Supramolecular chemistry deals with the association of several chemical species, in an organized way and according to well defined purposes. Based on a molecular engineering approach, supramolecular structures can be designed from pre-formed building blocks, providing a promising route from chemistry to molecular nanotechnology. New supramolecular systems have been assembled in our laboratory with the use of bridging unities such as tetrapyridylporphyrins, porphyrazines and polypyrazines, connecting transition metal complexes and clusters. These systems display a very exciting electrochemical and catalytic behavior, and interact with DNA, generating ¹O2 and leading to efficient oxidative clivage for photodynamic terapy applications. Molecular interfaces have been developed, exhibiting photocurrent response in the presence of visible-UV light, and rectifying properties in the presence of electroactive species. Successful applications of the supramolecular species in chemical and bio-sensors have been developed.