[Cd₂((S,S)‑IBPhe)₂(2,2′-bipy)₂]·2H₂O and [Cd₂((R,R)‑IBPhe)₂(2,2′-bipy)₂]·2H₂O (IBPhe = Isophthaloyl-bis-phenylalanine): One-Dimensional Chiral Coordination Polymers with Selective Dye Adsorption

Two novel Cd-based noncentrosymmetric (NCS) chiral coordination polymers (CPs), [Cd₂((S,S)-IBPhe)₂(2,2′-bipy)₂]·2H₂O [Cd(S)] and [Cd₂((R,R)-IBPhe)₂(2,2′-bipy)₂]·2H₂O [Cd(R)] (IBPhe = isophthaloyl-bis-phenylalanine), have been synthesized through hydrothermal reactions. Cd(S) and Cd(R) crystallize in the monoclinic polar space group, P2₁ (No. 4), and exhibit rigid one-dimensional (1D) chain structures maintained by π–π interactions between organic ligands, as well as C–H···π interactions with adjacent chains. The solid-state photoluminescence data reveal intriguing blue light emission characterized by a phosphorescence decay time of about 0.41 ms, attributed to ligand-to-ligand charge transfer effects. Impressively, these Cd-based compounds exhibit a high degree of stability across various solvents and pH conditions. Furthermore, their exceptional adsorption capacities for Congo red are evidenced by maximum adsorption efficiencies of 850.82 mg/g for Cd(S) and 817.71 mg/g for Cd(R). These findings underline the potential of these NCS chiral coordination polymers for diverse applications ranging from efficient dye removal to enhanced photoluminescence.