This study reports on the synthesis, structural characterization and gas sorption studies of a homometallic 2D Cd
2+ MOF and two heterometallic 3D Cd
2+/Ca
2+ and Cd
2+/Sr
2+ -MOFs based on the angular tetracarboxylic ligand 3,3′,4,4′-sulfonyltetracarboxylic acid (H
4STBA). The homometallic 2D Cd
2+ MOF with the formula [NH
2(CH
3)
2]
+2[Cd(STBA)]
2−n·nDMF·1.5nH
2O—(
1)
n·nDMF·1.5nH
2O was synthesized from the reaction of CdCl
2·H
2O and 3,3′,4,4′-diphthalic sulfonyl dianhydride (3,3′,4,4′-DPSDA) with stoichiometric ratio of 1:1.3 in DMF/H
2O (5/2 mL) at 100 °C. The two heterometallic Cd
2+/Ca
2+ and Cd
2+/Sr
2+ compounds were prepared from analogous reactions to this afforded (
1)
n·nDMF·1.5nH
2O with the difference that the reaction mixture also contained AE(NO
3)
2 (AE
2+ = Ca
2+ or Sr
2+) and, in particular, from the reaction of AE(NO
3)
2, CdCl
2·H
2O and 3,3′,4,4′-DPSDA with stoichiometric ratio 1:1.1:1.4 in DMF/H
2O (5/2 mL) at 100 °C. Notably, compounds [CdCa(STBA)(H
2O)
2]
n·0.5nDMF—(
2)
n·0.5nDMF and [CdSr(STBA)(H
2O)
2]
n·0.5nDMF—(
3)
n·0.5nDMF are the first heterometallic compounds M
n+/AE
2+ (M = any metal ion) reported containing ligand H
4STBA. The structure of (
1)
n·nDMF·1.5nH
2O comprises a 2D network based on helical 1D chain secondary building unit (SBU) [Cd
2+(STBA)
4−)]
2−. The 2D sheets are linked through hydrogen bonding interactions, giving rise to a pseudo-3D structure. On the other hand, compounds (
2)
n·1.5nH
2O and (
3)
n·1.5nH
2O display 3D microporous structures consisting of a helical 1D chain SBU [Cd
2+AE
2+(STBA)
4−)]. All three compounds contain rhombic channels along c axes. The three MOFs exhibit an appreciable thermal stability, up to 350–400 °C. Gas sorption measurements on activated materials (
2)
n and (
3)
n revealed moderate BET surface areas of 370 m
2/g and 343 m
2/g, respectively, along with CO
2 uptake capacity of 2.58 mmol/g at 273 K.
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