Electronic devices shrunk to the molecular level exhibit quantum effects that lead to unique charge transport properties being completely unattainable at macroscopic scales. A better understanding of these phenomena is undoubtedly going to advance the field of molecular electronics. This project will focus on the synthesis of porphyrin-based molecular circuits (like rings, connected rings, and balls) on the size of several nano-meters and the study of their charge transport behaviour. Reporter units will be incorporated into the porphyrin circuits in the form of paramagnetic metals placed in well-defined positions and electron paramagnetic resonance spectroscopy will be used to probe the through-bond interactions between these metals as a measure for quantum interference. This will be achieved by determining the exchange interaction. Porphyrin circuits of different sizes and branching points will be synthesised and studied to probe the length dependence of coherent charge transport.