The present invention generally relates to the fabrication of molecular electronics devices from molecular wires and Single Wall Nanotubes (SWNT). In one embodiment, the cutting of a SWNT is achieved by opening a window of small width by lithography patterning of a protective layer on top of the SWNT, followed by applying an oxygen plasma to the exposed SWNT portion. In another embodiment, the gap of a cut SWNT is reconnected by one or more difunctional molecules having appropriate lengths reacting to the functional groups on the cut SWNT ends to form covalent bonds. In another embodiment, the gap of a cut SWNT gap is filled with a self-assembled monolayer from derivatives of novel contorted hexabenzocoranenes. In yet another embodiment, a device based on molecular wire reconnecting a cut SWNT is used as a sensor to detect a biological binding event.