In Situ "One-Pot" Construction of Luminescent Mixed-Ligand Cadmium-Based Coordination Polymers for Al³⁺ Ion Detection

As one of the most effective, powerful, yet technically challenging synthetic methods, the in situ "one-pot" approach is widely regarded as a promising strategy for constructing coordination polymers, as it eliminates the need for the time-consuming presynthesis of an organic ligand. Through the in situ formation of (E)-1-(3,5-di(1H-imidazol-1-yl)phenyl)-N-(4H-1,2,4-triazol-4-yl)methanimine (L) as the main ligand through the reaction between 3,5-di(1H-imidazol-1-yl)benzaldehyde and 4-amino-4H-1,2,4-triazole during the solvent thermal process, we present an in situ one-pot synthetic approach for constructing two mixed-ligand Cd(II)-based coordination polymers [Cd(L)(TDC)]_n (1) and {[Cd(L)(HBTC)]·DMF·0.5H₂O}_n (2) using 2,5-thiophene dicarboxylic acid (H₂TDC) and 1,3,5-benzenetricarboxylic acid (H₃BTC) as incorporated ligands, respectively (DMF: N,N-dimethylformamide). The luminescent properties of compounds 1 and 2 were explored. 1 and 2 exhibit high sensitivity and selectivity for the luminescence detection of Al³⁺ ions in comparison to other metal ions, with the detection limits of 0.59 μM for 1 and 0.66 μM for 2.