Two new Mg(II)-based coordination polymers, {[Mg 3 (tci) 2 (DMAC) 4 ]·2DMF} n ( 1 ) and [Mg(bci)(H 2 O) 2 ] n ( 2 ) (H 3 tci = tris(2-carboxyethyl) isocyanurate, H 2 bci = bis(2-carboxyethyl) isocyanurate, DMAC = N,N′-dimethylacetamide, DMF = N,N′-dimethylformamide), were synthesized by using two similar flexible ligands with different number of arms, and characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis, X-ray powder diffraction and TGA. Complexes 1 and 2 exhibit a structure progression from a rare two-dimensional (2D) kgd sheet to a three-dimensional pillar-layer structure involving the layer of Mg(II)–carboxylate connected by bci 2 − ligands. The structure dissimilarity between them was dependent on the different number of arms of the two ligands. In addition, the solid state luminescent property and CO 2 adsorption of complex 1 were also investigated. [ABSTRACT FROM AUTHOR]