The stoichiometric reaction of copper(II) chloride with iminodiacetic acid (H2ida), and lanthanide(III) chloride in water yields the heteropolynuclear complexes [Ln2Cu3(ida)6]·xH2O. In this work, the synthesis and full characterization of those complexes with Ln=Ce, Ho is presented. The structures are based on [Cu(ida)2] building blocks, linked by the Ln ions via carboxylate bridges. The formation of nanochannels along the crystallographic c axis is verified. The comparison with analogous complexes containing other Ln ions, shows that the channels are perfectly tuneable in size along the series. These chemical systems were also investigated in solution (25.0°C, I=0.5M Me4NCl) by potentiometry. The same kind of polynuclear species have been found in aqueous solution.