The crystalline sponge method, invented by the Fujita group at the University of Tokyo in 2013 allows to analyse the structure of non-crystallisable compounds by single-crystal X-ray diffraction through inclusion of them as guest molecules within a metal-organic framework. Since we assume that the ligands known to the literature do not produce cavities large enough to incorporate tetrazole-based iron(II) coordination complexes that act as spin-crossover materials and which we want to analyse with this method, the need for a novel ligands to build up the MOF arises. Therefore, novel ligands that supposedly increase the size of the cavities for the guests within the host structure were synthesised. Two out of four candidates where successfully produced. One of the two ligands formed a one-dimensional coordination polymer structure with ZnCl2. Crystal structures of the ligand and the coordination polymer were elucidated by single crystal X-ray diffraction.