4,4′-biphenylene spaced lipophilic bis-β-diketone ligands of the type 4,4′-bis(RC(O)CH2C(O))C12H8 (R = Pr, Ph, hexyl, octyl, nonyl) have been prepared and used for the liquid–liquid extraction of d-block metal ions. These ligands are expected to interact with divalent metal ions to form charge-neutral trinuclear metallocycles of type [M3(L3)3(solvent)] as has been demonstrated with the previously reported derivative of H2L3(R = tBu), the X-ray structure of which is reported. Liquid–liquid extraction studies were performed in a two-phase water/chloroform system employing a radiotracer technique for cobalt(II) and zinc(II). These experiments involved the systematic variation of ligand, metal and 4-ethylpyridine concentrations to probe the stoichiometries of the species extracted. Synergistic extraction was observed when 4-ethylpyridine was present with the ligand in the organic phase. Competitive extraction studies demonstrated the ligands are highly selective for copper(II) over cobalt(II), nickel(II), zinc(II) and cadmium(II).