The influence of structural isomerism on fluorescence and organic dye selective adsorption in two complexes based on flexible ligands.

Based on Cd(NO3 )2 ·4H2 O and 4,4'-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid (H3 cpbda), two isomeric coordination polymers, {[Cd1.5 (cpbda)(bpa)(H2 O)2 ]·1.5H2 O}n (1), [Cd(H2 cpbda)2 (bpa)0.5 (H2 O)]n (2), were synthesized by using different solvent-systems. The complexes were characterized by single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction, and thermogravimetric analysis. Owing to the obvious structural difference between the two isomeric complexes, the further fluorescence sensing and dye selection and adsorption were investigated. The 3D tight stacking structure of 1 strengthened the fluorescence emission and the loose 2D layer structure of 2 generated the active selection and adsorption of the Malachite Green Oxalate (MGO) dye.