Lanthanide-Based Lamellar Nanohybrids:  Synthesis, Structural Characterization, and Optical Properties

Abstract

A general nonaqueous route has been applied for the preparation of lanthanide ordered nanocrystalline hybrid structures. In a simple one-pot reaction process, Ln(III) isopropoxides (Ln = Gd, Sm, Nd) were dissolved in benzyl alcohol and reacted in an autoclave between 250 and 300 °C. This approach leads to crystalline lanthanide oxide layers regularly separated from each other by organic layers of intercalated benzoate molecules. They display good thermal stability for temperature up to 400 °C. The gadolinium-based nanohybrids showed outstanding optical emission properties when doped with terbium(III) and europium(III).

Efficient and tuneable photoluminescent boehmite hybrid nanoplates lacking metal activator centres for single-phase white LEDs

“…11), revealing the presence of four components in the ultraviolet at 255, 285, 340 and 365 nm. The excitation components at 285 and 365 nm have already been observed for analogous benzoate-capped nanoparticles 41,43 , being ascribed to the singlet excited states (S 2 and S 1 , respectively) of the phenyl rings. The components at 255 and 340 nm are assigned to the boehmite phase.…”

“…1a). The peaks at 1,602, 1,496 and 1,452 cm À 1 appearing in all the samples are associated with the C ¼ C stretching modes of the phenyl rings [41][42][43] . The two absorptions centred at 1,510 and 1,432 cm À 1 are due to the asymmetric (n as ) and symmetric (n s ) stretching vibrations of carboxylate group (-COO À ) associated with the benzoate moieties bound to the particle surface.…”

“…This is achieved by the development of hybrid organic-inorganic nanoparticles based on boehmite prepared by a one-pot non-aqueous approach. The synthesis relies on the 'benzyl alcohol route' [39][40][41][42][43] procedure involving the reaction of aluminium isopropoxide in benzyl alcohol at temperatures above 300°C. The reaction procedure readily gives access to few-nm thick boehmite nanoplates capped with in situ-formed benzoate ligands.…”

Nonaqueous Sol–Gel Routes to Metal Oxide Nanoparticles

“…49,50 A mechanism in which hydride-transfer reactions form benzoic acid and toluene from benzyl alcohol via benzaldehyde, catalyzed by the growing metal oxide species, was proposed. The benzoate molecules obviously restrict the growth of the metal oxide and direct their assembly into the hybrid structure.…”

“…As a representative example, Figure 3a shows TEM images of the neodymium oxidebenzoate nanohybrid. 50 However, benzoate molecules formed in situ are also able to induce the growth of nanoparticles with a one-dimensional morphology. The reaction of lanthanum isopropoxide in a mixture of benzyl alcohol and 2-butanone in the presence of potassium permanganate yielded La(OH) 3 nanoparticles with a fibrous shape (Figure 3b).…”