Leonis L. da Luz

Inkjet Printing of Lanthanide–Organic Frameworks for Anti-Counterfeiting Applications

Photoluminescent lanthanide-organic frameworks (Ln-MOFs) were printed onto plastic and paper foils with a conventional inkjet printer. Ln-MOF inks were used to reproduce color images that can only be observed under UV light irradiation. This approach opens a new window for exploring Ln-MOF materials in technological applications, such as optical devices (e.g., lab-on-a-chip), as proof of authenticity for official documents.

Controlling the energy transfer in lanthanide–organic frameworks for the production of white-light emitting materials

Visible color tunable and white-light emitting Ln-MOFs were obtained via layer-by-layer epitaxial growth of different [Ln2(Mell)(H2O)8] compounds, where Mell is mellitate anion and Ln = Eu3+, Tb3+ and Gd3+. The RGB-MOF, RBG-MOF, BRG-MOF and BGR-MOF materials exhibit white-light emission and CIE coordinates (0.337, 0.336), (0.339, 0.330), (0.338, 0.337) and (0.333, 0.336), upon excitation at 361, 347, 378 and 360 nm, respectively. These values are very close to the standardized value of (0.33, 0.33).

Supramolecular luminescent hydrogels based on β-amino acid and lanthanide ions obtained by self-assembled hydrothermal reactions

Using the hydrothermal method, we obtained new hydrogels based on lanthanide ions and iminodiacetic acid. The hydrogels of europium and terbium show reddish and greenish luminescence, respectively. A mixed Eu–Tb gel system was prepared and the luminescent properties were studied.

Lanthanide-Organic Gels as a Multifunctional Supramolecular Smart Platform

A multifunctional smart supramolecular platform based on a lanthanide-organic hydrogel is presented. This platform, which provides unique biocompatibility and tunable optical properties, is synthesized by a simple, fast, and reproducible eco-friendly microwave-assisted route. Photoluminescent properties enable the production of coated light-emitting diodes (LED), unique luminescent barcodes dependent on the excitation wavelength and thin-films for use in tamper seals. Moreover, piroxicam entrapped in hydrogel acts as a transdermal drug release device efficient in inhibiting edemas as compared to a commercial reference.

Urchin-like artificial gallium oxide nanowires grown by a novel MOCVD/CVD-based route for random laser application

A novel procedure based on a two-step method was developed to obtain β-Ga2O3 nanowires by the chemical vapor deposition (CVD) method. The first step consists in the gallium micro-spheres growth inside a metal-organic chemical vapor deposition environment, using an organometallic precursor. Nanoscale spheres covering the microspheres were obtained. The second step involves the CVD oxidization of the gallium micro-spheres, which allow the formation of β-Ga2O3 nanowires on the micro-sphere surface, with the final result being a nanostructure mimicking natures sea urchin morphology. The grown nanomaterial is characterized by several techniques, including X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, transmission electron microscopy, and photoluminescence. A discussion about the growth mechanism and the optical properties of the β-Ga2O3 material is presented considering its unknown true bandgap value (extending from 4.4 to 5.68 eV). As an application, the scattering properties of t...