Selective Low-Level Detection of a Perilous Nitroaromatic Compound Using Tailor-Made Cd(II)-Based Coordination Polymers: Study of Photophysical Properties and Effect of Functional Groups.

Three coordination polymers (CPs 1 - 3 ) are prepared based on diverse electron-donating properties and coordination arrangements of conjugated ligands. Interestingly, this is also reflected in their photophysical properties. The distinguishable high emissive nature of the luminescent coordination polymer shows its potentiality toward the detection of the perilous substance 2,4,6-trinitrophenol (TNP) or picric acid (PA). TNP has a higher propensity among explosive nitroaromatic compounds (epNACs) due to its significant π···π interaction with the free benzene moieties present in the CPs. Among CPs 1 - 3 , 2 exhibits the highest sensitivity and selectivity toward TNP because of the most favorable π-π stacking with the conjugated organic linker. The calculated limit of detection (LOD) and corresponding quenching constant ( K SV ) from the Stern-Volmer (SV) plot for 1 , 2 , and 3 are found to be 0.68 μM and 7.49 × 10 4 M -1 , 0.41 μM and 8.01 × 10 4 M -1 , and 1.18 μM and 8.1 × 10 4 M -1 , respectively. The fluorescence quenching mechanism is also highly influenced by their structure and coordination arrangement.