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(NO 3 ) 3 · x H 2 O are carried out to assemble eight Ln(III) coordination polymers [Ln 2 (2,5-TDC) 3 (1,10-Phen) 2 (H 2 O) 2 ] [Ln = Pr ( 1 ), Nd ( 2 )], {[Tb(2,5-TDC) 1.5 (1,10-Phen)(H 2 O)]·DMF} ( 3 ), and [Ln(2,5-TDC) 1.5 (1,10-Phen)]· x H 2 O (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 × 10 4 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 .