Analysis of Luminescent Gunshot Residue (LGSR) on Different Types of Fabrics.

The collection of gunshot residue on fabric can be an arduous task due to the microscopic size of particles (blind collection) and sheddability of some fabrics. The introduction of luminescent markers and consequent formation of luminescent gunshot residue (LGSR) can facilitate this analysis. In this study, different fabrics were analyzed in order to verify the persistence of the LGSR on them, the possibility of collecting and analyzing particles by video spectral comparator (VSC) and SEM/EDS. Also, different colored fabrics were used as targets in order to investigate influence of fabric color on LGSR visualization. Furthermore, the influence of the fabric type in the distribution of the LGSR deposited around the projectile´s hole entrance was evaluated. The fabric sheddability did not alter collection of the particles or analysis. It was possible to observe and collect LGSR on all tested fabrics, even after the fabric had been shaken, or in colored fabrics.

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.

Ionically tagged iron complex-catalyzed epoxidation of olefins in imidazolium-based ionic liquids.

A new ionophilic ligand and a new ionically tagged imidazolium-based iron(III) complex were synthesized and applied in the air oxidation (also hydrogen peroxide) of alkenes in imidazolium-based ionic liquids. At least ten recycling reactions were performed. The epoxidized olefin was obtained in very good yields of 84-91 %. Some important mechanistic insights are also provided based on electrospray ionization quadrupole-time of flight mass spectrometry for the oxidation reaction. These results indicate that oxidations can take place by two different pathways, depending on the reaction condition: a radical or a concerted mechanism. These results contribute towards a better understanding of iron-catalyzed oxidation mechanisms.