchanged in this medium for more than 20 h.

An unprecedented family of lanthanide-containing coordination polymers with highly tunable emission properties.

Reactions in water between mixtures of rare earth ions (Ln =Y, La-Tm, except Pm) and the sodium salt of terephthalic acid lead to an infinite family of isostructural heteropolynuclear coordination polymers. The monophasic character of the synthesized powders as well as the isostructurality of the heteropolynuclear compounds with the previously described mononuclear [Tb(2)(C(8)H(4)O(4))(3)(H(2)O)(4)](infinity) are ascertained on the basis of the X-ray powder diffraction diagrams. One family of heterodinuclear compounds has been studied in detail, that is, [(La(2-x)Y(x))(C(8)H(4)O(4))(3)(H(2)O)(4)](infinity) with 0 < or = x < or = 2. This study demonstrates the random character of the spatial distribution of the metallic ions. In order to demonstrate the high modularity of the physical properties, the solid-state luminescent properties of the compounds of general formula [(Eu(2-x)Tb(x))(C(8)H(4)O(4))(3)(H(2)O)(4)](infinity) with 0 < or = x < or = 2 have been studied and compared to those of the corresponding mixtures of [(Eu(2))(C(8)H(4)O(4))(3)(H(2)O)(4)](infinity) and [(Tb(2))(C(8)H(4)O(4))(3)(H(2)O)(4)](infinity). In order to confirm the general character of these studies, the compound containing in equal proportions all 13 rare earth ions between La and Tm (except Pm) plus Y has been synthesized and characterized. At last, the solid-state luminescent properties of compounds belonging to the ternary system [(Ce(2-x-y)Eu(x)Tb(y))(C(8)H(4)O(4))(3)(H(2)O)(4)](infinity) with x + y < or = 2 are briefly described.

Syntheses, Crystal Structures, and Gas Storage Studies in New Three-Dimensional 5-Aminoisophthalate Praseodymium Polymeric Complexes

The hydrothermal reaction of 5-aminoisophthalic acid and praseodymium oxide in different acids results in two new praseodymium coordination polymers, {Pr(2)(aip)(3)(H(2)O)(2) x 3 H(2)O}(n) (1) and {Pr(2)(Haip)(2)(aip)(NO(3))(2) x 8 H(2)O}(n) (2) (aip = 5-aminoisophthalate). Complexes 1 and 2 are two distinct three-dimensional metal-organic frameworks constructed from the linkage of rod-shaped praseodymium carboxylate secondary building units and phenyl rings. Both dehydrated coordination frameworks are estimated using a computational method based on Connollys algorithm, indicating that dehydrated compound 1 cannot host molecules other than water molecules or He, whereas dehydrated compound 2 is able to host molecules with kinetic radii as big as 2.3 A. The potential specific accessible surface of this compound is 792 m(2) g(-1). Meanwhile, N(2) sorption measurements reveal that dehydrated compound 2 having a high 230 cm(3)/g (287 mg/g) N(2) storage capacity at 77 K and 1 atm is in fairly good agreement with our calculation results. Moreover, powder X-ray diffraction measurement results demonstrated that the stable channels of dehydrated compound 2 can reversibly host other small solvent molecules (e.g., water, methanol, and ethanol) and grand canonical Monte Carlo simulation is applied to predict its hydrogen storage capacity.

Luminescent lanthanide-based hybrid coatings deposited by atmospheric pressure plasma assisted chemical vapour deposition

A new atmospheric pressure plasma route toward the formation of smart hybrid coatings is presented. As an example, luminescent lanthanide-containing coordination polymers were embedded in a silica matrix.