Four isomorphic two-dimensional (2D) homo-and heterometallic coordination polymers (CPs), [(CdxMn1-x)(3)(HEBTC)(2)(DMSO)(6)] with x = 1 (1), 1/3 (2), 0.5 (3), and 2/3 (4) were prepared by conventional one-pot self-assembly approach, using Cd2+ or mixtures of Cd2+ and Mn2+ with 1,1'-ethynebenzene-3,3',55'-tetracarboxylic (H4EBTC) under solvothermal conditions. The crystal structures of four isomorphic CPs are composed of center-symmetric trinuclear metal dusters building units linked by HEBTC3- ligands, extending into (3, 6)-connected topological 2D nets. Four CPs are isomorphic to the Mn-CP, [Mn-3(HEBTC)(2)(DMSO)(6)], we recently reported. The solid-state photoluminescence of 1-4 shows dual emissions at ambient condition, where the emission bands centered at ca. 390 and 562 nm in 1 are assigned to the fluorescence and phosphorescence within HEBTC3- ligand, respectively; however, the emission bands centered at around 397 and 470 nm in 2-4 are attributed to fluorescence, corresponding to electron transition within HEBTC3- ligand and MLCT transition between HEBTC3- ligand and Mn2+ ion. In addition, the origin of isomorphism between 1 and Mn-CP is also discussed.