A new 2D samarium compound Sm(2,4′-bpdc)(2,4′-Hbpdc)H 2O n ( 1) (2,4′-H 2bpdc = 2,4′-biphenyldicarboxylic acid) has been successfully constructed by the hydrothermal reaction of Sm 2O 3 with 2,4′-H 2bpdc, and characterized by elemental analysis, IR spectroscopy and thermogravimetric analysis, as well as single-crystal X-ray diffraction. The results reveal that complex 1 possesses a 2D framework with 4 4 topology constructed from one-dimensional lanthanide-carboxylate meso-helical chains Sm(O–C–O) 2 n ( Δ + Λ ) and (2,4′-bpdc 2−) 2 pillars; this complex represents the first example of a lanthanide compound containing 2,4′-biphenyldicarboxylate as the sole ligand. Moreover, compound 1 displays a certain photoluminescent property and high thermal stability. One new 2D framework with 4 4 topology constructed from one-dimensional lanthanide-carboxylate meso-helical chains Sm(O–C–O) 2 n ( Δ + Λ ) and (2,4′-bpdc 2−) 2 pillars, which represents the first example of a lanthanide complex possessing the ligand 2,4′-biphenylcarboxylate with different coordination modes. Display omitted ► A number of lanthanide metal–organic frameworks (LMOFs) with fascinating architecture have been synthesized via dicarboxylate ligands. ► However, few effort has been devoted to the investigation of transition/lanthanide-metal coordination chemistry involving 2,4′-biphenyldicarboxylic acid up to now. ► To the best of our knowledge, the compound Sm(2,4′-bpdc)(2,4′-Hbpdc)H 2On ( 1) (2,4′-H2bpdc = 2,4′-biphenyldicarboxylic acid) reported in the manuscript is the first example of the lanthanide coordination polymer containing single 2,4′-H2bpdc ligand.