A set of new aluminium complexes of norfloxacin (NOR) and ciprofloxacin (CIP) that shows an improvement in their pharmaceutical properties were studied using solution and

solid state Nuclear Magnetic Resonance (NMR). The complexes synthesized with two different methods were compared. One of these methods will allow to formulate the compounds at production scale. High resolution 13C spectra were obtained with the cross

polarization and magic angle spinning (CP-MAS) experiment. These spectra were assigned by comparing with the solution data of the pure drug and by using a quaternary carbon edition technique. The proton relaxation times in the rotating frame, T1rH  were measured trough the 13C spectra for all the complexes. The 13C magnetization as a function of the variable time pulse is described by a two exponential decay, evidencing that the complexes are non-homogeneous. The short T1rH values are in the range 0.2-0.5 ms and the long values in the range 2-5 ms. 27Al MAS NMR spectra revealed an octahedral coordination between the aluminium ion and oxygens of pure drug, supporting a 3:1 ligand:metal stoichiometry in both CIP and NOR complexes.