Computational and Spectroscopic Studies of the Pyrazoline Based Chemosensor for Mo⁶⁺ Detection

The present research work presents a novel fluorescence-based chemosensor (5R)-5-[4-(dimethylamino)phenyl]-3-(3-hydroxyphenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamide (DHPC) for the specific detection of Mo⁶⁺ ions. DHPC demonstrates a strong "turn-off" fluorescence response upon interaction with Mo⁶⁺ ions, enhanced by paramagnetic quenching processes. The sensor exhibits remarkable selectivity towards different metal ions (Al³⁺, Co²⁺, Ni²⁺, Hg²⁺, Cd²⁺, Pb²⁺, Mg²⁺, Cu²⁺, Sn²⁺, Ba²⁺, Zn²⁺, K⁺, Na⁺, Ca²⁺, and Mo⁶⁺), as confirmed by fluorescence and UV-Vis absorption spectroscopy. The determined limit of detection (LOD) is 1.74 μM which confirmed pyrazoline sensitivity. Density functional theory (DFT) analyses provide crucial understanding regarding the electrical properties of sensor, chemical interactions, and fluorescence quenching phenomena. This study advances the understanding of pyrazoline based fluorescence sensors, providing the entrance for greater metal ion sensing applications. The practical application was evaluated using water samples, including tap, mineral, and river water, exhibiting high recovery rates with no interference.