PEI functionalized NaCeF4:Tb3+/Eu3+ for photoluminescence sensing of heavy metal ions and explosive aromatic nitro compounds

Analytical Tools and Methods for Explosive Analysis in Forensics: A Critical Review

This review summarizes (i) compositions and types of improvised explosive devices; (ii) the process of collection, extraction and analysis of explosive evidence encountered in explosive and related cases; (iii) inter-comparison of analytical techniques; (iv) the challenges and prospects of explosive detection technology. The highlights of this study include extensive information regarding the National & International standards specified by USEPA, ASTM, and so on, for explosives detection. The holistic development of analytical tools for explosive analysis ranging from conventional methods to advanced analytical tools is also covered in this article. The most important aspect of this review is to make forensic scientists familiar with the challenges during explosive analysis and the steps to avoid them. The problems during analysis can be analyte-based, that is, interferences due to matrix or added molding/stabilizing agents, trace amount of parent explosives in post-blast samples and many more. Others are techniques-based challenges viz. specificity, selectivity, and sensitivity of the technique. Thus, it has become a primary concern to adopt rapid, field deployable, and highly sensitive techniques.

Dual-Ligand Strategy Employing Rigid 2,5-Thiophenedicarboxylate and 1,10-Phenanthroline as Coligands for Solvothermal Synthesis of Eight Lanthanide(III) Coordination Polymers: Structural Diversity, DFT Study, and Exploration of the Luminescent Tb(III) Coordination Polymer as an Efficient Chemical Sensor for Nitroaromatic Compounds

Lanthanide coordination polymers (Ln-CPs) are potential chemosensors when fabricated to depict a detectable change in optical properties on interaction with target analytes. This work investigates the interaction of nitroaromatic compounds with Ln-CPs leading to induced changes in fluorescence emission intensity, a crucial strategy to develop a selective and sensitive system for the sensing of nitroaromatics. Approaching toward this objective, solvothermal reactions of 2,5-thiophenedicarboxylic (2,5-TDC) acid, 1,10-phenanthroline (1,10-Phen), and Ln(NO3)3·xH2O are carried out to assemble eight Ln(III) coordination polymers [Ln2(2,5-TDC)3(1,10-Phen)2(H2O)2] [Ln = Pr (1), Nd (2)], {[Tb(2,5-TDC)1.5(1,10-Phen)(H2O)]·DMF} (3), and [Ln(2,5-TDC)1.5(1,10-Phen)]·xH2O (Ln = Tb (4), Dy (5), Ho (6), Er (7), and Yb (8)); x = 0 for CP 4, 5, 6, and 8 and x = 1 for CP 7 with two different space groups and dimensions. The as-synthesized polymers 1-8 are characterized by powder X-ray crystallography, infrared spectroscopy, and thermogravimetric analysis. The structure-corroborated density functional theory (DFT) studies are done on the selected CPs to investigate the interactions between different structural motifs of the assembled CPs. The luminescence properties of CP 4 are explored in detail and are found to be highly sensitive for the detection of p-nitrotoluene as indicated by the most intensive fluorescence quenching with the lowest limit of detection (0.88 ppm) and high quenching constant (4.3 × 104 M-1). Other nitro compounds (viz., o-nitrobenzaldehyde, m-nitroaniline, picric acid, m-dinitrobenzene, p-nitrophenol, and p-nitroaniline) are also screened for potential sensing by CP 4.