Guanine-rich oligonucleotides can form non-canonical secondary structures that are referred to as G-Quadruplex and are present not only in the telomeres but also in promotor regions of some oncogenes. Due to their biological relevance, G-Quadruplexes are attractive targets for small molecules design. The research presented in this thesis aimed (i) to design and synthesize for the first time a platinum(IV) salphen complex featuring two chlorides at the axial positions, which could be switched on/off upon reduction using bio-reducing agents, thus rendering a good G4 binder; (ii) to create a dyad system featuring a fluorescent NBD moiety and Ni salphen, in order to achieve fluorescence quenching of the NBD moiety in the absence of G-Quadruplex DNA, for an "on-off" effect; and (iii) to design a bimetallic complex, and to attempt its synthesis. The interaction between the metal complexes and G-quadruplex DNA was examined by means of circular dichroism (CD), fluorescence and UV-vis titrations.