Thermal Modulation of Coordination Geometry and Dimensionality in Cd(II) Frameworks from 3‐(1H‐1,2,4‐Triazol‐1‐yl)isophthalic Acid and 2,6‐Bis(1H‐imidazol‐1‐yl)pyridine Ligands

Three cadmium(II) coordination polymers were synthesized using 3,5‐bis(1H‐1,2,4‐triazol‐1‐yl)benzoic acid (H 3 bcpt) and 2,6‐bis(imidazol‐1‐yl)pyridine (biimpy) ligands under hydrothermal conditions with varying temperatures. Structural analysis revealed that increasing temperature led to a gradual evolution from a 1D chain (compound 1 ), to a 2D layer with dinuclear Cd units (compound 2 ), and finally to a robust 3D framework (compound 3 ). These transformations arise from changes in coordination geometry and ligand binding modes. All compounds exhibit enhanced solid‐state photoluminescence compared to the free ligands, with compound 3 showing the highest emission intensity at 398 nm. The emission enhancement correlates with increased structural rigidity and dimensionality, as well as π ··· π stacking interactions. Powder XRD and TGA confirm phase purity and thermal stability. This study demonstrates that hydrothermal temperature is an effective tool for tuning the structure and optical properties of Cd(II)‐based coordination materials.