Application of the Metal–Organic Framework [Eu(BTC)] as a Luminescent Marker for Gunshot Residues: A Synthesis, Characterization, and Toxicity Study

The 3D metal–organic framework (MOF) [Eu­(BTC)] (where BTC = trimesic acid) was synthesized in 20 min by a microwave-assisted hydrothermal method with a yield of 89%. A structural and spectroscopic study, performed by X-ray diffraction, thermogravimetry, and photoluminescence spectroscopy, showed that this framework has high crystallinity, thermal stability, and luminescence. This MOF had a red-orange luminescence when excited with ultraviolet (UV) radiation (λ = 254 nm) and a high potential for use as a luminescent marker for gunshot residues (GSR). When added to 9 mm nontoxic ammunition, it greatly improved quality of the crime scene investigation, allowing for direct visualization of the luminescent GSR on the shooter’s hand and firearm and at the firing range using only a portable UV lamp. The marked luminescent GSR was easily collected and characterized by nondestructive techniques, including with a Video Spectral Comparator and scanning electron microscopy/energy-dispersive spectroscopy, wherein the presence of Eu³⁺ ions was confirmed. Furthermore, the oral acute toxicity of this MOF was assessed in adult female Wistar rats using the Organisation for Economic Cooperation and Development 423 guidelines. This study classified the MOF [Eu­(BTC)] in a less toxic Globally Harmonized System category (category 5), with a LD₅₀ (lethal dose) of 5000 mg/kg, ensuring a wide security range for its application

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