The present invention relates to a catalyst free method for the synthesis of a ligand for polymeric tri-dimensional porous network comprising reacting a. at least one amine of formula (VII), (VIII), (IX), (X) or (XIII), with b. at least one aromatic compound Ar of formula (XI) and (XII), particularly at least one aromatic compound Ar of formula (XI), yielding a linear ligand (LL) of formula (IV), a branched ligand (BL) of formula (V) or a tricyclic ligand (TL) of formula (VI). The invention further relates to a metal organic framework (MOF) comprising the general formula M-L, wherein M is a transition metal, particularly selected from Zr, Ti, Hf, Cu, Ni Mn, Fe, Al, Cr, Zn, Mg and Co, and L is a ligand of general formula (I), (II) and (III) and a ligand for polymeric tridimensional porous network, of formula (IV), (V) and (VI).