Abstract: The present invention relates to a molecular sensor for detecting the presence of a target analyte comprising a nitro-containing explosive molecule, the sensor comprising: a support substrate; a pair of electrodes comprising (i) a first electrode and (ii) a second electrode, wherein at least one of (i) and (ii) is at the substrate; an electron donor (ED) molecule capable of forming an electron donor-acceptor (EDA) complex with the nitro-containing explosive molecule; and wherein the ED molecule is disposed between the electrodes and is attached to each electrode by an alligator clip comprising a pendant group, thereby forming a nanojunction between the electrodes; a detection means operably connected to the pair of electrodes, the detection means capable of detecting a change in the electrical resistance or in the capacitance of the sensor when the ED molecule forms an EDA complex with the explosive molecule, the sensor thereby detecting the presence of the explosive molecule.